Effect of electropulsing treatment on the precipitation behavior of MnS in sulfur-containing microalloyed 49MnVS3 steel

Abstract

An experimental investigation has been conducted with respect to the influence of electropulsing treatment (EPT) on the 2D and 3D morphologies, distribution, number and size of MnS precipitates in the high-sulfur micro-alloyed 49MnVS3 steel. After the application of electric current pulse with a peak pulsed voltage of 30 V, the microstructure was refined due to the increasing nucleation rate of particles in liquid steel. Moreover, compared with the untreated steel with spherical MnS randomly distributed in the matrix, the MnS precipitates moved directionally to aggregate on the bottom and top surfaces of the ingot in order to minimize the free energy of the system in case of EPT. For untreated steel samples, the number of MnS was 409 (bottom), 579 (middle) and 437 (top), while that of the treated samples were 226 (bottom), 38 (middle) and 224 (top) in the scanning area of 2.65 × 107 µm2 with ASPEX. The number of MnS with small size decreased while the large-size MnS increased with the application of EPT.