Surface Analysis of PM Martensitic Steel Before and After Consolidation: Part 2: Surface Analysis of Compacted Material

Abstract

Martensitic steel powder (Fe12Cr) was consolidated using hot isostatic pressing (hipping) at three combinations of temperature, pressure, and time: 770°C/150 MPa/8 h; 1000°C/50 MPa/2 h; 1150°C/ 150 MPa/2 h. The two lower hipping temperatures were chosen to obtain fracture along the prior particle boundaries (PPBs). Thereby, it was possible to study the reaction products formed on the PPBs during consolidation using Auger electron spectroscopy. During consolidation at 770°C the manganese and chromium oxides formed on the surface of the powder during atomisation are coarsened. At 770 and 1000°C silicon, vanadium, and nitrogen diffuse to the PPBs and form compounds. After compaction at 1000°C no MnO was detected on the fracture surface, which indicates that MnO is reduced at higher temperatures. Raising the hipping temperature to 1150°C enhances densification, thus no PPB failure is observed. PM/0440B