Mechanical Materials

MechanicalEngineeringDesign

MechanicalMaterials

Dirk Pons

Mechanical Materials Third Edition, 2011

This book gives propertiesfor various materials that areused in mechanical design.The intention is to givegeneral information on eachtype of material, with typicalstrength properties. Basicdescription of metallurgy isincluded where relevant,though the main focus of thebook is on design.

This material is provided under aCreative Commons license(AttributionNon-Commercial No Derivatives), seebelow for details. The Author[s] acceptno liability for the use or inability to usethe material in this book.

Published in New Zealand518 Hurunui Bluff RdHawardenNew Zealand

Copyright © Dirk Pons

About the AuthorDirk Pons PhD CPEngMIPENZ MPMI isprofessional EngineerTohunga Wetepangaa n d a C h a r te r e dProfessional Engineer inNew Zealand. Dirk is aSenior Lecturer at theUniversity of Canterbury,New Zealand. He holds aPhD in mechanicalengineering and amasters degree inbusiness leadership. TheA u t h o r w e l c o m e sc o m m e n t s a n ds u g g e s t i o n [email protected]

Mechanical properties of materials1 PHYSICAL PROPERTIES OF MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 IRON-CARBON METALLURGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.1 Manufacture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.2 Iron - Iron Carbide Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.3 Alloys of Iron and carbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.4 Strengthening of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.4.1 Strain Hardening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.4.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 WROUGHT ALLOY STEELS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133.1 General Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133.2 Steels to BS970 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163.3 Steels to AISI-SAE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233.4 Casting Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243.5 Structural Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 CAST IRON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 STAINLESS STEELS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.1 Ferritic Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315.1.1 Super Ferritic Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315.2 Martensitic Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335.3 Austenitic Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355.3.1 Heat Resisting Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375.3.2 Austenitic Stainless Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385.3.3 Cast Austenitic Stainless Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395.4 Duplex Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415.5 Precipitation Hardening Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425.6 Available forms of Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435.6.1 Stainless Steel Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435.6.2 Stainless Steel Tube and Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 455.6.3 Stainless Steel Plate and Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 475.6.4 Stainless Steel Fasteners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 485.7 Basic Metallurgy of Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 495.8 Colour Coding for Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 516 HIGH NICKEL AND SPECIAL ALLOYS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 527 ALUMINIUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557.1 Wrought Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557.2 Cast Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567.3 Heat Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567.4 Aluminium Finishes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577.5 General Physical Properties of Aluminium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577.6 Mechanical Properties of Aluminium Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577.7 Product sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 608 COPPER ALLOYS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 628.1 Mechanical Properties of Coppers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 628.2 Mechanical Properties of Copper Based Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . 639 POLYMERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 659.1 Linear and Cross Linked Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 659.2 Mechanical Properties of Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 669.3 Polymers for wear applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7310 ELASTOMERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7510.1 Rubber Sheeting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7510.2 Expanded Rubber and Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7511 OTHER MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7611.1 Human bone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Mechanical materials

4

Mechanical properties of materials

This chapter gives properties for various materials that are used in mechanicaldesign. The intention is to give general information on each type of material, withtypical strength properties. Basic description of metallurgy is included whererelevant.

1 PHYSICAL PROPERTIES OF MATERIALS

The following table gives some physical properties for general classes of materials.

Material ModulusofelasticityE [GPa]

Modulusof rigidityG [GPa]

Poisson’s ratio

DensityD[ kg.m-3]

Coefficientof thermalexpansion[10-6 /oC]

Thermalconductivity[W. m-1

.oC-1]

Specificheat [ J.kg-1. oC-

1]

Aluminiumalloys

72 27 0,32 2800 22 173 920

Berylliumcopper

127 50 0,29 8300 17 147 420

Brass,Bronze

110 41 0,33 8700 19 78 420

Copper 121 46 0,33 8900 17 381 420

Iron, greycast

103 41 0,26 7200 12 50 540

Iron,ductile

172 11-13 25-36 500-700

Magnesium alloys

45 17 0,35 1800 26 95 1170

Nickelalloys

207 79 0,30 8300 13 21 500

Steel,carbon

207 79 0,30 7850 12 47 460

Steel,alloy

207 79 0,30 7700 11 38 460

Stainlesssteel

190 73 0,30 7700 14 21 460

Titaniumalloy

114 43 0,33 4400 9 12 500

Zinc alloy 83 31 0,33 6600 27 111 460

Reference:JUVINALL R, MARSHEK K, 1991, Fundamentals of Machine Component Design, John Wiley.


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2 IRON-CARBON METALLURGY

The iron carbon alloys include, in order of increasing carbon content, pure iron, mild(low carbon) steels, high carbon steels, and cast irons.

2.1 Manufacture

Iron ore consists of iron oxides, with other elements. The ore is melted with coke(pure coal, ie carbon), which removes the oxide part as CO2. Limestone is added toseparate the rock part of the ore, which then floats off. The iron that is left is calledpig iron. It has a high carbon content (eg 10%) and many other impurities. Pig iron isnot particularly useful on its own, and is subsequently converted into either cast ironor steel.

M Cast iron is made by melting pig iron and adding coke, limestone and scrapiron to reduce the carbon content to around 3%.

M Steel is made by blowing oxygen over or through molten pig iron, whichremoves the carbon and impurities by oxidisation. Next the oxygen is removedby adding manganese, aluminium or silicon. Alternatively the steel may bemelted under a vacuum. After this stage the material is called commerciallypure iron, and it has a very low carbon content. The material is soft andunsuitable for structural use. Therefore carbon is re-added in a controlled way,to create steel.

Alloying elementsThe effects of the major elements in steels and cast iron are as follow:* Carbon strengthens iron by forming different crystal structures to pure iron.

Higher carbon content increases hardness, but reduces ductility.* Manganese removes oxygen during steel formation. Also promotes the

formation of pearlite.* Sulphur is a deoxidiser. It has the useful property of making the steel easier to

machine. However it can reduce high temperature ductility unless manganeseis present.

* Silicon is a major component in the ore, and is also added as a deoxidiser.The inclusions which remain in the steel cause weakness.

* Hydrogen is responsible for hair line cracks, also called hydrogenembrittlement. This can be a problem in forging and in steels used in space.Hydrogen is removed by melting the steel under a vacuum.


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Iron-iron carbide diagram

2.2 Iron - Iron Carbide Diagram

The iron - iron carbide diagram shows the phases (molecular lattice structure) ofvarious compositions of iron and carbon, and their temperature dependence. Thediagram is valid for slow cooling only, such that diffusion can occur even in the solidstates. Iron and carbon form an intermediate iron-carbide compound called

cementite, with composition Fe3C, at 6,7% mass Carbon. Higher carbon contents arenot of practical interest.

The top lines show the transformation of liquid to solid. Regions just below the toplines are where the material is partly molten and partly solid. Internal lines showchanges in crystal structure of the solid (called phase or polymorphic changes). Theimportant phases are ferrite and austenite. The upper region of delta phase is notsignificant in this discussion.


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2.3 Alloys of Iron and carbon

The main types of iron-carbon alloys are :

PURE IRONCommercial purity iron (not the same as cast iron which has a high carbon content)consists of only ferrite grains. Non-metallic inclusions may also be present betweenthe grains. Pure iron is not really used as a structural material.

MILD STEELFor example take a composition of 0,5% carbon, as shown on the diagram below. On cooling from the molten state, austenite starts to solidify in small nuclei. The solidgranules have a composition richer in Fe, and the remaining liquid is poorer in Fe.The exact compositions are given by drawing a horizontal line at the temperatureconcerned: where this line meets the boundaries represents the compositions. Asthe temperature drops, so the compositions change, by means of diffusion. Whenthe temperature intersects the solidus austenite line, then all the remaining liquidtransforms into austenite. The entire structure is now austenite, and if cooling is slowthen diffusion evens out the composition. At some temperature below 910oC, someof the austenite crystal structure changes to ferrite. On further cooling to below720oC the remaining austenite microstructure changes to ferrite and cementite,


8

which are in microscopic layers. This combination of ferrite and cementite is calledpearlite. The final state at room temperature is thus ferrite grains mixed with pearlite.

In practice the steels with more than 0,4% carbon are usually fast cooled rather thanslowly, and microstructure is different to that described above. This forms martensite,a hard material. If the nominal carbon content had been 0,83%C, then the final statewould be pearlite only.

HYPEREUTECTOID STEEL This is steel with a very high carbon content, between 0,83% and 1,7%. Forexample, follow the changes for a steel with 1,5% carbon. On cooling from themolten state, austenite starts to solidify. At the solidus line the remaining liquidsolidifies to austenite too. As the temperature drops further it leaves the pureaustenite region, and cementite starts to form. Just below 720oC, all the remainingaustenite changes to ferrite and cementite, which are layered together as pearlite.The final state at room temperature is thus cementite grains mixed with pearlite.Steels have a maximum of 1,7% Carbon. Higher carbon content materials are calledcast irons.

CAST IRONThe term “cast iron” makes most people think of pure iron. However cast iron is farfrom being pure iron: instead it contains very high carbon content. A typicalcomposition might be 3% carbon, as shown on the diagram below. On cooling fromthe molten state, austenite starts to solidify. Just above 1130oC, the remaining liquidhas the eutectic composition of 4,3% C. Further cooling results in the eutectic liquidsolidifying into austenite and cementite. Just below 720oC, all the austenite changesto ferrite and cementite (pearlite). The final state at room temperature is thuscementite grains mixed with pearlite. This is called white cast iron. Cementite isbrittle, and its high concentration in white cast iron makes this a weak material.


9

Cast irons have carbon contents of 2 to 5%. Melting temperature is lower than forsteels, as shown on the iron-iron carbide diagram. This makes the cast irons easierto cast than steels. Cast irons have a high content of cementite, which is brittle.However the cementite can be encouraged to decompose to ferrite and chunks ofcarbon. The several types of cast iron are distinguished by the state of thecementite.

2.4 Strengthening of materials

There are two ways of increasing the strength of a material. The one is by strainhardening, and the other is by heat treatment. The comments below apply tomaterials generally, but to steels in particular.

2.4.1 Strain Hardening

Strain hardening is plastic deformation of the material, which causes the yieldstrength to be increased (but ductility to decrease). The mechanism is thatdislocations are driven to their limits by the deformation, such that they are run upagainst barriers (eg grain boundaries, inclusions, carbides) and cannot move further.Dislocations are imperfections in the lattice structure of a material.


10

Strain hardening is also called cold work. It is usually applied during the rolling orextrusion of the material. It is an important hardening mechanism for pure materialswhich cannot be heat treated. Aluminium is a typical material that is routinely strainhardened. Strain hardening may be undone by annealing.

2.4.2 Heat Treatment

Heat treatment is the controlled heating and cooling of a material so as to changethe microstructure. There a number of terms which describe different aspects of thisprocess.

AnnealingIn this heat treatment the material is heated (but not melted), so that all the alloyingelements including precipitates are taken back into solution. Dislocations are alsosmoothened out by high temperature diffusion. Then the material is cooled slowly.Final mechanical properties are low strength but high ductility. Annealing is alsocalled solution heat treatment, or normalisation.

Low carbon steels are usually used in the normalised condition, since they arepractically impossible to harden. Medium carbon (mild) steels are usually used in thequenched and tempered condition. High carbon steels are used in the heat treatedcondition, that is quenched and controlled tempering.

Quench hardeningThis is a process whereby the high temperature microstructure is cooled so quicklythat it does not have time to change into the usual phase, but must instead go intoanother form. When austenite is cooled slowly, so that diffusion can occur, itchanges to ferrite and cementite. However this is suppressed if the austenite iscooled fast, and it changes suddenly into a different crystal structure calledmartensite. The microstructure of martensite is fine needles or plates. These finehard particles of Martensite strengthen a material by preventing dislocationmovement.

It is important to quench the austenite fast enough, otherwise diffusion will allowpearlite to form. This information is shown on a temperature-time-transformation(TTT) diagram. Steels with carbon contents less than 0,4% require very fast coolingrates to form martensite. The fast quench is very difficult with the thick sections oftenused in engineering. Increasing the carbon content (or other alloying elements, egNi) of the steel causes martensite to form at lower cooling rates, which are moreeasily obtained. For any given steel there exists a critical cooling rate, and the steelshould be cooled faster than this if martensite is required. Quenching is done inwater or oil. Water gives the faster quench.

