Abstract: In order to reduce the oxygen content in heavy duty carburized gear steel and improve the fatigue life of gear materials, the oxygen content of finished forging was analyzed, and it was found that the ordinary production process couldn’t meet the requirements of customers. Therefore, the LF refining slag changing plus double VD vacuum refining operation process was developed, and the experimental results before and after optimization were compared by using on-line oxygen meter,Aspexautomatic inclusion scanninganalyzer,oxygen nitrogen hydrogen analyzer and XRF fluorescence analyzer. The research shows that the optimized process can reduce the oxygen mass fraction of the forging to 6×10^-6, and reduce the test value of the maximum inclusion size in the steel from 137.5 μm to 51.2 μm, successfully meet the needs of customers, and provide technical guidance for EBT+LF+VD+IC production process to produce ultra-low oxygen heavy duty carburized gear steel.

Key words: inclusion, oxygen content, gear steel, production process