sintering densification; HK30 stainless steel; viscoelasticity theory; metal injection molding

The HK30 stainless steel powder was mixed with 0.4%, 0.8%, 1.2% (mass fraction) Ti, and the samples were prepared by powder injection molding. The density, microstructure, microhardness and shrinkage rate of the samples were measured. The densification process was modeled based on viscoelasticity theory. The equation of densification rate was established. The results show that Ti addition reduces the sintering activation-energy and improves the sintering densification in initial stage, but it reduces the final density. The microhardness of austenite near Ti particle is lower than that of other areas. Because Ti has a higher affinity for C and O, which reduces the impurity levels in the austenite. The reduction of impurities is conducive for densification during the initial stage of sintering. In the final stage, supersolidus liquid-phase sintering has the largest contribution on densification. Because carbon is combined with Ti, the amount of liquid phase is reduced and therefore the sintering densification is hindered.