Hot ductility of C–Mn and microalloyed steels evaluated for thin slab continuous casting process

Abstract

Hot ductility of three grades of C–Mn steel and four grades of microalloyed steel have been evaluated simulating the bending or straightening operation in thin slab continuous casting process. The minimum bending or straightening temperature has been determined from the hot ductility curves generated by plotting per cent reduction in cross-sectional area of specimens against different test temperatures. The results have been discussed by analysing the force elongation curves and the fractographs of all the steels, and possible explanations for the results obtained have been presented. In microalloyed steels containing Nb, multiple troughs are observed in the hot ductility curves instead of single trough observed for remaining steel grades. The ductility is not recovered at 700°C in steels containing Nb, unlike the remaining steel grades. Among the C–Mn steels, steels with higher S content show less ductility. Intergranular fracture is observed in specimens in which ductility obtained is low.