Abstract: The “B type” elongated inclusions should be avoided for pipeline steel to prevent crack generation during service. Calcium treatment is usually performed to control the composition of inclusions. However, the feeding amount of calcium wires is lack of good guidance in industrial operations. And different feeding amounts of calcium wires might induce different yields of calcium, resulting in different inclusion characteristics from expected. In the current work, the evolution of inclusions during the production route of “BOF→LF→RH→CC” with various feeding amounts of calcium in X80 pipeline steels was investigated. The novel evolution of composition, number density of inclusions were analyzed, and the reasons for the evolution were discussed. In addition, thermodynamic calculations were performed based on the current composition of steels to predict the evolution of inclusions.
Authors: Fei Li, Hao Zhou, Shusen Li, Feng Zhang,Ying Ren, and Wen Yang
Keywords: Calcium Treatment, Pipeline Steel, Inclusion, Thermodynamic Calculation