Classification of Steels-1 (1)
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Transcript of Classification of Steels-1 (1)
Classification of Steels & Cast Iron
and Associated Properties
Dr G Balachandran
Chief Technical Officer
Kalyani Carpenter Special steels Ltd.,
Mundhwa, Pune - 411036
Fe-C Phase Diagram
A1
A2
A3
Acm
A4
Effect of Alloying Elements
Single Phase • Ferrite (α-Fe)
• Austenite (γ-Fe)
• Delta Iron (δ-Fe)
• Graphite (C)
• Martensite
What are Phases?
Multi-Phase • Pearlite (α-Fe + Fe3C )
• Bainite
α-Fe + Fe3C
γ-Fe + Fe3C
• Dual Phase
Austenite (γ-Fe)
• Duplex Phase
Austenite (γ-Fe) + α-Fe
• Carbides
Composition & Heat treatment modify the phase formation
- This influences the mechanical properties
Ferrite Iron Phase
• Body-center cubic crystal structure
• Stable up to 912°C in Fe-C system
• Density: 7.86 grams/cm 3 at 20°C
• Soft and very ductile phase
Austenite Iron Phase
• Face-center cubic crystal structure
• Stable from 740°C to 1493°C
• Density: 7.84 grams/cm 3 at 20°C
• Strong, hard and tough phase
Delta Iron Phase
• Body-center cubic crystal structure
• Stable from 1394 °C to 1538°C
• Forms at very high temperatures
Understanding Phases & Crystal structure
0.08%C 0.20%C 0.60%C
Plate like cementite morphology Cementite as spherodite
Understanding Phases
Dual Phase Structures Pearlite – Ferrite + Fe3C
Diffusion of Carbon in Pearlite
Pearlite Formation
• Austenite precipitates Fe3C at
Eutectoid Transformation
Temperature (727°C).
• When slow cooled, this is Pearlite
(looks like Mother of Pearl)
(a) coarse pearlite (b) fine pearlite 3000X
Bainite Microstructure • transforms similar to martensite by shear but has carbides interspersed • C > 0.1%. • Transforms to ferrite + cementite with sufficient time & temp - semi-stable at <150°C • • Upper bainite (550-350°C) - Rods of Fe3C • Lower bainite (350-250°C) – Plates of Fe • High Si material bainite has austenite + carbide
Bainite & Ausferrite
Lower bainite Upper bainite Ausferrite
Martensite Phase
• Body centered tetragonal crystal structure
• C>0.1%
•At adequate time and temperature
- forms ferrite + cementite
• Density: 7.8 g./cc at 20°C
• Very hard & strong phase
with minimal ductility
• Needle-like microstructure
Non Equilbrium Phase- Martensite
Tempered Martensite
• Precipitates C saturated in the matrix
- forms equilibrium ferrite + carbide
Plate martensite+
Retained austenite Lath martensite
Non Equilbrium Phase- Martensite
Retained Austenite
If we end up heat treatment in between Ms and Mf then
- Residual austenite transforms to bainite/pearlite as a f(cooling rate)
Even below Mf some Retained austenite is present
Amount of retained austenite = f( Ms-Mf)
- If (Ms-Mf) is narrow retained austenite increases
- increases with alloying element Mn, Cr, Ni & C
Below Ms & close to Ms
slower cooling enhances martensite formation
Below Ms & close to Mf
accelerated cooling enhances martensite formation
Graphite Carbon Phase
• Layered hexagonal structure
• Covalent bonded atoms in each layer
• Density: 2.25 grams/cm 3 at 20°C
• Layers easily slide against each other and make
graphite a solid lubricant
• Soft and low strength
Graphite Phase in Iron
Graphite distribution in gray cast iron, spheroidal & compacted
Carbide Phases in Iron
Carbides in Steels
First Group : M3C M7C3 M23C6 + M6C ( M4C)
- Cr, Mo, W
- W3C, Mo2C
Second Group: MC
- V, Ti, Nb, Ta (bcc)
- High Alloy Steels
Wt.%i Cr Mo W
<2% (Fe,Cr)3C (Fe,Mo)3C (Fe,W)3C
6-10% (Fe,Cr)3C+ (FeCr)7C3 Fe3Mo3C Fe3W3C
10-20% (FeCr)23C6 Fe3Mo3 Fe3W3C+Fe3W2
Non Carbide forming Elements : Si, Ni, Cu, Al
Neutral Element : Co
Carbide formers: Fe, Mn, Cr, Mo, W, Nb, V, Zr, Ti
Spheroidite
• If tempered for a long time,
Fe3C forms “spheres” and
grows inside Ferrite.
