SCHEMATIC REPRESENTATIONS OF

THE DIFFERENT ASPECTS OF METAL

IN DIFFERENT STEPS

Step1

• First differences in metal appear as shape, colour and weight

Step 2- after proper preparation

• A group of cells called crystals appear in random shapes and sizes

Third step-

• Crystals, composed of small particles called atoms. Atoms are arranged in a definite pattern

Fourth step

• Orderly arrangement of atoms form crystallographic planes which are alligned along the three dimensions

Fifth step

• Particles within a crystal are called atoms

Sixth step• Atoms are positioned in solids in an orderly

arrangement. Imaginary lines drawn through the centre of adjacent atoms form geometric shapes

BCC FCC HCP

Seventh step

• Atoms are composed of the same particles. Difference in atoms is in the number of particles and arrangement.

ATOMS

AVERAGE SIZE 1 X 10 -7 mmCONSISTS OF A MASSIVE CORE- NUCLEUSSURROUNDED BY NEGATIVE ELECTRIC

CHARGES- ELECTRONSNUCLEUS WITH PROTONS & NEUTRONSATOMS ELECTRICALLY NEUTRALELECTRONS REVOLVE IN DEFINITE ORBITS(PAULI EXCLUSION PRINCIPLE- 2 electrons in 1

orbit)

Properties of metallic elements

CHEMICAL PHYSICAL MECHANICALRelated to structural arrangement of particles. Eg: no: of shells,

no: of protons,

TABLE

Related to behaviour of atomic structure- wt/unit volume, rate of heat transfer, electrical resistance, thermal expansion, melting temperature etc.

Examined and evaluated by observing materials’ reaction to application of force.

Eg: hardness, strength, ductility, fatigue etc.

STRUCTURE OF METALSSTRUCTURE OF METALS- - The important aspect of any materialThe important aspect of any material Relationship between structure and properties Relationship between structure and properties

to be studiedto be studiedMetallic objects -an aggregate of many small Metallic objects -an aggregate of many small

crystalscrystals - - POLYCRYSTALLINEPOLYCRYSTALLINECrystals in these materials referred to asCrystals in these materials referred to as

GRAINSGRAINSExamination of structure with microscopes of Examination of structure with microscopes of

100X to 1000X 100X to 1000X and aboveand aboveThis study calledThis study called MICROSTRUCTURE MICROSTRUCTURE studystudy

- This study is of great use to a metallurgist- This study is of great use to a metallurgist

.

ZOOMZOOM

POWER OF 10

FROM MICRO TO MACROCOSMOS

This is a trip at high speed, jumping distances by factor of 10.

Start with 100 equivalent to 1 meter, and increasing sizes by factor of 10s ,or 101 (10 meters), 102 (10x10 = 100 meters, 103 (10x10x10 = 1.000 meters), 104 (10x10x10x10 = 10.000 meters),

so on, until the limit of our inmagination in direction to the macrocosmos.

Later let’s return, a little faster, up to the point where we started and continue our trip in the opposite direction reducing distances of travel by factors of 10 into the

microcosmos.

Observe the constancy of the laws of the universe and think about how much the human race still needs to learn...

BON VOYAGE!

Distance to a bunch of leaves, in the garden

100

1 meter

Start our trip upwards .... We could see the foliage.

101 10 meters

At this distance we can see the limits of the forest and the edifications

102

100 meters

We will pass from meters to kilometers..

Now it is possible to jump with a parachute ...

103

1 km

The city could be observed but we really can not see the houses

104

10 km

At this height, the state of Flórida - USA, can be seen..

105

100 km

Typical sight from a satellite

106

1.000 km

The north hemisphere of Earth, and part of South America

107

10.000 km

The Earth starts looking small...

108

100.000 km

The Earth and the Moon’s órbit in white....

109

1 millón de km

Part of the Earth’s Orbit in blue

1010

10 Millons de km

1011

100 millons de km

Órbits of: Venus and Earth...

Órbits of: Mercury, Venus, Earth, Mars and Júpiter.

