Vacuum Carburization of High-Performance Automotive PM Parts

Automotive gears, particularly highly stressed engine and transmission helical gears, traditionally are machined from wrought bar stock and subsequently heat treated to develop the required surface hardness and tooth bending fatigue durability. Conventional powder metallurgy components, given their high residual porosity, cannot meet stringent bending and surface fatigue requirements, and, therefore, generally have not been considered for use in such high performance applications.

However, since 1994, innovations and advances in PM materials and net-shape processing at Stackpole Ltd., have been well proven in high volume production on complex geometry parts, and have demonstrated the cost advantages of PM [1]. A combination of several key technologies, such as appropriate alloying, net-shape forming, high-temperature sintering, densification and vacuum carburizing, is used to raise the performance level of PM steels to the required level.