• Very soft, easy to machine
Transformation diagrams
- predicts microstructures that forms from austenite
- as a function of time, temperature and cooling rate
• Time-temperature transformation (TTT) diagrams
- Extent of transformation with time at a constant temperature.
• Continuous cooling transformation (CCT) diagrams
- Extent of transformation as a function of time for a continuously
decreasing temperature.
Austenite Transformation Diagrams
Time-Temperature Transformation
Continuous Cooling Transformation 34CrNiMo6 Steel
Slow Cooling
Time in region
indicates amount of
microconstituent!
Medium Cooling
Cooling Rate, R, is
Change in Temp /
Time °C/s
Fast Cooling
This steel is very
hardenable… 100%
Martensite in ~ 1
minute of cooling!
Tempering in 34CrNiMo6 Influence of tempering
temperature on
Mechanical Properties
Carbon
Clustering
Spinodal
decompose
Meta
stable
carbide
Retained
austenite
decompose
Cementite
Alloy
carbides
Coarsening
of carbides
in ferrite
Tempered Martensite Embrittlement
300oC Embrittlement
Stage 2:
Retained austenite
carbides + ferrite
HC steel more Ret Aust
Stage 1:
Forms very small
Metastable carbides
(10 nm)
Hypoeutectoid steels forms
ε-carbide (Fe2.4C)
Hypereutectoid steels forms
Hagg (Fe2.2C)+η-(Fe2C)
Stage 3:
Metastable carbides
fine globular cementite
Relevant Material Properties
• Discontinuous Yielding and Lüder’s Lines
• YS, TS, el., K, n, and r
– r value is used to express the anisotropy of materials
• Planar anisotropy
• Normal anisotropy
t
wr
4
2 45900 rrrrm
4
2 45900 rrrr
Cast Irons
Cast Iron
• 2 to 4%C
• 1-3% Si improve castability
• C is in the form of
– graphite & cementite
• Features:
– Low melting temperature
(1153ºC to 1400ºC)
– Low shrinkage
– Easily machinable
– Low impact resistance
– Low ductility
Materials Selection
• Mechanical properties
– Stiffness, strength, ductility, fatigue, creep
• Manufacturability
– Machining, Mechanical working, Casting, Welding
• Physical properties
– Density, Melting point, Thermal conductivity
• Cost
– Availability, ease of processing
Cast Irons
• Microstructure of cast iron modified
by heat treatment
– Pearlite
– Ferrite
• Gray cast iron
– Fracture surface appears gray
because of graphite flakes
• White cast iron
– Fracture surface appears white
(shiny)
Cast Iron Family
Cast Iron Family
Cast Irons
• Types
Gray cast iron
- Carbon as graphite flakes
2.5 - 4% C and 1 - 3% Si (Promotes formation of graphite)
Nodular cast iron
• Carbon as spherical graphite nodules
• 3-4% C & 1.8 -2.8 % Si + Mg or Ce, and low impurities
Cast Irons
Types
– White cast iron
• Carbon as cementite
– Malleable cast iron
• Carbon as irregular graphite nodules
• Heat treating white cast iron
Gray Iron Microstructure
Spherodised Graphite Microstructure
Spheoridal Graphite Iron Austempered Ductile Iron
Spherodised Graphite Iron Microstructure
Gray Iron Mechanical Properties
Grade
Tensile
Strength
(In MPa)
Hardness
(BHN)
IS : 210-
1978
(Indian
Std)
ISO / R 185-
1961
(Int. Std)
BS 1452 :
1961
(UK Std)
DIN 1691-
1964
(German
Std)
ASTM A-48-
1976
(American
Std.)
