Insights into Interfacial Structure of Slag–Metal Interface During Desulfurization Through XPS and DFT Simulations

Ultra-low sulfur steel has excellent resistance to pitting and hydrogen-induced cracking, is mainly used for gas pipeline steel, drilling structural parts of offshore platforms. This study reveals the limiting aspects desulfurization at slag–metal interface from perspective experimental theoretical calculations. Based on XPS results, quantitative analysis shows that relative contents Si O are decreasing Ca, Mn S increasing as etching depth increases interface. exists a divalent (Mn2+), negative (S2−), Fe Fe–O Fe–S same time. Under conditions in this study, composed bridged oxygen (BO) non-bridged (NBO), content BO gradually decreases NBO deepens. With basicity, interfacial increases. The increase basicity leads faster diffusion therefore decrease experiment simulation system, two main exchange reactions occur interface, one reaction between Mn/Si, other with oxygen. Afterwards, Sulfur enters slag forms stable sulfides Ca/Mn