Optimization and industrial tests of LF refining slag for gear steel (8620H)
WU Hui-qiang1,LIN Lu2,GU Chao3
1. Technology Center, Hangzhou Iron and Steel Group Company, Hangzhou 310022, Zhejiang, China 2. Metallurgical Technology Institute, Central Iron and Steel Research Institute, Beijing 100081, China 3. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China
Abstract：The iso-activity lines of CaO and Al2O3 in CaO-SiO2-Al2O3-5%MgO quaternary system were calculated by FactSage thermodynamics software. And the effects of bacisity of refining slag, ratio of w(CaO)/w(Al2O3), and MI index on the adsorptioncapacity of Al2O3 inclusions were mainly discussed through the figures of iso-activity line. The results showed that the main compositions of refining slag suitable for the production of gear steel (8620H) in Hangzhou Steel were that the contents of CaO, Al2O3,, SiO2 and MgO were in the range of 50%~55%, 25%~30%, 10%~12% and 5%~8%, respectively. Applying this refining slag in industrial tests, the total oxygen content decreased from 0.001 5% to 0.001 0%. Besides, the average size of inclusions in billets also significantly decreased from 2.1 to 1.5 μm, and the large inclusion content decreased from 31.9mg/10kg to 26.4mg/10kg. Thus, the industrial tests received good results.
2016, Vol. 26 
