Effects of Sintering Temperature and Holding Time on Densification and Mechanical Properties of MIM HK30 Stainless Steel

Abstract

The sintering process of HK30 stainless steel (SS) prepared by metal injection molding (MIM) was studied. The effects of the sintering temperatures (1270, 1280, and 1300 ℃) and holding times (1, 3, 5, 7, and 9 h) on the densification, microstructure, and mechanical properties were investigated. To achieve a stable high performance, the sintering process should be carried out at 1280 ℃ for 7 h. The obtained density, micro-hardness, tensile strength, and elongation are 7.61 g/cm3, 187 HV1.0, 570 MPa, and 31%, respectively, attaining the standard of forged HK30 SS. The average grain size of the samples is 64 μm. In addition to the grain growth, the higher sintering temperature of 1300 ℃ led to over-heating or over-burning, which reduced the bonding strength between grain boundaries. As a result, the density and mechanical properties decreased.