Tool Steel Classifications

Topics Covered

Introduction
Classification

Introduction

Tool steels are a family carbon and alloy steels having distinct characteristics such as hardness, wear resistance, toughness, and resistance to softening at elevated temperatures.

Tool steels comprise carbide-forming elements such as chromium, vanadium, molybdenum and tungsten in different combinations. They also contain cobalt or nickel which improves their high-temperature performance. They are generally heat-treated to improve the hardness and used for stamping, forming, shearing and cutting metals and forming of plastics. They are classified according to their composition and properties into various categories.

Classifications

Tools steels fall into three basic categories:

  • Cold work tool steels
  • Hot work tool steels
  • High-speed tool steels

Cold-work steels are further subdivided into:

  • Air-hardening
  • Medium-alloy cold-work steels
  • High-carbon, high-chromium cold-work steels
  • Oil-hardening cold-work steels

Hot work steels are subdivided into:

  • Chromium
  • Tungsten
  • Molybdenum hot work steels

High-speed tool steels are divided into:

  • Molybdenum
  • Tungsten
  • Intermediate high-speed steels

Other types of tool steels include:

  • Water-hardening tool steels
  • Shock-resistant tool steels
  • Low-carbon tool steels
  • Low-alloy special purpose tool steels.

The following table shows the composition limits of various types of tool steels.

