M35 Steel

The cobalt content in this high-performance high-speed steel results in high red hardness and tempering resistance. As a consequence, this grade is particularly suitable for conditions involving thermal stresses and discontinuous cutting. Under the name Rapidur 3245, AISI M 35 + S and material number 1.3245, this steel grade is supplied with a higher sulphur content (S = 0.10 %).

Tensile strength	481 MPa
Yield Strength	419 MPa
Elongation	34 %
Impact Toughness	12 KV/Ku(J)
Hardness	421 HBW
Modulus of elasticity	07 GPa

 

Heat Treatment & Processes:

Heat treatment:

The form and size of each component, as well as other external elements, will affect the heat treatment process, which includes the kind of furnace, quenching media, workpiece transfer facilities, and the heating temperatures including the rate of heating, cooling, and soaking durations.

 

Hardening:

Pre-heat the M35/DIN 3243/AISI M35 to 450–500°C and then to 820–870°C in two steps. Heat the material further until the final hardening temperature reaches between 1050 and 1250°C. Harden in a controlled furnace or vacuum for maximum results, or in a salt bath that has been thoroughly rectified.

 

Quenching:

Quenching mediums are heated oil, pressurized gas, or salt. To attain the necessary characteristics for pressurized gas, a quick quench rate to below 1000°F (538°C) is essential. For oil, quench at 900°F (482°C) or until it becomes black, then cool to 150–125°F (66–51°C) in calm air. Equalise, then cool in calm air to 150-125°F (66-51°C) for salt that is kept at 1000-1100°F (538-593°C).

 

Tempering:

Temper immediately after quenching in a temperature range of (510-620°C).

 

Forging:

Pre-heat M35/DIN 3243/AISI M35 to 450–500°C, then immediately raise the temperature to 950–1100°C for forging. Under 950°C, do not forge. After forging, cool very gently.

 

Stress Relieving:

To reduce the chance of distortion, stress relief is advised to be performed following machining and before hardening. Heat the component to 600–700°C and soak thoroughly for around two hours to reduce tension. Cool the boiler gradually.

 

Annealing:

After hot working and before re-hardening, M35/DIN 3243/AISI M35 Steel must undergo the annealing process. Heat at a maximum rate of 220°C per hour at 850°C. Always maintain temperature for two hours, or one hour every 25 mm of thickness. The furnace gradually cools. The hardness of the M35 annealed material should be 260 Brinell or less.

 

Normalizing:

M35/DIN 3243/AISI M35 is provided in an annealed, machineable state. Only when the steel has been hot wrought, forged, or toughened by the toolmaker will re-annealing be required. M35 high-speed steel should be heated to 850°C at a maximum rate of 220°C per hour.

 

Welding:

Special welding techniques including preheating and filler materials made from base material composition are used. After that , let the components cool gently.

 

Soft annealing °C	Cooling	Hardness HB
820 – 860	Furnace	max. 269

 

Stress-relief annealing °C	Cooling
630 – 650	Furnace

 

1st pre-heating °C	2nd and 3rd	Hardening °C	Quenching	Tempering °C	Hardness after Teperature HRC
up to approx. 400 in an air-circulating furnace	850 and 1050	1190 – 1230	Saltbath, at least 550 °C Oil ,Air	at least twice 540-570	64 – 67

 

1 For cold-forming tools with a complex geometry, a hardening temperature at the lower end of the quoted range is recommended. The stated hardening temperatures apply to saltbath hardening only. For vacuum hardening, we suggest a reduction of 10 °C to 30 °C.