Metallographic observations during the sintering of BM2 type of high speed steels

Abstract

Metallographic changes during the sintering of BM2 type of high speed steels have been investigated by scanning electron microscopy, in the range of optimum sintering to oversintering. The primary carbides observed are MaC and a small quantity of MC; in the oversintered structure an additional carbide with eutectic morphology was seen. It is a chromium and molybdenum rich phase in BM2+ 0 to 4% cobalt (0.9 to 1.2% carbon) alloy, whereas in BM2+ 8% cobalt (0.9% carbon) the eutectic phase is MC. Under certain conditions MaC was also detected in the post-sintered alloy.