Abstract: Complex precipitation of MnS and oxides is beneficial to reduce the harm of oxide and maintain the advantage of sulfide. In the current work, the characteristics of complex inclusions of MnS and oxide in the bloom of heavy rail steel were investigated. It was found that the fully surrounded oxide-sulfide complex inclusions were mostly nearly spherical, and more like to form near the surface. While oxide inclusions with a small amount of MnS being precipitated on the surface were observed mainly in the inner part of the bloom. The number density of complex inclusions was largest near the surface of the bloom, and decreased towards the center of bloom. The diameter of the complex inclusions as well as the size of the oxide core were larger near the region of the quarter of the bloom thickness and width. The characteristics of the complex inclusions were greatly affected by the sulfur segregation, the variation of local cooling rate, and the formation of pure MnS.
Authors: Wen Yang, Xuewei Zhang, Yanping Chu, and Lifeng Zhang
Keywords: Heavy rail steel, Complex precipitation, MnS, Oxide, Element segregation