连铸关键工艺对200 mm×200 mm断面SWRH82B铸坯均质性的影响

Effect of key continuous casting process on homogeneity of 200 mm×200 mm SWRH82B billet

通过铸坯酸洗腐蚀低倍拍照、中心偏析及半宏观偏析检验,研究了不同电磁搅拌、浇铸过热度及二冷强度对200 mm×200 mm断面连铸SWRH82B铸坯均质性的影响规律,考察了铸坯均质性对盘条中心晶界渗碳体评级的影响。制定了200 mm×200 mm断面连铸SWRH82B的关键工艺,实现了铸坯低偏析控制,为盘条组织性能控制奠定了重要均质性基础。结果表明,M-EMS电流强度300 A,F-EMS电流强度200 A,浇铸钢液过热度(25±2)℃,弱二冷工艺所得铸坯均质性最优,其中中心C偏析度平均为1.08,轧制的盘条中心晶界渗碳体评级2.0级以下的比例达96%,盘条拉拔断丝率平均2.3次/100 t。

The effect of electromagnetic stirring,degree of superheat and secondary cooling intensity on the homogeneity of 200 mm×200 mm continuous casting SWRH82B billet was studied and the influence of the homogeneity of casting billet on the rating of the central grain boundary cementite of wire rod was investigated through central and semi-macro segregation tests and macrostructure tests on the continuous casting billet.The key continuous casting process of 200 mm×200 mm SWRH82B steel was developed.The low segregation control of the continuous casting billet was achieved,and an important homogeneous foundation for the control of microstructure and performance was laid.The test results showed that the homogeneity of continuous casting billet can be optimized by using the technologic parameters of M-EMS current intensity of 300 A,F-EMS current intensity of 200 A,superheat degree of(25±2)℃and weak secondary cooling process.With these process technologic parameters,the central carbon segregation degree of the billet can be decreased to 1.08 in average,the proportion of grain boundary cementite of as-rolled wire rod rating not higher than 2.0 reached 96%,and the average wire breaking rate was decreased to 2.3 times per 100 tons in average.