Relative plasticity of manganese sulphide inclusions during rolling of some industrial steels

16 mm thick plates were rolled from slabs of four different steels in the temperature range 1200°–790°C. The length of manganese sulphide inclusions was assessed on longitudinal sections and the index of relative plasticity calculated. Results show that incomplete recrystallization of austenite between rolling passes increases the relative plasticity of manganese sulphide inclusions much more than solution hardening. Rolling of steel in the temperature range of high relative plasticity can double the length of inclusions on the longitudinal section. Partial transformation of austenite to ferrite during rolling decreases the relative plasticity of manganese sulphide inclusions in a limited temperature range.