Acciaiper stampie utensili

Mouldand tool steelsOn CD-ROM

Domenico Surpi

CONTENTS

BASIC PRINCIPLES ...............................................................................................................................................................................5

MOULD STEELS MAkINg .................................................................................................................................................................6

HEAT TREATMENTS .............................................................................................................................................................................8

FACTORS WHICH MAY INFLUENCE THE SERVICE-LIFE OF MOULDS ................................................................................12

TIPS ON AVOIDINg DAMAgE TO MOULDS ........................................................................................................................... 14

POLISHINg AND PHOTOENgRAVINg ...................................................................................................................................... 17

TOOL STEEL WELDINg .................................................................................................................................................................... 18

CHOICE OF WELDINg TECHNIQUE ........................................................................................................................................... 21

SUggESTED OPERATINg PARAMETERS FOR WELDINg ................................................................................................. 24

TOOL STEELS ....................................................................................................................................................................................... 27

STEELS FOR CONSTRUCTION AND gENERAL USES .......................................................................................................... 28

STEEL COMPARISON TABLE ......................................................................................................................................................... 30

HARDNESS CONVERSION TABLE ............................................................................................................................................... 32

HV-HRC and HRC-HV-HB-HRA-HRB-RM for carbon alloy steels (in accordance with table ASTM A 370 - 03A)

HARDNESS CONVERSION TABLE ...............................................................................................................................................34

HB-HRC-HRB-HRA (applicable to stainless austentic steels in accordance with ASTM A 370 - 03A)

5BASIC PRINCIPLES

The first essential rule, is that the steel fibres must work perpendicularly to the main direction of the forces.

In order to withstand the high temperatures, temperature changes and high pressures to which they are

subjected, moulds for the injection, hot forming and extrusion of metals are manufactured mainly from

forged materials.

The treatments which these materials undergo may be classified into two categories:

- core treatments, which affect the steels properties down to the core and include: annealing, normalization, stress-relief, hardening and tempering;

- surface treatments, which modify only the properties of the surface layer of the mould and include: nitriding, case-hardening and oxidation.

If, on the other hand, a material different to the base material is deposited, the process is called plating or

coating (chromium plating, nickel plating, PVD and CVD coatings).

Die Steel 1.2738 hardened and tempered

6MOuLd STEELS MAKING

The integrated cycle of mould and tool steel production usually starts with selected scrap.

The first stage of processing takes place in an electric arc furnace, followed by refining and vacuum degas-

sing in a ladle furnace.

This process can result in the production of polygonal ingots for the forging plant, or of round ingots to be

recast, for example, under electro-conductive slag to make new forging ingots.

This last operation, performed under specific conditions, gives the product almost identical mechanical pro-

perties in all directions (longitudinal, tangential, radial) and assures constant quality.

3) Refining ladle metallurgy: gascontent reduction (hydrogen,oxygen, nitrogen) argonstirring newslagcreation

4) Refining ladle metallurgy: chemicalanalysis control analysiscorrection throughthe additionofalloy elements finalchemical analysiscontrol

1)Selectedscrap. Scrapwithlow contentofCu,Pb andother unwantedelements thatcanadversely affectthepurityof thefinalsteel

2)Three-phaseelectric arcfurnace: reductionof sulphurand phosphoruscontent oxidation completeslagging chemicalanalysis control ladletapping

[in collaboration with Danilo Arosio ]

712)Certification: accordingto customer specifications andinternational standards

6)Uphillcasting: castingprotected againststeel reoxidation morecontrolover liquidsteelflow constantcooling betteringotmatrix structure

5) Refining ladle metallurgy: vacuumcreation gascontent reduction (hydrogen,oxygen, nitrogen) chemicalanalysis finalcontrol ingotmould tapping

7)ESR=ElectroSlag Remelting: lowimpurities, absenceofcavities anduniformity ofstructure furtherimprovement ofmechanical properties(isotropy)

8)Forging: reductionratio accordingto specificheatingand coolingprocedures

9) Heat treatment: specialmulti-phase cyclescanassurean optimaland uniformannealing structure specificthermal phasesforoptimizing andbestexploiting thepotentialof everygrade ofsteel

10)Mechanical processing: pre-machiningto obtainmould shapesascloseas possibletotheir finalsizeand derivemaximum benefitfromall possibleeffects ofsubsequent tempering

11)Controls: inclusions decarburization hardness macrographies structures grainsize tempering mechanicaltests

Via Filippo da Desio, 53 Desio (MI) Tel.

0362 631145 Fax 0362 301451 Email

Via Sandro Pertini, Loc. Francolino

Carpiano (Mi) Tel. 02 98859110 Fax 02 98859817

Inspection Certificate Abnahmerprfzeugnis

Test Report Werkzeugnis

Document No Beleg Nr.

Date Datum

/ Material Identification / MaterialbeschreibungSteel/Sthal 1.2311 Geschmiedet

Norm/Norm Werkstoff 1.2311

Delivery condition / Lieferzustand Bonifica

Shape Size / Profil Abmessung P 200 x 396 x 1197

Your Order/Ihr Auftag 100683

Our confirmation/ UnsereBestatigung 007471

Transport document/Liefershein 002427 del 031210

Quantity / Menge 1

Our Heat number Chargennummer

External lot Externe Partie

61000760

On the heat / Auf der Schmelze Chemical analysis / Chemische Zusammensetzung

On the product / Auf dem Produkt C % Si % Mn % P % S % Cr % Mo % Ni % Cu % Al % Pb % 0,41 0,30 1,39 0,011 0,001 1,93 0,18 0,18 0,018 B % V % Ca % Co % Ti % W % Te % Bi% Nb% Cr+Mo+Ni%

Reference Test Piece/ Anhaltswerte

Mechanical properties / Mechanische Eigenschaften TEST N.

On the product / Auf dem Produkt

Impact test / Kerbzhigkeit Rm (N/mm2) Rp 0,2 % (N/mm2) A % C % (Z%) C C

Grain Size / Korngrsse

Non metallic inclusions / Nichtmetallische Einschlsse

Hardness / Hrte

Reference Heat treatment Anhaltswert fr Wrmebehandlung UNI 3245 ASTM E 112

292 304 290

/ Jominy test / Stirnabschreckprobe mm 1,5 3 5 7 9 11 13 15 20 25 30 35 40 45 50 mm 1 2 3 4 5 6 7 8 9 10 11 13 15 20 25 30

/ Nondestructive testing / Zerstrungsfreie Prfungen

Antimixing Verm ischungsausschliessung

Magnetic test Magnetproben

Decarburization

Entkohlung

UT control

Ultraschallprfung /Yes/Ja /Yes/Ja /Norm /Norm /Class / Klass /No/Nein /No/Nein IT 669 REV.3 U.T.1

/ Remarks / Bemerkungen

CONTROLLO QUALIT

N.B. I prodotti forniti sono conformi ai requisiti dellordine.

