Abstract：In order to reduce the boron content and inclusions of gear steel,in view of the high purity requirement of high-quality sulfur gear steel, the FactSage was used to calculate the chemical reaction equilibrium between B2O3 and Al, the iso-activity diagram of gear steel, and the ternary phase diagram of MgO-Al2O3-SiO2. The calculation results show that the higher content of Al in the molten steel can reduce the B2O3 remaining in the molten steel. Increasing the content of Al2O3 in the refining slag and increasing the content of MgO in the tundish dry material with decreasing the content of SiO2 can improve the cleanness of the molten steel of gear steel. When the above countermeasures were applied to industrial producing, the w(T[O]) of gear steel were less than 0.001 2%, the contents of B of gear steel were less than 0.000 5%, the levels of A-type inclusion were less than 2.0 and those of other type inclusions were less than 1.0 in gear steel. The qualification rate was improved from 71.5% to 100%. There was no large particle inclusion in the steel. The cleanness of sulfur bearing gear steel was significantly improved after process optimization.
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2021, Vol. 56 
