Effect of Cooling Rate in Sinter-Hardening on the Microstructures and Properties of a Hybrid P/M Steel

摘要

Sinter-hardening is becoming a widely used process for the production of high strength P/M parts. If martensite is produced directly from the sintering furnace, it is possible to-produce parts with properties close to those of quenched and tempered steels without the need for a separate heat treatment step. The success of sinter-hardening depends on its ability to produce microstructures of high martensite content consistently during accelerated cooling after sintering. This study examines and illustrates the effects of changes in cooling rate from the sintering temperature on the microstructure, hardness and properties of a hybrid P/M steel. It is demonstrated how the sinter-hardening process can be improved from a comparison of the cooling rates determined from instrumented Jominy bars and the sintering furnace.