1012

1 billón de km

At this height of our trip, we could observe the Solar System and the orbits of the planets

1013

10 billons de km

1014

100 Billons de km

The Solar System starts looking small...

The Sun now is a small star in the middle of thousands of stars...

1015

1 trillón de km

At one light-year the little Sun star is very small

1016

1 light-year

Here we will see nothing in the infinity....

1017

10 light-year

“Nothing” Only stars and Nebulae...

1018

100 light-years

1019

1,000 light-years

At this distance we started travelling the Via-Láctea (Milky Way), our galaxy.

We continued our travel inside the Via-Láctea.

1020

10,000 light-years

We started reaching the periphery of the Via-Láctea

1021

100,000 light-years

At this tremendous distance we could see all the

Via-Láctea & other galáxies too...

1022

1 millión light-years

From this distance, all the galaxies look small with inmense empty spaces in between.

The same laws are ruling in all bodies of the Universe.

We could continue traveling upwards with our imagination, but now we will return home quickly

1023 - 10 million light-years

1022

1021

1020

1019

1018

1017

1016

1015

1014

1013

1012

1011

1010

109

108

107

106

105

104

Questions that come to our minds ...

Who are we? Where are we going? From where did we come from?

103

Or... What do we represent in the Universe?

102

In this trip “upwards” we went to the power of 23 of 10

101

Now we are going to dig inside of the matter in an inverse trip...

We arrived at our starting point. We could reach it with our arms...

100

Getting closer at 10 cm ...We can delineate the leaves.

10-1

10 Centímeters

At this distance it is possible to observe the structure of the leaf.

10-2

1 Centímeter

The cellular structures start showing...

10-3

1 Millímeter

The cells can be defined.

You could see the union between them.

10-4

100 microns

Start our trip inside the

cell...

10-5

10 microns

The nucleus of the cell is visible.

10-6

1 micrón

Again we changed the messuring unit to adapt to the minúscule size. You could see the chromosomes.

10-7

1.000 Angstroms

In this micro universe the DNA chain is visible.

10-8

100 Angstroms

...the chromosómes blocks can be studied.

10-9

10 Angstroms

It appears like clouds of electrons... These are carbon átoms that formed our world.

You could notice the resemblance of the microcosmos with the macrocosmos...

10-10

1 Angstrom

In this miniature world we could observe the electrons orbiting the atoms.

10-11

10 picómeters

An inmense empty space between the nucleous and the electron orbits...

10-12

1 Picómeter

At this incredible and minuscule size we could observe the nuceous of the atom.

10-13

100 Fentómeters

Now we could observe the nucleous of the carbon atom

10-14

10 Fentómeters

Here we are in the field of the scientific imagination, face to face with a proton.

10-15

1 Fentómeter

Examine the ‘quark’ partícules

There is nowhere more to go...

At the limits of current scientific knowledge .

This is the limit of matter...

10-16

100 Atómeters

And now ...Are you the center of the universe?

Are you the special creature of the Creatión?

What is behind those limits? Are there any limits?

Note that going “downwards” we could only go to the power of minus 16ªof 10 and reached the (known?) limits of matter... But upwards we went to the power of 23ª of 10 and stopped... But really we could have continued our trip with out limits to our imagination!!!!

... then?

...who says that we are alone in the universe?

SCHEMATIC REPRESENTATIONS OF SCHEMATIC REPRESENTATIONS OF THE DIFFERENT ASPECTS OF METALTHE DIFFERENT ASPECTS OF METAL

IN DIFFERENT STEPSIN DIFFERENT STEPSFirst differences in metal appear as shape, colour and weightFirst differences in metal appear as shape, colour and weight

A group of cells called crystals appear in random shapes and sizesA group of cells called crystals appear in random shapes and sizes

Crystals, composed of small particles called atoms. Atoms are Crystals, composed of small particles called atoms. Atoms are arranged in a definite patternarranged in a definite pattern

Orderly arrangement of atoms form crystallographic planes which are Orderly arrangement of atoms form crystallographic planes which are aligned along the three dimensionsaligned along the three dimensions

Particles within a crystal are called atomsParticles within a crystal are called atoms

Atoms are positioned in solids in an orderly arrangement. Imaginary Atoms are positioned in solids in an orderly arrangement. Imaginary lines drawn through the centre of adjacent atoms form geometric lines drawn through the centre of adjacent atoms form geometric shapesshapes

Atoms are composed of the same particles. Difference in atoms is in Atoms are composed of the same particles. Difference in atoms is in the number of particles and arrangement.the number of particles and arrangement.