Designation Compositiona, %
AISI UNS C Mn Si Cr Ni Mo W V Co
Molybdenum high-speed steels
M1 T11301 0.78-0.88 0.15-0.40 0.20-0.50 3.50-4.00 0.30 max 8.20-9.20 1.40-2.10 1.00-1.35 -
M2 T11302 0.78-0.88; 0.95-1.05 0.15-0.40 0.20-0.45 3.75-4.50 0.30 max 4.50-5.50 5.50-6.75 1.75-2.20 -
M3, class 1 T11313 1.00-1.10 0.15-0.40 0.20-0.45 3.75-4.50 0.30 max 4.75-6.50 5.00-6.75 2.25-2.75 -
M3, class 2 T11323 1.15-1.25 0.15-0.40 0.20-0.45 3.75-4.50 0.30 max 4.75-6.50 5.00-6.75 2.75-3.75 -
M4 T11304 1.25-1.40 0.15-0.40 0.20-0.45 3.75-4.75 0.30 max 4.25-5.50 5.25-6.50 3.75-4.50 -
M7 T11307 0.97-1.05 0.15-0.40 0.20-0.55 3.50-4.00 0.30 max 8.20-9.20 1.40-2.10 1.75-2.25 -
M10 T11310 0.84-0.94; 0.95-1.05 0.10-0.40 0.20-0.45 3.75-4.50 0.30 max 7.75-8.50 - 1.80-2.20 -
M30 T11330 0.75-0.85 0.15-0.40 0.20-0.45 3.50-4.25 0.30 max 7.75-9.00 1.30-2.30 1.00-1.40 4.50-5.50
M33 T11333 0.85-0.92 0.15-0.40 0.15-0.50 3.50-4.00 0.30 max 9.00-10.00 1.30-2.10 1.00-1.35 7.75-8.75
M34 T11334 0.85-0.92 0.15-0.40 0.20-0.45 3.50-4.00 0.30 max 7.75-9.20 1.40-2.10 1.90-2.30 7.75-8.75
M35 T11335 0.82-0.88 0.15-0.40 0.20-0.45 3.75-4.50 0.30 max 4.50-5.50 5.50-6.75 1.75-2.20 4.50-5.50
M36 T11336 0.80-0.90 0.15-0.40 0.20-0.45 3.75-4.50 0.30 max 4.58-5.50 5.50-6.50 1.75-2.25 7.75-8.75
M41 T11341 1.05-1.15 0.20-0.60 0.15-0.50 3.75-4.50 0.30 max 3.25-4.25 6.25-7.00 1.75-2.25 4.75-5.75
M42 T11342 1.05-1.15 0.15-0.40 0.15-0.65 3.50-4.25 0.30 max 9.00-10.00 1.15-1.85 0.95-1.35 7.75-8.75
M43 T11343 1.15-1.25 0.20-0.40 0.15-0.65 3.50-4.25 0.30 max 7.50-8.50 2.25-3.00 1.50-1.75 7.75-8.75
M44 T11344 1.10-1.20 0.20-0.40 0.30-0.55 4.00-4.75 0.30 max 6.00-7.00 5.00-5.75 1.85-2.20 11.00-12.25
M46 T11346 1.22-1.30 0.20-0.40 0.40-0.65 3.70-4.20 0.30 max 8.00-8.50 1.90-2.20 3.00-3.30 7.80-8.80
M47 T11347 1.05-1.15 0.15-0.40 0.20-0.45 3.50-4.00 0.30 max 9.25-10.00 1.30-1.80 1.15-1.35 4.75-5.25
M47 T11348 1.42-1.52 0.15-0.40 0.15-0.40 3.50-4.00 0.30 max 4.75-5.50 9.50-10.50 2.75-3.25 8.00-10.00
M62 T11362 1.25-1.35 0.15-0.40 0.15-0.40 3.50-4.00 0.30 max 10.00-11.00 5.75-6.50 1.80-2.10 -
Tungsten high-speed steels
T1 T12001 0.65-0.80 0.10-0.40 0.20-0.40 3.75-4.50 0.30 max - 17.25-18.75 0.90-1.30 -
T2 T12002 0.80-0.90 0.20-0.40 0.20-0.40 3.75-4.50 0.30 max 1.0 max 17.50-19.00 1.80-2.40 -
T4 T12004 0.70-0.80 0.10-0.40 0.20-0.40 3.75-4.50 0.30 max 0.40-1.00 17.50- 19.00 0.80-1.20 4.25-5.75
T5 T12005 0.75-0.85 0.20-0.40 0.20-0.40 3.75-5.00 0.30 max 0.50-1.25 17.50-19.00 1.80- 2.40 7.00-9.50
T6 T12006 0.75-0.85 0.20-0.40 0.20-0.40 4.00-4.75 0.30 max 0.40-1.00 18.50-21.00 1.50- 2.10 11.00-13.00
T8 T12008 0.75-0.85 0.20-0.40 0.20-0.40 3.75-4.50 0.30 max 0.40-1.00 13.25-14.75 1.80- 2.40 4.25-5.75
T15 T12015 1.50-1.60 0.15-0.40 0.15-0.40 3.75-5.00 0.30 max 1.00 max 11.75- 13.00 4.50-5.25 4.75-5.25
Intermediate high-speed steels
M50 T11350 0.78-0.88 0.15-0.45 0.20-0.60 3.75-4.50 0.30 max 3.90-4.75 - 0.80- 1.25 -
M52 T11352 0.85-0.95 0.15-0.45 0.20-0.60 3.50-4.30 0.30 max 4.00-4.90 0.75-1.50 1.65- 2.25 -
Chromium hot-work steels
H10 T20810 0.35-0.45 0.25-0.70 0.80-1.20 3.00-3.75 0.30 max 2.00-3.00 - 0.25-0.75 -
H11 T20811 0.33-0.43 0.20-0.50 0.80-1.20 4.75-5.50 0.30 max 1.10-1.60 - 0.30- 0.60 -
H12 T20812 0.30-0.40 0.20-0.50 0.80-1.20 4.75-5.50 0.30 max 1.25-1.75 1.00- 1.70 0.50 max -
H13 T20813 0.32-0.45 0.20-0.50 0.80-1.20 4.75-5.50 0.30 max 1.10-1.75 - 0.80- 1.20 -
H14 T20814 0.35-0.45 0.20-0.50 0.80-1.20 4.75-5.50 0.30 max - 4.00- 5.25 - -
H19 T20819 0.32-0.45 0.20-0.50 0.20-0.50 4.00-4.75 0.30 max 0.30-0.55 3.75- 4.50 1.75-2.20 4.00-4.50
Tungsten hot-work steels
H21 T20821 0.28-0.36 0.15-0.40 0.15-0.50 3.00-3.75 0.30 max - 8.50- 10.00 0.30-0.60 -
H22 T20822 0.30-0.40 0.15-0.40 0.15-0.40 1.75-3.75 0.30 max - 10.00-11.75 0.25- 0.50 -
H23 T20823 0.25-0.35 0.15-0.40 0.15-0.60 11.00-12.75 0.30 max - 11.00-12.75 0.75- 1.25 -
H24 T20824 0.42-0.53 0.15-0.40 0.15-0.40 2.50-3.50 0.30 max - 14.00-16.00 0.40- 0.60 -