FG 150 15 10 GG-15 20A/25A 150 130-180
FG 200 20 12 GG-20 30A 200 160-220
FG 220 14 220 180-220
FG 260 25 17 GG-25 35A 260 180-230
FG 300 30 20 GG-30 45A 300 180-230
FG 350 35 23 GG-35 50A 350 207-241
FG 400 40 26 GG-40 60A 400 207-270
Gray Iron Mechanical Properties
Grade
Tensile
Strength
(In MPa)
Yield
Strengt
h
(In
MPa)
%E
Hardne
ss
(BHN)
(ISO Standerd
1083,
UK Standard
B52789,
Indian Standard IS
1862)
ASTM A 536
(American
Standard)
SAE J434C
(American
Standard)
Ferritic grade
350/22 350 215 22 107-130
370/17 370 230 17 <179
400/18 60-40-18 D4018 400 259 18 120-140
400/15 400 250 15 130-180
400/12 400 250 12 <201
420/12 60-42-10 420 278 12 140-155
Ductile Iron Mechanical Properties
Grade
Tensile
Strength
(In MPa)
Yield
Strengt
h
(In
MPa)
Elongat
ion
%
Hardne
ss
(BHN)
(ISO Standerd
1083,
UK Standard
B52789,
Indian Standard IS
1862)
ASTM A 536
(American
Standard)
SAE J434C
(American
Standard)
Intermediate grade (Ferrite + Pearlite)
450/10 65-45-12 D4512 450 305 10 150-172
500/7 70-50-05 500 339 7 172-216
80-55-06 D5506 552 379 6 187-255
Intermediate grade (Pearlite + Ferrite)
600/3 80-60-03 600 372 3 216-247
Pearlitic grade
700/2 100-70-03 D7003 700 416 2 247-265
800/2 800 471 2 245-335
900/2 120-90-02 900 526 2 280-360
Ductile Iron Mechanical Properties
White Cast Iron Mottled Cast Iron Malleabled Cast Iron
White Cast Irons
Classification of Steels
Nomenclature of Steels
• Common nomenclature AISI/SAE and ASTM
– The American Iron and Steel Institute (AISI)
– Society of Automotive Engineers (SAE)
– American Society for Testing and Materials (ASTM)
• Others GOST, Japan, Russia, DIN, AFNOR etc.
• Universal/Unified Numbering System (UNS)
ASTM Specification
• ASTM A 582/A 582M-95b (2000), Grade 303 Se – Free maching bar
A- Means Ferrous Metal includes steels, cast iron, alloy & stainless steels
No.582 – Arbitrary – no relevance to properties
M- Metric or SI units, Absence of N => fps units
95 => year of adoption or last revision
B => third revision in the std
2000 => year of last approval
Grade 303 Se => indicates grade
ASTM Specification
Grade: describes chemical composition
Type : indicates the type of deoxidation followed
Class: Indicates strength level or surface finish
Sometimes this may not be followed
ASTM A 106-02a Grade A, Grade B, Grade C – Seamless Carbon pipe for high temp
service
Grade A :0.25%C (max) ; >45 ksi Tensile strength
Grade B :0.30%C (min) ; >60 ksi Tensile strength
Grade A :0.35%C (max) ; >70 ksi Tensile strength
ASTM A 276-03, Type 304, 316, 410 – Stainless and Heat resisting Bars and shapes
Type 304, 316, 410 are based on SAE designation for stainless steel
ASTM Specification
In Pipes-P, Tubes-T and Forging-F products
• ASTM A 335/A 335M-03, Grade P22 Seamless Ferritic Alloy Steel Pipe for
High temperature service
• ASTM A 213/A 213M-03a, Grade T22, Seamless Ferritic and Austenitic Alloy
Steel Boiler, superheater and Heat Exchanger Tubes
• ASTM A 312/A 312M-03, Grade TP304, Seamless and Welded Austenitic
stainless steel Pipes
• ASTM A 336/A 336M-03a, Grade F22 – Steel Forgings, Alloy for pressure and
High Temperature Parts
UNS Designation
Alpha numeric with a letter followed by five numbers
Represents only chemical composition
Not a specification
SAE 1040 is represented as UNS G 10400