HEAT TREATMENTS

Heat treatments may lead to considerable changes in the properties of steel which can sometimes exceed

those induced by changes in the chemical composition of the steel. From a practical point of view, the tran-

sformations which heat treatment can cause to strength, yield point, elongation, contraction, toughness and

modulus of elasticity are of particular interest. Alloy steels subjected to incorrect heat treatment may give

poorer results than correctly treated carbon steels. A list of the main types of heat treatment is given below,

but the technical data sheets for the individual steels give the parameters which are recommended on the

basis of experience.

AnneAlingThe main requirement of this heat treatment is to reduce the hardness of hot-deformed, rolled and cold-

drawn materials. Annealing is introduced in some cases to eliminate stresses or non-homogeneous structu-

res. The temperature is held for 1 hour 30 minutes for every inch of thickness (e.g. 300x100 flat; dwell time

5 hours).

CAse-hArdeningHeat and chemical treatment for increasing the carbon content on the surface. Carbon increases hardness

and combats wear.

Chromium plAtingElectroplating treatment for forming a film of extremely hard chromium on ground bars. This treatment pro-

vides abrasion- and corrosion-resistance, and a lower friction coefficient between moving parts; especially

with rubber gaskets.

heAt treAtmentSeries of heat operations for changing the properties and/or structure of a ferrous material.

heAtingThis involves increasing the temperature of a product with a pre-set thermal gradient. It is generally carried

out very slowly, at a maximum of 50 C/h, and never higher than 150 C/h.

interrupted quenChingThis involves interrupting the cooling cycle at a pre-set temperature (~500-600 C) and maintaining this

temperature for a specific time before cooling down to 50 C. This is usually carried out to minimise the

probability of crack formation, or to produce a particular structure in the piece.

8

nitridingHeat and chemical treatment for obtaining higher nitrogen content on the surface. Nitrogen increases

hardness and combats wear.

normAlizAtionThis is carried out at a temperature of just over Ac3 +50/70 C (Ac1 for hypereutectoid steels C% > 0.80)

followed by cooling in still air. The main aim is to homogenise the structure and to reduce the size of the

grain enlarged by previous hot transformation operations. This treatment is not recommended for tool steels

or self-hardening steels. Normalization is also used to regenerate the structure damaged by the hardening

and tempering heat treatment, when the desired mechanical values have not been obtained. Hardening and

tempering should not be carried out more than twice on the same material. If necessary, carry out the nor-

malization before repeating the hardening and tempering. Repeated treatments, in oxidising environments,

inevitably create an addition of decarburization and this fact must be taken into due account.

pre-heAtingHeating the material with intermediate breaks (400-600 C) before reaching the pre-set temperature for

austenitization. The process is mainly used to reduce stresses and differential expansion induced by hot

deformation cycles and machining. The break at the pre-heating temperature must ensure a uniform tempe-

rature throughout the entire section.

quenChing And temperingHardening treatment composed of quenching and tempering to obtain the desired combination of mecha-

nical properties and good ductility and toughness. It should be noted that, if it is necessary to repeat the

hardening and tempering on the same material, the temperature of the first treatment must be higher than

that of the second. See also quenching, tempering.

quenChingThis is the cooling of a ferrous product faster than in still air. It is good practice not to use a quenching

medium that is more drastic than necessary, as the faster the cooling, the greater the stresses induced in

the part. Quenching baths must be stirred to prevent vapour bubbles adhering to the material. The most

commonly used baths are: gas mixtures (for treatment below freezing), water, salt baths, polymers (water

with additives), oil, forced or still air. The weight of the baths must be at least 10-15 times greater than that

of the material to be quenched. The temperature of the bath at the end of quenching must not exceed 49

C. The temperature is normally maintained for 30 minutes for every inch of thickness (e.g. 300x100 flat;

time 2 hours).

9

seCondAry hArdeningHardening achieved after one or more tempering operations (550-600 C), which precipitate a compound

(oversaturated carbides) that destabilises the austenite due to the thermal effect and transforms it into in

martensite or bainite during cooling. In this way there is an increase in hardening and the phenomenon is

called secondary hardening.

soft AnneAlingThis is carried out at 30-50 C below the Ac1 point.

This treatment does not modify the structure but adequately softens and eliminates stresses due to previous processes.

The cooling (approx. 10C/h, normally 5-10 C per minute for carbon steels and 20-40 C per hour for alloy steels) may

be carried out either in a furnace or in air.

stress reliefTreatment aimed at reducing stresses (due to cold straightening, sudden cooling, machining, etc.) without

reducing the hardness. The process is generally carried out at 50 C below the temperature of the last tem-

pering carried out on the hardened parts or products which are used with very high strengths. Cooling must

be carried out very slowly, generally in a furnace.

temperingThis is the heat treatment which a ferrous product undergoes after hardening by quenching, to achieve the

desired mechanical properties.

After quenching, the material is highly stressed and these stresses must be eliminated as their force, if it

exceeds the failure load, could break the material.

This is one of the purposes of tempering. The second is to lower the strength until a compromise is reached

between a good failure load and good toughness (impact strength). The temperature is normally maintained

for 1 hour for every inch of thickness

(e.g. 300x100 flat; time 4 hours).

thermoChemiCAl treAtmentA process performed in a suitably selected medium/environment to change the chemical composition of the

base material.

WeAr-resistAnt CoAtingIn recent years there has been a progressive increase in the use of wear-resistant coatings. Titanium nitride

is the best known of the coatings: thanks to its high degree of hardness and a very low friction coefficient,

it enables a considerable reduction in abrasive wear, which is the main cause of a reduction in the efficiency

10

of machine tools. New coatings have also been developed to resolve specific problems, to such a point that

high-speed, dry machining is possible.

The fields of application of the tools are constantly expanding with constant improvements in the die-

casting or extrusion of aluminium, injection of plastics, drawing or shearing, as well as in the automotive

and food industry.

The advantages may be seen in the longer service life of the coated piece, reduction in maintenance requi-

rements and machine downtimes, and increased productivity.

Coating techniques are so detailed and difficult to explain that this is best left to the experts in this particular

sector; a description is merely given of some of their experiences and the most commonly used systems:

The PVD technique (Physical Vapour Deposition) is carried out at low temperatures, guarantees an excel-lent finish and applies various types of coatings, including self-lubricating ones, as well as possible multi-

layer combinations.

Disadvantages: it is not effective when there is limited space for vapour circulation, since the formation of gases does not allow good penetration.

The CVD process (Chemical Vapour Deposition) provides coatings with better characteristics, both in terms of thickness and adhesion. Performance is also better, especially when the material coated is used in cold

deformation processes. The trickiest problem lies in the deposition temperature of approx. 1.050 C, which

sometimes causes deformations to exceed the tolerances set by the designer.

Disadvantages: coatings with different materials are not possible e.g. TiANl, the thickness at the edge of the coatings tends to be rounded, toxic metal chlorides are used.

The PACVD process (Plasma Assisted Chemical Vapour Deposition) has a greater resistance to abrasion than the PVD process and does not have the disadvantages of the CVD method. Due to the size of the plants

it is possible to coat very large pieces. The finish is similar to that of PVD. Performance has been observed to

be better than that of the PVD technique when used with drawing.

