Effects of sintering schedule on the characteristics of Fe-based powder compacts formed through warm compaction route

Abstract

This paper presents the sintering characteristics of Fe-based powder compacts formed through the warm compaction method. Iron powder ASC100.29 (73 wt%), chromium powder (22 wt%), and aluminium powder (5 wt%) were mixed mechanically for 60 mins in preparing the feedstock. The powder mixture was subsequently compacted at 200ºC through simultaneous loading of 325 MPa from upper and lower punches. The defectfree green compacts were then sintered in an argon gas fired furnace at a rate of 10ºC/min by varying the sintering time (30, 60, and 90 mins) and temperature (600, 750, and 900ºC), respectively. The sintered samples were characterized through physical and mechanical properties and their microstructures were analysed through scanning electron microscopy. The results revealed that sintering at 900ºC for 90 mins contributed to the highest volumetric expansion and relative density change, which are not expected in the powder metallurgy industries. A moderate sintering temperature of 750ºC for a holding time of 60 mins was found to produce a sintered sample with higher bending strength. In these sintering conditions, better dispersion of the alloyed elements is also observed.