Post on 13-Feb-2018
transcript
7/23/2019 Presentation on Heat Treatments
1/34
Introduction toIntroduction toHeat TreatmentsHeat Treatments
7/23/2019 Presentation on Heat Treatments
2/34
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.
7/23/2019 Presentation on Heat Treatments
3/34
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
7/23/2019 Presentation on Heat Treatments
4/34
Types Of HeatTypes Of Heat
TreatmentTreatment AnnealingAnnealing
NormaliingNormaliing
HardeningHardening
TemperingTempering
!tress "elieving!tress "elieving #arburiing#arburiing
NitridingNitriding
7/23/2019 Presentation on Heat Treatments
5/34
AnnealingAnnealing
7/23/2019 Presentation on Heat Treatments
6/34
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.
7/23/2019 Presentation on Heat Treatments
7/34
Solution AnnealingSolution Annealing
7/23/2019 Presentation on Heat Treatments
8/34
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
7/23/2019 Presentation on Heat Treatments
9/34
NormalizingNormalizing
7/23/2019 Presentation on Heat Treatments
10/34
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'&
7/23/2019 Presentation on Heat Treatments
11/34
HardeningHardening
7/23/2019 Presentation on Heat Treatments
12/34
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.
7/23/2019 Presentation on Heat Treatments
13/34
TemperingTempering
7/23/2019 Presentation on Heat Treatments
14/34
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.
7/23/2019 Presentation on Heat Treatments
15/34
7/23/2019 Presentation on Heat Treatments
16/34
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.
7/23/2019 Presentation on Heat Treatments
17/34
!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
7/23/2019 Presentation on Heat Treatments
18/34
CarurizingCarurizing
7/23/2019 Presentation on Heat Treatments
19/34
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.
7/23/2019 Presentation on Heat Treatments
20/34
!"e#t of alloying!"e#t of alloying
elementselements Di, 5, #o, Al, !i, 1n.
7/23/2019 Presentation on Heat Treatments
21/34
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
7/23/2019 Presentation on Heat Treatments
22/34
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.
7/23/2019 Presentation on Heat Treatments
23/34
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.
7/23/2019 Presentation on Heat Treatments
24/34
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.
7/23/2019 Presentation on Heat Treatments
25/34
$olydenum$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.
7/23/2019 Presentation on Heat Treatments
26/34
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.
7/23/2019 Presentation on Heat Treatments
27/34
&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
7/23/2019 Presentation on Heat Treatments
28/34
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.
7/23/2019 Presentation on Heat Treatments
29/34
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.
7/23/2019 Presentation on Heat Treatments
30/34
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.
7/23/2019 Presentation on Heat Treatments
31/34
$anganese$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.
7/23/2019 Presentation on Heat Treatments
32/34
HT of various 9radesHT of various 9rades
Normaliing
1aterial Temperature
A'& )'' ( )*' deg #
A%* 0, 0** )'' ( )*' deg # 5#6 )'' ( )*' deg #
7/23/2019 Presentation on Heat Treatments
33/34
!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 #
7/23/2019 Presentation on Heat Treatments
34/34
'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.