Effects of aging treatment on the precipitation behavior of ε-Cu phase and mechanical properties of metal injection molding 17-4PH stainless steel

摘要

This study mainly investigates the influence of artificial aging at 480 degrees C, 520 degrees C and 620 degrees C on the microstructure and mechanical properties of metal injection molding (MIM) 17-4PH. The results show the microstructure of the as-sintered MIM 17-4PH to be mainly composed of lath martensite, delta-ferrite, and nodular SiO2 inclusions. The effect of precipitation hardening is to strengthen the MIM 17-4PH by the precipitation of a large number of fine spherical epsilon-Cu phases on the lath martensite matrix, which effectively block the movement of dislocations. The highest hardness is obtained by artificial aging at 480 degrees C for 4 h. As the aging temperature increases, the epsilon-Cu phase grows coarser, which results in over aging of the MIM 17-4PH and decreases the hardness. (C) 2018 Elsevier B.V. All rights reserved.