Method for making powder metal forging preforms of high-strength ferrous- base alloys

摘要

The invention involves a method for making powder metal forging preforms of high strength ferrous-base alloys in which the times and temperatures for reducing oxides, sintering, and carburizing are substantially reduced as compared to conventional techniques. The method includes simultaneously sintering and carburizing the preforms in the hot zone of a sintering furnace at temperatures below 2000° F. and for a period of time above austenitic temperature not exceeding about 35 minutes. After carburizing the preforms are rapidly cooled to freeze the case carbon gradient obtained in the hot zone.