Institute of Powder Metallurgy and Additive Manufacturing, School of Metallurgical Engineering,Xi’an University of Architecture and Technology, Xi’an 710055, China
M2 high speed steel is the most widely used and representative tool steel. The use of selective electron beam melting (SEBM) additive manufacturing technology to form M2 high speed steel can effectively avoid the problems of coarse microstructure and carbide segregation by traditional wrought technology, and is expected to significantly improve its mechanical, wear and other properties. In this paper, M2 high speed steel bulk specimens were prepared on 316L stainless steel substrates with different scanning parameters and two powder bed preheating temperatures, focusing on the effects of scanning parameters and powder bed preheating temperatures on the microstructure of formed M2 high speed steel in terms of density，grain size and carbides. Under the optimized parameters, the densities of the formed M2 high speed steel reached 99.7%, the average grain size was 3~6 μm, and the carbides were small and uniformly distributed. The hardness and wear properties of SEBM formed M2 high speed steel were analyzed by Vickers hardness tests and friction tests. The results show that the Vickers hardness of formed M2 high speed steel with optimized parameters can reach 1034.2HV0.2, which is much higher than that of commercial M2 high speed steel tools (815HV0.2~845HV0.2), and the wear rate is only (3.58±0.36)×10-5mm3·N-1·m-1, which is 13.7% lower than that of tempered wrought counterpart. In addition, the wear mechanism of SEBM formed M2 high speed steel are mainly abrasive wear and adhesive wear.