Development of a polyoxymethylene-based feedstock for metal injection molding using 09Cr16Ni4Nb stainless steel powder

Stainless steel powders are among the most widely used raw materials for the production of small, high-precision engineering components by metal injection molding (MIM), a process that combines metal powders with molten polymer binders. This study focuses on the development of feedstock composition and processing parameters for MIM production using domestically sourced components: a martensitic stainless steel powder grade 09Cr16Ni4Nb, a polyoxymethylene-based binder, and processing additives including stearic acid, beeswax, and low-density polyethylene. The starting stainless steel powder had a spherical morphology with a predominant particle size range of 8–23 μm. Scanning electron microscopy, melt flow index (MFI) testing, and helium pycnometry were employed to investigate the microstructure, rheological behavior, and physical properties of the resulting feedstock granules. Dependencies of MFI on the feedstock composition, metal-to-polymer ratio, type and content of additives, and particle size distribution of the metallic phase were established. The optimal feedstock formulation was determined experimentally. The microstructure and physical properties of sintered samples produced from the developed feedstock were evaluated and compared with those made from imported Catamold ® feedstock. It was demonstrated that standard heat treatment modes are suitable for MIM-fabricated parts, as the phase transformation behavior of the studied steel does not differ from that of conventionally processed materials. The results confirm that components manufactured from the in-house feedstock comply with relevant regulatory standards and match the performance of their imported counterparts.