Disadvantages: limited suitability in the presence of small holes and channels.

Diesduringmachining

11

12

FACTORS wHICH MAy INFLuENCE THE SERvICE - LIFE OF MOuLdS

Corrosion Corrosion in moulds for die-casting is defined as the damage caused by the constraint that is created betwe-

en the steel of the mould and the molten metal with which it comes into contact.

The phenomenon depends mainly on temperature, which plays a fundamental role in the solubility of the

various chemical elements.

Corrosion, like gluing, is governed by the formation of inter-metallic phases (two metallic elements mixed

together in precise proportions, which enable stacking of the elements of a crystalline structure that dif-

fers from the two initial ones).

Furthermore, the formation of hot cracks enables, for example, aluminium injected under pressure, to pene-

trate into these cracks and to grip onto the moulds, thereby damaging their operation.

ABrAsion Abrasion is caused by the presence of hard particles, which remove and abrade the surfaces of the moulds

with which they come into contact. The pressure exerted by the material to be moulded, and its temperature,

determine the speed of wear. The most critical geometries of the moulds are those which create the greatest

rubbing, such as continuous changes of section and sharp edges.

If the surface hardness of the mould is very high, it is therefore possible to overcome these shortcomings.

For example, with PVD coatings, hardness can reach 2200 HV and above, which is twice the hardness ob-

tainable by nitriding: so this will, without doubt, be able to prevent wear.

thermAl ChoC The repeated heating and cooling cycles which moulds undergo during die-casting result in alternating

expansion and contraction. The surfaces in contact with the metal to be moulded heat up and increase in

volume, thereby producing compression forces. When there is no longer contact with the moulded parts, the

hot surfaces are often cooled suddenly (this is not recommended when the moulds are at a temperature of

over 150-200 C), forcing the steel to contract by tensile forces.

The more frequently this expansion and contraction occurs, the greater the progressive damage to the surfa-

ce. In practice, preference tends to be given to steels with a high hot elastic limit and good fatigue resistance,

but, above all, the moulds must be heated to a uniform temperature of at least 300 C before being brought

into service. This operation has two advantages: C before putting them into service. This operation has two

advantages: reducing the fragility caused by temperature changes and reducing the thermal gradient betwe-

en the surface and the core, which is the cause of thermal fatigue.

13

differenCes BetWeen hot-WorK And Cold-WorK tool steels Tool steels for Hot-Work (operating temperature between 450 C and 650 C) must possess: good workability of the tool in the annealed state and, in some cases, when quenched and tempered good dimensional stability during heat treatment high resistance to hot wear good resistance to temperature changes and heat fatigue/stress good mechanical strength and toughness at high temperatures

Tool steels for Cold-Work (operating temperature less than 200 C) must possess: high levels of hardness (reachable in many cases with high carbon content) excellent toughness excellent resistance to wear and cutting excellent depth of hardening

Dieduringfinishingphase

14

TIPS ON AvOIdING dAMAGE TO MOuLdS

DEFECT CHARACTERISTIC CAUSE CORRECTIVE ACTION

Overheating Failure at edges due to fusion at the edges of the grain.

Material kept at temperatures for too longor at temperatures which are too high.

Do not keep at temperatures for longer than necessary to heat the core and use the transformation temperatures recommended in the data sheets

Hardening cracks

Cracks during hardening.

Structural transformation not completedor presence of residual austenite.

Carry out subcooling during tempering.

Transformation still in progress at endof hardening.

Start tempering immediately.

Presence of sharp edges near section changes.

Use wide radiuses of curvature and mild means of cooling.

Means of tempering too drastic. Quench in polymer or oils baths.

Irregular failure. Non-uniform heating.

Carry out pre-heating, with pauses, before reaching the austenitization temperature (hardening).

Over-heating. Reduce austenitization temperature.

Tempering cracks Very thin and generally straight discontinuities.

Sudden temperature changes due tointroduction of moulds into high temperature furnaces.

Carry out pre-heating, with pauses, which slow down the stresses before reaching the desired tempering temperature.

DecarburizationRemoval of carbon from surface of material.

Steel placed in contact with oxidising atmospheres and high temperatures.

Ensure adequate machining allowance. Protect moulds with suitable paints. Use furnaces with controlled atmospheres.

DeformationsAlteration of initial shape and dimensions.

Non-uniform heating.Carry out pre-heating at max. 50C/h and homogenisation pause

Cooling too drastic. Cool with less drastic means, e.g. oil, forced air

Incorrect position during heat treatment.Optimise supports and, when possible, heat and temper in vertical position.

Deformation or machining stresses.

Take breaks at 450-500 C, annealing and stress relief before hardening. Pre-rough machining with at least 4 mm of machining allowance, harden and temper and then move to finishing phase.

Internal defects

Porosity and cavities inside mould

Reduction Ratio (r.r.) incorrect.For forged products apply r.r. > 3.5:1and for rolled products r.r. > 6:1

Blowholes Material manufactured withunsuitable casting.

Use vacuum cast steels, E.S.R. or V.A.R.Repair defects with suitable welding techniques TIg (Tungsten Inert gas) or MMA (Manual Metal Arc).

Irregular hardness Low hardness value.

Presence of decarburization. Eliminate the decarburated zone and repeat check.

The material has not reached the austenitization temperature.

Check that the hardening temperature is as established for the type of steel to be heat treated.

kept at inadequate temperature.For the hardening phase the recommended time at temperature is h per inch of thickness; for tempering 1 h per inch of thickness.

Insufficient hardening. Use means of quenching with a higher heat exchange.

15

DEFECT CHARACTERISTIC CAUSE CORRECTIVE ACTION

Irregular hardness

Low hardness value.

Unsuitable cooling

Check that the weight of the hardening baths is at least 10-15 times that of the pieces to be hardened.Check that the baths are agitated and that vapour pockets do not form.Check that the temperature of the baths (water, polymer and oil) is not greater than 49 C at the end of hardening.

Unsuitable temperingtemperature

Check that tempering temperature is not too high.

High hardness value.

Presence of segregations Carry out homogenisation annealing before hardening.

Low temperingtemperature

Check that temperature is as established to obtaindesired hardness.

Thermal fatigueBreakage or failure during operation.

Loss, by the steel, of the initial mechanical characteristics.

Check that the type of steel used and its structure is as specified.

Temperature variations and dynamic loads repeated over time. Combat the phenomena with nitriding treatments,

PVD, CVD.Expansion of material when heated and contraction when cooled

Inclusions Impurities (oxides, sulphurs, aluminas etc.) embedded in the steel.

They can dissolve in the presence of aggressive materials leaving micro-craters. They are harmful in the photoengraving and polishing processes.

Specify high micro-purity steels, e.g. ESR or VAR.Repair with suitable welding, e.g. TIg or MMA.

Lack of toughness Tendency to become brittle.

Long temperature breaks between 200 and 400 C results in loss of cementite at the grain edges.

Avoid breaks and cross the temperature range quite fast.

grain coarsening.Check that forging, rolling, hardening temperatures, etc. are not too high

Failure in operation

Crash.

