Editorial Feature

M2 Molybdenum High Speed Tool Steel (UNS T11302)

Topics Covered

Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
     Heat Treatment


Molybdenum high speed steels are designated as Group M steels according to the AISI classification system. Over 95% of high-speed steels manufactured in the US are group M steels. Tungsten is present in all types from M1 to M10, except M6, and cobalt is not present in any these steels. Molybdenum high speed steels have similar performance when compared to tungsten high-speed steels. However, the initial cost of molybdenum tool steels is lower. Titanium nitride, titanium carbide and several other coatings can be used in the tools made of this kind of steels through physical vapor deposition process to improve the performance and life span of the tool.

This article will provide an overview of M2 molybdenum high speed tool steel, which has high carbon content and better wear resistance than M1 molybdenum high speed tool steel.

Chemical Composition

The following table shows the chemical composition of M2 molybdenum high speed tool steels.

Element Content (%)
C 0.78-1.05
Mn 0.15-0.40
Si 0.20-0.45
Cr 0.20-0.45
Ni 0.3
Mo 4.50-5.50
W 5.50-6.75
V 1.75-2.20
Cu 0.25
P 0.03
S 0.03

Physical Properties

The physical properties of M2 molybdenum high speed tool steel are given in the following table.

Physical properties Metric Imperial
Density 8.16 g/cm3 0.294 lb/in3
Melting point 4680°C 2600°F

Mechanical Properties

The mechanical properties of M2 molybdenum high speed tool steel are tabulated below.

Mechanical properties Metric Imperial
Hardness, Rockwell C (tempered at 1150°F, quenched at 2200°F) 62 62
Hardness, Rockwell C (as hardened, quenched at 2200°F) 65 65
Compressive yield strength (when tempered at 300°F) 3250 MPa 471000 psi
Izod impact unnotched (when tempered at 300°F) 67 J 49.4 ft-lb
Abrasion (loss in mm3, as-hardened; ASTM G65) 25.8 25.8
Abrasion (loss in mm3, tempered at 1275°F; ASTM G65) 77.7 77.7
Poisson's ratio 0.27-0.30 0.27-0.30
Elastic modulus 190-210 GPa 27557-30458 ksi

Thermal Properties

The following table shows the thermal properties of M2 molybdenum high speed tool steels.

Thermal properties Metric Imperial
CTE, linear (@20.0 - 100°C/ 68.0 - 212°F) 10 μm/m°C 5.56 μin/in°F
CTE, linear (@20.0 - 500°C/68.0 - 932°F) 12.2 μm/m°C 6.78 μin/in°F
CTE, linear (@20.0 - 850°C/68.0 - 1560°F) 12.6 μm/m°C 7 μin/in°F

Other Designations

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Other designations that are equivalent to M2 molybdenum high speed tool steels include:

  • AFNOR 06-05-04-02
  • DIN 1.3343
  • UNI KU
  • JIS SKH9
  • SS 2722
  • B.S. BM 2
  • FED QQ-T-590
  • ASTM A597 (CM-2)
  • ASTM A600
  • SAE J437
  • SAE J438
  • UNS T11302

Fabrication and Heat Treatment


Shaping of M2 tool steels can be carried out using grinding methods. However, they have poor grinding capability and hence they are regarded as "medium" machinability tool steel under annealed conditions. The machinability of these steels is only 50% of that of the easily machinable W group or water hardening tool steels.

Heat Treatment

M2 tool steels are pre-heated prior to hardening at 815.5°C (1500°F) followed by rapid heating from 815.5°C (1500°F) to 843.3°C (1550°F). These steels are then cooled for 3 to 5 min and quenched in air, salt bath, or oil.


M2 tool steels are annealed at approx 885°C (1625°F) and cooled at 72°C (162°F) per hour or even less.


M2 steels are tempered at 565.5°C (1050°F) to obtain Rockwell C hardness from 60 to 65.


Finally, M2 steels are hardened by heat treatment and quenching.


M2 tool steels are suitable for making cutting tools.


  1. atul Sc atul Sc India says:

    What will the hardness of m2 be after annealing?

    • john john United States says:

      255 HRc Max, after annealing

    • john john United States says:

      Should 255 HBS Max, after annealing

  2. Neel Patil Neel Patil India says:

    Is M2 steel Ductile or Brittle?

    • Kevin Keel Kevin Keel United States says:

      more brittle than ductile, but probably closer to "spring hard" and not quite "glass hard". M2 is more commonly known as "HSS", a blanket term, and is used to make cutting tools - drill bits, lathe bits, milling cutters, etc.

  3. ahaaaa aheee ahaaaa aheee Egypt says:

    can high speed steels warm rolled (400-700°C) without cracking ?

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of AZoM.com.

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