PRECIPITATION BEHAVIOR OF SULFIDES IN TI- ADDED ULTRA LOW-CARBON STEELS IN AUSTENITE

The influences of S and Ti contents as well as slab reheating temperat ure on the precipitation behavior of sulfides in hot-rolled bands in T i-added ultra low-carbon steels have been investigated. The results ob tained are as follows: In the specimens with the same 0.02% Ti content , Ti4C2S2 decreases and TiS increases in number as S content increases while in the specimens with the same 0.008% S content, TiS decreases and Ti4C2S2 increases in number as Ti content increases. The number of TiS increases when the slab reheating temperature is high. The solubi lity products of TiS and Ti4C2S2 in austenite have been also experimen tally determined as follows: log[Ti][S]=- 3252/T-2.01 log[Ti][C](0.5)[ S](0.5) =-5208/T-0.78 The experimental results above agree well with t he results calculated using these solubility products. The reliability of solubility products determined in this study are checked and it is confirmed that the solubility products in this study is in good agree ment with the published experimental results.