The limiting ruling section of a steel is the maximum diameter of round bar that canbe heat treated successfully all the way through. Hardenability refers to the ease with


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which a steel may be fully quenched to martensite, and is typically measured by theJominy end-quench.

Martensite has high internal residual stresses, and a slightly larger volume than theaustenite. Furthermore there may be stresses due to the different cooling ratesbetween the inside and the surface. Consequently the material may crack duringquenching. Martensitic reactions occur in steels, and also many other metal alloys.

Martempering is a two stage quenching process, where the steel is cooled fast to atemperature just above that at which martensite starts to form (about 300oC). Thematerial is held at this temperature for a while, to relieve the stresses. After a fewminutes at this temperature, bainite would begin to form, but before that the steel isquenched again to form martensite.

TemperingMartensite is formed by rapid quenching, but thereafter a tempering heat treatment isusually applied. Tempering involves reheating the material (so that some of themartensite converts to other structures), and then slow cooling. The effect is toreduce the hardness and strength, but to increase the ductility. The temperingtemperature is less than the annealing temperature. The higher the temperature thegreater the ductility. For steels, tempering is usually done between 450oC and 650oC,and the material may be held at the temperature for an hour. The martensiteconverts into cementite and ferrite, in a fine microstructure called sorbite.

Tempering is not without problems, as brittleness can occur in the followingconditions:* Tempering steel between 250oC and 350oC causes loss of notch toughness,

called brittle tempering. The mechanism is that residual austenite converts tobainite, expanding in the process.

* Alloyed steels may also show temper brittleness if exposed to temperaturesbetween 550oC and 600oC. The materials should be cooled fast through thisdanger zone.

* Blue brittleness occurs in mild steels exposed to 300oC.

AustemperingUnder slow cooling, austenite would transform to pearlite. However under suitablecooling rates the austenite changes to bainite. This has the same composition aspearlite, but the microstructure is slightly different. The process of forming bainite iscalled austempering, and it is used in some steels.

AusformingThis is a special process for increasing strength of steels. It involves heating thematerial to the austenite phase, cooling to about 500oC, strain hardening (cold work),quenching to form martensite, and finally tempering.


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MaragingThis heat treatment can be applied to Iron-nickel alloys (no carbon). On slow coolingthe microstructure is martensite. When tempered at about 500oC for several hours,precipitates form, and these strengthen the material. This is also called precipitationhardening. The effect also occurs with aluminium alloys.


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3 WROUGHT ALLOY STEELS

Steel is one of the most familiar materials in mechanical engineering. This sectiondescribes the steels that are alloys of iron and carbon, together with small amountsof other elements. The other large group of steels are the stainless steels, and theseare left to the next chapter.

Design choicesThe designer has to specify a steel according to three basic parameters: * alloy composition * shape of section (eg round vs channel)* size (eg diameter)

In theory any grade of steel is available in any section at any size, providing that youare prepared to pay for it. In practice only certain commonly used combinations arereadily available. From the view of the designer, the easiest way to put some orderinto all the many combinations is to classify a steel according to one of the followingbasic applications:* Wrought steel in the form of round and rectangular bars. This material is used

to fabricate parts by metal removal processes (machining).* Casting steel, which is poured into moulds.* Structural steel, in various sections, is used for fabricating structures

(columns, beams etc). Sometimes these are large structures, like factories.* Flat products: strip, sheet, and plate.

Each of these categories may have its own particular favourite alloy compositions,shape and size combinations, and these are not usually available in the othercategories. The steels are described below according to these categories.

3.1 General Properties

HardnessHardness is used to check on heat treatment. It is also sometimes used todistinguish different steels, although chemical analysis is better for this(spectroscopic analysis is usually used). However mechanical designers usually findstrength properties more useful than hardness. Hardness is quicker, easier, and lessdestructive to measure than ultimate tensile strength, and therefore it is often used toestimate tensile strength. The relationship between Brinell hardness Hb and ultimatetensile strength Rm for steels is approximately as follows:


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Hardness equivalents

There are a number of measurements of hardness. Some hardness equivalents areshown in the table and figure below.

Brinell Vickers Rockwell C120o diamondcone with 150kg load

Rockwell B1/16" steel ballindenter with 100kg load

675598540

575350

401

494454430

474542


Brinell Vickers Rockwell C120o diamondcone with 150kg load

Rockwell B1/16" steel ballindenter with 100kg load

15

375352331311

389363339316

40373533

293277262

296279263

312926

248235223

248235223

242220

1029997

212202192

212202192

969492

183174166

183174166

908886

159153146

159153146

848280

140134128124

140134128124

78767371

Modified from Stainless steel buyers guide 1992, SASSDA, Johannesburg.

Physical propertiesTypical physical properties for steels are:

Density:Modulus of Elasticity:Torsion modulus of elasticity:Specific heat capacity:Thermal conductivity:Coefficient of thermal expansion:

7870 kg/m3

200 GPa65 GPa455 J/(kg.oC)70 W/(m.oC) at 300oC13 :m/(m.oC) between 0oC and 300oC

Source: Stainless steel buyers guide 1992, SASSDA, Johannesburg.


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3.2 Steels to BS970

There are many name systems for steels, and several are in use. Some of the mainsystems are the British (BS), the German (DIN) and the American (ASME).

The system of an En number for each steel is an old British one, which was widelyused. It is now obsolete, but remnants of it may still be found. It has largely beenreplaced with the new British standard, as follows.

Steels are classified according to BS 970, as xxxAyy, where:xxx Plain carbon steels and carbon manganese steels use 000 to 199, which is

100x the Mn content.Free cutting steels use 200 to 240, where the xx of 2xx is 100x the sulphurcontent.Direct hardening alloy steels, including alloy steels capable of surfacehardening by nitriding, 500 to 999.Stainless steels use 300 to 449

A Supply requirements:A Analysis (some spring steels)H Hardenability (some spring steels)M Mechanical propertiesS Stainless steel (wrought)C Stainless steel (cast)

yy Represents 100x carbon content for the carbon steels, otherwise arbitrary.

Abbreviations are as follow.

SYMBOLS DESCRIPTION

Rm

Re

Rp0.2

Rf

HBHVHRC

tensile strength yield strengthproof strength uncorrected fatigue strengthBrinell hardnessVickers hardnessRockwell hardness, C scale


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Tensile strength rangesReference symbols that are used for the condition or tensile ranges of hardenedsteel are:

Symbol Tensile Strength

Range [MPa]

Hardness

range, BrinellHB

P 540 - 695

Q 617 - 772 179-229

R 695 - 850 201-255

S 772 - 927 223-277

T 850 - 1004 248-302

U 926 - 1081 269-331

V 1004 - 1158 293-352

W 1081 - 1235 311-375

X 1158 - 1313

Y 1235 - 1390

Z 1544 min

The same letters always represent the same lower limit of the tensile range. In orderto get a particular steel to a given condition, it will be necessary to follow a particularheat treatment procedure. These procedures and the milestone temperatures aregiven in the standards. These details are not included here. From a designperspective it is important to note that the composition determines the hardenability,and that not every tensile strength range can be attained by a given steel.

Most of the steel alloys listed in the tables are available in the form of round bar. A(limited) range of diameters will be available from any one supplier. Typicalapplications for the better alloys are for shafts and for relatively small machine parts,and the round section is usually suitable. Some of the grades for which there issufficient demand may also be available in other sections, such as rectangular. Thedesigner may have a choice of condition within the round sections, between "asrolled" (also called "black") and "bright bar". The former has scale on it from the hotrolling process and this gives it a dark grey appearance. "Bright bar" looks shinysince this scale has been removed, and the bar has been gauged (eg to h11). "Brightbar" may be sufficiently accurate for use in less critical machine parts, but not "asrolled" bar. Note that the B designation after some of the old En numbers does notrefer to the bright condition but to the alloy composition.


18

PLAIN CARBON STEELSThe lower carbon grades, up to 0,20% (xxxM20) are used for cold formed products,rivets, stampings, machine parts. They can be carburised. Carbon contents up to0,4% (xxxM40) give stronger steels (l\although with less ductility), which are suitablefor shafts, gears, forged parts. They can be carburised, and heat treatment is alsopossible.

Designation Condition Rm Tensilestrength[MPa]

Re Yieldstrength[MPa]

Elong-ation Other propertiesE: Elastic Mod.[MPa]J: Mod. Rigidity[MPa]

Comments

070M20 normalisedP

400 200355

21% En3A, 3C

070M26 normalisedPQ

216355417

20%

080M30 normalisedPQ

231340417

19% En5

080M36 normalisedQR

247401463

18%

080M40 normalisedQR

510 247386463

17% En8

080M46 normalisedQRS

278370448525

15%

080M50 normalisedRST

278432494571

14% En43A


600 309417478571

13% En9

120M19 normalisedPQR

262355448510

19% En14A


293340432510

17% En14A

120M28 normalisedQR

309417510

17% En14B




Elong-ation Other propertiesE: Elastic Mod.[MPa]J: Mod. Rigidity[MPa]

Comments

19


324401479571

16% En14B


340417510571

16% En15B


355401324556

15% En15

PLAIN CARBON STEELS: FREE CUTTING STEELSThese steels are alloyed to provide greater ease of machinability. Otherwiseincreasing strength generally means greater difficulty of machining.



Elong-ation

Other propertiesE: Elastic Mod.[MPa]J: Mod. Rigidity[MPa]

Comments

216M28 normalisedPQ

-355432

En8M


-340401494

225M36 normalisedQR

-401479


-340401479


-401463540


-448525602

220M07 normalised 360 215 En 1A


20

DIRECT HARDENING ALLOY STEELSIncluding alloy steels capable of surface hardening by nitriding, designation 500 to999.



Elong-ation


Comments

503M30 QRS

432525587

17%1715

503M40 = En12

526M60 TV

617741

En11

530M40 RST

525587680

En18

605M30 RSTUV

525587680757849

605M36 R 494 En16

606M36 RST

525587680

En16M

608M38 RSTUV

494556680757849

En17

640M40 RSTU

525556680757

En111

653M31 STU

556680757

En23

708M40 RSTU

525556680757

En19A

709M40 RSTUV

494556680757850

En19

722M24 T 680 suitable for nitriding,En40B

785M19 Q 448 En13




Elong-ation


Comments

21

816M40 STUV

556680757850

En110

817M40 TUVWXZ

64975785094210191235

En24

823M30 TUVWXZ

64974185094210191235

En24

816M40 STUV

556680757850

En110

817M40 TUVWXZ

64975785094210191235

En24

823M30 TUVWXZ

64974185094210191235

En24

826M31 TUVWXZ

64974185094210191235

En25

826M40 UVWXYZ

741833927101910971235

En26

830M31 TUVW

649757850942

En27

835M30 Z 1235 En30B

897M39 Z 1235 suitable for nitriding,En40C

905M31 RS

525587

suitable for nitriding,En41A




Elong-ation


Comments

22

905M39 RST

525587680

suitable for nitriding,En41B

945M38 RSTUV

494587680757850

suitable for nitriding,En100

STEELS FOR CASE HARDENING



Elong-ation


Comments

523M15 quenched 618 13% En206

527M20 quenched 772 12% En207

635M15 quenched 772 12% En351

637M17 quenched 927 10% En352

655M13 quenched 1004 9% En36A

659M15 quenched 1313 8% En39A

665M17 quenched 772 12% En34

665M20 quenched 850 11% En34

665M23 quenched 927 10% En35

805M17 quenched 772 12% En361

805M20 quenched 850 11% En362

805M22 quenched 927 10% En363

805M25 quenched 1004 9% En363

815M17 quenched 1081 8% En353

820M17 quenched 1158 8% En354

822M17 quenched 1313 8% En355

832M13 quenched 1081 8%

835M15 quenched 1313 8% En39B

045M10 quenched 432 18%

080M15 quenched 463 16%

210M15 quenched 463 16%

130M15 quenched 649 14%


23

214M15 quenched 649 12%

3.3 Steels to AISI-SAE

The American steel naming system has four (or five) digits. The first digit is for themain alloying element (1 carbon, 2 nickel, 3 Ni + Cr, ...), the second digit is thepercentage of that alloying element, and the last two (or three) digits give 100 timesthe carbon content.

