Effect of Permanent Magnet Stirring on Solidification of High‐Sulfur Micro‐Alloyed Steel under Different Magnetic Flux Densities

Abstract

The effects of permanent magnet stirring (PMS) with different center magnetic flux densities (0, 850, 1450, and 1800 Gs) on the solidification process of high‐sulfur micro‐alloyed 49MnVS3 steel are investigated by analyzing the MnS precipitation, microstructure, and tensile properties. The results indicate that with an increase in the magnetic flux density, an enhanced turbulent flow is introduced to the melt, and the MnS precipitates are not limited by grain boundary and distributed randomly and uniformly in the steel. When the magnetic flux density of PMS increases from 0 to 1800 Gs, the mean length of MnS decreases from 6.8 to 2.9 μm, and the number density of MnS increases from 1562 to 2293 n mm−2. Meanwhile, the content of the intragranular ferrite (IGF) increases from 0.4% to 3.1%, and the ratio of IGF in the total ferrite increases significantly from 4.2% to 30.1%, due to the growing precipitation of finer MnS‐ (Nb, V, Ti) (C, N) complex inclusions after PMS that induces the formation of IGF. In addition, both the tensile strength and toughness of the steel are improved under PMS with enhanced magnetic flux densities, which is attributed to the increased small‐sized MnS precipitates and promotes the formation of IGF.