Research on the microstructures and mechanical properties of high speed steel M2 produced by spray forming and traditional melting

Two kinds of high speed steel specimens (M2, W6Mo5Cr4V2) were prepared by spray forming and traditional melting, respectively. The annealing structures, non-metal inclusions, hardness after quenching and tempering, microstructures, and mechanical properties of M2 specimens in the same size at the same location were studied by metallographic microscope and M-200 wear tester. In the results, the carbides in spray formed M2 specimens show more uniform distribution and smaller size, and the carbides in traditional melted M2 specimens are present as the zonal distribution. In the same heat treatment process, the tempering hardness of M2 specimens prepared by spray forming and traditional melting is similar at the same location. Compared with the traditional melted M2 specimens, the wear resistance of spray formed M2 specimens is increased by ~41%. The number of MC carbides in spray formed M2 specimens with the size more than 2μm is apparently higher than that in the traditional melted M2 specimens, resulting in the higher wear resistance of spray formed M2 specimens in the same hardness. It can be seen that the microstructures and mechanical properties of spray formed M2 specimens are better than those of the traditional melted M2 specimens, showing the advancement of spray forming technology.