Powder Metallurgical Solution for a Complex Geometry Coupler Requiring High Dimensional Stability and Microstructural Uniformity through Heat Treatment

Powder metallurgy is the fabrication process of compacting metal powders to shape and sintering these compacts to yield the final material’s properties. The PM compaction process allows for complex geometries to be formed that would normally lead to long and expensive machining processes from wrought steels and special alloy selection can allow for hardening of the microstructure during the sintering procedure. The sinter hardened (SH) alloys exhibit good mechanical properties, along with good hardenability and dimensional stability and may be a suitable replacement for wrought steels where low distortion from heat treatment or microstructural control is required. In this study, it was found for a complex geometry coupler application, a SH alloy could successfully replace an austenitizing heat treatment process with a low alloy steel. The low alloy steel was found to have micro heterogeneities that lead to premature failure in the application. Dimensional distortion and production variance were also of concern with the low alloy steel. The SH material demonstrated acceptable physical properties, hardness and microstructural uniformity to solve the concerns with the low alloys steel. Post processing optimization also added to the life performance of the coupler by tailoring the final microstructure to mating components.