Argon-atmospheric sintering process of stainless steel 17-4 precipitation hardening from metal injection molding product

Abstract

Metal injection moulding (MIM) is a metalworking technology for producing a small and complex product as well as high efficiency. In this process, the sintering parameter is an important process that must be controlled especially the sintering atmosphere to optimise the product. In the previous study, the sintering process was conducted by using a vacuum atmosphere that resulted in the formation of porosity as a major problem. This study was aimed to understand the influence of argon atmosphere in the sintering process with different temperature in order to improve the relative density of 17-4 PH Stainless Steel. The 17-4 PH Stainless Steel feedstock injected to the mould using injection moulding machine. After injection, the solvent debinding process was carried out at 50 oC with hexane solution for 1.5 h. Thermal debinding was performed at 510 oC using a vacuum furnace with heating rate and holding time were 1 °C min−1 and 60 min, respectively. Afterwards, the resulting sample was heated at the various sintering temperature of 1320 °C, 1340 °C, 1360 °C, and 1380 °C with 5 °C min−1 heating rate and 90 min holding time in an argon atmosphere with flowing rate of 1 litre min−1. These study revealed an argon atmosphere sintering process influenced the content reduction of porosity due to increasing relative density. According to these results, the optimum sintering temperature by using an argon atmosphere was achieved at 1360 oC.