抄録
The effects of vanadium, from 1 to 10 mass %, on the formation of carbides of as cast high carbon high speed steels containing 1.6 and 2.1mass%C were investigated by SEM, TEM and EDS analyses. In the 1%V steels, M7C3 and M6C type eutectic carbides formed on the primary austenite boundary. In the 3%V steels, V-rich MC type eutectic carbide was found to exist. In steels with V above 3% the amount of MC carbide increased while those of M7C3 and M6C decreased with increasing V content. In both the 8% and 10%V steels, primary MC and eutectic M3C carbides were observed. Carbon content influenced the start and finishing temperatures of the eutectic reaction and the microstructure, i. e. both the temperatures decreased and the length of needle-like eutectic carbides became longer in the 2.1%C steels. While the hardness of the steels with V below 5% did not change with V content, it began to drop suddenly in the steels with V above 8% due to the existence of ferritic matrix.
