The structure and properties of heat-treated and coated W-Mo-V plus Si plus Nb high-speed steels

This paper presents the results of investigations regarding the phase trans formations occurring during the heat treatment of W-Mo-V + Si + Nb high-spe ed steels. It was found that investigated steels demonstrate their maximum secondary hardness, about 66 HRC, in connection with the precipitation of M 4C3 carbides in tempered martensite after austenitizing at 1240 degrees C a nd tempering at 540-570 degrees C. The paper presents also results of inves tigations regarding the erosion resistance of TiN and Ti(C,N) PVD coatings deposited on the investigated steels. TiN and Ti(C,N) coatings deposited in the PVD process yield, respectively, three and seven times greater erosion resistance of the steel surface and demonstrate good adhesion to the inves tigated steels forming the substrate. Quantitative metallography methods as well as mass loss and created craters 3-D measurements were employed to ev aluate the erosion resistance of the investigated coatings. It was found th at the surface topography influences the erosion resistance of PVD vacuum a re method coatings. The investigated coatings are not affected by the type of the substrate high-speed steels. (C) 1999 Elsevier Science S.A. All righ ts reserved.