Structure and phase composition of high-speed steels

Abstract

This work is devoted to the study of the structure and phase composition of high-speed steels R6M5, R9 and R18. High service properties of high-speed steel tools are achieved by heat treatment. Therefore, the sample blanks for the study were cut from cutting tools from R6M5, R9 and R18steels, which were subjected tothe usual standard heat treatment for these steels. Installed that the structure of high-speed steels R6M5, R9 and R18 in the initial state, i.e. after standard heat treatment, consists of martensite and special carbides. The carbide particles are evenly distributed in the matrix and are close to the correct spherical shape. Thus in the structure of steels R6M5 and R9 are carbides of type М6С, MC, and in the structure of steel R18 only carbides of the type М6С. EBSD analysis showed that M6C carbides are most optimally combined with the Fe3W3C cubic phase, and the MS type carbide corresponds to the VC phase. Electron microscopic analysis showed that in addition to M6C and MС carbides, high-speed steel contains small amounts of «cementite» type М3С carbides.