Effect of Mn on solubility of Ti-sulfide and Ti-carbosulfide in ultra-low C steels

Abstract

To clarify the thermodynamic stability of Ti4C2S 2 and TiS in ULC Ti-added IF steels, extraction by potentiostatic electrolysis method and chemical analysis were conducted with ULC Ti-added IF steels containing various amounts of Mn and heated at various temperatures. As the results, the solubilities of Ti4C2S2 and TiS increased with an increase in Mn content. Ti4C2S 2 was more stable than TiS between 950 and 1 250°C. Following solubility products were obtained. log(Ti] · [C]0.5- [S] 0.5=0.392-7 004/T- (4.783-7 401/T) · [Mn] log[Ti] 2/3· [S]=-0.021 -5 847/T-(3.360-5 195/7) · [Mn] © 2008 ISIJ.