Impact of Sintering Parameters on Sintering Densification and Mechanical Properties of High-Performance Powder Metallurgy (HPM) 17-4PH Compacts

The press-and-sinter (PS) process often uses coarse powders, leading to low-density compacts and poor mechanical properties for 17-4PH. To improve these properties, fine 17-4PH powders, usually used in metal injection molding (MIM) process, were considered. However, fine powders pose challenges in the PS process due to their high friction, which leads to difficulties in molding. In this study, we used granulated 17-4PH MIM powders with excellent flowability for the PS process. We examined the effect of sintering temperature on the sintered density and mechanical properties of 17-4PH compacts. Results show that temperatures above 1260°C introduce the δ phase, enhancing diffusion rate, pore spheroidization, and grain refinement. Sintering at 1320°C in a H2 atmosphere yielded parts with the highest density (7.4 g/cm3) and optimal mechanical properties. In contrast, temperatures above 1360°C caused uneven alloy distribution and grain coarsening, reducing performance. Our results show that the HPM process achieves mechanical properties comparable to those of MIM parts, while offering lower costs and shorter manufacturing times. This gives PM products a competitive edge in commercial applications.