How to correctly understand M42 steel for Hss twist drill bit ?
[ Published:2019/5/14  Read:539 times  Source:tenyu]

M42 steel (W2Mo9Cr4VCo8) is a 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 knife cooling. High hardness of steel, up to 70HRC, good hot hardness, high temperature hardness, easy to grinding. The cutting tools made of this steel can cut iron-based superalloys, cast superalloys, titanium alloys and ultra-high-strength steels, but the toughness is somewhat inferior, and the lower limit of the temperature at quenching should be adopted. Due to the good grinding performance, it can be used to make a variety of high-precision and complex tools.

W2Mo9Cr4VCo8 steel code M42 is a U.S. grade super hard cobalt high speed tool steel. The mass fraction of vanadium in M42 steel is not high (1%), and the mass fraction of cobalt is high (8%). Cobalt can promote carbides during quenching and heating. Dissolved in the matrix in large amounts, using high matrix hardness to improve wear resistance. The hardness, hot hardness, abrasion resistance and grinding ability of the steel are all very good. Heat treatment hardness can reach 67~70HRC, but special heat treatment methods are also used to obtain a hardness of 67 ~ 68HRC, which improves the cutting performance (especially intermittent cutting) and improves the impact toughness. The steel can be made into various kinds of tools, and it is very effective in cutting difficult-to-machine materials, and because of its good grinding performance, it can be made into complex tools. However, China lacks cobalt resources, and cobalt high-speed steel is expensive, which is about ordinary high-speed steel. 5~8 times.
Domestic Cobalt High Speed Steel has been improved in quenching and tempering hardness, hot hardness, and serviceability, and it has approached or reached the level of imported steel. After quenching and tempering, the hardness is ≥67HRC, and the uniformity is ≤±0.5%. Product specifications: φ10~150mm, hot rolled, forged round steel, rectangular materials, square steel, forgings, etc. Organize production according to GB/T 9943-2008 standard or user requirements.
Superhard speed steel is developed on the basis of the advantages of high-carbon high-speed vanadium high-speed steel and high-carbon high-cobalt high-speed steel in order to meet the needs of machining hard-to-cut materials, such as heat-resistant alloys. Generally hardness ≥64HRC when used. The process performance of this steel is better than that of M2Al steel, and the hot and cold processing performance is better. The hardness after quenching and tempering is the same as that of M35 steel, which is (66±1)HRC.

M42 powder high-speed steel, more detailed microstructure, better performance, the price is relatively higher.

so the hss twist drill bit cobalt  will be expensieve.

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