10xx plain carbon11xx free cutting, with sulphur12xx free cutting, with sulphur and

phosphor13xx manganese up to 1,9%23xx nickel 3,5%25xx nickel 5 %31xx nickel 1,25% chromium 0,6%32xx nickel 1,75% chromium 1,0%33xx nickel 3,5% chromium 1,5 %34xx nickel 3,0% chromium 0,8 %303xx corrosion and heat resisting40xx molybdenum 0,25%41xx molybdenum 0,20%, chromium

1%43xx molybdenum 0,23%, chromium

0,8%, nickel 1,8%46xx molybdenum 0,25%, nickel

1,75%51xx chromium 0,8%514xx corrosion and heat resisting515xx corrosion and heat resisting52xx chromium 1,5%61xx chromium 0,78%, vanadium

0,13%86xx nickel, chromium, molybdenum92xx manganese, silicon93xx nickel, chromium, molybdenum

In front of the number is placed a letter, whichspecifies how the steel is to be produced:A basic open hearth alloy steelB acid Bessemer carbon steelC basic open hearth carbon steelD acid open hearth carbon steelE electric furnace steel (carbon or alloy)

If there is no prefix, then it is taken to be C.

If letters B or L appear in the middle of the steel’snumber, then this shows that Boron or Lead havebeen included.

Suffix letters (after the number) refer tospecifications for:A analysis (chemical composition)H hardenability


24



Elong-ation


Comments

1002 A 290 131

1010A 303 200

1018A 341 221

1020HR 455 290

1045 HR 638 414

1212 HR 424 193

4340 HR 1041 910

52100A 1151 903

Carburising steels

1015 503 317 32 HB 149

1022 565 324 27 HB 163

1117 662 407 23 HB 192

1118 779 524 17 HB 229

4320 1006 648 22 HB 293

4620 793 531 22 HB 235

8620 896 531 22 HB 262

E9310 1165 952 15 HB 352

Reference: JUVINALL R, MARSHEK K, 1983, Fundamentals of Machine Component Design. John Wiley.

3.4 Casting Steel

Foundries have stock of certain grades of steel, and may also be able to castproprietary alloy compositions. No data are given here for cast steels as there is alarge choice of materials, many of them proprietary. Remember that ductile iron is aserious contender for casting, with mechanical properties in many cases better thancast steels.

3.5 Structural Steel

Structural steel is pre-formed steel used for the fabrication of structures. Oneapplication is in buildings (typically factories and warehouses), for which the steelframework is constructed (fastened or welded) on a concrete foundation and coveredwith cladding (steel, aluminium or other sheets, usually with some profile). Internalarchitecture may also be made from structural steel. Another application is the


25

fabrication of bases for machines. There are several types of section used forstructural purposes. * hot rolled sections include angles, channels, H and I sections, plates, flats,

squares and rounds. These tend to be relatively thicker than the othersections.

* cold formed sections. These include various angles, C and S shapes. Theyhave uniform thickness throughout, being made from sheet material. Lips aretypically provided at the edges.

* hollow sections, including round, square and rectangular tubes. These arefabricated by rolling and welding processes, and may have an internal seam.

* plate and sheet

There are several standards to which structural steel is produced. Differentstructures are produced in different standards. For applications where mechanicalproperties are non-critical, steel may be ordered as “commercial” or "mild steel".Geometry and Material properties are given in a separate chapter.


26

4 CAST IRON

Cast irons are available in a number of types: white, grey, malleable, ductile (alsocalled nodular, or spheroidal graphite), and austenitic. See the section on the ironcarbide diagram for details of the metallurgy of the cast irons.

White cast ironThe microstructure at room temperature is cementite mixed with pearlite. White castiron is brittle, but hard and wear resistant. The material is not usually used on its ownin castings. A typical use is to form a hard surface layer on a casting. This is done byplacing metal chill plates in the mould, next to which white cast iron will form, whilethe rest of the casting will be in the grey cast iron state. White cast iron may betransformed to malleable cast iron.

Grey cast ironThis cast iron contains silicon, which causes the cementite to change into ferrite(pure iron) and graphite flakes. The graphite flakes make the material softer, easierto machine, and somewhat sound absorbent. However the tensile strength isrelatively low. There a several forms of grey cast iron, with different degree ofdissociation of the cementite* pearlitic grey cast iron: the cementite in the pearlite is left as it is, but that in

the primary grains of cementite is converted* ferritic grey cast iron: all the cementite, in the pearlite and the primary grains

of cementite, is convertedGrey cast iron may be heat treated to change the structure from pearlitic to ferritic orthe other way. Heat treatment is also used to remove residual stresses (at about620oC), for annealing and hardening. Small amounts of phosphorus lower thefreezing temperature, giving fluidity in casting, and less shrinkage.

Malleable cast ironThis is a white cast iron that is heat treated to change the microstructure. White castiron is heated to about 850oC for several days, during which the cementite changesto ferrite and blobs of carbon. This gives ductility. A variant is to create pearliteinstead of ferrite. The carbon can also be oxidised out of the surface layer to createwhiteheart cast iron.

Ductile iron This has spheres of carbon in ferrite or pearlite, like malleable cast iron. Howeverthis state is created during solidification (by adding magnesium) rather than by heattreatment. This is a major advantage to the foundry. Other names are nodular castiron, and spheroidal graphite cast iron. The material has relatively high strength andductility. As cast the matrix around the carbon will be pearlite, but this can be heattreated into ferrite or martensite. The material is widely used for engineeringcomponents, even those that are relatively highly stressed, eg crankshafts, gears,


27

brake drums, machine parts. Larger wall thicknesses are possible than withmalleable iron.

Austenitic cast ironThese materials contain alloying elements that allow austenite to exist down to roomtemperatures (instead of changing into pearlite). Corrosion resistance is good.

Mechanical properties follow.

Designation Condition Rm

Tensilestrength[MPa]

Re Yieldstrength[MPa] or0,2%proof

Elong-ation

OtherpropertiesE: ElasticMod. [GPa]J: Mod.Rigidity[GPa]

Comments

WHITE CAST IRONS

2,75% C 250 - 300 0 400-550HB.Hard, brittle,used for wearresistantsurfaces

3,25% C 300-450 0

GREY CAST IRON

3,25%C ascast

150-250 100-200 0,5 180-240 HBCommonusage

3,25%Cannealed

125-200 85-140 0,5-1,0

100-150 MB

2,75% 300-400 200-275 0,5 210-320HB

–

UltimateCompressivestrength[MPa]

–

Ultimate shearstrength[MPa]

ASTM 20 152 572 179 E 66-97J 27-39

HB156.Endurance 69MPa. Soft ironcastings

ASTM 25 179 669 220 E 79 - 102J 32 - 41

HB 174.Endurance 79MPa..Housings, ICengine blocks

ASTM 30 214 752 276 E 90 - 113J 36 - 45

HB 210.Endurance 97MPa. Brakedrums

ASTM 35 252 855 334 E 100-119J 40 - 48

HB 212.Endurance110 MPa.Brake drums





Elong-ation


Comments

28

ASTM 40 293 965 393 E110 - 138J 44 - 54

HB 235.Endurance128 MPa.Cylinderliners,camshafts

ASTM 50 362 1130 503 E 130-157J 50 - 55

HB 262.Endurance148 MPa.High strength

ASTM 60 431 1293 610 E 141-162J 54 - 59

HB 302.Endurance169 MPa .High strength

• •

MALLEABLE CAST IRON

2,5%Cblackheart

350-400 260-300 10-20 110-140HBBlack & whiteused forengineeringparts, vehiclecastings

2,5%Cwhiteheart

400-450 280-320 5-20 120-220HB

DUCTILE IRON

SABS 936/937 (1970)

SABSSG38

375 245 17 E: 172 HB180Endurancelimit 0,55xRm

SABSSG42

410 275 12 E: 172 HB200Endurancelimit 0,54xRm

SABSSG50

490 345 7 E: 172 HB170-240Endurancelimit 0,49xRm

SABSSG60


SABSSG70


SABSSG80


International standard ISO 1086 (1976)





Elong-ation


Comments

29

ISO 800-2 800 480 2

ISO 700-2 700 420 2

ISO 600-3 600 370 3

ISO 500-7 500 320 7

ISO 400-12 400 250 12

ISO 370-17 370 230 17

German standard DIN 1693

GGG-40 400 250 15

GGG-50 500 320 7

GGG-60 600 380 3

GGG-70 700 440 4

GGG-80 800 500 2

GGG-35,3 350 220 22

GGG-40,3 400 250 18

References: JUVINALL R, MARSHEK K, 1991, Fundamentals of Machine Component Design, John Wiley.KARSAY SI, Ductile iron castings, Ferrous Casting Centre PO Box 785711 Sandton 2146 South Africa.


30

A common misconception is thatstainless steels are non-magnetic. Infact only the austenitic 300 seriesalloys are non-magnetic.

An excellent South African reference on all stainlesssteel matters is the Southern Africa Stainless SteelDevelopment Association (SASSDA), whichproduces technical literature and an annual supplierguide on behalf of the industry. Their address is POBox 4479, RIVONIA 2128. Telephone (011) 803-5610.

5 STAINLESS STEELS

A stainless steel is a ferrous steel with at least 11% chromium. The materials havegood corrosion resistance because a layer of chrome oxide naturally forms on theexposed surfaces, and prevents further corrosion. If this passive layer is damaged,then a new layer forms. However corrosion will occur if the passive layers areremoved continuously, or prevented from forming.

There is a common belief that stainlesssteels are much stronger than carbonsteels. This is generally wrong: the ordinarystainless steels have mechanical propertieswhich are similar and even less than thosefor ordinary carbon steels. Designersusually use stainless steels not so much forstrength but for corrosion resistance.

The designations used for wrought steels generally follow the USA AISI system,which is basically similar to the British and Canadian. The German DIN system hasmore limited use. Cast stainless steels follow the USA ASTM system, which differsfrom the British.

SYMBOLSRm ultimate tensile strength Re yield strengthRp0.2 proof strength Rf uncorrected fatigue

(endurance) strengthHB Brinell hardnessHV Vickers hardnessHRC Rockwell hardness, C scaleNote (1): Q denotes quenching, T tempering,

P,R,S,T refer to strength range as per conventional steelsNote (2): The AISI steels are sometimes not used for casting.


31

5.1 Ferritic Stainless Steels

These are the conventional ferritic stainless steels.

Composition: Chromium eg 18%, no nickel, low carbon

Properties: Magnetic, non hardenable, poor welding (TIG may be best), moderatecorrosion resistance, low hardness, medium strength, good ductility,moderate impact resistance, good scaling resistance, medium strengthat elevated temperatures

Forms: Available in sheet, coil, tube, plate. Generally thin gauge material, up toplates in the case of 3Cr12.

Applications: Sinks, architectural trim, conveyors, fume extractors. Usually used ascorrosion resistance sheet.

Common grades: 3Cr12, 430. Always used in annealed condition.

Description Designation Condition(1)

Rm

[MPa]Re

[MPa]Elong-ation[%]

Otherproperties

Comments

FERRITIC STAINLESS STEELS

3Cr12 weldable (MMA, MIG,TIG) with 309L filler

AISIwrought

403 softened 415 280 20 170 HBN 13Cr 0,12C

AISIwrought

430 softened 430 280 20 170 HBN276 MPafatigue

general purpose17Cr

5.1.1 Super Ferritic Stainless Steels

These steels substitute for austenitic stainless steels where stress corrosion cracking(SCC) and pitting are problems.

Composition: Chromium 18%, molybdenum 2% (or 26/1)

Properties: Resist pitting and stress corrosion cracking, properties similar to ferritic.Poor weldability.

Forms: Available as sheet, tube.


32

Applications: Sheet products: heater panels, solar heaters, heat exchanger tubing.Welded products are made from thichnesses less than about 5mm.

Common grades: Common grades 444. Proprietary alloys are also available.

The family of Ferritic stainless steels, and their derivatives consists of the following. The main characteristic or niche application of each alloy is given.430 general purpose446 scaling resistance442 scaling resistance444 SCC resistance429 weldability405 resistant to hardening409 automotive exhausts430F machinability430FSe machine texture434 auto trim436 heat and corrosion resistance

Physical propertiesTypical physical properties for select steels are:

430 3Cr12 444 409

Density [kg/m3] 7800 7700 7800 7800

Modulus of Elasticity [GPa] 200 207 200

Torsion modulus of elasticity[GPa]

65 -

Max continuous temperature[oC]

750 600

Specific heat capacity [J/(kg.oC)] 460 460

Thermal conductivity [W/(m.oC)at 300oC]

23 (24)

Coefficient of thermal expansion[:m/(m.oC) between 0oC and300oC]

11 11,3 10,6 (11,7)



33

5.2 Martensitic Stainless Steels

There is only one group of martensitic stainless steels. All the other stainless steelshave low carbon, except the martensitic group. Here the carbon is used to givehardenability through the formation of martensite.Composition: Chromium eg 18%, high carbon,

Properties: Hardenable, poor welding, moderate corrosion resistance, magnetic,medium to high strength, good to fair ductility, moderate to poor impactresistance, fair scaling resistance, medium strength at elevatedtemperatures

Forms: Available in bar and strip.