G – is prefix for Carbon and alloy steel
Next four numeric degits are SAE designation of the steel
The intermediate letters “B” & “L” is replaced by the fifth digit
Prefix E – EAF makes 5th digit
SAE Grades with hardenability requirement are given by “H” HXXXXX
Carbon and Alloy Steels not referred to in SAE system categorized prefix “K”
ASTM Specification
• ASTM A 582/A 582M-95b (2000), Grade 303 Se – Free maching bar
A- Means Ferrous Metal includes steels, cast iron, alloy & stainless steels
No.582 – Arbitrary – no relevance to properties
M- Metric or SI units, Absence of N => fps units
95 year of adoption or last revision
B=> third revision in the std
2000 => year of last approval
Grade 303 Se => indicates grade
AISI/SAE Classification of Steels
• Four digit
– First two digits identify the alloy type
– Last two digits indicate the carbon content
Example
• AISI/SAE 1020 - Plain carbon steel (10xx) which has 0.20 wt.% carbon (xx20)
• Plain carbon steel (10xx) are inexpensive, limitations include
– Poor hardenability because the critical cooling rate is very high
– Rapid cooling leads to distortion and cracking
– Poor corrosion resistance
– Poor impact resistance at low temperature
• Alloy steels were developed to address these issues
– Alloying changes the eutectoid composition, the eutectoid carbon content and the critical
cooling rate
– These alloys are more expensive, but a better combination of properties is obtained
1015 1040 1095
Plain Carbon Steels
AISI/ SAE Classification
1213 Plain Carbon AISI Grades
10XX Mn =1% Max
15XX Mn=1.0 to 1.6%
13XX Mn=1.6-1.9%
11XX Resulfurised
12XX Resulphurised & rephosphorised
Generally when alloying elements >1.5%
it is low alloy steel (13XX )
Above alloying elements >8%
high alloy steel
Comite’ Europeen de Normalisation [CEN] for steels is EN 10027
Part 1 Steel Names
Part 2 Steel Numbers
EN 10027-1 Based on application and mechanical or physical properties
A letter indicates application a number follows qualifying properties
S – structural steel L- Line pipe steel
R – Rail steel P- Pressure related
EN 10028-3 steel name P275N
EN 10027-2 Steel designated based on chemical composition
Divided into 4 sub-groups
EN 10222-2 steel name 13CrMo4-5
EN 10250-4 steel names X2 CrNi18-9
European Standard
European Standard
EN 10027-2 - system for assigning number
Steel Numbers 1.XXXX
1 refers to steel
First two digits represent steel group number
EN 10222-2 Steel Name 18CrMo4-5, steel number 1.7335
EN 10250-4 Steel Name X2CrNi18-9, steel number 1.4307
Carbon & Alloy Steels
Cr & Cr-Mo Steels
Ni-Cr-Mo Steels
Cr-Mo-Al, Cr-V & B Steels
Structural Steel Plates
Structural Carbon Steel Plates
Structural Carbon Steel Plates
Alloy Steel & HSLA Plates
Pressure Vessel Steels
Pressure Vessel Plate Steels
Similar specification exists for different steel grades
High alloy steel [stainless steels]
Specification exists for steel
Tubes, Pipes, Forgings, Bars, Strips
Application based steels
- Springs, bearings, valves, etc.
Further Specification in Steels
Further Classification of Steels
Classification of Steels
Classification by structure Classification by Commercial name or application
Alloys without Eutectic (<2%C)
Ferritic
Ferrite - pearlitic
Pearlitic
Martensitic
Bainitic
Austenitic
