Influence of sulfur and Mn/S ratio on the hot ductility of steels during continuous casting

The influence of S and (Mn/S) on the crack susceptibility of continuous casting steels was studied. It is theoretically demonstrated that there is a critical value of the (Mn/S) ratio, (Mn/S) c , under which a high susceptibility to cracking, during casting or deformation of as‐cast material, is expected. The value of (Mn/S) c increases as the S content of the steel decreases. Based on literature data and results from rolling continuous casting billets the following experimental equation has been found: (Mn/S) c = 1.345 · S −0.7934 . A high similarity between this experimental equation and the theoretical one is achieved. A comparison between the equation found and previous expressions from literature was carried out. The MSC index as the ratio between the (Mn/S) ratio of a steel and the corresponding critical one was defined. The MSC index is a useful tool for the analysis of experimental results from literature.