Study on the Influence of Silicon and Aluminum on the Microstructure and Properties of Low Cobalt M42 High-Speed Steel

Abstract

M42 HSS (W2Mo9Cr4VCo8 ) is widely used as a high cobalt super-hard high-speed steel (HSS) for various cutting tool materials, but high cobalt HSS does not bring good economic benefits. In this paper, the effects of Si and Al on the organization and mechanical properties of low cobalt M42 HSS were investigated. The microstructure of HSS was analyzed by OM, SEM, EDS, XRD, etc. Rockwell hardness test, impact toughness test and flexural strength test were conducted. The results of the study showed that only increasing the Si content in M42 HSS containing 4.0% Co did not significantly improve the material organization and properties, and caused a sharp deterioration in impact toughness. After adding 1.0% Si and 1.0% Al to M42 HSS containing 4.0% Co, Si and Al can partially replace Co, resulting in a more uniform and diffuse carbide distribution. The hardness of the material is increased to 68.3 HRC and the impact toughness is increased to 13.8 Jꞏcm-2, which has better overall mechanical properties and can meet the processing and cutting requirements under actual working conditions.