Hardenability of PM Steel Alloyed Using Tailored Master Alloys

Abstract

The ferrous powder metallurgy industry is facing major upheavals currently, which, however, also offer opportunities. New materials and concepts, made possible by tailored design, are a way to prepare for new challenges. Alloying of PM steel through the master alloy route is a concept that combines efficient usage of alloying elements, also of such with high oxygen affinity, with accelerated homogenization via liquid phase sintering. Thus, improved properties can be attained while maintaining dimensional precision, which makes the PM route more attractive. In the present study, different master alloys containing Fe, Si, C, Cr and / or Mn have been admixed to plain iron base powder, the mixes then being consolidated by pressing and sintering. The materials thus produced are compared to two commercial sinter hardening PM steel grades in terms of hardenability. CCT diagrams are presented for all materials, and hardness data from quenching dilatometer experiments are compared to the hardness values achieved by sinter hardening in the lab furnace as well as by a classical quench-and-temper treatment.