Abstract
It is the purpose of this paper to discuss the effect of alloying elements upon the composition, the crystal structure and the distribution of sulfides in steels. Examinations of these sulfides by electrolytic isolation, X-ray diffraction and chemical analysis, coupled with microscopic observations, led to the following conclusions: (1) Co, Ni, Mo, W and Si have little effect on sulfides in steels except that these elements slightly dissolve into FeS. These sulfides appear in continuous network at the grain boundaries of matrix. (2) Cr and V concentrate in great amount into FeS, replacing the iron atoms in FeS lattice to attain the composition CrS and VS. These sulfides form a broken network pattern. (3) Mn, Nb, Ti, Zr and Al concentrate into sulfide phase, forming MnS, NbS, TiS, ZrS and Al2S3, respectively. NbS, TiS and Al2S3 form a peculiar network pattern, while MnS and ZrS are grobular, and disperse in the matrix. (4) FeS, CrS, VS, NbS and TiS have a NiAs-type hexagonal structure,but MnS and ZrS have a NaCl-type cubic one.