Applications: Heat treatment is used to control strength and hardness: eg for blades,shafts, springs, cutlery

Common grades: Common alloys are 410, 420, 431.The family of Martensitic stainless steels, and their derivatives consists of thefollowing. The main characteristic or niche application of each alloy is shown.410 general purpose414 corrosion resistance431 corrosion resistance422 mechanical properties at higher temperatures403 turbine parts420 mechanical properties420F machinability416 machinability416Se machined texture440C hardness440B toughness440A additional toughness


34


Rm

[MPa]Re

[MPa]Elong-ation[%]

Otherproperties

Comments

MARTENSITIC STAINLESS STEELS

AISIwrought

410 Q&T P 540-695

370 20 152-207HBN

13Cr 0,12C

AISIwrought

420 Q&T RQ&T S

695-850850-925

525585

1513

201-255HBN223-277HBN

AISIwrought

420 Q&T RQ&T S

695-850850-925

525585

1513

201-255HBN223-277HBN

AISIwrought

416 Q&T RQ&T S

695-850850-925

525585

1110

201-255HBN223-277HBN

AISIwrought

431 Q&T T 925-1000

680 11 248-302HBN

AISIwrought

441 Q&T T 925-1000

680 11 248-302HBN

ASTM cast CA-15 annealed 620 450 18 170-240 Equivalent to AISI 410.Rotor blades, pumps,valves

ASTM cast CA-40 annealed 690 485 15 Equivalent to BS420C29

ASTM cast CB-30 annealed 450 205 - Equivalent to DINX-22CrNi17

ASTM cast CB-7Cu quenched - - - Equivalent to 17-4PH.Pistons, valve seats,.

ASTM cast CA-6NM annealed 760 550 15 220 Equivalent to BS425C11.Water turbine casings.

ASTM cast CC-50 annealed 880 - - Equivalent to BS452C11.Construction parts.


35


410 416 420 431

Density [kg/m3] 7800 7800 7800 7800

Modulus of Elasticity[GPa]

200 200 200 200

Torsion modulus ofelasticity [GPa]

Max continuoustemperature [oC]

Specific heat capacity[J/(kg.oC)]

Thermal conductivity[W/(m.oC) at 300oC]

Coefficient of thermalexpansion [:m/(m.oC)between 0oC and300oC]

11,4 11,0 10,8 11,0


5.3 Austenitic Stainless Steels

The conventional austenitic stainless steels are a large group. All the austeniticsteels contain chromium and nickel.

Composition: Chromium 18%, nickel 8%, low carbon <0,08%. Molybdenummay be added (2-3%) for additional corrosion resistance. Lowcarbon grades (max 0,03% C) are denoted by L. Ti or Nb maybe used as stabilisers

Properties: Excellent corrosion resistance, easily weldable (MMA, MIG, TIG,SAW), cold work hardenable, good cryogenic prop, easilycleananable, tolerates up to 925oC. Non-magnetic when in fullyannealed condition, low hardness, medium strength, excellent togood ductility, excellent impact resistance, excellent scalingresistance, high strength at elevated temperaturesBUT don't like acids or halide ions (Cl)

Forms: Available as strip, coil, plate, sheet, tube, rod, wire.


36

Applications: Widely used in food processes, cryogenic, chemical processes.high temperature heat exchangers, low temperature gasstorage. Often cold worked, which increases strength butdecreases ductility.

Common grades: Common grades 304, 316.


Rm

[MPa]Re

[MPa]Elong-ation[%]

Otherproperties

Comments

AUSTENITIC STAINLESS STEELS

AISIwrought

304 & 304L softened 465 170 40 183 HBN 241 MPa fatigue. Used infasteners, grade DINK18-8. 18Cr 10Ni 0,06C(L: 0,03C)

AISIwrought

312 softened 495 195 40 183 HBN

AISIwrought

316 & 316L softened 465 170 40 183 HBN 269 MPa fatigue. Used infasteners, grade DINK18-8-2. 17Cr 11Ni2,5Mo 0,07C (L: 0,03C)

AISIwrought

317 softened 465 170 40 183 HBN 18Cr 13Ni 3,5Mo

AISIwrought

303 softened 510 210 40 183 HBN


37

5.3.1 Heat Resisting Stainless Steels

This is a special group of austenitic stainless steels, suitable for higher temperatureduty (up to 1100oC).

Composition: High chromium 24%, nickel eg 20%,

Properties: Resist oxidisation at high temps, good hi temp strength

Forms: Available as plate

Applications: Typically furnace parts.

Common grades: Common grades 309, 310.


Rm

[MPa]Re

[MPa]Elong-ation[%]

Otherproperties

Comments

HEAT RESISTING STEELS

cast (2) 309 515 240 10 23Cr 14Ni

AISIwrought

310 softened 540 215 40 207 HBN 217 MPa fatigue. 24Cr 20Ni


38

5.3.2 Austenitic Stainless Alloys

This is another group of special austenitic stainless steels. The steels are highlyalloyed, giving greater corrosion resistance than the conventional austenitics.

Composition: Chromium 20-27%, nickel 25-42%, molybdenum 3-6%, lowcarbon, highly alloyed Fe< 50%

Properties: Properties as for austenitic ss, weldable, resist pitting corrosion& SCC

Forms: Available as sheet, plate, tube.

Applications: Generally for high corrosion resistance, eg petrochemical industries.

Common grades: Proprietary alloys


Rm

[MPa]Re

[MPa]Elong-ation[%]

Otherproperties

Comments

AUSTENITIC STAINLESS ALLOYS

DIN G-NiMo30

negotiable 495 320 6

DIN G-NiMo16CrW

negotiable 495 320 40

DINNiCr15Fe

as cast 485 195 30

The family of Austenitic stainless steels, and their derivatives consists of the following. The maincharacteristic or niche application of each alloy is given.302 general purpose302B scaling resistance202 general purpose205 less Ni201 less Ni304 corrosion resistance304L resists sensitization by low

carbon304N mechanical properties304LN mechanical properties308 welding material321 resists sensitization by Ti347 resists sensitization by Ta and

Nb348 limited Co and Ta for nuclear

use316 corrosion resistance

316L resists sensitization by lowcarbon

316LN mechanical properties 316F machinability


39

316N strength317 corrosion resistance317L resists sensitization by low

carbon309 heat resistance, 309S similar310 more heat resistance, 310S

similar314 even more heat resistance329 resists SCC330 resists thermal shock305 reduced work hardening384 less work hardening301 reduced work hardening303 machinability303Se surface texture


304 310 316 321

Density [kg/m3] 7900 7900 8000 7900

Modulus of Elasticity [GPa] 195 205 195 195


85 70 70 72


925 1150 925 950

Specific heat capacity [J/(kg.oC)] 503 503 503 503


17,4 15,2 16,4 (18)


17,8 16,5 17,5 17,8


5.3.3 Cast Austenitic Stainless Alloys

Stainless steels may be cast, but a remelted bar of say 316, will not show the samemechanical properties of the original wrought material. In order to get the mechanicalproperties of a particular wrought steel ina casting, it is necessary to change thecomposition. There is an AISI designation for cast stainless steels. However (inSouth Africa) the cast steels rather follow the ASTM system.

Composition: Chromium 20-27%, nickel 25-42%, molybdenum 3-6%, lowcarbon, highly alloyed Fe< 50%


40

Properties: Properties as for austenitic ss, weldable, resist pitting corrosion& SCC

Forms: Available as sheet, plate, tube.

Applications: Generally for high corrosion resistance, eg petrochemicalindustries.


Rm

[MPa]Re

[MPa]Elong-ation[%]

Otherproperties

Comments

CAST AUSTENITIC STAINLESS STEELS

ASTMA743

CF-8 quenched 450 195 35 130-200HB

pumps, stirrers

ASTM CF-8M quenched 485 205 30 130-200HB

ASTM CF-3 quenched 450 195 35

ASTM CF-3M quenched 485 205 30

ASTM CG-8M quenched 520 240 25 130-200HB

chloride resistance

ASTM CN-7M quenched 430 170 35 130-200HB

sulphuric acid resistance

ASTMA297

HH as cast 515 240 10 chain links, furnace parts

ASTM HK as cast 450 240 10

ASTM HT as cast 450 - 4 furnace parts

ASTM HU as cast 450 - 4

ASTM HX as cast - - - furnace parts, grates

ASTM HC as cast 380 - - furnace nozzles

ASTM HD as cast 515 240 8 screw conveyors


41

5.4 Duplex Stainless Steels

These stainless steels are hybrids of the austenitic and ferritic stainless steels. Theyhave a mixed ferritic/austenitic (i.e. duplex) structure.

Composition: Chromium 18-26%, nickel 5-7%, molybdenum 3%Properties: Highly resist SCC, high strength, good weldabilityForms: Available as plate, sheet, tube.Applications: Heat exchanger, vessels (especially Chlorides)Common grades: Proprietary alloys


Rm

[MPa]Re

[MPa]Elong-ation[%]

Otherproperties

Comments

DUPLEX STAINLESS STEELS

cast DINX2CrNiMoN22.5

annealed 680 450 30

cast ASTM CD-4MCu orDINX8CrNiMo27.5

quenched 689 483 16 190-230HBN


DIN X2CrNiMoN22.5

Density [kg/m3] 6800

Modulus of Elasticity [GPa] na


na


na

Specific heat capacity [J/(kg.oC)] na


na


na


42

5.5 Precipitation Hardening Stainless Steels

These are stainless steels that produce a microscopic precipitate on aging. Thisprecipitate strengthens the material. The aging heat treatment determines themechanical properties.

Composition: 15,5% Chromium, 3% Ni, max 0,07% Carbon, plus otherelements

Properties: Hardenable, weldable, good corrosion resistance (similar to304), high strength, good impact resistance, resists SCC

Forms: Available in forged bar (round, hexagonal, square) and forgings.

Applications: Can be forged or cast. Machinable before and after agehardening. Marine applications, gas turbine blades

Common grades: Common alloy is 17-4PH. Usually supplied in solution heattreated condition, and requires age hardening to develop desiredstrength. The higher the aging temperature the low the strength.The metallurgical process should be obtained from the supplier ifnecessary.

Description Designation Condition(Heattreatment)

Rm

[MPa]Re

(0,2%)[MPa]

Elong-ation[%]

Ultimateshearstrength[MPa]

Bendingfatiguestrength10^7 &10^8 cycles[MPa]

Brinell hardness

PRECIPITATION HARDENING STAINLESS STEELS

wrought 17-4PH H900H925H1025H1075H1100H1150

137913101172113810341000

1276120711381034 931 862

141415161719

1179- 972 931- 855

621 & 503607 & 510572 & 538- & -- & -621 & 621

420409352341332311

ASTM cast CB-7Cu quenched - - - - - Equivalent to 17-4PH


PH13-8Mo

15-5PH 17-4PH 17-7PH

Density [kg/m3] 7800 7800 7800 7800

Modulus of Elasticity [GPa] 203 196 196 204


43



Specific heat capacity [J/(kg.oC)]



11,2 11,4 11,6 11,6

5.6 Available forms of Stainless Steels

The common forms of stainless steel are* plate, sheet, strip* round bar, rod wire* pipe* sections

5.6.1 Stainless Steel Bar

AvailabilityBar refers to shapes including round, square, hexagon, angles, tees, channels. Baris produced according to various ASTM standards, depending on the usage of theproduct. The standard for general engineering applications is ASTM A484. A widevariety of products and sizes are produced, including:* round bar (hot rolled, rough turned, turned, precision ground)* square bar (hot rolled)* flat bar (hot rolled, cold drawn, ground)

TolerancesFor products produced according to standards, the tolerances on dimensionsdepend on the shape and the size. Values are tabulated by suppliers.

