Presentation on Heat Treatments

7/23/2019 Presentation on Heat Treatments

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Introduction toIntroduction toHeat TreatmentsHeat Treatments


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What is HeatWhat is Heat

Treatment ?Treatment ? A combination of heating andA combination of heating and

cooling operation, timed andcooling operation, timed andapplied to a metal or alloy inapplied to a metal or alloy in

the solid state in a way that willthe solid state in a way that will

produce desired properties, andproduce desired properties, and

improve the exist properties.improve the exist properties.


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Purpose of HeatPurpose of Heat

TreatmentTreatmentTo relieve internal stresses.To relieve internal stresses.

To decrease extra hardness.To decrease extra hardness.To improve the Ductility.To improve the Ductility.

To obtain the homogeneousTo obtain the homogeneous

microstructure.microstructure.

To obtain the desired physicalTo obtain the desired physical

propertiesproperties


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Types Of HeatTypes Of Heat

TreatmentTreatment AnnealingAnnealing

NormaliingNormaliing

HardeningHardening

TemperingTempering

!tress "elieving!tress "elieving #arburiing#arburiing

NitridingNitriding


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AnnealingAnnealing


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AnnealingAnnealing

This process consists of heating theThis process consists of heating the

steel to austenitising temperature $%&'steel to austenitising temperature $%&'

( )*& deg #+ and cooling slowly to room( )*& deg #+ and cooling slowly to roomtemperature to reduce hardness andtemperature to reduce hardness and

improve machinability.improve machinability.


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Solution AnnealingSolution Annealing


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Solution AnnealingSolution Annealing

!olution annealing consists of austenitising!olution annealing consists of austenitising

stainless steel at '-' ( &' deg # andstainless steel at '-' ( &' deg # and

cooling very fast by uenching in air $or+cooling very fast by uenching in air $or+

water.water.

/.g. #0%, #0%1, #02, #021, -A, &A/.g. #0%, #0%1, #02, #021, -A, &A


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NormalizingNormalizing


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NormalizingNormalizing

Normaliing consists of heating aNormaliing consists of heating a

ferrous alloy %3& ( )&' deg #ferrous alloy %3& ( )&' deg #

temperature followed by cooling in stilltemperature followed by cooling in stillair to room temperature. /g4 5#6,air to room temperature. /g4 5#6,

A'&A'&


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HardeningHardening


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HardeningHardening

It is the heat treatment in which materialIt is the heat treatment in which material

is heated up to austenitiing temperatureis heated up to austenitiing temperature

and then uenched it rapidly in water orand then uenched it rapidly in water oroil, to give the Hardness.oil, to give the Hardness.

The Hardening leads to increase inThe Hardening leads to increase in

Hardness 7 strength while ductilityHardness 7 strength while ductility

decreases.decreases. Hardening gives 1artensitic structure.Hardening gives 1artensitic structure.


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TemperingTempering


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TemperingTempering

It is the heat treatment where material isIt is the heat treatment where material is

heated below the critical temperature,heated below the critical temperature,

soa8 it for some time and then slowlysoa8 it for some time and then slowlycool it to room temperature.cool it to room temperature.

It increases the ductility and toughness.It increases the ductility and toughness.

It reduces hardness 7 strength somewhatIt reduces hardness 7 strength somewhat

but relieves the residual stresses.but relieves the residual stresses.


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Stress RelievingStress Relieving

Heating to a suitable temperature,Heating to a suitable temperature,

holding long enough to reduce residualholding long enough to reduce residual

stresses, and then cooling slowlystresses, and then cooling slowlyenough to minimie the developmentenough to minimie the development

of new residual stresses.of new residual stresses.


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!urface Heat Treatments!urface Heat Treatments

The chemistry of the material at surfaceThe chemistry of the material at surface

is changed in these processes.is changed in these processes.

They introduces the extra # , N to theThey introduces the extra # , N to the!urface. 9iving high hardness values at!urface. 9iving high hardness values at

surface but tough 7 softer at the core.surface but tough 7 softer at the core.

The processes areThe processes are #arburiing#arburiing

NitridingNitriding

#yaniding#yaniding


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CarurizingCarurizing


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CarurizingCarurizing

1aterial is heated up to1aterial is heated up to

austenitiing temperature in #: 7austenitiing temperature in #: 7

#:#:**atmosphereatmosphere And then after su;cient soa8ingAnd then after su;cient soa8ing

time it is uenched in water or oil.time it is uenched in water or oil.


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!"e#t of alloying!"e#t of alloying

elementselements Di, 5, #o, Al, !i, 1n.


