Powder injection molding and sintering of austenitic stainless steel

Abstract

This paper describes powder metallurgy (P/M) processing approach to consolidate ferrous alloys for automotive applications. The net shape and corrosion/oxidation requirements in automotive components, such as exhaust flanges, necessitate P/M<i> </i>processing route giving the advantage of alloying flexibility and precision manufacturing. One variant of P/M<i> </i>processing is powder injection molding (PIM) where complex-shaped components on a large scale are fabricated. In this study, experiments were performed on 316L stainless steels using compacts shaped by pressing and powder injection molding (PIM). In the conventional process, the austenitic stainless steel compacts were solid-state sintered at 1250°C<i> </i>and supersolidus liquid phase sintered (SLPS) at 1400°C. The injection molded 316L stainless steel feedstock were Injected, thermally debound and sintered. The rheological behavior of the binder was investigated through <i>in</i> <i>situ </i>imaging. Density of the stainless steel samples sintered by supersolidus liquid phase sintering was higher than the solid-state sintered samples. The effect of sintering temperature on the microstructural evolution was characterized. The PIM stainless steel components attained nearly full density with a uniform shrinkage.