Influence of Co on the microstructure and mechanical properties of M42 high-speed steel

Abstract M42 high-speed steel (W 2 Mo 9 Cr 4 VCo 8 ) is a kind of high cobalt super-hard (HSS), which extensively used in various cutting tool materials, but because the price cobalt, HSS does not bring good economic benefits. In this thesis, consequences contents (0.0%, 2.0%, 4.0%, 6.0%, 8.0%) on organization and mechanical properties have been studied. The microstructure was analyzed by OM, SEM, EDS, Rockwell hardness test, impact toughness flexural strength test were conducted. results show that helps to increase nucleation rate eutectic carbide precipitation hinder its growth during tempering refine size carbide, can be maintained above 68 HRC when content 4%-8%; however, also significantly reduces HSS, each 2% decreases about J·cm −2 . From point view savings, 4%, hardness, toughness, other at higher level.