M42 High Speed Steel

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Product Description

M42 Molybdenum High Speed Tool Steel

Equivalent grades: SKH59/W2Mo9Cr4VCo8

M42 high speed steel is a cobalt molybdenum tools steel, the addition of 8% cobalt means that M42 delivers superior red-hardness when compared to M2. The composition of M42 makes for a good balance of toughness and hardness and can be found widely used for all types of cutting tools, often used for machining materials and super alloys that are difficult to machine. M42 high speed steel has a heat-treated hardness in the range 68 to 70 HRC.

Related Specifications : 1.3247


M42 is a high-speed steel for conditions that demand excellent hot hardness. M42 is suitable for cutting tools such as, twist drills, broaches, taps, milling cutters, saws, reamers, bandsaw blades and cold work tools.

If the higher red-hardness of M42 if not required for your application then consider M2 high speed steel.

M42 High-speed steel stock

Stockholders and supplier of M42 high speed steel in round, flat and square bar and deliver to the whole of the UK.

Round Bars 1mm – 150mm
Square bar from 4.5mm to 130mm
Flats from 3x7mm to 50 x 380mm

M42 steel properties

Typical chemical composition of AISI M42 High Speed Steel







1.08% 8.00% 9.40% 3.90% 1.20% 1.50%


Heat treatment of M42 high-speed steel

The following information is provided for guidance only. The rate of heating, cooling and soaking times will vary due to the shape and size of each component and other external factors.

Annealing M42

It is recommended that M42 is annealed after hot working and before re hardening. Heat to 850°C – 900°C at a rate of no more than 220°C per hour. Hold at temperature for a minimum of two hours or one hour per 25mm of thickness. Cool slowly to 700°C.

Stress relieving M42

Heat to 600°C – 700°, soak for approx. 2 hours at temperature, slow cool to 500°C.


Hardening M42 high speed steel is carried out in two steps. Pre heat the steel thoroughly to 450°C – 500°C, then increase heat to 1050°C – 1190°C, hold for a short time then quenching to about 550°C. Finally cool in air to hand warm.


Temper M42 at between 510-595°C three times for at least 1 hour at full temperature is recommended. Cool in still air to room temperature between tempering treatments.

Tempering M42 high speed Steel

Tempering °C









Forging M42

Pre heat slowly to 650 – 760°C and soak. Increase more quickly to the forging temperature of 1010 – 1150°C and equalise prior to forging. If the temperature drops below 980°C re-heating will be required. Cool the M42 very slowly after forging.