Precipitation Hardened
AusteniticFerritic
Duplex structure
Steel
Plain Carbon
Low Carbon Steel (<0.2)
Medium Carbon Steel (0.2-0.5)
High Carbon Steel (0.2-0.5)
Low alloy steel (<8%)
High alloy steel (>8%)
Corrosion resistant steels
Heat Resistant steels
Wear resistant steels
Carbon and Alloy steels
• Composition & Processing are controlled
- to meet property requirements of different applications
• Alloying elements are added to steels for
Hardenability
Strength
Hardness
Toughness
Wear resistance
Workability
Weldability
Machinability
Steel Classification
Nb, Ti, V, Al, Cr, Ni, Mo
Co, Cu, Mo, W, Mn, Si, Steel
Plain Carbon Steel Alloy Steel
Low
Carbon
Steel
Medium
Carbon
Steel
High
Carbon
Steel
Low
Alloy
Steel
High
Alloy
Steel
C>0.9 C=0.2-0.5 C<0.2 Alloying
Element <5%
Alloying
Element >5% Flat products
Structural
Rolled steels
Machine parts
Heat treatable
Tool steel
Wear, abrasion
Heat resistance
Corrosion
resistance
Automotive Panels
Steel wt.%C
Low Carbon < 0.25
Very Low Carbon <0.10
Extra Low Carbon <0.06
Ultra Low Carbon <0.005
Advanced High Strength Steels
Advanced High Strength Steels
Hot Rolled Plates
Cold Rolled Plates Dual Phase
Steel
Martensitic
steel
Advanced High Strength Steels
TRIP
Steel
TWIP
Steel
5 Grades
YS=280/500
UTS=600/800
%E=30/20
n=0.21 to 0.14
r=1.0
YS=450
UTS=800
%E=26/32
n=0.24
r=0.9
YS=700
UTS=800
%E=10/15
n=0.13
r=1.0
YS=950/1250
UTS=1200/1520
%E=5/4
n=0.07/0.065
r=1.0
Grades
YS=352 / 586
UTS=469 / 676
%E=52 / 17
n=0.15 / 0.12
r=1.1 / 1.0 / NA
Complex
Phase
Steel HSLA
steel YS=200/324
UTS=800/1750
%E=90
n=0.5
r=1.0
HSLA
(Microalloyed
Bainitic)
steel
Grades
YS=350 / 586
UTS=407 / 676
%E=52 / 17
n=0.17 / 0.12
r=1.1 / 1.0 / NA
Development of Austenitic Stainless Steels
302 302B
Si added for
scale resistance
304
Lower C
Reduce carbide
304L
Welding
347
Nb, Ta
stabilisers
348
Nb, low Ta, Co
Nuclear application
321
Ti
stabilisers
316
Mo
Corrosion Resist.
High temp. strength
317
More Mo
Better
corrosion
Resist
317L
Welding
301
Lower Cr,Ni
Work Hardening
improved
303
S added
Improved
Machinability
201
Ni, replaced partly
By Mn & N
Cost savings
303Se
Se added
Improved
machine surface
305
Increased Ni
Lower
work hardening
308 to 310
Cr, Ni increase
Corrosion Resist
Scael Resist
308
Cr, Ni increase
Corrosion Resist
Scael Resist
0.15C/18Cr/5Ni
18Cr/12Ni
17Cr/7Ni 18Cr/9Ni-0.07(S+Se) 0.05C/18Cr/8Ni 0.1C/17Cr/12Ni/2Mo 0.15C/20Cr/11Ni
Precipitation Hardened Stainless Steels
Precipitation Hardened
Austenitic Martensitic Semi Austenitic
A286
0.08C-1.4Mn-15Cr
-26Ni-1.3Mo- 2 Ti-
0.35Al-0.3V-0.003B
17-7 PH
0.07C-0.6Mn
-17Cr-7Ni-1.15 Al
17-4 PH
0.07C-0.2Mn-16Cr
-4Ni-0.2Nb-3.4Cu
17-4 PH
15-5 PH
13-8 17-7 PH
11-10 PH
Custom 450
Custom 455®
Custom 465®
Custom 475™
C Cr Ni Mo Co Ti Cb Cu Al
0.04 16.5 4.2 -- -- --
0.3 3.3
0.01
15.0 4.0 -- -- --
0.3 3.5 --
0.05 12.7 8.0 2.3 -- -- -- --
1.2
0.07 17 7 -- -- -- -- --
1.15
0.03 11 10 2.0 --
0.9 -- --
0.2
0.05 14.8 6.5 0.8 -- --
0.6 1.5 --
0.05 11.5 8.6 -- --
1.3 0.3 2.2 --
0.05 12.0 11.0 1.0 --
1.7 -- -- --
0.05 11.0 8.0 5.0 8.5 -- -- --
1.25
Precipitates :
Cu, NiTi, Ni3Al, Ni3Mo
Low C
Lath martensite aged
Martensitic Stainless Steels
420
403
Same alloy
Higher quality
416
S added
Machinability
410 Nb
Nb easens
Heat treatment
Improve prop
410
Lower C
Corrosion Resist.
