Abstract: Micro-alloying is a conventional measure to ensure the strength of steel bars. In the V-added rebars, the existing nitrogen increasing measures like adding VN and nitriding ferroalloys have defects such as high cost and low nitrogen recovery rate. We have developed a novel nitrogen-oxygen mixed blowing process of the converter to effectively increase the nitrogen in steel. Through controlling nitrogen blowing time, nitrogen and oxygen ratio, mixed blowing time and optimizing blowing process of the convertor, the nitrogen content range of 90-145 ppm in liquid steel has been steadily realized. The ferroalloy FeV instead of VN or nitriding ferroalloys has been used for batch production of bars. On this basis, the development and stable production of low-cost high-nitrogen HRB500 steel bars are successfully achieved which have the advantages of stable mechanical properties and good aging resistance properties.
Authors: Yunge Wang, Huaqiang Hao, Menglong Li
Keywords: Nitrogen-oxygen mixed blowing; High-strength steel bar; Vanadium