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Steel M35 Heat Treatment Process

AISI M35 high-speed steel is a cobalt-containing material with excellent comprehensive performance. It has excellent high temperature resistance, wear resistance and stability, etc. It is often used to produce high-demand and high-quality tools, molds and knives. However, in order for steel m35 to perform at its best in various fields, its reasonable heat treatment process is crucial. Therefore, Songshun is committed to strictly requiring and optimizing the heat treatment process to ensure the best performance of m35 hss. This article will explore the heat treatment process and precautions of steel m35 in detail.


First, the preheating of steel m35 is divided into two steps. The temperature range is usually controlled at 400-500℃ and 730-900℃, and maintained for a period of time to ensure that the steel structure is evenly heated and the stress is reduced, the temperature gradient inside the steel is reduced, and cracks are avoided during quenching.


M35 steel can be heated at 1190-1210℃ (salt bath furnace) or 1200-1220℃ (box furnace/controlled atmosphere furnace), kept warm for 5-10 minutes, and quickly cooled to room temperature to form martensite structure to increase hardness. The quenching medium is oil, air cooling or salt bath. The hardness is usually between 64 HRC and 67 HRC. This step is a necessary process to improve the hardness and wear resistance of steel m35. It is necessary to strictly control the quenching temperature and speed to avoid cracks and deformation.


Tempering must be performed immediately after quenching. The tempering temperature of high-speed steel m35 is usually 540-560°C. It is recommended to perform triple tempering, 2 hours each time. It can be adjusted according to different needs. Steel m35 can also be tempered between 560-620°C and then cooled to room temperature. The hardness after tempering is 64-67HRC. Tempering can obtain tempered troostite, and can also eliminate the internal stress generated during quenching, improve the toughness of steel, and reduce hardness. Different tempering temperatures and times can produce different results of hardness and toughness. So be careful not to over-temper and reduce hardness.


Steel m35 has high hardness and brittleness after forging, which is not convenient for cutting, so the annealing process must be carried out after hot working, forging or before re-hardening. The annealing temperature is controlled at 850°C – 900°C at a maximum rate of 220°C per hour, and the temperature is always maintained for 2-4 hours, and then slowly cooled in the furnace at a rate of 10 to 20°C per hour, or cooled in the air. The final hardness achieved after annealing should be a maximum of 269HB or less. If cold drawing is performed, stress relief annealing is recommended. This process can be used to eliminate work hardening, adjust the organizational structure of steel parts, eliminate stress, reduce deformation, and improve processability, plasticity and toughness.

At Songshun, customers usually require m35 materials to be delivered after annealing + other processing methods (peeling, light drawing, grinding or polishing, etc.).

When performing the heat treatment process for steel m35, factors such as temperature, time, cooling medium and equipment will directly affect the quality and performance of the steel. Therefore, in order to improve its performance and service life, Songshun Steel can only provide customers with high-quality and high-performance m35 steel by strictly controlling process parameters and optimizing heat treatment processes to meet different application requirements.


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Dongguan Songshun Mould Steel Co., Ltd.

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