MECHANICAL PROPERTIES OF METAL INJECTION MOLDED (MIM) 17-4PH STAINLESS STEEL

摘要

Metal injection molding (MIM) is a promising process for the manufacture of near-net shape gas turbine engine components using powder metallurgy. MIM provides an alternative to more costly, conventional, near-net shape processes such as investment casting. In the present study, the mechanical properties of MIM-17-4PH stainless steel were investigated. The MIM-17-4PH test bars evaluated were processed using gas atomized 17-4PH powders with a proprietary powder size distribution and a polyacetal binder, and were heat treated to the H1150 condition after sintering. The results obtained from the MIM-17-4PH bars were compared with those of investment cast 17-4PH bars heat treated to the same condition. Both materials exhibited similar hardness and tensile strength at room and elevated temperatures. The high-cycle fatigue strength of the MIM-17-4PH bars was found to be more than 20% higher than that of the cast 17-4PH bars. However, the MIM material displayed substantially less ductility and impact toughness, as well as slightly lower Young's modulus, than the cast material. It is also noted that the mechanical properties of the MIM material can be significantly improved by hot isostatic press, which reduces the internal porosity levels of the material.