Improvements in sintered density and dimensional stability of powder injection-molded 316L compacts by adjusting the alloying compositions

Powder injection molding is a process that provides advantages when making small parts with high density and complicated shapes. However, dimensional control of powder injection-molded stainless steel parts is difficult due to the presence of the liquid phase and the large amount of shrinkage that occurs during sintering. This study examines whether such a problem can be overcome through adjustments in the alloy composition and by making use of Thermo-Calc analysis. The results show that, with an increase in the molybdenum content up to the maximum limit according to existing specifications, a compact can be sintered to high densities without the presence of the liquid phase, while maintaining it in the dual-phase region of γ + δ. In addition, dimensional control is improved. A slower heating rate is also found to be beneficial. These results are explained through dilatometric analysis and phase diagrams that are calculated using the Thermo-Calc program.