Properties of metallic Properties of metallic elementselements

1.1. CHEMICAL – CHEMICAL – related to structural related to structural arrangement of particlesarrangement of particles

2.2. PHYSICAL- PHYSICAL- related to behaviour related to behaviour of atomic structureof atomic structure

3.3. MECHANICAL- MECHANICAL- examined and examined and evaluated by observing the reaction evaluated by observing the reaction of materialof material

METALLOGRAPHIC METALLOGRAPHIC SPECIMEN PREPARATIONSPECIMEN PREPARATION

THIS IS AN ARTTHIS IS AN ART

TECHNIQUES VARY FROM ONE LAB TO ANOTHERTECHNIQUES VARY FROM ONE LAB TO ANOTHER

VARIATION IN PROCEDURE DEPENDING ON METAL VARIATION IN PROCEDURE DEPENDING ON METAL TO BE EXAMINEDTO BE EXAMINED

BUT, BASIC OPERATIONS SIMILARBUT, BASIC OPERATIONS SIMILAR

With iron and steel as specimen, methods With iron and steel as specimen, methods explainedexplained

Cut the object and prepare a flat Cut the object and prepare a flat surface on one side of specimen surface on one side of specimen

Mount specimen in a small plastic Mount specimen in a small plastic disc (25 mm dia and 12 mm thickdisc (25 mm dia and 12 mm thick))

Expose surface on one side of discExpose surface on one side of disc

- For this,- For this,place specimen inside the ring place specimen inside the ring mould, pour epoxy resin into mould mould, pour epoxy resin into mould and fill the ring, allow resin to and fill the ring, allow resin to harden, and finally invert.harden, and finally invert.

Four basic steps on this specimenFour basic steps on this specimenFine Grinding Fine Grinding Rough polishing Rough polishing Final polishing Final polishing EtchingEtching

Plastic disc

Metal Specimen

Reduces thickness of the deformed layer below the specimen surface

Fine Grinding Fine Grinding Grinding using silicon carbide powders Grinding using silicon carbide powders

bonded onto specially prepared papers.bonded onto specially prepared papers. Specimen hand rubbed against the abrasive Specimen hand rubbed against the abrasive

paper laid on a flat surfacepaper laid on a flat surface (or on horizontal flat rotating wheels)(or on horizontal flat rotating wheels) Surface lubricated with water- for flushing Surface lubricated with water- for flushing

actionaction Three grades of abrasives used- 320, 400, Three grades of abrasives used- 320, 400,

600 grit( size 33, 23, 17 microns)600 grit( size 33, 23, 17 microns) Movement of specimen in one direction onlyMovement of specimen in one direction only From one paper to another, the specimen From one paper to another, the specimen

rotated through 45rotated through 4500 to have new scratches to have new scratches on previously cut. Continued till scratches on previously cut. Continued till scratches from preceding stage disappears.from preceding stage disappears.

Rough polishingRough polishing Critical stage.Critical stage. Abrasive is Abrasive is powdered diamond dust of 6 micronspowdered diamond dust of 6 microns Powder in an oil- soluble pastePowder in an oil- soluble paste Small quantity placed on nylon cloth- covered Small quantity placed on nylon cloth- covered

surface of rotating polishing wheelsurface of rotating polishing wheel Lubricant- Lubricant- specially prepared oilspecially prepared oil Specimen pressed against cloth with considerable Specimen pressed against cloth with considerable

pressurepressure Not held in a fixed position, but moved around the Not held in a fixed position, but moved around the

wheel wheel in direction opposite to rotation.in direction opposite to rotation. Thus, more uniform polishing action.Thus, more uniform polishing action. Diamond particles remove deep layer of deformation Diamond particles remove deep layer of deformation

remaining from fine grindingremaining from fine grinding

Final polishingFinal polishing Fine scratches and thin distorted Fine scratches and thin distorted

layer from rough polishing stage layer from rough polishing stage removed.removed.

