Abstract: The BOF→LF→RH→CC process, by which the data shows the higher alloy yield rate and component-targeting rate, and the less nitrogen content in the steel, has been adopted in the production of high-strength steel WYS700 after the contrast test. In order to ensure a smooth casting, the molten steel has been light calcium treated, in which the dosage of calcium silicon was 0.88 kg/t. After that, the continuous casting has been raised from 4 heats to 7 heats. Through the scanning electron microscope, the nonmetallic inclusion in tundish was observed as sphere and scattered basically, small than 5 μm in principle, which can denature to improve the continuous cast-ability. Through the optimization of component, temperature, water yield, casting powder, and flow field, the leakage rate of high-strength steel was reduced from 1.90 % to 0.35 %, and the crack defective percentage of casting blank was reduced from 5.5 % to 0.45 %.

Key words: CSP, high-strength steel, inclusions, calcium treatment, crack