Microstructure and mechanical properties of 17-4PH steel and Fe-Cr-B alloy mixed material manufactured using powder injection molding

This study investigated the microstructure and mechanical properties of 17-4PH precipitation hardened martensite stainless steel and Fe-Cr-B based alloy mixed material manufactured using powder injection molding. 17-4PH stainless steel powder was mixed with 5 wt%, 10 wt% and 20 wt% Fe-Cr-B based alloy (M alloy) powder to manufacture three different PIM mixed materials. Initial microstructural observations confirmed the δ-ferrite phase and martensite phase in the matrix region in all three PIM mixed materials, and (Cr, Fe)₂B phase was found in the strengthening phase, boride region. Room temperature tensile tests determined the yield strengths of the 5 wt%, 10 wt% and 20 wt% M added mixed materials to be 568.2 MPa, 674.0 MPa and 697.7 MPa, and the ultimate tensile strengths to be 1141.5 MPa, 1161.0 MPa and 1164.6 MPa, respectively. Fracture surface observation confirmed ductile fracture in the ferrite phases, and brittle fracture in the martensite phase and (Cr, Fe)₂B phase. Also, as the M powder fraction increased, the fracture mode of the (Cr, Fe)₂B phase was confirmed to shift from intra-phase fracture to inter-phase fracture. Based on the above-mentioned findings, the deformation and fracture behavior of new mixed materials manufactured using powder injection molding was identified, and its application possibilities were also discussed.