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Purpose of AlloyingPurpose of Alloying

Improve HardenabilityImprove Hardenability

Improve strength at ordinary temperaturesImprove strength at ordinary temperatures

Increase wear resistanceIncrease wear resistance Improve corrosion resistanceImprove corrosion resistance

Improve toughness without a


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AluminumAluminum

It hardens the material by solidIt hardens the material by solid

solutioningsolutioning

It restricts grain growth.It restricts grain growth.

!trong gra=tier.!trong gra=tier.

Deoxidies the alloy.Deoxidies the alloy.


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ChromiumChromium

It increases hardenabilityIt increases hardenability

It increases resistance toIt increases resistance to

corrosion and oxidation.corrosion and oxidation. It gives strength at highIt gives strength at high

temperatures.temperatures.

9ives abbrasive 7 wear9ives abbrasive 7 wearresistance.resistance.


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CoaltCoalt

#obalt gives red hardness to the#obalt gives red hardness to the

alloy. That is the ability to retainalloy. That is the ability to retain

the hardness at elevatedthe hardness at elevatedtemperatures.temperatures.

Decreases hardenabilyDecreases hardenabily

Increases wear resistance.Increases wear resistance.


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$olydenum$olydenum

Increases corrosion resistance inIncreases corrosion resistance instainless steels.stainless steels.

9ives abrasion resistance.9ives abrasion resistance. Increases hardenability.Increases hardenability. ?essen the tendency of temper?essen the tendency of temper

brittleness.brittleness. It provides hardness by ageIt provides hardness by age

hardening system.hardening system.


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Ni#%elNi#%el

Increases the toughness of theIncreases the toughness of the

alloy at lower temperatures.alloy at lower temperatures.

Increases the strength to theIncreases the strength to the

alloy at lower temperatures.alloy at lower temperatures.

"etains austenite at room"etains austenite at room

temperature even if thetemperature even if the

chromium percentage is high.chromium percentage is high.


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&anadium&anadium

Increases hardenability.Increases hardenability.

It promotes =ne grain at elevatedIt promotes =ne grain at elevatedtemperature.temperature.

"esist tempering and causes"esist tempering and causes

secondary hardeningsecondary hardening


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TungstenTungsten

It gives hard and wear resistanceIt gives hard and wear resistance

particles to increase wearparticles to increase wear

resistance.resistance. It promotes hardness at elevatedIt promotes hardness at elevated

temperatures.temperatures.

It increases hardenability.It increases hardenability. It gives age hardening system toIt gives age hardening system to

the alloys.the alloys.


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TitaniumTitanium

It forms hard carbides whichIt forms hard carbides which

provides age hardening systemprovides age hardening system

in alloys.in alloys.

It prevents localied depletion ofIt prevents localied depletion of

chromium in stainless steelschromium in stainless steels

during long heating.during long heating.


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Sili#onSili#on

@sed as a deoxidier.@sed as a deoxidier.

Improves electrical 7 magneticImproves electrical 7 magnetic

propertiesproperties Increases hardenabilityIncreases hardenability

!trengthened low alloy steels.!trengthened low alloy steels.

Hardens the alloy with loss inHardens the alloy with loss inplasticityplasticity

Improves the oxidation resistance.Improves the oxidation resistance.


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$anganese$anganese

It reduces the brittlenessIt reduces the brittlenessoccurred by sulfur.occurred by sulfur.

Increases the hardenability.Increases the hardenability. Hardens the material byHardens the material by

reducing the plasticity.reducing the plasticity.


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HT of various 9radesHT of various 9rades

Normaliing

1aterial Temperature

A'& )'' ( )*' deg #

A%* 0, 0** )'' ( )*' deg # 5#6 )'' ( )*' deg #


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!tress "elieving!tress "elieving

1aterial1aterial TemperatureTemperature 5#6, A'&, ?#6, ?##,5# '' ( -' deg5#6, A'&, ?#6, ?##,5# '' ( -' deg

## A&& 9r.3' 7 A& 9r.3'A&& 9r.3' 7 A& 9r.3' '' ( -''' ( -'

deg #deg #

A%* 9r 0, 0A%* 9r 0, 0 '' ( -' deg # '' ( -' deg #

A-%3 9r. -A, -DA-%3 9r. -A, -D *' ( -' deg # *' ( -' deg #

5#), 0**, -', #A&5#), 0**, -', #A& 3& ( 3'' deg # 3& ( 3'' deg #

#&, #*#&, #* 3'' ( 3*' deg # 3'' ( 3*' deg #


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'urna#es'urna#es

The 0urnaces are classi=ed in soThe 0urnaces are classi=ed in so

many ways. According to their use,many ways. According to their use,

type, position, fuel used etc.type, position, fuel used etc.Type4Type4

6ogie Hearth6ogie Hearth

1uBe 0urnace1uBe 0urnaceCit type furnaceCit type furnace

!eal uench furnace.!eal uench furnace.

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Presentation on Heat Treatments

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