Surface finishThe surface finish for bars is as follows.

1 Hot worked only(a) scale not removed(b) rough turned (round bar only) (hardenable steels may be annealed

beforehand)(c) pickled (possibly with blast cleaning)

2 Heat treated (annealed)


44

(a) scale not removed(b) rough turned (round bar only)(c) pickled, possibly with blast cleaning(d) cold worked (drawn or rolled)(e) centre-less ground (round bar only)(f) polished (round bar only)

3 Annealed and cold worked (Available for alloys 302, 303Se, 304, 316)(d) cold worked (drawn or rolled)(e) centreless ground (round bar only)(f) polished (round bar only)

Hollow bar is produced in 316 to the following nominal sizes.

OD [mm] 32 36 40 45 50 56 63 71 75 80 85 90 95 100

ID [mm] 2016

252016

282520

322820

363225

403628

50403632

56454036

40 63504540

45 71635650

50 80716356

OD [mm] 106 112 118 125 132 140 150 160 170 180

ID [mm] 80716356

90807163

90807163

100908071

106908071

1121009080

1251069580

132122112

140130118

150140125

OD [mm] 190 200 212 224 236 250

ID [mm] 160150132

160150140

170130

170130

190150

200


45

There are a number of ways in whichpipes may be joined together:(1) welded mitre joints(2) butt welding pipes to appropriate

fittings (elbow, tee, reducing,flange etc)

(3) screwed fittings which mate withappropriate threads cut on thepipe

(4) fittings with ferrules, where theferrules seal onto the pipe

All the of fittings are available in stainlesssteel. They are available in several alloys.The fittings are usually made by shapingoperations such as forging.

5.6.2 Stainless Steel Tube and Pipe

Tube refers to thin walls, and pipe to thicker walls. There are several types ofproduction process.* hot worked seamless tube/pipe, produced by extrusion * cold worked tube/pipe, which uses extruded raw material. Cold worked

products have better surface texture, and finer tolerances. A wide range ofsizes is available from OD 3 mm to 610 mm.

* centrifugal casting, for outer diameters greater than 65 mm. Length is limitedto about 5 m.

* continuously welded: a continuous strip is folded over and welded (usuallyTIG) longitudinally. The outside weld bead is removed, but not the inner bead.

* fabrication welded: pieces of plate/sheet are pressed to shape and weldedtogether

* spiral welded: a continuous strip is formed and welded into a helix. Weldingcould be both inside and outside, or justoutside.

Pipe/tube is typically used for carrying fluidswhere duty involved one or more of temperature,corrosion, and hygiene. Historically pipes havebeen designated by the bore (inside) diameter,which then determined outer diameter. Withimprovement in materials, the wall thicknesscould be reduced, allowing larger bores. Thenominal bore size is still used, but it now bearslittle relation to any actual pipe dimension! Thereare also several standards for pipe dimensions,the principal of which has been the BritishStandard Pipe (BSP).

Seamless and longitudinally Welded pipe is produced in 304 and 316 to the followingnominal sizes.

Nominal bore[mm or inches]

Schedule Outer diameter[mm]

Inner diameter[mm]

3 mm or 1/8" 104080

10,2910,2910,29

7,86,835,46

6 mm or 1/4" 10 BSP std40BSP heavy80

13,7213,3613,7213,3613,72

10,49,39,258,077,67

10 mm or 3/8" 104080

17,1517,1517,15

13,8412,5210,74




Inner diameter[mm]

46

15 mm or 1/2" 51040ISO heavy80160XX heavy

21,3421,3421,3421,3421,3421,3421,34

18,0317,1215,814,913,911,86,4

20 mm or 3/4" 51040BSP std80160XX heavy

26,6726,6726,6726,6726,6726,6726,67

23,422,520,920,518,915,611,0

25 mm or 1" 5BSP light10ISO std40BSP std80160XX heavy

33,434,033,433,733,434,033,433,433,4

30,128,727,927,726,626,724,320,715,1

32 mm or 11/4"

5104080160

42,1642,1642,1642,1642,16

38,936,735,132,529,5

40 mm or 11/2"

510ISO std40BSP heavy80160

48,348,348,448,348,248,348,3

45,042,741,940,939,338,134,0

50 mm or 2" 51040BSP std80160XX heavy

60,3360,3360,3360,3360,3360,3360,33

57,054,852,551,449,342,938,2

80 mm or 3" 5104080160XX heavy

88,988,988,988,988,988,9

84,782,877,973,766,758,4

95 mm or 31/2"

5104080

101,6101,6101,6101,6

97,495,590,185,4

100 mm or 4" 510BSP std4080160

114,3114,3114,3114,3114,3114,3

110,1108,2107,0102,397,287,3




Inner diameter[mm]

47

125 mm or 5" 5104080

141,3141,3141,3141,3

135,8134,5128,2122,3

150 mm or 6" 5104080160

168,28168,28168,28168,28168,28

162,7161,5154,1146,3131,8

200 mm or 8" 510204080

219,08219,08219,08219,08219,08

213,5211,6206,4202,6193,7

250 mm or 10" 510204080S

273,05273,05273,05273,05273,05

266,5264,7260,4254,5247,7

300 mm or 12" 510204080S

323,85323,85323,85323,85323,85

315,5314,7311,2304,8298,5

350 mm or 14" 10 355,6 342,9

400 mm or 16" 1020

406,4406,4

393,7390,6

450 mm or 18" 10 457,2 444,5

500 mm or 20" 10 508,0 495,3

5.6.3 Stainless Steel Plate and Sheet

AvailabilitySheet is material less than 3,5 mm in thickness. The common dimensions are:Thickness: 0,55/ 0,7/ 0,9/ 1,2/ 1,5/ 2,0/ 2,5/ 3,0 mmArea Size: 1000x2000/ 1250x2500/ 1500x3000/ mmxmmAll combinations of thickness and size are possible.

Plate is material of at least 3,5 mm in thickness. The common dimensions are:Thickness: 3,5/4,5/6/8/10/12/16/20/25/30mmArea Size: 1000x2000/ 1250x2500/ 1500x3000/ 1500x5000/ 1500x6000 mmxmmAll combinations of thickness and size are possible.

TolerancesThe form tolerances are followed according to standards such as ASTM, BS 1449Part 4, and DIN 17440.

Surface finishStainless steel sheet and plate is available in a number of surface finishes.


48

Mill finish Rough-ness [:mCLA]

Appearance Process

0 Scaly black Hot rolled, annealed. No pickling or passivating.Not advised to be used in this form.

1 Frosty. Hot rolled, annealed, pickled, passivated. Forindustrial applications

2D 0,4-0,1 Dull matt Cold rolled after: annealed, pickled, passivated.Used for deep drawing.

2B 0,1-0,5 Reflective Additional cold roll of 2D material. Used fordrawing. Polishes easier than 2D.

2BA 0,05-0,1 Polished, near mirror Termed "Bright Annealed". Additional cold roll of1 material with polished rollers.

3 0,4-1,5 abrasive directionapparent

Ground in one direction with 80-100 grit abrasive.Used where surface is to be polished afterwards.

4 0,2-1,0 smooth unidirectionalgrinding

Ground in one direction with 150 grit abrasive.Used where reflectivity is not required.

6 satin texture(multidirectionalgrinding marks)

Ground with abrasive grit on a rotating mop.

7 0,02 reflective Buffed surface

8 0,02 mirror Buffed

5.6.4 Stainless Steel Fasteners

The commonly used stainless steel fasteners are those of 304 and 316 alloys.Fasteners in other special alloys are less easily available. Fasteners are produced toDIN standards, and are designated:

Alloy type Designation304/305 K18-8 (or A2)316 K18-8-2 (or A4)

Standard parts produced in these grades include nuts, bolts, cap screws, set screws,washers.


49

5.7 Basic Metallurgy of Stainless Steels

Stainless steels are corrosion resistant because they form a strong, adherent layer ofchrome oxide on the exposed surfaces, and this prevents further corrosion. Thispassive film forms naturally, and it can also be made to form by chemical treatment(passivation). However to form the film, the steel needs to have at least 11%chromium, and enough oxygen in the environment. Although the passive filmregenerates when damaged, corrosion will occur if the passive layers are removedcontinuously, or prevented from forming (eg lack of oxygen).

A stainless steel which otherwise should resist corrosion may become locallysensitive to chemical attack. This is called sensitisation, and it is due to precipitationof chrome carbides between the grains, at a critical temperature. In those regions thechromium is therefore no longer available to resist corrosion. Inside the grains thechromium is usually unaffected, as the atom is too large to diffuse quickly. Thereforethe corrosion is limited to the grain boundaries. It is called intergranular corrosion, orknife edge corrosion.

Annealing is a heat treatment that fully softens the steel. The steel is heated to acertain temperature (less than melting), at which all compounds re-dissolve intosolution. Thereafter the steel is cooled in such a way that the elements remain insolution. For most steels the cooling needs to be slow, but for austenitic stainlesssteels the cooling must be rapid in order to retain the austenitic microstructure.Quenching rates from fastest to slowest are: brine, water, oil, moving air, still air.

The heat affected zone (HAZ) is a strip alongside a weld, and its characteristic is thatit has been subject to a range of temperatures from melting (at the weld) to ambient(at some distance away). Somewhere in the HAZ will be a line of grains that weresubjected to say 600oC, and etc. The problem is that certain temperatures causechanges in the grain structure (depending on the alloy). Thus the mechanical andcorrosion properties of the steel will not be uniform. Annealing could be used torestore the grain structure.

Pickling is the chemical removal of scale from stainless steel, which would otherwiseinterfere with the formation of the passive layer. The scale usually forms on weldingor other high temperature processes. Pickling is done with hydrofluoric and nitricacids. It is usually followed by a passivating process.

Passivation is a chemical process whereby a stainless steel is subject to nitric acid(usually paste or solution). The nitric acid promotes the formation of the passive layerof chrome oxide on the surface of the steel. This layer would form naturally, but notnecessarily as well. The acid also cleans the surface.

While stainless steels have fair to excellent corrosion resistance, they are not totallyimmune to corrosion. Types of corrosion include:


50

Abrasive corrosionThis is mechanical abrasion from moving surfaces or particles. Chemicalattack occurs at the newly exposed surfaces. Also called Fretting (typicallywhen small oscillating movements occur between two surfaces).

Intergranular corrosionAt critical a temperature, Chrome carbides form at the grain boundaries,thereby deactivating the Cr, and also causing brittleness. Corrosion occursbetween the grains. To avoid this problem

* reduce the time that the steel spends at the critical temperature (usually in therange 450oC to 850oC).

* use stabilisers, that is elements that soak up the carbon more readily thanchromium, thus leaving the Cr to provide the corrosion resistance. Typicalstabilisers are Titanium (Ti), Niobium (Nb), Tantalum (Ta).

* use low carbon alloys (L designations in stainless steels), so that there is lesscarbon around in the first place.The critical temperature usually occurs somewhere in the heat affected zone(HAZ) alongside a weld. Thus the HAZ is vulnerable to corrosion andembrittlement.

Pitting corrosionThis is a highly localised form of corrosion. Pits are created in the materialwhile the rest of the surface may be undamaged. Chlorides cause this type ofcorrosion in stainless steels.

Crevice corrosionSmall closed volumes do not get adequate oxygen diffusion, and this causesprotective oxide films to corrode. Bacteria can also cause this type ofcorrosion if their numbers are sufficient to block of an area of the surface. Thisis called microbiologically induced corrosion (MIC). The wastes from thebacteria may also be corrosive.

Stress corrosion cracking (SCC)A combination of stress and aggressive chemicals is very harmful to allmaterials, for the following reasons. Small cracks are basically latticeimperfections, and exist in practically all engineering materials. The cracksgrow when the local deformation is sufficient to overcome the bonds betweenthe lattice molecules. The deformation may be related to the applied stress.Also, the lattice bonds may be weakened by chemicals that have affinity forthe lattice molecules. Furthermore chemical reaction rates increase withtemperature. Thus SCC is worsened by

* higher stress* more aggressive media* increased temperature

Alloying elements


51

The functions of the alloying elements in stainless steels are basically:Cr forms a stable chromium oxide film on the surface, which halts further

oxidisation.Ni promotes the formation of an austenitic grain structureC provides heat treatability if used in sufficient quantities (martensitic ss)Mo promotes the stability of the chromium oxide film Ti stabiliser (forms carbides in preference to Cr)Mn promotes the formation of an austenitic grain structureS increases machinability, but decreases corrosion resistanceSe increases machinability, especially surface finishNb stabiliserTa stabiliserN promotes the formation of an austenitic grain structureSi decreases viscosity of molten steels for casting, also resists high temperature

oxidation of wrought steels

5.8 Colour Coding for Stainless Steels

Stainless steel pipe, tube and sections are colour coded with painted ends or endplugs.