414
Ni added
Corrosion
reist
431
Cr increase
Corrosion
resist
440C
C increased
For quench hadness
Cr increased for
Corrosion resist
420F
S added
Improved
Machinability
440B
C decreased
Toughness
improved
440F
Se added
improved
machinability
405
Al added
Minimise
air hardening
Non-hardenable
440A
C decreased
Toughness
improved
0.15C-13Cr
0.15C-12Cr
0.12C-16Cr-0.07Se
Ferritic Stainless Steels
430
430F
S added
Improved
machinability
409
Cr reduced
Cost saving
Ti added for
improved
fabrication
430 Ti
Ti added
Improved
Fabricability
442
Cr added
improved
Scale resist
446
Cr increased
Scale resist
improved
25%Cr 18%Cr 13%Cr
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Classification of Tool & Die Steels
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Alloy classification of tool steels
W – water hardening
O – oil hardening
A – air hardening
D – high %C (1.5-2.25%C); high %Cr
(~12%Cr) (cold work dies – really a stainless steel;
excellent wear resistance)
Cold Work Tool steels
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Classification of Tool steels
Grade Prefix Specific grades
Cold Work W- water hardened
O- Oil hardened
A- Air hardened Med alloy
D- High C, High Cr
W1, W2, W5
O1,O2, O6, O7
A2, A4, A6, A7, A8, A9, A10, A11
D2, D3, D4, D5, D7
Shock
Resistance
S S1, S2, S4, S5, S6, S7
Hot Work H H10-H19 Cr type
H20-H39 W type
H40-H-59 Mo type
High Speed M (Mo)
T (W)
M1, M2, M3-1, M3-2,M4, M6, M7 M10,
M33, M34, M36, M41, M42, M56, M50
T1, T4, T5, T6, T8, T15
Special
purpose
P
L
Mold steel P6, P20, P21
Die Steel: L2, L6
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Elements in Tool steels Element Dissolved
in ferrite
Combined
in carbide
Combined
as carbide
Compound Elemental
Nickel Ni Ni3Al
Silicon Si SiO2.MxOy
Manganese Mn ------- Mn (Fe,Mn)3C MnS; MnO-
SiO2
Chromium Cr-------- Cr (FeCr)3C
Cr7C3
Cr23C6
Molybdenum Mo------- Mo Mo2C
Tungsten W------- W W2C
Vanadium V------- V V4C3
Titanium Ti------- Ti TiC
Columbium Cb --------- Cb CbC
Aluminium Al Al2O3:AlN
Copper Cu (small)
Lead Pb Pb
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• Shock resistance (cold applications)
Medium %C
Toughness is the main concern
<5% total alloys
• High speed tool steels
Tx – tungsten
Mx – Molybdenum
Up to 25% total alloy content
High %C – sharpness held e.g. HSS – drills for metal
Shock Resistant Tool Steels
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Requirements: Used at low temperature –toughness
Cold-work tool steels include all class S alloys.
Among the toughest of the tool steels,
Typically used for screw driver blades, shear blades, chisels, knockout
pins, punches, and riveting tools.
Tool steels – Shock Resistant
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Cold work tool steels:
use limited cold conditions
will soften if over tempered 17-95°C
Up to ~5% total alloy content; high %C
High %C steels:
High hardness therefore
good sharpness and wear resistance
All high-chromium class D,
Medium-alloy air-hardening class A alloys,
Water hardening W alloys
Oil hardening O alloys
Typical applications include cold working operations such as stamping
dies, draw dies, burnishing tools, coining tools, and shear blades
Cold Work Tool Steels
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Requirements: Used at high temperature – toughness
Hot-work tool steels include
All chromium, tungsten, and molybdenum class H alloys
They are typically used for forging, die casting, heading, piercing, trim,
extrusion, and hot-shear and punching blades.
Hot Work Tool Steels
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• Hot work tool steels:
Hot application H1x, H2x, H3x
Cr, Mo, W – main alloy elements
H1x – Cr
H2x, H3x – W
H4x, H5x – Mo’
• Medium carbon
• Up to 25% alloy content
• Toughness at high temperature is main requirement
Hot Work Tool steels
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Special Purpose Tool Steels
• Plastic Mold Steel
• P6, P20, P21 series, NAK 52
• Die Steels :L2, L6
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Requirements: Used at high temperature –sharpness
High-speed alloys include
molybdenum class (M1 to M52)
tungsten class (T1 to T15)
Up to 25% Total alloy content
High C gives sharpness
High-speed tools steels are hardened to 62-67 HRC
Maintains hardness in service temperatures as high as 540 °C
very useful in high speed machinery.
Typical applications are end mills, drills, lathe tools,
planar tools, punches, reamers, routers,
taps, saws, broaches, chasers, and hobs.
High Speed Steels
Conclusion
Basic Classification of steel grade has been introduced
You can send your questions to [email protected]