HIGH MACHINABILITY IRON BASE SINTERED ALLOY FOR VALVE SEAT INSERTS

摘要

A ferrous sintered valve seat material is made of mixed powders comprising a sinter-hardenable phase and a finely dispersed carbide phase. The powder mixture comprises a sinter-hardening prealloyed powder forming 75 to 90 wt.% of the mixture and a tool steel powder with finely dispersed carbides forming 5 to 25% of the mixture. Machinability additives of MnS, CaF2 or MoS2 types are added in an amount of 1 to 5 wt.%. Improved thermal conductivity is obtained by infiltrating the compact with Cu up to 25wt.%.