Alumina powder AlAlumina powder Al22 O O33 (gamma form)(gamma form) of of 0.05 micron used. 0.05 micron used.

Placed on cloth covered wheel, Placed on cloth covered wheel, distilled water used as lubricant.distilled water used as lubricant.

Cloth contains nap. Cloth contains nap. A scratch free surface with no A scratch free surface with no

detectable layer of distorted metal detectable layer of distorted metal obtained.obtained.

EtchingEtching After final polishing, granular structure not seen After final polishing, granular structure not seen

under microscopeunder microscope. . Grain boundaries have Grain boundaries have thickness of the order of a few atoms. Resolving thickness of the order of a few atoms. Resolving power of microscope too low to reveal this.power of microscope too low to reveal this.

ETCHANT used to make the boundary visible. ETCHANT used to make the boundary visible. Polished surface immersed in a weak acidic or Polished surface immersed in a weak acidic or

alkaline solution.alkaline solution. Eg: NITAL- 2% nitric acid in alcohol. Eg: NITAL- 2% nitric acid in alcohol. (or applied by rubbing with cotton swab wetted (or applied by rubbing with cotton swab wetted

with etchant.)with etchant.) Metal dissolved from metal surface. Attacks grain Metal dissolved from metal surface. Attacks grain

boundaries more rapidly. boundaries more rapidly. Shallow steps on the surface reveal the Shallow steps on the surface reveal the

boundaries. Vertical surfaces will not reflect in boundaries. Vertical surfaces will not reflect in the same fashion as smooth horizontal surface.the same fashion as smooth horizontal surface.

Reveals crystal boundariesReveals crystal boundaries

Before etchingAfter etching

Electro-polishing and electro-etchingElectro-polishing and electro-etching In some metals- stainless steel, In some metals- stainless steel,

titanium, zirconium etc.- distorted titanium, zirconium etc.- distorted layer removal difficult. Mechanical layer removal difficult. Mechanical polishing not successful.polishing not successful.

Polished by electropolishing Polished by electropolishing techniquetechnique. Specimen made anode and . Specimen made anode and insoluble material used as cathode in insoluble material used as cathode in an electrolytic bath. With proper an electrolytic bath. With proper current density, specimen surface is current density, specimen surface is dissolved. dissolved. (bath and current (bath and current controlled)controlled)

When composition of bath and When composition of bath and current density varied, procedure is current density varied, procedure is electro-etching.electro-etching.

The most commonly used etchants

Etchant Composition Conc. Conditions Comments

Kalling's No. 1

Distilled waterCuCl2Hydrochloric acidEthanol

33 ml1.5 grams33 ml33 ml

Immersionetching at 20DegreesCelcius

For etchingmartensitic stainlesssteels. Martensite willbe dark and the ferritewill be colored.

Kalling's No. 2

CuCl2Hydrochloric acidEthanol

5 grams100 ml100 ml

Immersionetching at 20DegreesCelcius

For etching duplexstainless steels andNi-Cu alloys andsuperalloys.

Kellers Etch

Distilled waterNitric acidHydrochloric acidHydrofluoric acid

190 ml5 ml3 ml2 ml

10-30secondimmersion.Use onlyFreshetchant

Excellent foraluminum and alloys immersion for 10-20seconds ; titaniumalloys immersion for10-20 seconds.

Etchant Composition Conc. Conditions Comments

Kroll’s Reagent

Distilled waterNitric acidHydrofluoric acid

92 ml6 ml2 ml

15 secs

Excellent for titaniumand alloys. Swabspecimen up to 20seconds.

