Full Densification in PM Steels Through Liquid Phase Sintering and HIP Approach

High-density powder metallurgy (PM) components are required for high-performance applications. Liquid phase sintering (LPS) is one such method to improve the densification, especially the master alloy route is preferred due to the flexibility in tailoring the alloying contents. In this study, gas atomised Ni-Mn-B master alloy powder of size fraction < 45 µm was admixed with water atomised iron and Mo-prealloyed powder. During sintering, there was a significant densification due to LPS where the liquid formation occurred in two stages, one from the master alloy melting and another from the eutectic liquid formation, enabling densities > 95%. The microstructural investigation revealed that the surface densification was achieved after sintering in H2 containing atmosphere. Capsule free hot isostatic pressing was performed on these samples to achieve full density. This approach of combining LPS and capsule free hot isostatic pressing demonstrates the potential in reaching full densification in high-performance PM steel components