Project Description

AISI M42 high speed tool steel manufacturers and suppliers, supplied in round bar,square bar,flat bar,plate,sheet and wire.M42 tool steel, a type of molybdenum high speed tool steel,which add  additional 8% -10% cobalt.It has  good wear resistance,hot hardness,high hardness capability (can be hardened to 68-70HRC)and  good machinability.These properties make the steel widely used in metal manufacturing industries,such as machining high-strength and pre-hardened steels, high-hardness alloys, and the difficult-to-machine, nonferrous super alloys used in the aerospace, oil, and power generation industries.M42 high speed steel

1.Supply Form & Size & Tolerance

Round bar
ProcessCold DrawnHot RolledHot ForgedFree Forging
Flat bar
WidthMax 800mmMax 800mmMax 800mm
ProcessCold DrawnHot RolledHot Forged

Remark:Tolerance can be customized as per requests

2.Chemical Composition

ASTM A600M421.05-1.150.15-
DIN EN ISO 49571.32471.05-
JIS G4403SKH591.05-

3.Physical Property

Modulus of elasticity,N/mm2220x 10^3
Thermal conductivity,W/m °C20
Specific heat,J/kg °C429
Electrical Resistivity,ohm*mm2/m0.52
Machinability35-40% of a 1% carbon steel

4.Thermal Expansion

10^-6 m/(m*K)

10^-6 in/in °F

5. Mechanical Property

Hardness, Rockwell C(oil quenched from 1163°C, 5 minutes)65.8
Hardness, Rockwell C (oil quenched from 1177°C, 5 minutes)65.5
Hardness, Rockwell C (oil quenched from 1204°C, 5 minutes)64.3
Izod impact unnotched (oil quenched at 1191°C; 510°C temper temperature)13.6 J
Izod impact unnotched (oil quenched at 1191°C; 622°C temper temperature)24.4 J
Poisson's ratio0.27-0.30
Elastic modulus190-210 GPa


Pre heat the AISI M42 with two steps.First,heat slowly and uniformly to 650-760°C with a rate not exceeding 220°C per hour,second,heat more quickly to the forging temperature of 1050-1150°C.Re-heating is necessary when temperature below 850°C. Slow cooling in furnace after forging.


Annealing must be performed after hot working and before re-hardening.Heat the temperature to 770 to 840°C with a rate not exceeding 220°C per hour(one hour per 25mm of thickness),soak for at least two hours. Controlled slow cooling in furnace at 10 to 20°C per hour to approximately 600°C, continue cooling to ambient temperature in the furnace or in air. Hardness after annealing 269Brinell, maximum.

8.Stress Relieving

It is recommended to stress relieve after machining and prior to hardening to minimise the possibility of distortion.Heat in a neutral atmosphere to the  temperature of 600 to 650°C, and  soak for approximately two hours,followed by slow cooling in the furnace.M42 can be finish machined before heat treatment.


Pre heat M42 uniformly to 780-840°C, transfer to the hardening furnace, (salt bath or controlled atmosphere furnace recommended) operating at 1170-1200°C, depending on the degree of hardening required for application, and the size of the tool. It is important that the temperature be accurately controlled to avoid overheating.After a short hold at the hardening temperature, quench the component without further soaking into salt at 540-595°C or warm oil. If salt quenched allow the component to equalise at the bath temperature and then complete the quench in still air.


Tempering should be carried out immediately after quenching. Heat slowly and uniformly to the tempering temperature 510-560°C,soak well not less than 2 hours(one hour per 25mm of total thickness).Triple tempering is required. Intermittent cooling, in air, between tempers is required for a minimum of 1 hour. Obtainable hardness of 67 to 69 HRC.

Triple Temper, °F7008009009501000105011001150
Rockwell C,Hardness6363.767.769.568.266.564.859.2


AISI M42 is a high-speed steel suitable for cutting tools,and widely used in metal manufacturing industries.

Typical use include:Twist drills, taps, milling cutters, reamers, broaches, saws, knives, and thread rolling dies.

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