On the Configuration of Titanium Sulphide in Steels

Abstract

Effect of Ti/S ratio on the distribution, shape and structure of titanium sulphide in steel were studied. In Ti/S ratio range less than 0.35, sulphide inclusions in cast steels were randomly distributed in globular shapes and had a wide range of sizes as type I. At about 0.5 Ti/S ratio, they appeared on primery grain boundaries as type II, and in Ti/S ratio range over 1.3, they were formed as Fe-TiS eutectic as type II. FeS films in caststeels were changed in to globular shapes by addition of titanium. These were explained by solution of titanium sulphides in FeS. Thus, the low melting point of FeS were raised and the hot warkability of steels were improved by solution of titanium sulphides.
Titanium sulphides appeared pink-gray globular shapes in microscopic light field. Thier particles were about 0.3-0.5μ size, but grown up to about 3.5μ size or changed into a rod shape in accordance with solubilities of other inclusions, such as nitrides or oxides. It was considered that titanium carbides were primarily formed and secondarily titanium sulphides, and then titanium nitrides and titanium oxides were formed in the process of solidification of titanium steels. This order was contrary for heat formation of each titanium compound, and, in particle size of each inclusions, titanium carbides were of the most fine particle and suc-cessively followe din size titanium sulphides, nitrides and oxides. It was confirmed that titanium sulphides in steels were TiS and the structure were of a hexagonal B 8 modified type as dete-rmined by X-ray diffraction methods of residues.