HEAT TREATMENT OF P/M IRON BASE PARTS

The present paper has outlined the heat treatment technologies of powder hot-forged parts with high density, repressed and resintered parts with medium density and P/M rolled parts with high density surface and with porous core. Emphasis has put on a process to achieve high concentration carburization by using heterogeneous austenite carburization. Experiments have shown that carburizing temperature in a range of Ac₁-Acm, i.e. 850-920℃, and according to projects 3、4 for heterogenuous carburization, for iron base structural parts containing chromium, carbon contents in carburized case can be over 2% and carbide contents can be over 50%.The carbide was uniformly distributed fine particles.The wear resistence of repressed and resintered parts,which were carburized was higher than that of 20^# steel pasts which were carbon-nitrided, by 2.22 times.