Abstract: For a steel factory production of 55SiCr spring steel，the reduction of area of the oil quenched and tempered treatment wire rod after processing is less than 40%， which affects the subsequent spring coiling process and the service life of the spring. The casting billet and wire rod were evaluated by methods of low-magnification pickling test， tensile test， oil quenched and tempered treatment， drill cuttings test， etc， it was found that the center segregation of the casting billet was the main cause of poor drawing performance. Through the optimization test study of continuous casting process， the results showed that high superheat had a significant effect on the segregation of billet and the drawing performance of wire rod.When the superheat was 35 ℃ compared with 18 ℃， the reduction of area and elongation increased by 2% and 0. 8% respectively. The electromagnetic stirring current of the mold was increased from 150 A to 320 A， and the center equiaxed grain rate was increased from 8%-8. 5% to 10. 5%， but the average center carbon segregation index also increased. When using the same mould electromagnetic stirring technology， reducing the electromagnetic stirring intensity at the solidified end was beneficial to improve the center segregation. When the average center carbon segregation index of the slab decreased from 1. 10 to 1. 02， the reduction of area of the oil quenched and tempered treatment wire rod increased from 39% to 47%.

Key words: Spring Steel, Superheat, Electromagnetic Stirring, Center Segregation, Reduction of Area

摘要： 针对某钢厂生产的55SiCr弹簧钢，用户加工后的油淬火钢丝断面收缩率在40%以下，影响后续卷簧过程和弹簧的使用寿命，通过低倍酸洗试验，拉伸试验，油淬火调质处理，钻屑试验等方法对铸坯和线材进行评价检测，发现铸坯中心偏析是导致拉拔性能差的主要原因，通过开展连铸工艺优化试验，研究结果表明：高过热度控制对铸坯偏析及线材拉拔性能有显著影响，过热度为 35 ℃相较于过热度 18 ℃，断面收缩率和伸长率分别提高 2%和 0. 8%；结晶器电磁搅拌电流从150 A增加到320 A，中心等轴晶率由8%~8. 5%增加到10. 5%，但是中心碳平均偏析指数也随之增加；相同结晶器电磁搅拌工艺时，降低凝固末端电磁搅拌强度有利于改善中心偏析；铸坯中心碳平均偏析指数由1. 10降低到1. 02时，油淬火调质态线材断面收缩率由39%增加到47%。

关键词: 弹簧钢, 过热度, 电磁搅拌, 中心偏析, 断面收缩率