Influence of slag composition on bearing steel cleanness

Al2O3 and high Al2O3 content composite oxides are the main types of inclusions in aluminium killed bearing steel, and these also have the most significant impact on rolling contact fatigue (RCF) life. The calculation results in the phase diagram by using the FactSage showed that the activity of Al2O3 reached the minimum with the slag composition in a low melting point area at a MgO content less than 5%; a basicity of 5 to 8 and a ratio of CaO/Al2O3 of 1·5 to 2·0 in slag. This slag was most effective in improving the absorption ability of slag for inclusions in bearing steel. By using the experimental slag, the total oxygen could be reduced to 7–10 ppm at Hangzhou Iron and Steel Group Company (HIRGC).