Sudden failure of the mould.

Pre-heat the moulds to 300C before use.Do not cool tools suddenly after use.Check that the steel is as specified by the designer and that it has undergone suitable heat treatment

Unsuitable reduction ration.

See internal defects.When possible, the fibres of the material should be worked perpendicular to the direction of greatest stress to which the mould is subjected.

Witness marks Traces of coarse surface.Loss of height of press during forging or marks of rolling rollers

Increase the machining allowance.Carry out cosmetic- welding.

WearParts of the mould abraded by particles of very hard material.

Loss of efficiency of the work surface due to continuous use.

Carry out hardening aimed at reducing the friction (nitriding or PVD, CVD coatings).

16

Injectionmoulds

17

POLISHING ANd PHOTOENGRAvING

The profile of a mould polished with a mirror-like finish may be adversely affected by subsequent photoen-

graving, since the lapping, carried out with special pastes, leaves a surface film. This invisible layer, which is

very oily, may be removed by chemical products, but these may adversely affect the sheen of the polishing.

If the chemical treatment is particularly aggressive, it may result in harmful oxidation.

A high-quality surface finish has the following advantages:

it facilitates extraction of the moulded piece; it reduces the risk of triggering cracks due to overloading or fatigue (a rough profile favours local increase of the forces);

it reduces the risk of local corrosion (a rough profile has greater reactivity compared to a smooth profile because there is an increase in the surface area exposed to the corrosive environment);

it increases wear-resistance, within certain limits (removing rough peaks increases the contact area betwe-en the parts and improves the distribution of forces improbe)

SYMBOLS AND LEVEL OF FINISHINgRa m Rt m Rz m Conventional symbols Surface description.0.025 0.25 0.1

Superfinishing. Polishing with diamond paste.

0.05 0.5 0.20.1 0.8 0.4 Lapped, high level of finish, perfectly smooth.0.2 1.6 0.8 Lapped for seal joints.0.4 2.5 1.6 ground, electric spark machining.0.8 4 3.2 Extra fine with machine tools.1.6 8 6.3 Very smooth with machine tools.3.2 16 12.5 Smooth with machine tools.6.3 25 25 Medium with machine tools.12.5 50 50 Coarse with machine tools.25 100 100 ~ Raw.50 -- 200 ~ Raw.

- Roughness is the series of micro-geometrical imperfections present on a surface prepared with any

machining process.

- Roughness is measured on the surface in a transversal direction to the main grooves.

- Roughness Ra is expressed in m.

lenghtofsection

measuredprofile

mean line

TOOL STEEL wELdING

Optimizing the life-cycle of a tool is a common need for all users. The possibility of restoring a worn mould,

modifying the geometry of a matrix or adjusting machining errors in tool-making ensures that production

resources are managed to best effect. From this point of view, correctly performed tool steel welding offers

many advantages.

In spite of substantial progress made through years of research and study of welding processes, tool steel

welding operations require specific preparation and skill.

For this reason, we recommend that you follow the instructions given in this technical sheet, without omit-

ting the most important element; the skill and technical preparation of the welder, his qualifications and the

suitability of the welding equipment.

Key fACtorsDuring steel welding, it is important to remember that the weld deposit should behave in a similar way to

the base metal. This is a fundamental need for tool steel in order to avoid behavioural heterogeneity.

hArdness And toughnessHardness and toughness of the weld joint are the most significant parameters for evaluating the success of

the weld.

A significant shift of these two properties, in comparison with those of the base steel, could compromise the

solidity of the component.

high temperAture resistAnCeIn case of welding on hot work tools, the welded areas have to exhibit the same heat-resistance properties

as the base steel.

With a carefully selected filler metal and appropriate pre- and post-welding heat treatment, it is possible to

obtain deposit material with the right mechanical properties to provide optimum resistance to external stress.

phot-etChABility And polishABilityWhen working on moulds for plastic, it is necessary to choose the electrode according to surface finish

required for the final moulded parts. In the case of photo-etched moulds, it is imperative that the weld be

invisible, otherwise the moulded piece will be rejected; the same applies to specular polished moulds. We

recommend that you follow the operating instructions given in this technical sheet, and use the suggested

consumables.

[source Lucchini RS ]

18

19

MAIN WELDINg TECHNIQUES USED IN THE TOOL STEEL FIELD (MMA, TIg AND LASER)

MMA (Manual Metal-Arc Welding) is probably the best known technique.

The welding process is performed by creating a voltage difference between the electrode and the work

piece to be welded. By bringing the two parts into contact, a short circuit is created, with subsequent local

overheating caused by the Joule effect on the electrode. The latter starts to melt and to deposit material on

the work piece. Under these conditions, a modest voltage is sufficient to strike an electric arc for the welding

process.

The electrodes used in MMA welding have a surface layer that deoxidizes and purifies the molten pool,

protects it against airborne contamination and enriches it with alloy elements. Arc welding is recommended

in many and diverse situations, especially when a high quantity of filler material needs to be deposited.

TIg (Tungsten Inert gas) welding is an autogenous process, where the heat is generated by the arc between

the non-consumable tungsten electrode and the work piece. Tungsten is particularly well suited to this kind

of application because of its very high melting point and its excellent thermionic properties. The welding

takes place in a protected atmosphere by virtue of the shielding effect of an inert gas, such as Argon.

By means of this process, it is possible to weld with or without filler material, as in the case of low-thickness

work. The electrode has a circular section and dimensions and chemical composition compatible with the

base metal.

The LASER technique is used for micro-welding to adjust machining errors in tool-making, to modify work

piece design, to recover tooling damaged during service and to repair incidental surface defects. The main

advantages of the laser technique are as follows:

possibility of operating on small areas with minimum filler material; minimum invasive effect on the areas surrounding the welded spot (transition zone); speed of execution, because usually there is no need for core heat treatment before and after welding; high polishability and photo-etchability on the welded area; possibility of carrying out the work with the piece in situ.

MMATechnique TIGTechnique LASERTechnique

20

LASER (Light Amplification by Simulated Emission of Radiation) is an electromagnetic wave beam, moving in

the same direction and producing very high specific powers (107-109 W/cm2).

Unlikely other welding techniques, laser welding can be executed without filler material.

In the case of tool steel, Laser welding is always executed with filler material, in the form of a wire with a che-

mical composition compatible with the base material and with a diameter of 0.2-0.8 mm.

The predominant heat transmission mechanism is conduction. The possibility of focusing its action on a very

restricted area is one of the most advantageous features of Laser welding.

It is possible to operate on very small areas, of even less than 1-2 mm . So micro-welding can be used to remedy

even defects measuring less than a tenth of a millimetre deriving from mechanical grinding.

PhotoengravingDie

21

CHOICE OF wELdING TECHNIquE

The choice of welding technique depends on many factors, ranging from metallurgical to economic and

logistical.

MMA Welding is ideal for work requiring the deposit of a high quantity of material. For example, it is parti-

cularly suitable for modifying the shape of a mould to accommodate a variation in piece design.

