Influence of Hot Isostatic Pressing on Microstructure and Tensile Properties of Nickel-Free Stainless Steel for Metal Binder Jetting

Abstract

Additive manufacturing processes continue to grow in popularity. Hereby, metal binder jetting (MBJ) has a high potential for series production of highly complex parts with added value compared to other production technologies. Applications already exist in thermal management, filtering, or fluid distribution. As with beam-based additive manufacturing processes, the materials available for MBJ are still limited. Especially in the area of nickel-free stainless steels; for example, for medical applications, there are hardly any options available. Therefore, this study investigates a newly developed nickel-free stainless steel specifically designed for the MBJ process. Particular attention is paid to the microstructure and the mechanical properties such as hardness and tensile strength. In addition, the investigation focuses on the potential of hot isostatic pressing (HIP) after sintering to favorably influence the microstructure and the mechanical properties. The results show that in the as-sintered state, a maximum porosity of 2.8% is present, which can be completely removed by hot isostatic post-densification. HIP post-densification improves both the yield strength and the tensile strength by about 10%. The increase in elongation at break is around 50%.