GCr15轴承钢235mm×265mm方坯连铸工艺的优化

Optimization of Concasting Process for 235 mm×265 mm Bloom of GCr15 Bearing Steel

西宁特钢的GCr15轴承钢连铸坯由90 t UHP Consteel EAF-LF(VD)-CC流程生产。通过全程保护浇铸,钢中平均氧含量减少3.15×10^(-6);控制钢水过热度≤20℃,拉速0.7～0.8 m/min,二次冷却比水量0.40 L/kg,铸坯平均等轴晶率≥60%,且铸坯质量明显提高;在上述优化工艺参数下,采用3.25 Hz/250 A结晶器电磁搅拌和20 Hz/300 A凝固末端电磁搅拌,铸坯中心碳偏析指数为0.99～1.20。

Cast bloom of GCr15 bearing steel is produced by 90 t UHP Consteel EAF-LF（VD）-CC flow sheet at Xining Special Steel. With shielded casting practice in whole casting process, the average oxygen content in steel decreased by 3.15×10^-6; by controlling the degree of superheat of molten steel ≤20℃, the casting speed 0. 7-0. 8 m/min and the secondary cooling water rate 0.40 L/kg, the average equiaxial crystal zone ratio of bloom was ≥60% and the quality of bloom obviously increased; and with above optimized process parameters and using 3.25 Hz/250 A EMS for mold and 20 Hz/300 A EMS for solidified front, the carbon segregation index in center of bloom was 0：99 - 1.20.