Furthermore, because of its easy transportability, welding can be performed on site with no need to disman-

tle or transport the mould. This technique generates considerable heat in the areas adjacent to the welded

spot; it is therefore necessary to take good care of pre-heating and stress relieving procedures.

TIg welding is suitable for smaller repairs on moulds compared with the MMA technique, and generates

less heat.

TIg equipment is less portable than MMA, because of its jet shielding and torch cooling system.

LASER welding is suitable for making repairs with a minimum deposit of material. It is recommended when

the required deposit

thickness is from 0.2 mm to 1-1.5 mm and with a size in proportion to the welded thickness.

mmA Welding eleCtrodesArc-welding electrodes are covered with a layer of material that varies according to the kind of the end use.

The most common coatings are as follows: Acid, Rutilic, Cellulosic and Basic.Acid coating is formed by iron oxide, iron alloys of Mn-SI and silicate. Such electrodes have good weldability and easily removable slag. In case of multiple welding runs, we recommend that you remove the slag genera-

ted by the previous weld layer. Acid coating cannot withstand high drying temperatures. For this reason, it is

not possible to remove all traces of moisture, thus increasing the risk of cracking in cold conditions.Rutilic coating is formed by titanium dioxide, also known as rutile, which gives the deposit high fluidity and an excellent aesthetic appearance. As with acid coating, these electrodes should be avoided if there is a risk

of crack formation in hot or cold conditions.Cellulosic coating is formed basically by cellulose and by Mn and Si. These electrodes, like basic ones, can generate melted pool at high temperature. During melting a high hydrogen content develops within the

coating, thus increasing the risk of crack formation in cold conditions.

Basic coating is formed by iron oxides, iron alloys of Mn-Si, silicates and calcium carbonate and magnesium,

and also fluorite. The presence of carbonates eliminates all impurities, such as sulphur and phosphor, from

the pool, thus giving the deposit a high level of purity and excellent mechanical properties. Basic electrodes

can be dried at high temperatures, thus reducing the risk of crack formation in cold conditions. We recom-

mend drying the electrode at high temperature before the use, and keep it warm even after removal from

the oven. This last category of electrode is the most recommended for tool steel welding.

All coated electrodes are sensitive to moisture, therefore we recommend that you take good care of storage

22

procedures. It is good practice to keep consumables in a temperature- and moisture-controlled room and

to keep the electrode warm in a small oven before use. For further details, please refer to technical sheets

supplied by the electrode manufacturer.

tig Welding eleCtrodesTIg welding electrodes generally have a very similar chemical composition to the base metal with the addition of

a small quantity of deoxidizers. Unlike coated electrodes used in MMA welding, they do not suffer from problems

relating to moisture absorption from the atmosphere. However, it is recommended that you keep them in dry

and protected places.

lAser Welding eleCtrodesLaser welding electrodes are very similar to those used in TIg welding, but have a smaller diameter section.

The most widely used sizes are from 0.2 mm to 0.8 mm, according to application.

Their chemical composition is modulated according to the desired mechanical properties to be achieved.

reCommended operAting proCeduresWe recommend that you assign mould repair work to Personnel of proven expertise in possession of suita-

ble equipment. For all tool steels that have to be welded, a pre-heating and stress relieving cycle has to be

scheduled in order to avoid the risk of dangerous cracks.

pre-heAtingPre-heating treatment of the final piece is a very important phase of the welding process. If oven pre-heating

of the mould is not possible due to size and/or for logistical reasons, pre-heating with thermal blankets is

permissible. We discourage pre-heating by means of a torch or flames because this technique does not gua-

rantee a controlled temperature and can modify the microstructure of the steel; it also generates potentially

dangerous residual tensions in the piece. Pre-heating must be used for all tool steel welding, except in the

above-mentioned situations. During pre-heating, adhere to temperature increase rates of not more than

50C/h and dwell times of one hour for every 25 mm of piece thickness.

post-Welding heAt treAtmentThe aim of post-welding heat treatment is to relieve stress on the material and to restore the former mechani-

cal properties of the piece. It is an extremely important phase within the welding process, which considerably

influences the operating behaviour of the element. In this case too, whenever a treatment of the entire piece

is not possible in a proper oven, you can execute local stress relief by means of thermal blankets or inductors.

The use of torches, flames or similar techniques is not recommended. The recommended post-welding heat

treatments are listed in the attached tables. For further details, refer to the technical sheets of each steel.

23

surfACe prepArAtion guidelinesSurface preparation plays a decisive role in the welding process. We recommend always removing any trace

of dirt and rust before starting to weld, and avoiding welding in the vicinity of sharp corners. When repairing

cracks, it is necessary to grind the defective area and join it. The minimum recommended angle is 30 and

the joint groove has to be 1.5 mm larger than the diametric section of the electrode to be used. We also

recommend testing with penetrating fluids or magnetic testing on the whole area to be welded, in order to

locate possible surface defects, which have to be removed by grinding.

lAyer sequenCe proCeduresgenerally it is not advisable, even if the filler material is limited, to weld in a single run, insofar as two or

more runs are preferable. In this case, we recommend that you proceed as follows:

with the first run a layer should be deposited with a small diameter electrode and with a low current, thus limiting the size of the heat-affected area;

the second run should be performed with the same parameters as the previous one and aims to temper the first layer below in order to restore its toughness;

subsequent runs can be carried out with a higher current and a larger diameter electrode; the final run has to create a higher layer than the work piece surface level.It is good practice to hold the electrode at an angle of 70 - 80 to the direction of forward movement.

Control teChniquesAfter welding, a non-invasive control is recommended, such as ultrasound testing, testing with penetrating

fluids or magnetic testing. The choice depends on the kind of welding and the operating conditions. Our

technical support service can assist you in determining and defining the most appropriate control method.

Ceq CArBon equivAlent perCentAgeC + Mn / 6 + (Cr + Mo + V) / 5 + (Ni + Cu) / 15 (general use formula).For cool welding without stress relief do not exceed values of 0.40 - 0.43.

Above these values, pre-heating and stress relief are necessary in order to avoid the risk of dangerous cracks.

C + Mn/4 + Si/4 (Carbon steel formula). We suggest 0.42 as a maximum value for cool welding without stress relief. Above this value, please refer to general use formula.

Layersequenceprocedures.Inspectionarea.Surfacepreparation.

