M42 High Cobalt Toughness High Speed Steel Vacuum Heat Treatment Process

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M42 steel is high cobalt toughness high speed steel, mainly used for high toughness precision wear-resistant hardware cold die, can also be used for cutting tools and knives cooling.Steel hardness, up to 70HRC, good thermal hardness, high temperature hardness, easy to grind.The cutting tools made of this steel can cut iron base superalloy, cast superalloy, titanium alloy and ultra-high strength steel, but the toughness is slightly poor, so the temperature of quenching should adopt the lower limit.Because of the good grinding performance, it can be used to manufacture a variety of high precision and complex tools.

Features:

High red heat hardness, high wear resistance and cutting ability, high impact toughness.Fine and uniform grain, high toughness.

Application:

Tool industry: scraper, hobbing knife, iron knife, drill, etc

Forging industry: forging die

Screw industry: hexagonal head molding mold, tooth attack, punch

Heat treatment:

The heat treatment temperature of M24 high speed steel is 800~880℃ in the model RVGQ-669 high pressure true air quenching furnace produced by Shanghai Ghang Vacuum Co., Ltd. The furnace is cooled to 600℃ at 10~20℃, and the hardness is above HB269.
Stress relief: temperature 650~750℃, cooling in furnace.

Chemical composition:

C :1.00~1.15
Si :≥0.65
Mn :≥0.40
P :≥0.030
S :≥0.030
Cr :3.50~4.50
V :0.95~1.35
W :1.15~1.85
Mo :9.0~10.0
CO :7.50~8.50

Related information:

High speed steel generally do not do tensile strength test, and metallographic, hardness test.Rockwell hardness of tungsten and molybdenum high speed steels can reach more than 63 and that of cobalt high speed steels can reach more than 65 after correct heat treatment.The acid – soaked low – fold structure of steel shall not be visible to the naked eye shrinkage hole, peel.Center loose, generally loose should be less than 1 grade.The content of metallographic examination mainly includes three items: decarburization layer, microstructure and carbide inhomogeneity.High speed steel should not be significantly decarburized.There should be no fishbone – like eutectic leitsite in the microstructure.In high speed steel, the degree of carbide inhomogeneity has the greatest influence on quality. Metallurgical and mechanical departments attach great importance to the degree of carbide inhomogeneity.According to different uses of steel, different levels of unevenness of carbides can be required, usually less than grade 3.

In addition to its high hardness, high wear resistance and enough toughness, there is also an important factor of red hardness in the manufacture of cutting tools with high speed steel.Red hardness refers to the ability of the cutting edge to resist softening under red heat during high speed cutting.One way to measure the hardness of red is to heat the steel to 580 ~ 650℃, keep it warm for 1 hour, and then cool it, and then measure the hardness value after repeated 4 times.The quenching temperature of high speed steel is generally close to the melting point of steel, such as 1210 ~ 1240℃ for tungsten high speed steel, 1180 ~ 1210℃ for high molybdenum high speed steel.After quenching, it is generally required to temper 3 times between 540 ~ 560℃.Increasing quenching temperature can increase the red hardness of steel.In order to improve the service life of high speed steel tool, its surface can be strengthened, such as low temperature cyanidation, nitriding, sulfur nitriding, etc.

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