Abstract: The metallurgical production flowsheet of copper-clad steel 6A (/% : 0.03 ~ 0.06C, 0.02 ~ 0.05Si, 0.15 ~0. 25Mn, ≤0.015P, ≤ 0.015S, 0.02 ~0.05Al) is hot metal desulphurization- 120 t BOF-LF-140 mm x 140 mm billet casting-continuous rolling to Φ6.5 mm coil- annealing. The breaking wire of copper-clad steel 6A during cold-drawing process from Φ6.5 mm cold-drawing to Φ0.45 mm wire has been analyzed by scanning electron microscope. Results show that there are coarse spheroidized cementite clusters at center line near the fracture of Φ0. 45 mm wire. During cold-drawing process due to the hardness of pearlite higher than that of ferrite, the fine cavities initiate at tip of pearlite and with increasing drawing passes the cavities evolve as transverse ℃- shape cracks finally led to wire breaking. With decreasing carbon and manganese content in steel respectively from 0. 05% and 0.23% to 0.03% and 0.17% , decreasing overheating extent of liquid in tundish from 35 ℃ to 25 ℃ and optimizing electromagnetic stirring parameters from 250M, 1. 2 Hz to 400 A, 1. 2 Hz, the phenomenon of pearlite clusters at coil center is improved and the cold-drawing wire broking ratio decreases from 1. 0 times per ton steel to 0. 2 times per ton steel.

摘要： 铜包钢6A(/%:0.03～0.06C,0.02～0.05Si,0.15～0.25Mn,≤0.015P,≤0.015S,0.02～0.05Al)冶金生产流程为铁水脱硫-120 t BOF-LF-140 mm×140 mm方坯连铸-连轧至Φ6.5 mm盘条-退火。运用扫描电镜分析了Φ6.5 mm铜包钢6A盘条冷拔至Φ 0.45mm的断丝。结果表明,Φ0.45 mm钢丝断口附近的中心线位置存在粗大球化渗碳体团,在拉拔过程中,珠光体较铁素体硬度高,珠光体端部萌生细小的孔隙,随着拉拔道次的增加,逐渐扩大成了横向Y形裂纹并最终导致断丝。通过将钢中碳和锰含量分别从0.05%和0. 23%降至0.03%和0.17%,中间包钢水过热度从35℃降至25℃,电磁搅拌由250 A,1.2 Hz优化成400 A,1.2 Hz,改善了盘条中心位置的珠光体团聚现象,冷拔断丝率从吨钢1. 0次降低至0. 2次。