Effect of Shape of MnS Inclusion on Ductility of Rolled Plate

Abstract

A study has been made of the effect of shape of MnS inclusion on the directionality of mechanical properties using a commercial grade 0.13%C-1.34%Mn steel. Shapes of inclusion are varied with temperature and reduction ratio of rolling. Mechanical properties of longitudinal (L), transverse (C) and through-hickness (Z) directions are measured.
MnS inclusion deforms to greater extent as rolling temperature decreases and relative plasticity of inclusion (ratio of plasticity of inclusion to that of matrix) is about 0.5 at 1250°Cand 1.0 at 900°C. The variation of ductility (reduction of area and Charpy shelf energy) with rolling conditions is clearly described as a function of IAR (inclusion aspect ratio) in each direction.
Efforts are made on expressing the ductility in one parameter regardless of direction and rolling conditions and it is found that Charpy shelf energy can be described as a function of log (1-2f_A/2f_A), where 2f_A is the area fraction of MnS inclusions on the ductile fracture surface of a test piece.