The effect of PSD on properties of unimodal and bimodal powders using 17-4 PH stainless steel powder

17-4 PH is a martensitic precipitation-hardening stainless steel that possesses an outstanding combination of superior physical and mechanical properties, good toughness, resistance to corrosion, and is easily machinable and weldable. It is widely used in the chemical, petrochemical, and aerospace industries. In this paper, we study the effect of the particle size distribution of unimodal and bimodal powders on properties of 17-4 PH stainless steel parts manufactured through metal injection molding (MIM). Unimodal and bimodal injectable MIM feedstocks of 60 vol% solids loading were prepared using powders of three different particle sizes with a wax-based binder system. The results show that coarser particle sizes (unimodal or bimodal) exhibit relatively lower shrinkage levels which is desirable for dimensional control but inferior “as-sintered” mechanical properties. The finer particle sizes (unimodal or bimodal) exhibited inferior rheological feedstock properties but comparatively superior “as-sintered” mechanical properties. The study suggests that bimodal feedstocks of finer particle sizes exhibit a favorable combination of rheological properties and “as-sintered” mechanical properties.