Powders coarser than and similar to those for most metal injection molding processes were compared
to each other. The 13μm and 7μm water-atomized SUS316L powders were pressed so as to form compacts 10 mm in diameter and about 7 mm in height with a low density of about 4.85 Mg/m³ which is rather close to that of the injection molded samples. They were sintered at 1373-1673K for 60 min in hydrogen.
The 7μm powder densified with the disappearance of small pores and the transitional growth of large pores as the sintering temperature rose, though the 13μm powder changed the pores into rounded shapes at low temperatures, and quickly reduced the total porosity at temperatures above 1573K. At 1623K or above, the difference between the pore structures of these powders almost disappeared. Any differences in tensile strength and elongation of these powder samples prepared actually by metal injection molding, also disappeared at 1623K.
The shrinkage of unidirectionally pressed compacts by sintering and that by cold isostatic pressing showed a similar anisotropy, giving a larger shrinkage in the lateral direction in both cases.