Areatocheckbeforetoweld

24

suggested operAting pArAmeters for Welding

INTERNAL CODE

WERkSTOFF EN WELDINg TECHNIQUES

MMA TIg LASER

EskyLos 2083 1.2083 X40Cr14 AWS A5.4 E410-15EN 1600 E 13 B 53

AWS A5.9 ER410 SALTEX Cr13 INOX

BeyLos 2083 / II40 1.2083 X40Cr14

II33 1.2085 X33CrS16 given the presence of sulfur is not recommended for welding

keyLos 2311 / BP35 1.2311 40CrMnMo7 AWS A5.5 E8018 AWS A5.28 ER 80S SALTEX 300SALTEX 300 PHOTOSALTEX 300 MIRRORkeyLos 2312 / BS35 1.2312 40CrMnMoS8-6

BeyLos 2329 1.2329 46CrSiMoV7 1) 4) 1) 4) --

EskyLos 2343 / BP 37 1.2343 X37CrMoV5-1 DIN 8555 E3-UM-50-ST1)

AWS A5.28 ER80S-B6 SALTEX 400SALTEX 460SALTEX Hot WorkEskyLos 2344 / BP40 1.2344 X40CrMoV5-1

BP30 1.2365 32CrMoV12-28 QRO 90 WELD

EskyLos 2367 ESR 1.2367 X38CrMoV5-3 DIN 8555 E3-UM-50-ST1)

AWS A5.28 ER80S-B6 SALTEX 400SALTEX 460SALTEX Hot Work

BP57 1.2711 54NiCrMoV6 UTP 73g4 UTP 73g4 ESAB Ok

BeyLos 2714 / BP56 1.2714 55NiCrMoV7 DIN 8555 E1-UM-350 AWS A5.28 ER 80S-B2AWS A5.28 ER 90S-B3

SALTEX 400SALTEX 300 PHOTO

keyLos 2738 / BP36 1.2738 40CrMnNiMo8-6-4 AWS A5.5 E9018-B3 AWS A5.28 ER 80S-B2 SALTEX 300

BF40 1.2767 45NiCrMo16 1) 4) 1) 4)

keyLos 6959 1.6959 35NiCrMoV12-5 1) 4) 1) 4)

ABP20 Euras 1) 4) 1) 4)

EskyLos 2001 Lucchini RS 2)

keyLos on Lucchini RS AWS A5.5 E8018-B2 AWS A5.28 ER 80S-B2

keyLos up Lucchini RS AWS A5.5 E8018-B2 AWS A5.28 ER 80S-B2

keyLos plus Lucchini RS AWS A5.5 E8018-B2 AWS A5.28 ER 80S-B2

25

INTERNAL CODE

WERkSTOFF EN WELDINg TECHNIQUES

MMA TIg LASER

B155 1.2379 X153CrMoV12 INCONEL 625 UTP 67S - CASTOLIN 6

B110 1.2516 120WV4 UTP 75 UTP A696

BF90 1.2842 90MnCrV8 UTP: 65D, 73 g2, 673

B TEN TENASTEEL INCONEL 625 UTP 67S - CASTOLIN 6

S355J2g3 1.0577 S355J2g3 AWS A5.5 E8018-C1

C20 1.1151 ~ C20E AWS A5.1 E6013

C25E 1.1158 C25E AWS A5.1 E6013

C30E 1.1178 C30E AWS A5.1 E6013

C45E BC45 1.1191 C45E AWS A5.1 E7018 AWS A5.1 E7018-1

AWS A5.18 ER 70S-6EN 1668 W3Si1

C50E 1.1206 C50E AWS A5.1 E7018

39NiCrMo3 / BC3930CrNiMo842CrMo4

1.65101.65801.7225

39NiCrMo3 30CrNiMo842CrMo4

AWS A5.5 E8018-B2AWS A5.5 E9018-B3

AWS A5.28 ER 80S-B2 SALTEX 300SALTEX 300 PHOTOSALTEX 300 MIRROR

41CrAlMo7-10 1.8509 41CrAlMo7-10 1) 3) 4) 1) 3) 4)

18NiCrMo5 UNI 1) 3) 4) 1) 3) 4)

41CrAlMo7-10 1.8509 41CrAlMo7-10 1) 3) 4) 1) 3) 4)

52SiCrNi5 1.7117 52SiCrNi5 not recommended

1) Please address to qualified producers.2) MMA Welding Repairing is not recommended for this kind of steels.3) Carry out the welding before superficial hardening using filler material with chemical composition similar to mold.4) UTP 641 kB (HB 250) - UTP 73g4 (HRC 40) - UTP 73g3 (HRC 45) - UTP 641 73g2 (HRC 55)

26

Machiningdepthonadie Finishedmould

27

TOOL STEELS

hot-WorK tool steels This category of steels must have special characteristics: resistance to non-continuous heat (450-600 C)

and insensitivity to coarsening, which happens when the material is exposed to high temperatures for long

periods of time. For special uses, where temperatures can reach 600 C, the steels normally contain a high

percentage of tungsten (18%). They are used for high-pressure dies and pipe expanders. The fields of use

include general moulds, moulds for die-casting and spindles for rolling mills. Nickel-chrome-molybdenum-

vanadium steels have good toughness even when hot and resist well to heat variations and tempering.

The main enemies for the productivity of dies have always been wear, failure and maintenance work, therefore

close contact between manufacturer and customer is needed to agree upon and optimise costs and quality.

Cold-WorK tool steelsThe particular characteristic of steels is their high carbon content, which gives the tools a high level of hardness. Their

use tends to be concentrated in those sectors in which wear, impact and shear stressess are present. Their main charac-

teristics are: hardness, toughness, wear resistance and hardenability. The hardness of steels for cold-work varies from

52 to 63 HRC, whilst the hardness for hot-work steels ranges from 36 to 54 HRC.

Alloy elements used in decreasing order of use they characterize

Mn-Mo-Cr-Si-Ni-V hardening depth

V-W-Mo-Mn-Cr strength

V-W-Mo-Cr-Mn resistance to wear

Mo-Cr-Mn dimensional stability

Pre-heating is recommended for these steels with thermal rates of no more than 50 C/hour and pause for homogeni-

zation before reaching the forging and quenching temperature.

Holding time at the pre-set temperatures are: h for every 25 mm of thickness during quenching and 1h every 25 mm

of thickness during tempering or stress relieving.

For cold-working steels, at least one phase of stress relieving is recommended before quenching, which must be im-

mediatelly followed by tempering when the material is still at a temperature of approximately 150 C. Moreover, after

tempering, cooling must be slow, to prevent both internal and external stresses. All the neccessary measures must then

be taken to prevent carbide precipitation along grain boundaries. It should be noted that sharp edges and significant

changes in section can generate cracks during quenching.

At least two tempering operations and protection with suitable paints must be provided for these steels, before

quenching. This will prevent decarburization, which, besides being harmfool for a number of well-known reasons, may

also influence results during the hardness control. generally, if the decarburized layer is not eliminated, there will be

abnormal values, which tend to be the low side.

28

STEELS FOR CONSTRuCTION ANd GENERAL uSES

The above category includes the steels listed below.

As indicated by the term, general use, this category includes all the main support elements, including

frames, systems, superstructures and all parts required to shape components, devices and mechanisms of

operating machines and the like.

These steels are easily processed both hot and cold. They have excellent hardening penetration and high

resistance to knocks.

S355J2 Shafts, machine parts subject to low stress, nuts and bolts, screws, levers, plugs, pins, bushes, joints, discs, small punches.

C20 Shafts, machine parts, toothed racks, nuts and bolts, bushes, automatic mechanisms, clutch pedals, mechanical parts.

C30E Shafts, machine parts, toothed racks, nuts and bolts, mechanical parts, bushes, automatic mechanisms, clutch pedals.

