2016 Volume 56 Issue 6 Pages 1023-1030
The sulfide morphology in SUS303 was investigated and the mechanism of monotectic sulfide formation was evaluated. The sulfide of metastable monotectic type was observed at the surface region of ingot with the higher solidification cooling rate and stable eutectic type was observed at the inner region. The formation of monotectic sulfide was promoted by Ca addition and the formation of eutectic type sulfide was promoted by Al addition with the lower oxgen content. It is thought that the nucleation behavior greatly affect the monotectic sulfide formation because of the lower interfacial energy with liquid oxide inclusion. However, solute distribution, undercooling and the decrease of S activity by adding Ca or increasing O content may also influence on the eutectic/monotectic morphology selection.