1. School of Materials and Metallurgy, Northeastern University, Shenyang 110004, Liaoning, China; 2.Laiwu Steel Group Co., Laiwu 271104, Shandong, China
Abstract：On the basis of analysis of the effect of sulpfide on pipeline steel, the production conditions of calciumtreatment on sulphide inclusion in pipeline steel were analyzed by using the principle of metallurgical thermodynamics with consideration of production practice of Laiwu Steel, and the inclusions in pipeline steel were examined. The results show that, during the refining of pipeline steel in Laiwu Steel, the final dissolved oxygen content in molten steel for most of the heats are higher than the theoretical value of 3.42×106 required for calciumtreatment, and the calcium content in molten steel has not reached the equilibrium value of calcium and sulfur, therefore, the sulfide inclusions have not been modified completely, and there are some MnS and MnSCaS in pipeline steel.