Grade Colour

303304304L316316L

Midnight BlueWhiteMedium YellowBrilliant GreenSignal Red

409410420430431

Light BlueGolden BrownBlackEau-de-NilMines grey


52

6 HIGH NICKEL AND SPECIAL ALLOYS

The very high nickel alloys are not called stainless steel, because they contain lessthan 50% Fe. High nickel alloys are particularly useful in aggressively corrosiveenvironments, or at high temperatures. Many of the alloys have high strength, butthey can also be difficult to machine.

Most of the alloys listed here are proprietary brands, since there is littlestandardisation in this specialist field. Sometimes similar products from differentmanufacturers have been grouped together is their properties are close enough. Mechanical properties are given for general design purposes, and the designer isadvised to contact suppliers for current data before committing design.

Description Designation Condition Rm[MPa]

Re[MPa]

Elong-ation[%]

Density;Elasticmodulus[g/cm3;GPa]

Comments

PURE NICKEL

food processing, high temp

Nickel 200VDM Nickel99,2VDM LCNickel 99,2

370 100 40 8,9;196

NICKEL COPPER

Monel 400Nicorros

485 195 35 8,8; 188

Monel K-500Nicorros Al

880 590 15 8,5; 185

PURE TITANIUM

Ti Gr 2 390-540 275 22 4,5; 110

CORROSION RESISTANT NICKEL BASE-ALLOYS

Hastelloy B-2 955 526 53 9,2; 217

Hastelloy C-276Nicrofer5716hMoW

792 356 61 8,9; 200

Hastelloy C-4Nicrofer6616hMoW

801 421 54 8,6; 211

Inconel 625Nicrofer6020hMoW

910 468 47 8,44; 205



Re[MPa]

Elong-ation[%]


Comments

53

Hastelloy GNicrofer4520hMoW

703 320 61 8,3; 195

Hastelloy G-3Nicrofer4221hMoW

682 303 53 8,2; 195

Incoloy 825Nicrofer 4221

655 345 40 8,1; 195

Alloy 20Carpenter20Cb3Nicrofer3620Nb

590 275 30 8,1; 200

Sanicro 28Nicrofer3127LC

500 210 40 8,1; 185

HEAT RESISTANT NICKEL BASE ALLOYS

Inconel 600Nicrofer 7216

550 200 30 8,5; 210

Inconel 601Nicrofer 6023

600 240 30 8,1; 210

Hastelloy XNicrofer4722Co

755 385 45 8,23; 197

Incoloy DSNicrofer 3718

550 230 30 8; 200

Incoloy 800Nicrofer 3220

500-750 210 30 8; 200

Incoloy 800HNicrofer3220H

450-700 170 30 8; 200

SPECIAL STAINLESS STEELS

Remanit 4462SAF 2205Cronifer2205LCNUranus 45N

620 450 25 7,8; 200

Alloy 904LCronifer1925LC2RK65254SLXRemanit 4539Uranus B6Special

485 205 35 8; 195



Re[MPa]

Elong-ation[%]


Comments

54

3RE60Cronifer1805LC

700-950 440 30 7,7; 198

SPECIAL CAST ALLOYS

ASTM cast N-12M - 495 320 6 construction parts inchemical industry

ASTM cast CW-12M - 495 320 40 construction parts inchemical industry

ASTM cast CZ-100 as cast 345 125 10 construction parts inchemical industry

ASTM cast M-35 as cast 541 232 10 construction parts inchemical industry

ASTM cast CY-40 as cast 485 195 30 construction parts inchemical industry


55

7 ALUMINIUM

Aluminium is a useful material in mechanical engineering, since it has good strengthrelative to its mass. Pure aluminium is relatively soft and weak, but the material canbe readily alloyed to improve the strength.

7.1 Wrought Alloys

A four digit number designates alloying elements. The number is followed by atemper designation. The meaning of the primary digit is as follows:

1xxx Aluminium 99% min2xxx Copper3xxx Manganese4xxx Silicon6xxx Magnesium and silicon7xxx Zinc8xxx Other

Temper WROUGHT ALLOYSCOLD WORKED SYMBOLS

Old(UK)

F As fabricated M

O Fully anealed O

H1x Strain harden only

H2x Strain harden and partially anneal

H3x Strain harden and stabilise (approx 125deg C)

Hx2 Strain hardened, 1/4 H2

Hx4 Strain hardened, half H4

Hx6 Strain hardened, 3/4 H6

Hx8 Strain hardened, fully (75% reduction in area) H8

Hx9 Extra hard


56

7.2 Cast Alloys

The USA designation is xxx.x where:

1xx.x Aluminium 99.xx % 2xx.x to 9xx.x Other alloysxxx.0 castingsxxx.1 ingotsxxx.2 ingots

7.3 Heat Treatment

Heattreatment

WROUGHT and CAST ALLOYSHEAT TREATMENT SYMBOLS

Old(UK)

F As fabricated M

O Fully annealed O

W Solution heat treated

T Thermally heat treated, heat treatable alloy T

T1 Cooled from elevated tempNaturally aged

T2 Cooled from elevated tempCold workedNaturally aged

T3 Solution heat treatedCold workedNaturally aged

TD

T4 Solution heat treatedNaturally aged

TB (W)

T5 Cooled from elevated tempArtificially aged

TE (P)

T6 Solution heat treatedArtificially aged

TF(WP)

T7 Solution heat treatedStabilised

T8 Solution heat treatedCold workedArtificially aged

TH


57

T9 Solution heat treatedArtificially aged Cold worked

T10 Cooled from elevated tempCold workedArtificially aged

7.4 Aluminium Finishes

M MECHANICALM1X As fabricatedM2X BuffedM3X Directionally textured (eg grind)M4X Non-directionally textured (eg grit blast)

C CHEMICALC1X Non-etch (eg chemical cleaned)C2X EtchedC3X BrightenedC4X Conversion coatings (eg chromates, phosphates)

A ANODICA1X General, including sulfuric, chromic, hard anodiseA2X Protective and decorative, <0.4mmA3X Architectural Class II, 0.4 to 0.7mmA4X Architectural Class I, over 0.7mm

R RESINS, eg paint, powder coatingV VITREOUS, eg porcelain, ceramicE ELECTROPLATING

7.5 General Physical Properties of Aluminium

Density 2.7 g/cm3Modulus of Elasticity 68.95x109PaThermal conductivity 0.5 W/(m.K)Coefficient of thermal expansion 24x10-6/deg C

7.6 Mechanical Properties of Aluminium Alloys

Values of strength properties are given as minimum or (typical).


58


UltimateTensileStrength[MPa]

Yield[MPa]

Elong-ation[%]

Other properties:Modulus ofElasticity;Torsion;Density[GPa;GPa;g/cm3]

Comments

1xxx COMMERCIALPURITY ALUMINIUM

Al 99,5% min resists corrosion,conducts heat &elec, ductile,reflective, non-heat treatable

1050 A OH4H8

85-95100-135 135 -175

(35)(100)(150)

3064

71; 26.5; 2.71 sheet

1050 A MO

6075

--

2535

extrusions

1070 A MOH4H8

6055100135

403595x

233812x

68.6; x; 2.7 rolled &extrusions

1100 OH12H28

7595150-170

2575(165)

2252

69; 26; 2.71 sheet

1145 O 55 (35) 20 69; 26; 2.7 rolled

1200 MOH4H8

7070110140-155

(50)(35)(105)(140)

-3054

70; 26.5;2.71 rolled,25x10-6 linexp /oC

Electricalpurity

1350 OH4H8

(75)95135

(35)--

3083

2xxx WROUGHT

ALLOY

poor corrosionresist, excelmachinability, heattreatable

2011 TF 310 230 6 71; 2,82; 27 see tablesfor heattreat

2014A T8 450 410 6

2017A TB/TD 390 235 12

2024 T 430 280 10

2030 TB/TD 375 235 7




Yield[MPa]

Elong-ation[%]


Comments

59

3xxx WROUGHT

ALLOY

resists corrosion,non-heat treatable

3003 H4 140 115 5

3004 H34H34welded

214144

14575

69 sheet

3005 H14 165 145 1-3 sheet

3103 H4 140 (135) 5

3105 H4 160 145 Ult shearstr 95MPa

5xxx WROUGHTALLOY

resists corrosion,non-heat treatable

5005 H4 (160) (150) (6)

5050 O (146) (68) 20 sheet

5052 O 170 65 17 sheet, plate

5083 H321H321welded

282268

165159

71.7 plate

5154A O sheet 215

5182 H8 (400) (375) (9) sheet

5251 H34H34welded

231170

15989

70 sheet, plate

5454 O 215 80

5657 O (120) sheet, highpurity

6xxx WROUGHT

ALLOY

heat treatable

6005 TB 175 100 extrusions

6060 TF (205) (175) extrusions




Yield[MPa]

Elong-ation[%]


Comments

60

6063 T6T6welded

206117

17275

69.6 extrusion

6070 TF 350 325 7

6082 T6T6welded

293165

255137

69.6 extrusion

6101A TF 200 170 extrusions

6261 T6T6welded

293165

255137

69.6 extrusion

6463 TB 130 75

7xxx WROUGHTALLOY

heat treatable

7017 TF (340)

7020 TF 310 270

7075 TF 540 480

8xxx OTHERELEMENT ALLOY

non-heat treatable

8006 H24 100 75 15

8011 O 75 40 (30)

7.7 Product sections

Aluminium is available in a number of product forms.

FLAT PRODUCTSM Commercial grade sheet from 0,5 mm to 3,0 mm thickness. Alloys 1200-H4

and 5251-H6. M Architectural grade sheet is also provided in alloy 1200.M Plate (4,5 mm to 9,5 mm) is available in Alloys 1200-H4 and 5251-H6. M Mining and marine plate is available in alloys 5083-H2.


61

STRUCTURAL PROFILESM Equal angles are available in alloys 6036-T6 and 6261-T6. Leg lengths vary

from 9,5 mm to 120 mm. Unequal angles are available in alloy 6063-T6M Channels are available in alloys 6036-T6 and 6261-T6. Web lengths vary from

9,5 mm to 177 mm. T sections are available in the same alloys.M Flat bar is available in alloys 6036-T6 and 6261-T6. Maximum width is

152mm.M Square bar is available in alloy 6261-T6. Maximum size is 50,8mm. Hollow

squares in 6063-T6.M Round bar is available in alloys 6036-T6, 6261-T6, 2014-T6 and 5083-M.

Diameters from 6 mm to 190 mm. Round tube in alloys 6036-T6 and 6261-T6.M Hexagon bar is available in alloy 6261-T6. Dimensions across flats 11,3 mm,

14 mm, 20,8 mm, 30,48 mm.

ARCHITECTURAL PROFILESM A large variety of profiles are made for windows, partitions, and shop-fitting.

Alloys are not specified.


62

8 COPPER ALLOYS

8.1 Mechanical Properties of Coppers

The material properties of some commonly used copper alloys are listed here.

