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| Study of Total Oxygen Content and Nonmetallic Inclusions in 20CrMoH Steel During Refining Process |
| LI Haibo1,LI Hong1,WANG Xinhua1,CHEN Tianming2,YANG Subo2 |
| 1. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China;2. Panzhihua Iron and Steel Research Institute, Panzhihua 617067, Sichuan, China |
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Abstract Industrial experiments of 20CrMoH steel, a typical gear steel, were carried out with new processes and new slags. Total oxygen content of steel was analyzed, as well as the formation mechanism of the calcium aluminates of very low molting point in the molten steel. From the results, several conclusions can be drawn. First, total oxygen content is decreased sharply during tapping after aluminum addition, and SiO2 in slag is the main oxygen source when (FeO%+MnO%) is lower than 0.005. Second, with the use of CaOAl2O3MgO refining slag of (CaO%) 5560, (Al2O3%) 3540, (MgO%)≤6, superclean molten steel can be produced with total oxygen content of 10-5. And further, the transformation of the calcium aluminates inclusions in secondary refining is similar to the transformation during calcium treatment. Finally, the transformation of aluminates in the molten steel to low melting point calcium aluminates can be achieved when the CaO/Al2O3 ratio of the slag is controlled between 1.501.65,as for calcium treatment, and Catreatment can be eliminated after RH.
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Received: 01 January 1900
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2007, Vol. 42 