Sintering of 17-4PH stainless steel powder assisted by microwave and the gradient of mechanical properties in the sintered body

The sintering of 17-4PH stainless steel powder using microwaves has rarely been reported with results better than those produced by sintering with conventional resistive heating. This study evaluates the effect of the sintering temperature, holding time, heating rate and the pre-sintering stage in microwave-assisted sintering. By optimizing the sintering step to determine the optimal process, a more homogeneous microstructure, a greater sintered density, a greater shrinkage and better mechanical properties were obtained using microwave-assisted sintering. The total process time of the microwave-assisted sintering was notably less than conventional sintering, and the peak temperature was 150 to 200 °C lower. In 17-4PH stainless steel powder, microwave-assisted sintering was demonstrated to produce significantly better mechanical properties than conventional sintering. Measurements of the hardness distribution within the sintered specimen described the gradient of the mechanical properties of the microwave-sintered components. This study highlights why PM 17-4PH stainless steels should be produced using microwave-assisted sintering.