SYMBOLS

Rm tensile strength Re yield strengthRp0.2 proof strength Rf uncorrected fatigue strengthHB Brinell hardnessHV Vickers hardnessHRC Rockwell hardness, C scale

Description

Designation

Condition (1)

RmUTS [MPa]

ReYield [MPa]

Elong-ation[%]

Hard-ness(min)

Density[g/cm3];ElasticModulus[GPa]

Comments

COPPER Cu

Hi conduct-ivity

SABS 805 as manuf 210 35 65HV 8,94; - electrical busbar, heatexchanger

phosphorusdeoxidised

SABS 404 half hard 240 10 70-95HV

corrosion resist

tin copper CRM 006 soft - 55HV resists creep,

zinc nickelcopper

CRM 020 hard - 130-160HV

resists creep & corrosion

ETP DIN E-Cu58 M 280 33 electrolytic tough pitch hiconductivity

FRHC DIN E-Cu57 M 280 33 fire refined tough pitch hiconductivity

DHP DIN SF-Cu M 270 38 Phosphorus deoxidisednon-As

Free cutting DIN CuSP M 300 33 sulpur copper

Resistancewelding

DIN CuCrZr precip.hardened

540 10

DLP DIN SE-Cu M 270 38 Deoxidised highconductivity copper

Electroplat-ing anode

ASTMC12220

M 215 50 hi residual phosphorusdeoxidised

CRM: Copalcor Rolled Metals, Box 14229, WADEVILLE 1422


63

8.2 Mechanical Properties of Copper Based Alloys

Description Designation Condition Rm

UTS [MPa]

Re

Yield[MPa]

Elong-ation[%]

Hard-ness


Comments

BRASS

Commonbrass (303i)

CuZn 37 soft1/4 hard1/2 hard

280325350

453520

80HV 8,5; - general use

Free cuttingbrass

ISOCuZn39Pb3

1/2 hard 430 27

Riveting &bendingbrass

ISOCuZn36Pb1

M 400 40

US freecutting brass

ISOCuZn36Pb3

M 395 30

Naval Brass CuZn38Sn1 M 420 35

High tensilebrass

CuZn39AlFeMn

M 495 30

Press rod ISOCuZn39Pb2

M 415 35

(202) SABSCuZn43Pb2

M 450 30 free machining

65/35 Brass(304)

1303 soft1/4 hard1/2 hard

280325350

453520

80HV75HV110HV

resists corrosion, goodcoldwork

70/30 Brass(306)

CuZn 30 soft1/4 hard1/2 hardhard

280325340385

5035205

80HV95HV100HV125HV

excellent ductility

80/20 Brass(308)

CuZn 20 soft1/2 hardhard

265310370

40105

80HV95HV120HV

good cold work

85/15 Brass(310)


245295340

3573

75HV95HV120HV

good cold work,architectural

64/36 Brass(311)

DIN CuZn3617660

soft1/4 hard1/2 hard

280325350

453520

80HV75HV110HV

good cold work, resistscorrosion

90/10 Brass(312)


245325325

3573

75HV95HV120HV

good cold work

Cap Copper(314i)

CuZn 5 - - - - soft, ductile

LeadedBrass (228)

1303 1/2 hardhardextra hard

370430510

1053

110HV140HV165HV

accurate machining

Tin Brass(313)

CRM 313 hard - 3 140HV readily polished, plated

70/30corrosionresist Brass(317)

CRM 317 soft1/4 hard1/2 hardhard

280325340385

5035205

80HV95HV100HV125HV

resists corrosion, poordeep drawing



UTS [MPa]

Re

Yield[MPa]

Elong-ation[%]

Hard-ness


Comments

64

BRONZE copper, tin

PhosphorBronze 5%Tin

CRN 034(i)DIN CuSn517662

soft1/4 hard1/2 hardhardextrahardspringhard

310350460525645-

4535104--

85HV110HV160HV189HV200HV215HV

8,8; - resists wear: spring,clutch plate

Aluminiumbronze

DINCuAl9Zn3Fe2

M 555 25

Aluminiumnickel bronze

DINCuAl10Ni5Fe4

M 740 20

Low fumingbronzewelding rod

DIN S-CuZn29Sn

M 460 35

Cu-Ni-Si DIN CuNi2Si precipitationhardened

550 12

Cu-Ni-Si DINCuNi1,4Si

precipitationhardened

590 12

SiliconBronze

DIN CuSi3Mn M 295 35

Notes Condition M : as manufactured References * SABS 1303 for brass alloys* CRM: Copalcor Rolled Metals, Box 14229, WADEVILLE


65

9 POLYMERS

9.1 Linear and Cross Linked Polymers

Polymers (or plastics) are made from monomer molecules that are bonded togetherto form long chains. The chains are of carbon, with other elements added. As chainlength increases so the molecular mass increases. The reaction is calledpolymerization. There are two classes of polymers:

LINEAR POLYMERSAlso called Thermoplastic, these are polymers in which the molecules remainlinear and separate after moulding. The molecule is chemically unchanged bymoulding, and can be remoulded repeatedly.

CROSS LINKED POLYMERSAlso called Thermoset, these are polymers in which the molecules cross-linkduring moulding. As this is a permanent chemical change, the moleculecannot be remoulded.

Theoretically any Linear plastic may be Cross Linked. The Cross-linked form, being more tightly bonded, is stronger, harder, and more resistant to corrosion.

Plastics of different type may be alloyed together. These are called plastic alloys,blends, or polyblends. A plastic alloy has mechanical mixture of the molecules (notchemical bonding). Another type of mixture is an interpenetrating polymer network(IPN), in which cross-linking traps a polymer within one of another kind. Yet anotherway of mixing polymers is to use a third molecule that is compatible with both othercomponents, and this is called grafting.

Fibres may also be added to reinforce the polymer, in which case it is called acomposite material.

The data given here represents typical properties at room temperature. Mouldingprocesses may change the properties significantly.

Reference:Plastics, Machine Design, October 1990, pp65-149


66

9.2 Mechanical Properties of Polymers


UTS[MPa]

Re

YIELD[MPa]

Elong-ation[%]

Elasticmodulus[GPa]

Density[kg/m3]

Comments

ABS (acrylonitrile-butadiene-styrene) & SAN

(acrylonitrile-styrene) - LINEAR

tough, hard, rigid, fair chem resist, low waterabsorb, high abras resist, may electroplate

ABS eg safety helmet, pipe &fittings, appliance housings/shells,chrome plated items, SAN eglens, syringe

ABS Medium impact 41 5-25 2,5 1040

High impact 41 5-20 2,3 1010

Superhighimpact

35 5-70 1,8 1020

SAN 62 1-4 3,1 1070

ACETAL - linear strong, stiff, excel dim stability, excel creepresist, excel vibrat fatigue, low friction, highchem resist,

homopolymers are harder,stronger, more rigid. Copolymersprocess easier. Use for hi tempfood/water contact

homo-polymer

69 40 3,6 1420 0,15 friction on steel30 MPa fatigue

copolymer 61 60 2,8 1410 0,15 friction on steel23 MPa fatigue

ACRYLIC - linear high optic clarity, excel resist outdoorweathering, hard glossy surface, excel elecprop, avail in colours

"Perspex"

cast sheet 72 10 5 3,1 1190

standard mouldinggrade

72 10 5 3,0 1190

high impact mouldinggrade

37 10 50 1,5 1150

ALKYD - cross linked polyester based resin, excel elec prop, excelheat resist, low water absorb, easy to mould,no volatiles

bulk & sheet mouldingcompounds. Usually contain fibrereinforce. Eg switch gear, eleccomponents

mineral filler 20 3,5-20 1600 177oC deflection

glass filler 28 14-20 2000 204oC deflection

ALLYL (DAP) - cross linked diallyl phthalate, excel dims stabil, excel elecprop, easy to mould, excel water & chemresist at high temp

polyester filler 35 4,4 1390

long glass filler 62 11 1700

short glass filler 48 12 1600

arc-track resist 48 13 1870



UTS[MPa]

Re

YIELD[MPa]

Elong-ation[%]

Elasticmodulus[GPa]

Density[kg/m3]

Comments

67

AMINO - cross linked

(UREA, MELAMINE)

abrasion & chip resist, good solvent resist,urea vs melamine: moulds faster, costs less,less heat resist, less chem resist

Eg elec parts, dinnerware

Urea cellulose 38 0,5-1 8,9 1470

Melamine cellulose 48 0,6 9,3 1470

maceratedfabric

55 0,6 9,6 1500

asbestos 38 0,3 13,4 1700

glass fibre 35 - 16,5 1800

CELLULOSICS -linear Natural polymer. Tough, hard, compounded,plasticizer determines props.

Film: cellophane. Fibre: rayon

cellulose acetate 15-48 0,5-2,8 1220

cellulose proplonate 10-50 0,5-1,5 1160

cellulose acetate butyrate 10-43 0,34-1,4 1150

ethyl cellulose 21-33 1,5-1,7 1090

ENGINEERING FILMS stronger than constituents

nylon 6 monaxial 345Axial69Trans

60Axial450Trans

nylon 6 biaxial 220 100-200

PET 138 60-165

CTFE 28 50-300

ECTFE 55 150-250

FEP 17 300

polyimide 56 95

EPOXY excel mech strength, excel elec prop, exceladhesion, low shrinkage

structures, encapsulation,coatings

mouldingcompound

with glassfibre

69 4 21 1600

mouldingcompound

with mineralfib

35 - - 1600

bisphenol Acasting resin

no filler 28 3-6 2,4 1110

bisphenol Acasting resin

silica fill 48 1-3 - 1600

casting resin cyclo-allphatic

69 2-10 4 1160



UTS[MPa]

Re

YIELD[MPa]

Elong-ation[%]

Elasticmodulus[GPa]

Density[kg/m3]

Comments

68

FLUOROPLASTICS - linear excel dielectric prop, excel chem resist, lowfriction, excel stabil at high temp, lowstrength, high cost

fluid conveying systems, loadsupports, release surfaces,electrical insul, ablative shields

PTFE 23 300 0,345 2130 dyn frict steel 0,05"Teflon"

FEP 20 300 - 2120 dyn frict steel 0,33

PFA 28 300 - 2120 dyn frict steel 0,214

PVDF 36 100-300

1,1 1750 dyn frict steel 0,14

CTFE 37 125 1,28 2130

modified ETFE 45 275 0,8 1700 dyn frict steel 0,40

LIQUID CRYSTAL POLYMERS - linear excel high temp strength, excel resistweather & radiation, good elec props, excelflame retard

glass filled 110 2 12 1700

mineralfilled

76 1,3 12 1860

unmodified,filled

138 1-7 1,0-4 1500

NYLON (POLYAMIDE) - linear excel toughness, excel wear resist, lowfriction, excel elec prop, excel chem resist.But hygroscopic, poor dimensional stability

4/6 97 20? 30 3,17 1130 high melt temp, highcrystallinity0,4 Rm MPa fatigue

6/6 83 20? 60 3,0 1140 widely used

6 79 20? 100 2,9 1140 absorbs more water,melts sooner than6/6

6/12 60 150 1,0 1070 low water absorb, butlower strength than6/6

11 60 300 1,0 1040 resists oils, low melttemp

cast 6 76 15-50 2,8 1150

"Vesconylon 6" 75 20 2,5 VescoPlastics; max9% water absorb; 0,2static friction; 120oCcont

"Hilube 20" 60 15 2,5 VescoPlastics; max6% water absorb;0,09 static friction;100oC cont



UTS[MPa]

Re

YIELD[MPa]

Elong-ation[%]

Elasticmodulus[GPa]

Density[kg/m3]

Comments

69

"6615" 85 25 2,9 VescoPlastics; max8,5% water absorb;0,2 static friction;140oC cont

"Hilube RFG" 140 40 8,0 VescoPlastics; max3% water absorb;0,12 static friction;160oC cont

"VESCONITE" - 30 VescoPlastics; negwater absorb; maxrubbing speed300m/min

"Nyoil" 80 Oil filled nylon; 0,2%water retention in24hr; friction 0,12

PHENOLIC - cross linked low cost, black or brown moulding

general purpose 45 7,5 1350

impact 41 8,2 1360

heat resist 35 9,6 1410

glass reinforced 41 14 1700

POLYAMIDE-IMIDE - linear high strength, high temp, req post mouldcure, high cost

bearing purpose 192 15 5,0 1420

graphite fibre 163 7 6,9 1460

glass fibre 30% 205 7 11,7 1610

POLYBENZIMIDAZOLE (PBI) fire protection; avail from HoechstCelanese

Celazole U-60 unfilled 159 3 5,9 1300

POLYCARBONATE - linear excel impact resist, transparent, exceloutdoor stability, excel creep resist, fairchem resist, aromatics may cause stress-cracks

general purpose 62 110 2,3 1200

high flexmodulus

55 10 3,1 1250

glass reinforced20%

110 4 6,0 1350

POLYESTER - linear excel dim stability & elec props & toughness& chem resist, sensitive to notch, pooroutdoors, poor in hot water

unreinforcedresin

55 5-300 2 1310



UTS[MPa]

Re

YIELD[MPa]

Elong-ation[%]

Elasticmodulus[GPa]

Density[kg/m3]

