Mechanism and Kinetics of Transformation of Alumina Inclusions by Ca Treatment

【作者】 韩志军； Lauri HOLAPPA；

【Author】 Zhijun HAN1, Liu LIU1, Minna LIND2 and Lauri HOLAPPA2 1) Department of Metallurgical technology, Central Research Institute of Iron and Steel, 100081Beijing China 2) Laboratory of Metallurgy, Helsinki University of Technology, P.O.Box 6200, 02015, Finland.

【机构】 钢铁研究总院工艺所； Laboratory of Metallurgy, Helsinki University of Technology, P.O.Box 6200, 02015, Finland.；

【Abstract】 Calcium treatment is nowadays a well-established method to improve steel castability and final properties e.g. machinability, toughness and surface quality. The effects of calcium are mainly based on its strong ability to form sulphides and oxides. The topic of the present paper concerns the basic mechanism and kinetics of the transformation process of alumina inclusions in steel when calcium introduced into the steel e.g. by wire feeding or powder injection. To clarify the mechanisms model experiments were performed by studying reactions between Al2O3 and CaO in a laboratory furnace as well as by performing Ca treatments in an 8 kg induction furnace for Al deoxidised melt. The phases formed during the reaction between Al2O3 and CaO were examined by SEM-EDS, and the proposed reaction sequence of Al2O3?CA6?CA2?CA?CAx(liquid) was discussed based on the experimental observations. The kinetics of the reaction of calcium with alumina inclusions were simulated by immersing alumina plates in a Ca treated steel melt in the induction furnace. Results were compared with observations of real inclusion transformation. Based on the results a kinetic model was proposed.更多还原