(1232) Effect of complex deoxidation on the solidification structure of Ni-Mn-Mo alloyed steel

摘要

The effect of combinations of several deoxidizers, i.e. Mg-Al, Mg-Ti, Al-Ti, and Ce-Al, on the solidification structure of Fe-2%Ni-1%Mn-1%Mo alloy melt was investigated using a melt sampling and quenching method. Using this method, we evaluated the catalytic potency of several complex inclusion particles by taking the inclusion evolution process into account. Fine equiaxed crystals were obtained in the Mg-Ti deoxidized steel wherein the MgO(MgAl2O4)-TiN complex compounds formed. However, the longer the holding time at high temperatures, the larger the fraction of Ti2O3 and very fine TiN that formed due to micro-segregation during solidification, resulting in poor equiaxed crystals. When the steel was deoxidized with Mg-Al, the initial structure was dominantly columnar. However, the longer the holding time, the larger the fraction of MgAl2O4 spinel, resulting in the formation of fine equiaxed crystals. Ce-Al complex deoxidation provided a relatively small portion of equiaxed crystals, whereas Ti-Al deoxidation produced the fewest equiaxed crystals due to the formation of alumina. The effectiveness of each inoculant particle for the crystallization of the primary delta-iron was explained well by the lattice disregistry concept.