Effect of Strain on Strain‐Induced Precipitation Behavior of MnS in 3% Si Steel

Abstract

Hot compression tests of 3% Si steel with a true strain range of 0.02–0.92 at a strain rate of 1 s−1 and a temperature of 1173 K, based on the Gleeble‐1500 thermo–mechanical simulator, are conducted. The effect of strain on the strain‐induced precipitation behavior of MnS is investigated via cold field‐emission ultrahigh resolution scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The experimental results obtained indicate that the volume density of MnS precipitates increases, whereas the mean diameter of MnS precipitates decreases with the increase in strain during the transient deformation stage. However, during the steady deformation stage, these parameters remain nearly constant. The precipitation behavior of MnS during the transient deformation stage is attributed to the increase in dislocation density with the increase in strain. More dislocations create a larger number of nucleation sites, which, in turn, increase the nucleation rate. At the same time, a model about static recovery affecting the dislocation density in the matrix after deformation is also proposed to elucidate the mechanism of the evolution of MnS in the aging process.