C50E Splines, toothed racks, crank shafts, rods and columns for presses, mechanical parts.

C45E Vacuum-processed steel, excellent for photoengraving, polishing, nitriding and welding, strong resistance to wear. Applications: small moulds for the car and food industries,

moulds for rubber moulding, moulds for compression moulding of thermosetting

compounds (SMC Sheet Moulding Compound, BMC Bulk Moulding Compound),

mould holders.

42CrMo4 High strength and mechanical properties, good machinability and micro-purity. Uses: small and medium sized moulds, moulds for the car and food industries, moulds for rubber

moulding, moulds for compression moulding of thermosetting compounds (SMC Sheet

Moulding Compound, BMC Bulk Moulding Compound), moulds holders and mechanical

parts generally.

39NiCrMo3 Easily heat-treated, this is the most common Italian hardened alloy steel. good machinability, excellent resistance to dynamic stress and torsional stress, easily

nitrided. Uses: gears, even large shafts, machine parts, tie rods, mould holders and

integral moulds.

29

30CrNiMo8 High strength and mechanical properties, good machinability and micro-purity, high resistance to stress even at working temperatures of up to 350 C, insensitive to

tempering brittleness, particularly suited for pieces subject to torsional stress. Uses:

medium sized moulds, moulds for the car and food industries, moulds for rubber

moulding, moulds for compression moulding of thermosetting compounds (SMC Sheet

Moulding Compound, BMC Bulk Moulding Compound), mould holders and

mechanical parts generally.

nitriding steelsThe peculiarity of nitrided steels is their high resistance to friction, even at high temperatures, up to 500 C.

It follows that, in poorly lubricated machine parts, the effect of fretting causes less damage than would occur

with case hardened pieces. A further features is its high resistance to sea water and steam.

The steel is treated in perfectly sealed, controlled-temperature furnaces, as harmful oxidation occurs on

contact with the air. The main component in this operation is gaseous ammonia, distributed uniformly. Ther-

mal hardening is recommended on rough-shaped materials free of any stress, polishing, cleaning, drying,

nitriding and final grinding.

41CrAlMo7-10 Applications: the field of extruded plastics, screws and extrusion cylinders, eccentric shafts, discs, injection pumps, pins and steam distribution chambers.

CAse-hArdening steelsA feature of these steels is their low carbon content, which assures a strong core after hardening and

tempering and good machinability after annealing. The steel is processed prior to case hardening and the

subsequent hardening and tempering phases.

18NiCrMo5 Use: gear parts subject to high stress and cam shafts.

spring steelsSprings are machine parts which must be made of steel which possesses the highest possible elastic deformation

capacities and the ability to withstand repeated stress.

52SiCrNi5 The inclusion of silicon increases hardenability and, consequently, hardness, increasing the elastic modulus. High hardenability steel.

The inclusion of nickel greatly improves strength.

30

ESR = ELECTRO SLAg REMELTINg

steels CompArison tABles

INTERNAL CODE WERkSTOFF N EUROPE EN CHINA gB RUSSIA gOST USA AISI-SAE USE

EskyLos 2083 ESR 1.2083 X40Cr14 ~ 420

HOT

WO

Rk TO

OL

STEE

LS

BeyLos 2083 / II40 1.2083 X40Cr14 ~ 420

II33 1.2085 X33CrS16

keyLos 2311 / BP35 1.2311 40CrMnMo7 (5CrMnMo)

keyLos 2312 / BS35 1.2312 40CrMnMoS8-6

BeyLos 2329 1.2329 46CrSiMoV7

EskyLos 2343 / BP 37 ESR 1.2343 X37CrMoV5-1 4Cr5MoSiV 4Ch5MFS H11

BeyLos 2343 1.2343 X37CrMoV5-1 4Cr5MoSiV 4Ch5MFS H11

EskyLos 2344 / BP40 ESR 1.2344 X40CrMoV5-1 4Cr5MoSiV1 4Ch4VMFS H13

BeyLos 2344 1.2344 X40CrMoV5-1 4Cr5MoSiV1 4Ch4VMFS H13

BP30 1.2365 32CrMoV12-28 4Cr3Mo3SiV 3Ch3M3F H10

EskyLos 2367 ESR 1.2367 X38CrMoV5-3

BP57 1.2711 54NiCrMoV6

BeyLos 2714 / BP56 1.2714 55NiCrMoV7 4ChMNFS

keyLos 2738 / BP36 1.2738 40CrMnNiMo8-6-4

BF40 1.2767 45NiCrMo16 45Ch2N4MA

keyLos 6959 1.6959 35NiCrMoV12-5 38ChN3MFA

ABP20 Euras

EskyLos 2001 Lucchini RS

keyLos on Lucchini RS

keyLos up Lucchini RS

keyLos plus Lucchini RS

31

INTERNAL CODE WERkSTOFF N EUROPE EN CHINA gB RUSSIA gOST USA AISI-SAE USE

B205 1.2080 X210Cr12 Cr12 Ch12 D3

COLD

WO

Rk TO

OL

STEE

LS

B155 1.2379 X153CrMoV12 Cr12MoV D2

B110 1.2516 120WV4

BF40 1.2767 45NiCrMo16 45Ch2N4MA

BF90 1.2842 90MnCrV8 9Mn2V O 2

B TEN TENASTEEL Tenasteel

S355J2g3 1.0577 S355J2g3 17g1S A350 LF2

gEN

ERAL

USE

AN

D CO

NST

RUCT

ION

STE

ELSC20 1.1151 ~ C20E 20 20A 070M20

C25E 1.1158 C25E 25 25 1025

C30E 1.1178 C30E 30 30 1030

C45E / BC45 1.1191 C45E 45 45 1045

C50E 1.1206 C50E 50 50 1050

39NiCrMo3 / BC39 1.6510 39NiCrMo3 39HNM 9840

30CrNiMo8 1.6580 30CrNiMo8 A320L43

42CrMo4 / BC42 1.7225 42CrMo4 42CrMo 40ChML A193-B7

41CrAlMo7-10 1.8509 41CrAlMo7-10 38CrMoAl 40X2MI-O J24056-E71400

NITRIDINg

18NiCrMo5 / BC18 UNI CASE HARDENINg

52SiCrNi5 1.7117 52SiCrNi5 Zg50CrMo 52XHC SPRINg STEELS

32

hArdness Conversion tABleHV - HRC and HRC-HV-HB-HRA-HRB-Rm for carbon / alloy steels (in accordance with table in ASTM A 370 - 03A)

HV HRC HV HRC HV HRC HV HRC HV HRC2270 85 1950 81 1633 77 1323 73 1004 692190 84 1865 80 1556 76 1245 72 940 682110 83 1787 79 1478 75 1160 71 920 67,52030 82 1710 78 1400 74 1076 70 900 67