NitalEthanol

Nitric acid

100 ml1-10 ml

Seconds to minutes

Most common etchantfor Fe, carbon andalloys steels and castiron - Immerse sampleup from seconds tominutes; Mn-Fe, MnNi,Mn-Cu, Mn-Co alloys–immersion up to a fewminutes.

Marble's Reagent

CuSO4Hydrochloric acidWater

10 grams50 ml50 ml

Immerse or swab for 5-60 secs.

For etching Ni, Ni-Cuand Ni-Fe alloys andsuperalloys. Add afew drops of H2SO4to increase activity.

EtchantCompos

itionConc. Conditions Comments

Murakami's

K3Fe(N)6KOHWater

10 grams10 grams100 ml

Pre-mix KOHand waterBeforeAddingK3Fe(CN)6

Cr and alloys (use fresh andimmerse); iron and steelsreveals carbides; Mo andalloys uses fresh andimmerse; Ni-Cu alloys foralpha phases use at 75Celcius; W and alloys usefresh and immerse; WC-Coand complex sinteredcarbides.

Picral

EthanoPicricacid

100 ml2-4 grams

Seconds to minutesDo not let etchant crystallize or dry –explosive

Recommended formicrostructures containingferrite and carbide.

Vilella’s Reagent

GlycerolHNO3

HCl

45 ml15 ml30 ml

Seconds to minutes

Good for ferrite-carbidestructures (temperedmartensite) in iron and steel

Guide to Acid Concentrations

Acid / BaseSpecific

gravity Concentration

Nitric (HNO3) 1.4 68-70%

Hydrofluoric (HF) - 40%

Hydrochloric (HCl) - 37-38%

Ammonium Hydroxide (NH4OH) - 35%

Metallographic Etchants

Aluminimum alloys High carbon Steel

Brasses and Bronzes Stainless Steel

Cast Iron Tin Alloys

Copper Alloya Zinc Alloys

Low carbon Steel Ceramics

CAUTION: Safety is very important when etching. Be sure to wear the appropriate protective clothing and observe all

METALLOGRAPHIC SPECIMEN PREPARATION-in brief Cut the object and prepare a flat surface on one side of specimen

Mount specimen in a small plastic disc (25 mm dia and 12 mm thick) Expose surface on one side of disc- For this, place specimen inside the ring mould, pour epoxy resin into mould and fill the ring, allow resin to harden, and finally invert. Four basic steps on this specimen

Fine Grinding Rough polishing

Final polishing Etching

silicon carbide powders bonded onto specially prepared papers water- for flushing

powdered diamond dust of 6 microns

Powder in an oil- soluble paste

specially prepared oil

Alumina powder Al2 O3 (gamma form) of 0.05 micron

distilled water

ETCHANTNITAL- 2% nitric acid in alcohol.

Electro-polishing and electro-etching

Specimen and Mount Holders• Specially Designed

Specimen Holders For SEM: • The specimen holders are

designed to improve productivity and allow one to view more than one sample at a time.

• This saves pump down time, keep chamber cleaner and get more work done.

• All mounts are machined from solid aluminum and come with spring clips/or setscrews to hold specimens securely.

• All mounts are made to fit onto the stage and are designed to fit through all standard specimen exchange ports, and have a center-threaded port to accept the Adapter Pins that fits SEM instrument.

Adapter A: Overall measurement: 28mm long x 3.1mm diameter (step-up portion is 6.25mm L x 4.8mm diameter),Adapter B: Overall measurement: 28mm long x 6mm diameter,Adapter C: Overall measurement: 34.5mm long x 16mm diameterAll adapters have a threaded portion 5mm in length.

Three different types of pin adapters, which are threaded and ready to screw on to the base of the holders are available.

Universal SEM Sample HolderTo hold almost any sample from 3mm to 29mm in diameter plus various odd shaped samples, with the dimensions not greater than 29mm. The samples are easily inserted or removed from the holder. The holder is made from aluminum and is with four removable sample arms so that it can hold very small samples as well, and it provides good electrical contact to the stage. The standard base measures: 48mm x 42mm x 12mm Thick.

