Abstract
By using reduced and carburized starting powder, SKH57 was vacuum-sintered, HIP-ed and then heat-treated. Then, its mechanical properties were studied as a function of sintering temperature (TS), quenching temperature (TQ), aging temperature (TA), etc. The following results were obtained. Under a suitable condition such as TS=1200°C, TQ=1170-1200°C and TA=560-590°C, the sintered alloy showed excellent properties such as 4.8-4.9GPa of TRS and 840-870 HV. The alloy commonly fractured from a small flat region (φ10-20μm) containing micropores along the former austenite grain boundaries. The micropores were considered to be caused by the reduction of a small amount of remained oxides, which took place during sintering. The strength of the alloy, therefore, was controlled by the size of flat region, but not by the primary carbide or the former austenite grain size.
