Development and prospects of molten steel deoxidation in steelmaking process

In the traditional long process of steelmaking, excess oxygen is blown into the converter, and then alloying elements are used for deoxidation. This inevitably results in a large amount of deoxidation products remaining in the steel liquid, affecting the cleanliness of the steel. With the increasing requirements for steel performance, it is necessary to not only reduce the oxygen content in the steel liquid, but also ensure its high cleanliness. After more than a hundred years of development, the total oxygen content in steel has been reduced from over 100×10^-6 to around 10×10^-6, and it can even be controlled below 5×10^-6 in some steel grades. A relatively stable and mature deoxidation technology has been formed, but further reducing the oxygen content in steel is no longer significant for improving steel quality. Our research team has developed a deoxidation technology for bearing steel based on the optimization of the entire process. It is a combination of silicon-manganese pre-deoxidation, ladle furnace diffusion deoxidation, and vacuum final deoxidation. We have successfully conducted industrial experiments on the production technology of interstitial free steel with natural decarbonization pre-deoxidation. The former can control the oxygen content in bearing steel to between 4-8×10^-6, change the type of inclusions, eliminate large particle Ds-type inclusions, improve the flowability of the steel liquid, and obtain a higher fatigue life. The latter not only reduces aluminum consumption and production costs but also significantly improves the quality of cast billets.