Vertical Mount for Thin Samples; Flat Base This is designed to hold thin samples vertically in the SEM or any microscope. It is 25mm in diameter and 10mm thick. Each of the two loader jaws can hold up to 3mm thick samples. The spring loader keeps thin samples vertical so that cross sections can be studied. This holder is very useful for cross sections of silicon wafers or multilayer capacitors.

Multi Pin Holder The Multi Pin Holder is designed to save time. It accommodates 3 or 5 of ½" dia.(12.5mm) surface, 1/8" dia. (3.1 75910 Specimen Holders For SEM 10-14 mm) pin.

ISI DS 130 and 150 First Stage Sample MountsIt is 10mm in diameter, 5mm high, copper sample holder to fit in the first stage of the ISI DS 130 and 150 SEM's. The inner cylinder is height adjustable so that one can adjust the sample to the correct working distance.

SEM Sample Holder SetFor convenience a SEM Sample Holder Set to fill all needs is available. The set consists of one universal holder, one vertical mount holder for thin samples, one 3-pin and one 5-pin configuration holder with a key for the set screw all in a finely finished wood box.

Pin Mount Stub AdaptersMade from aluminum, used to adapt 1/8" (3.1mm) pin diameter SEM stubs.Available in 10, 15, 16mm diameter as well.

Cross Sectional HolderMade from non-magnetic stainless steel with 3.1mm (1/8") diameter pin and adjustable angle turn-screw. Just insert specimens edge-on and observe the cross section directly

Four-Pin Stub HolderIt accommodates four pin type, up to 12.5 (1/2") surface specimen stubs, with 1/8" (3.1mm) diameter pin.

Five 10mm Stub HolderAccommodates five 10mm

diameter specimen stubs, with 1/8" (3.1mm) diameter pin

Thin Sample HolderIdeal for examination cross section of thin samples, such as wafers, multi-layer of capacitors, plastics, metals, etc. ½" diameter (12.7mm), 1/8" (3.1mm)dia. pin (3.1mm) with split openings up to ¼" (6.4mm). Available with either 8mm (5/16") pin height or 15mm (9/16") pin height. For ISI, JEOL, TOPCON: Double set screw for a secure holding of the specimen during observation. 15mm(9/16")(dia). x 10mm(3/8")(H), 6.4mm(1/4") split.

• METALLURGICAL LABORATORY TESTING

Metallurgical labs stocked with state-of-the-art of equipment that allows to help in materials selection, characterization, component and process design, qualification, failure analysis, and many other services.

• Specimen Preparation • Automatic grinding and polishing equipment • Abrasive cut-off wheels • Epoxy and cold mount • Large section specimen (up to 9 in.) metallographic preparation • Acid and electrolytic polishing/etching techniques • Specialized sectioning capability • Etching techniques for most common materials • Removal of rust and scale prior to failure analysis • Microstructural Analysis • Optical microscopes: magnification up to 2000x with oil immersion • Scanning Electron Microscope • Cambridge Stereoscan 360 • Windowless EDS capability for microstructural chemical analysis

• Image Analysis • Micro- and macro-digital photographic capability • Quantitative image analysis for:

– Area fraction – Feature measurement – Modularity – Grain size – Size distribution – Inclusion rating – Crack length

• Software-based weld profile measurement Conventional & digital macrophotograph capability

• Materials Testing • Hardness testing (Rockwell A, B, C) • Microhardness testing (Vickers, Knoop) • Magnet-gage for ferrite measurement

• Weldability Testing • Gleeble 1000 Thermal/Mechanical Simulator • Universal Varestraint • Oberlikon-Yanaco Hydrogen Analyzer with high-temperature

measurement capability • Heat Treatment • 3-cubic ft. convection furnace • 12-cubic ft. convection furnace • 9-cubic ft. oven • Nondestructive Evaluation (NDE) • Ultrasonic immersion testing • Ultrasonic contact testing • Eddy current testing • Meandering Winding Magnetometer (MWM) • Surface cleanliness monitor (Optical Stimulated Electron