Comments

70

reinforced glass 20-30%

113 1-3 8 1490

POLYESTER - cross linked excel balance of props, variety colours, highmould shrinkage, used with glass

boats, fish rods, panels, tanks.Bulk & sheet mouldingcompounds

contact lay-up mat 30-45% glass

62-124

5,5 1400-1600

contact lay-up woven 30-65% glass

207-380

6,9 1500-1700

contact spray-up 30-50%glass

62-124

5,2 1400-1600

compressionpreform

mat 25-50% glass

172-207

9-12 1500-1700

compressionbulk mould com

15-35%glass

28-69 9,6-14 1800-2100

compressionsheet MC

15-30%glass

55-138

9,6-14 1700-2100

cold presspreform

mat 20-30% glass

83-138

9-13 1500-1700

POLYETHERIMIDE - linear high temp mech properties

unmod resin 105 60 3 1270

reinforced 30% glass 170 3 9 1510

POLYIMIDE - cross linked, linear excel heat resist, high impact strength &wear resist, high cost

reinforced glass fibre 186 <1 22 1900

reinforced graphitepowder25%

66 <1 3,8 1510 friction 0,24 atPV=10000

laminates 345 <1 27 1950

POLYKETONES (eg POLYETHER-ETHER-KETONE) - linear

excel high temp props, strong, excelabrasion resist, good chem resist

PEEK un-reinforced

92 50 1,1 1320

PEEK 30% glass 157 2,2 - 1490

PEEK 30%carbon

208 1,3 - 1440

POLYOLEFINS (POLYETHYLENE,

PROPYLENE) - linear

Made from ethylene, propylene, butylene,methyl pentene, pentene, hexene. variousgrades. polyethylene: low cost, poor dimstability, poor heat resist, excel chem resist& elec props. polypropylene: excel resiststress cracking, excel chem resist, low cost



UTS[MPa]

Re

YIELD[MPa]

Elong-ation[%]

Elasticmodulus[GPa]

Density[kg/m3]

Comments

71

polyethylene low density 4-16 90-800 0,1-0,25 920

polyethylene mediumdensity

8-24 50-600 0,17-0,38 930

polyethylene high density 21-38 20-1000

0,4-1,2 950

polyethyleneUHMWPE

ultrahighmolecularweight

27-41 200-500

0,14-0,76 930

polypropylene unmodresin

35 10-20 1,1 905

polypropylene glass reinf 42-100

2-3,6 3,1-6,2 1100

polypropylene impactgrade

19-30 350-500

0,7-1,2 900

POLYPHENYLENE ETHER - linear excel dim stability, low water absorb, goodmech & elec props over wide temp range

standard 48-66 50-60 2,5 1060

glass reinf 100-122

4,6 7 1210

extrusion 54-76 15-60 2,5 1060

platable 48 60 - 1050

POLYPHENYLENE SULFIDE - linear excel chem and heat resist, excel low tempstrength, inert, flame retard

Ryton R-5 glass filled 110 1 9,6 1570 Phillips Chemical(USA)

POLYPHTHALAMIDE (PPA)-

PPA A-1133HS 33% glassreinf, dry

193 2 11,4 Heat deflection285oC. Amoco(USA), variousgrades.

POLYSTYRENE - linear low cost, rigid, clear, brittle, low waterabsorb, low heat resist, poor outdoors

polymer general purpose 35-83 0,5-2 3,5 1040

polymer impact 10-48 2-60 0,96-3,5 1030

copolymer clear 48-52 1,5 3 1080

copolymer impact 33-50 2-20 2 1050

copolymer glass reinf 10-20% 72-86 1,5 4-7 1130

POLYSULFONE, POLYETHERSULFONE

(SULFONE POLYMERS) - linear

excel mech props at high temp, resist water,sensitive to notch, high cost, sensitive to UV



UTS[MPa]

Re

YIELD[MPa]

Elong-ation[%]

Elasticmodulus[GPa]

Density[kg/m3]

Comments

72

polyaryl-sulfone(?)

70 50-100 2,5 1240

polysulfone 83 40 2,7 1370

polyether-sulfone 84 40-80 2,7 1370

POLYURETHANE - linear, cross linked variety, tough, excel abrasion & impactresist, good elec props & chem resist, poorin UV, yellow on aging

RIM process

self skinningfoam, rigid

17-20 8 1 560

POLYVINYL CHLORIDE (PVC) - linear variety, low cost pipes & fittings, flexible sheet

rigid 41-48 50-150 2,4-7 1300-1580

flexible 10-24 200-450

- 1200-1700


73

9.3 Polymers for wear applications

A major application for polymers in engineering is for wear parts. These includebushes (bearings), linear bearings (supports for sliding), gears, sprockets, linings forhoppers, and pistons. Of the many plastics available, the common selections forthese applications are as follow.

G Polyamide (nylon)The most common form of preformed section of nylon is 6/6. The commoncast form is nylon 6. The nylons have a good combination of toughness,strength, wear resistance, and they are relatively inexpensive. For greater loadbearing capacity, nylons are often impregnated with internal lubricants. Theseare called modified or filled resins. The biggest disadvantage of nylon is thepoor dimensional stability. It absorbs water (even from the atmosphere), andincreases in size (up to about 1%) as it does so. This property makes itdifficult to use for precision applications. The water absorption has a limit(about 8%), after which no further absorption occurs. Therefore nylon can beused submerged in water. However, if it should dry out, then the nylon willshrink, which could have consequences (bearing may seize).

G Acetal (also called polyoxymethylene POM)This plastic is strong, and stiff, with excellent dimension stability. It’s waterabsorbency is better than nylon. Acetal has excellent creep resistance,excellent vibration fatigue resistance. It has low friction, and high chemical resistance. Acetal comes in two forms: homopolymers and copolymers. Thehomoplymers are harder, stronger, more rigid. Copolymers process easier,and they have less porosity (therefore less place for bacteria to live). Acetalsmay be filled with lubricants such as PTFE, to increase the wear resistance.Plain unfilled acetal has slightly lower wear resistance than plain nylon.Machinability of acetal is excellent, and holds tolerances well. Typical uses foracetal are high temperature food/water contact, precision parts. Acetals havepoor resistance to strong acids or bases, or chloride solutions.

G Thermoplastic polyester (PET)This plastic is widely used for making fizzy drink bottles. It has high strengthand toughness, wears well, has excellent dimensional stability, excellentelectrical insulation properties, excellent chemical resistance (acids andchlorides included). However is it sensitive to notches, is poor outdoors, and ispoor in hot water (softens). Typical applications are food/beverage containers.Does not stain easily, due to low water absorbency. Other uses are bearings,pistons, electrical insulators.

G Ultra-high molecular weight polyethylene (UHMWPE)


74

The plain grade of polyethylene has good chemical resistance, but poordimensional stability, and poor heat resistance. The use of longer chainmolecules improves the mechanical properties, and the Ultra-high molecularweight grade is the strongest and the toughest of the polyethylenes.UHMWPE has very low friction (next best to PTFE), excellent wear resistance,and excellent chemical resistance. It also has low water absorption. But it isrelatively weak, and also has a low stiffness. Consequently dimensionalstability under load is poor. Reinforcement fibres or beads (glass or metal) aresometimes used to improve mechanical properties. Internal lubricants (MoS2)can also be used. Applications are linear motion guides, linings for hoppers,and underwater use. Not suitable for impact of hard particles or rocks. Alsonot suitable for temperatures much above about 65oC.

For higher pressures and temperatures, the following materials may be considered.They are however more expensive.G Polyamide-imideG Polyether-ether ketone (PEEK)G Polyimide (PI)G Polyphenylene sulphide (PPS)


75

10 ELASTOMERS

Elastomers include the rubber and synthetic rubber compounds. These materials arecommonly used in sheet form, or as solid mouldings.

10.1 Rubber Sheeting

DESCRIPTION DESIGNATION CONDITION Rm UTS[MPa]

Re

YIELD[MPa]

Elong-ation

Hard-ness

Otherpropert-ies

COMMENTS

RUBBER SHEETING Hard-ness ±5 IRHD

Wayne RubberCo (Pty) Ltd

General Purpose 2,5-13 235-490%

45-65

Insertion 3,6 260% 70

Gum 16 660% 40

Neoprene 4.5-13 415-565%

65

Nitrile 6,7 315% 60

EPDM 5,3 535% 70

Chlorobutyl 12,8 565% 60

Food quality 11,5 650% 55

Super red

10.2 Expanded Rubber and Polymer

These materials are also called foams. They may be made from either rubber(neoprene, styrene butadiene rubber, natural rubber, or EPDM) or polymer(polyethylene, polyester, polyether, PVC, or polyurethane). Typical uses are forsealing (eg for glazing, building cavities, expansion joints), sound insulation, thermalinsulation, sleeping mattresses.

The materials may be either open or closed celled. The open cell refers to internalcavities that are interconnected. These foams may be used for filtration. Closed cellfoams do not have interconnected internal cavities. They have greater spring thanopen cell foams, and return more quickly to original shape after deflection.

Foams are often available with adhesive backing.

Important design parameters for foams tend to be density and permissibletemperatures. Strength properties are often unavailable. Foams are usually used incompression, and have low shear strengths.


76

11 OTHER MATERIALS

11.1 Human bone

Bone is a composite structure, consisting of collagen (which is elastic) and calciumhydroxyapatite (which is rigid). Bone has the property of being able to repair itself,there being cells in the bone that reabsorb cracked material, and other cells that laydown new bone. This has the major advantage that bone is able to repair thedamage due to fatigue cracks. If however the healing process slows down (with age),or the cracks are put in too fast (running on concrete), then the repair can beoutpaced by fatigue, and a special type of fracture may occur. Medical practitionersoften call it “stress fracture”. Incidentally, one of the biggest problems with thedesign of implants to replace bone, is the need to match the stiffness of the implantto that of the bone. This is because the stiffer material will take greater load(consider a weight supported on identically shaped bricks of foam and wood, placedin parallel in the load path: which one carries the load?). Since bone is less stiff thanmost engineering materials, it avoids the load. This may seem at first like a goodthing, but it has a big disadvantage: any bone that is not used is reabsorbed by thebody. Therefore the bone wastes away, and eventually there may be insufficientbone to support the implant. This is one reason why some implants (e.g. forearm)are sometimes removed after the fracture heals. Typical data from CRC Handbookof engineering in Medicine and Biology:Density 1,6 to 1,7 g.cm-3

Parallel to axis of long bone Perpendicular to axis of longbone

Young’s Modulus kg.cm-3 1,74 x 105 1,17 x 105

Shear modulus kg.cm-3 3,33 x 104 -

Poisson’s ratio 0,46 0,58

Ultimate tensile strength kg.cm-3 1,35 x 103 6,18 x 102

Ultimate compressive strengthkg.cm-3

1,96 x 103 1,35 x 103

Ultimate torsion strength kg.cm-3 6,9 x 102 -

Elongation at failure 3 to 4% -


77

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8. Miscellaneous 1. Each time You Distribute or Publicly Perform the Work or a Collection, the Licensor offers to the recipient a license to theWork on the same terms and conditions as the license granted to You under this License. 2. If any provision of this License is invalid or unenforceable under applicable law, it shall not affect the validity orenforceability of the remainder of the terms of this License, and without further action by the parties to this agreement, suchprovision shall be reformed to the minimum extent necessary to make such provision valid and enforceable. 3. No term or provision of this License shall be deemed waived and no breach consented to unless such waiver or consentshall be in writing and signed by the party to be charged with such waiver or consent. 4. This License constitutes the entire agreement between the parties with respect to the Work licensed here. There are nounderstandings, agreements or representations with respect to the Work not specified here. Licensor shall not be bound by anyadditional provisions that may appear in any communication from You. This License may not be modified without the mutualwritten agreement of the Licensor and You. 5. The rights granted under, and the subject matter referenced, in this License were drafted utilizing the terminology of theBerne Convention for the Protection of Literary and Artistic Works (as amended on September 28, 1979), the RomeConvention of 1961, the WIPO Copyright Treaty of 1996, the WIPO Performances and Phonograms Treaty of 1996 and theUniversal Copyright Convention (as revised on July 24, 1971). These rights and subject matter take effect in the relevantjurisdiction in which the License terms are sought to be enforced according to the corresponding provisions of theimplementation of those treaty provisions in the applicable national law. If the standard suite of rights granted under applicablecopyright law includes additional rights not granted under this License, such additional rights are deemed to be included in theLicense; this License is not intended to restrict the license of any rights under applicable law.

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