HRCDiamond penetrator

HVVickers 30

HBBrinell 3000 kgf

HRADiamond penetrator

RmN/mm2

MPa

HRBBall1/16

HVVickers30

HBBrinell 3000 kgf

HRADiamond penetrator

RmN/mm2

MPa68 940 -- 85.6 -- 100 240 240 61.5 80067 900 -- 85.0 -- 99 234 234 60.9 78566 865 -- 84.5 -- 98 228 228 60.2 75065 832 739 83.9 -- 97 222 222 59.5 71564 800 722 83.4 -- 96 216 216 58.9 70563 772 706 82.8 -- 95 210 210 58.3 69062 746 688 82.3 -- 94 205 205 57.6 67561 720 670 81.8 -- 93 200 200 57.0 65060 697 654 81.2 -- 92 195 195 56.4 63559 674 634 80.7 2420 91 190 190 55.8 62058 653 615 80.1 2330 90 185 185 55.2 61557 633 595 79.6 2240 89 180 180 54.6 60556 613 577 79.0 2160 88 176 176 54.0 59055 595 560 78.5 2070 87 172 172 53.4 58054 577 543 78.0 2010 86 169 169 52.8 57053 560 525 77.4 1950 85 165 165 52.3 56552 544 512 76.8 1880 84 162 162 51.7 56051 528 496 76.3 1820 83 159 159 51.1 55050 513 482 75.9 1760 82 156 156 50.6 53049 498 468 75.2 1700 81 153 153 50.0 50548 484 455 74.7 1640 80 150 150 49.5 49547 471 442 74.1 1580 79 147 147 48.9 48546 458 432 73.6 1520 78 144 144 48.4 47545 446 421 73.1 1480 77 141 141 47.9 47044 434 409 72.5 1430 76 139 139 47.3 46043 423 400 72.0 1390 75 137 137 46.8 45542 412 390 71.5 1340 74 135 135 46.3 45041 402 381 70.9 1300 73 132 132 45.8 44040 392 371 70.4 1250 72 130 130 45.3 435

33

HRCDiamond penetrator

HVVickers 30

HBBrinell 3000 kgf

HRADiamond penetrator

RmN/mm2

MPa

HRBBall1/16

HVVickers30

HBBrinell 3000 kgf

HRADiamond penetrator

RmN/mm2

MPa39 382 362 69.9 1220 71 127 127 44.8 42538 372 353 69.4 1180 70 125 125 44.3 42037 363 344 68.9 1140 69 123 123 43.8 41536 354 336 68.4 1110 68 121 121 43.3 40535 345 327 67.9 1080 67 119 119 42.8 40034 336 319 67.4 1050 66 117 117 42.3 39533 327 311 66.8 1030 65 116 116 41.8 38532 318 301 66.3 1010 64 114 114 41.4 --31 310 294 65.8 970 63 112 112 40.9 --30 302 286 65.3 950 62 110 110 40.4 37029 294 279 64.6 930 61 108 108 40.0 --28 286 271 64.3 900 60 107 107 39.5 --27 279 264 63.8 880 59 106 106 39.0 36026 272 258 63.3 860 58 104 104 38.6 --25 266 253 62.8 850 57 103 103 38.1 35024 260 247 62.4 820 56 101 101 37.7 --23 254 243 62.0 810 55 100 100 37.2 34022 248 237 61.5 790 54 -- -- 36.8 --21 243 231 61.0 770 51 -- 94 35.5 33020 238 226 60.5 760 49 -- 92 34.6 320

Values shown in bold fall outside the ASTMtable but they are still reliable

Values shown in italics are due to passage from table 2to table 3 of ASTM A 370

Rockwell Hardness

HRC diamond penetrator 120 load 1470 N (150 kgf) duration 30 seconds

Rockwell Hardness

HRA diamond penetrator load 588 N (60 kgf)duration 30 seconds

Vickers Hardness

HV diamond penetrator 136load 294 N (30 kgf) duration 15 seconds

Rockwell Hardness

HRB ball 1/16load 980 N (100 kgf) duration 30 seconds

Brinell Hardness

HB ball 10 mm load 29.400N (3000 kgf) duration 15 seconds

Tensilestrength

Rm N/mm2 (Mpa)

34

hArdness Conversion tABleHB-HRC-HRB-HRA (applicable to stainless austenitic steels - in accordance with ASTM A 370 - 03A)

Hardness HRC150 - kgf

diamond penetrator

Hardness HRA60 kgf

diamond penetrator

Rockwell Superficial Hardness

15N Scale 30N Scale 45N Scale

diamond penetrator

48 74.4 84.1 66.2 52.1

47 73.9 83.6 65.3 50.9

46 73.4 83.1 64.5 49.8

45 72.9 82.6 63.6 48.7

44 72.4 82.1 62.7 47.5

43 71.9 81.6 61.8 46.4

42 71.4 81.0 61.0 45.2

41 70.9 80.5 60.1 44.1

40 70.4 80.0 59.2 43.0

39 69.9 79.5 58.4 41.8

38 69.3 79.0 57.5 40.7

37 68.8 78.5 56.6 39.6

36 68.3 78.0 55.7 38.4

35 67.8 77.5 54.9 37.3

34 67.3 77.0 54.0 36.1

33 66.8 76.5 53.1 35.0

32 66.3 75.9 52.3 33.9

31 65.8 75.4 51.4 32.7

30 65.3 74.9 50.5 31.6

29 64.8 74.4 49.6 30.4

28 64.3 73.9 48.8 29.3

27 63.8 73.4 47.9 28.2

26 63.3 72.9 47.0 27.0

25 62.8 72.4 46.2 25.9

24 62.3 71.9 45.3 24.8

23 61.8 71.3 44.4 23.6

22 61.3 70.8 43.5 22.5

21 60.8 70.3 42.7 21.3

20 60.3 69.8 41.8 20.2

35

Hardness HB3000kgf

ball 10 mm

Print mm

Hardness HRB100 kgf

ball 1/16

Hardness HRA60 kgf

diamond cone

N/mm2

for information a)

256 3.79 100 61.5 770

248 3.85 99 60.9 760

240 3.91 98 60.3 750

233 3.96 97 59.7 715

226 4.02 96 59.1 705

219 4.08 95 58.5 690

213 4.14 94 58.0 675

207 4.20 93 57.4 650

202 4.24 92 56.8 635

197 4.30 91 56.2 620

192 4.35 90 55.6 615

187 4.40 89 55.0 605

183 4.45 88 54.5 590

178 4.51 87 53.9 580

174 4.55 86 53.3 570

170 4.60 85 52.7 565

167 4.65 84 52.1 560

163 4.70 83 51.5 550

160 4.74 82 50.9 530

156 4.79 81 50.4 505

153 4.84 80 49.8 495

a) In stainless steels, the cold deformation created by the imprint may alter the hardness values.

Even a variation in the of just a few hundredths of a millimetre can affect the value.

Tensile testing is therefore recommended as the primary test to determine mechanical characteristics.

Dicembre 2010

gruppo Lucefin

via Ruc, 30 Esine (BS) Italy

www.lucefin.com

Progetto grafico: Parlatotriplo - gianico (BS)

Stampa: la Cittadina - gianico (BS)

Lucefin S.p.A.

25040 Esine (Brescia) ItalyTel. +39 0364 367700

www.lucefin.com