Emission [OSEE]) • Magnetic particle testing • Penetrant testing • Baroscope and visual inspection • Radiography

ThermographySTANDARD TESTING SERVICES

• Tensile Bend Fatigue • Charpy impact Fracture toughness (CTOD, J&K) • Heat treatment services (stress relief, normalizing ageing) • Weld cracking sensitivity tests (WIC, Y-groove, CTS, GBOP) • Diffusible hydrogen measurement (Mercury and gas chromatography) • Gleeble Thermo-mechanical simulator

– Weld simulation CCT curves – Process simulation – Thermal/mechanical simulation – Weldability (Varestraint, Sigmajig) – Microstructural characterization

• Optical Hardness Feature quantification • Weld procedure qualification • Residual stress measurements (blind-whole method)

– Digital image analysis SEM with

– EDS capability – Experimental stress analysis (strain gauging services) – High temperature testing up to 1200°C – Expert failure analysis – Welding services (PQR, test plate fabrication, etc.)

LATTICE, UNIT CELL,

BRAVAIS LATTICE

CO-ORDINATION NUMBER

ATOMIC PACKING FACTOR

MILLER INDICES

METAL IDENTIFICATION TESTSMETAL- COMPOSED OF SINGLE METALLIC ELEMENT/ GROUP OF ELEMENTS

ALLOY- MADE UP OF TWO OR MORE ELEMENTS, ONE METALLIC

METAL- CHARACTERISTICS- BASED ON GENERAL CONDITIONS

CRYSTALLINE WHEN SOLID GOOD CONDUCTOR OF HEAT & ELECTRICITY DEFORMS WITH APPLICATION OF STRESS IN PLASTIC

MANNER REFLECTS LIGHT WHEN POLISHED

ELEMENT

- SMALLEST DIVISIBLE PART OF A SUBSTANCE

METAL IDENTIFIATION TESTS

- TO SEPARATE COMMON METALS– MAGNETIC TEST– VISUAL OBSERVATION TEST– HARDNESS TEST– SURFACE REFLECTIVITY TEST– WEIGHT PER VOLUME TEST– CHEMICAL REACTION TEST– SPARK TEST

ASTM, ASM, Al. Assn., ASME, Society of Automotive Engineers, AWS, ANSI, Aerospace Materials Specification, Federal Specification (WW) etc.

MAGNETIC TEST Simple

Steel, Ni, Co, - magneticCu, Al, Tin, Zn, Cr, Mn- nonmagnetic

Exceptions too eg: Stainless steel

Corrosion resistant poor corrosion resistance.

No magnetic attraction highly magnetic

316 410

VISUAL OBSERVATION TEST

o Compare with standards

o COLOUR,

o SURFACE,

o SECTION AFTER FRACTURE etc.

HARDNESS TEST

FILE HARDNESS TEST- WITH FILE

USE SAMPLE AND COMPARE

OBSERVE SCRATCHES ON SURFACE

(eg: deep file scratches on structural steel, shallow on high carbon steel)

SURFACE REFLECTIVITY TEST

A VISUAL TEST

Compare ability to reflect light.

(eg: Al & Mg.- Al more than Mg.

Lead-tin: more tin- more reflectivity

WEIGHT PER VOLUME TEST

Small sample in a graduated container

Wt of metal/volume of water displaced

Compare with known samples

CHEMICAL REACTION TEST

Test reaction with certain acids

–simple / complex

METALS HAND BOOK, VOL 11. by American Society for Metals

Eg: carbon content of carbon steel, test for Mn,

SPARK TEST

To separate alloys containing known alloying elements

Eg: MS, carbon tool steel, Mn, S, Ni content steels etc.

Manganese Sulphur Nickel

REFER DATA BOOK FOR STANDARDS-

SYMBOLS FOR DIFFERENT CLASSES

UNIFIED NUMBERING SYSTEMS FOR METALS AND ALLOYS-

SAE 1975