H25 T20825 0.22-0.32 0.15-0.40 0.15-0.40 3.75-4.50 0.30 max - 14.00-16.00 0.40- 0.60 -
H26 T20826 0.45-0.55b 0.15-0.40 0.15-0.40 3.75-4.50 0.30 max - 17.25- 19.00 0.75-1.25 -
Molybdenum hot-work steels
H42 T20842 0.55-0.70b 0.15-0.40 - 3.75-4.50 0.30 max 4.50- 5.50 5.50-6.75 1.75-2.20 -
Air-hardening, medium-alloy, cold-work steels
A2 T30102 0.95-1.05 1.00 max 0.50 max 4.75-5.50 0.30 max 0.90-1.40 - 0.15-0.50 -
A3 T30103 1.20-1.30 0.40-0.60 0.50 max 4.75-5.50 0.30 max 0.90-1.40 - 0.80- 1.40 -
A4 T30104 0.95-1.05 1.80-2.20 0.50 max 0.90-2.20 0.30 max 0.90-1.40 - - -
A6 T30106 0.65-0.75 1.80-2.50 0.50 max 0.90-1.20 0.30 max 0.90-1.40 - - -
A7 T30107 2.00-2.85 0.80 max 0.50 max 5.00-5.75 0.30 max 0.90-1.40 0.50- 1.50 3.90-5.15 -
A8 T30108 0.50-0.60 0.50 max 0.75-1.10 4.75-5.50 0.30 max 1.15-1.65 1.00- 1.50 - -
A9 T30109 0.45-0.55 0.50 max 0.95-1.15 4.75-5.50 1.25-1.75 1.30-1.80 - 0.80- 1.40 -
A10 T30110 1.25-1.50c 1.60-2.10 1.00-1.50 - 1.55-2.05 1.25-1.75 - - -
High-carbon, high-chromium, cold-work steels
D2 T30402 1.40-1.60 0.60 max 0.60 max 11.00-13.00 0.30 max 0.70-1.20 - 1.10 max -
D3 T30403 2.00-2.35 0.60 max 0.60 max 11.00-13.50 0.30 max - 1.00 max 1.00 max -
D4 T30404 2.05-2.40 0.60 max 0.60 max 11.00-13.00 0.30 max 0.70-1.20 - 1.00 max -
D5 T30405 1.40-1.60 0.60 max 0.60 max 11.00-13.00 0.30 max 0.70-1.20 - 1.00 max 2.50-3.50
D7 T30407 2.15-2.50 0.60 max 0.60 max 11.50-13.50 0.30 max 0.70-1.20 - 3.80-4.40 -
Oil-hardening cold-work steels
O1 T31501 0.85-1.00 1.00-1.40 0.50 max 0.40-0.60 0.30 max - 0.40-0.60 0.30 max -
O2 T31502 0.85-0.95 1.40-1.80 0.50 max 0.50 max 0.30 max 0.30 max - 0.30 max -
O6 T31506 1.25-1.55c 0.30-1.10 0.55-1.50 0.30 max 0.30 max 0.20-0.30 - - -
O7 T31507 1.10-1.30 1.00 max 0.60 max 0.35-0.85 0.30 max 0.30 max 1.00-2.00 0.40 max -
Shock-resisting steels
S1 T41901 0.40-0.55 0.10-0.40 0.15-1.20 1.00-1.80 0.30 max 0.50 max 1.50-3.00 0.15-0.30 -
S2 T41902 0.40-0.55 0.30-0.50 0.90-1.20 - 0.30 max 0.30-0.60 - 0.50 max -
S5 T41905 0.50-0.65 0.60-1.00 1.75-2.25 0.50 max - 0.20-1.35 - 0.35 max -
S6 T41906 0.40-0.50 1.20-1.50 2.00-2.50 1.20-1.50 - 0.30-0.50 - 0.20-0.40 -
S7 T41907 0.45-0.55 0.20-0.90 0.20-1.00 3.00-3.50 - 1.30-1.80 - 0.20-0.30d -
Low-alloy special-purpose tool steels
L2 T61202 0.45-1.00b 0.10-0.90 0.50 max 0.70-1.20 - 0.25 max - 0.10-0.30 -
L6 T61206 0.65-0.75 0.25-0.80 0.50 max 0.60-1.20 1.25-2.00 0.50 max - 0.20-0.30d -
Low-carbon mold steels
P2 T51602 0.10 max 0.10-0.40 0.10-0.40 0.75-1.25 0.10-0.50 0.15-0.40 - - -
P3 T51603 0.10 max 0.20-0.60 0.40 max 0.40-0.75 1.00-1.50 - - - -
P4 T51604 0.12 max 0.20-0.60 0.10-0.40 4.00-5.25 - 0.40-1.00 - - -
P5 T51605 0.10 max 0.20-0.60 0.40 max 2.00-2.50 0.35 max - - - -
P6 T51606 0.05-0.15 0.35-0.70 0.10-0.40 1.25-1.75 3.25-3.75 - - - -
P20 T51620 0.28-0.40 0.60-1.00 0.20-0.80 0.40-2.00 - 0.30-0.55 - - -
P21 T51621 0.18-0.22 0.20-0.40 0.20-0.40 0.50 max 3.90-4.25 - - 0.15-0.25 1.05-1.25A1
Water-hardening tool steels
W1 T72301 0.70-1.50e 0.10-0.40 0.10-0.40 0.15 max 0.20 max 0.10 max 0.15 max 0.10 max -
W2 T72302 0.85-1.50e 0.10-0.40 0.10-0.40 0.15 max 0.20 max 0.10 max 0.15 max 0.15-0.35 -
W3 T72305 1.05-1.15 0.10-0.40 0.10-0.40 0.40-0.60 0.20 max 0.10 max 0.15 max 0.10 max -

aExcept group W, all steels contain 0.03 max S, 0.03 max P and 0.25 max Cu; group W contain 0.025 max S, 0.025 max P, and 0.20 max Cu. As mentioned, amount of sulfur may be increased from 0.06% to 0.15% to enhance the machinability of group A, M, T, H and D steels.
bPresent in various carbon ranges.
cPresence of free graphite in the microstructure.
dOptional.
eSpecified ranges of carbon are indicated using suffix numbers.

In the above table, a capital letter is used to identify each group of tool steels having similar properties and composition; within that group, each type of tool steel is assigned a code number.


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