Powder metallurgy of high speed-steel produced by solid state sintering and heat treatment

High-speed steel is successfully fabricated by solid state sintering of Fe, Co, WC, Mo2C, Cr3C2 and VC powders under vacuum. The sintering density, microstructure, phase structure, hardness, and transverse rupture strength of the specimens are examined. Results show that the density increases with increasing sintering temperature. Nearly full density is obtained without microstructural coarsening in the sintering temperature range of 1190–1210 8C. The optimum sintering temperature for the steel is 1200 8C. The suitable quenching temperatures range from 1200 to 1240 8C. After heat treatments, the microstructure consists of a martensitic matrix (grain size &5 lm) with a homogeneous distribution of MC and M6C carbides (average size lower than 1 lm). The highest hardness of 68.5 ± 0.3 HRC and the maximum transverse rupture strength of 3.58 ± 0.12 GPa is obtained for the specimen tempered at 560 8C.