Nonmetallic Inclusion Control of 350 km/h High Speed Rail Steel

Inclusion has an important effect on quality of high speed rail steel. In consideration of the lower acceptance percentage of the inclusion and its constraint against the requirement for large scale production of 350 km/h high speed rail steel in Panzhihua Iron and Steel (Group) Co, the technology of nonmetallic inclusion control for 350 km/h high speed rail steel was studied. An optimized model of the argon-blowing in ladle furnace (LF), the control of the components of the ladle slag, and the technique of calcium treatment for the molten steel was brought forward. Using the researched technology, the removal ratio of the inclusion was increased and the components, distribution, and shape of the inclusion in the rail steel were changed, which resulted in a reduction in the average total oxygen content to 10. 17 × 10−6 and an increase in the comprehensive acceptance percentage of the nonmetallic inclusion from 48. 21% to 98. 1%. Test has shown that this metallurgical technology can meet the requirement for large scale production of 350 km/h high speed steel in Panzhihua Iron and Steel (Group) Co.