架空绞线用热镀锌钢丝生产过程断丝原因分析

Wire drawing broken reason analysis in production process of hot galvanizing steel wire for overhead stranded conductors

针对架空绞线用热镀锌钢丝在生产过程中断裂的问题,对断裂原因进行分析。65钢盘条含碳量较高,轧制后易产生成分偏析,在晶界生成网状渗碳体,在拉力作用下,盘条易在渗碳体晶界处产生巨大的应力集中而形成微裂纹;表面处理采用机械除锈,氧化铁皮去除不彻底;拉拔过程中,部分压缩率过大,钢丝拉拔后不能有效降温。提出改进措施:不同直径的镀锌钢丝采用不同规格和材质的原料;采用酸洗磷化取代机械除锈,盐酸质量分数为15%～20%,酸洗时间约10 min,亚铁离子质量浓度≤200 g/L,磷化采用中温磷化,酸比为10～15,时间为10～15min,磷化膜厚度≥9μm;采用水箱拉丝机取代直进式拉丝机,改进配模工艺;控制脱脂温度,使成品钢丝的抗拉强度不超过标准值150 MPa。

The fracture reason was analyzed aiming at the fracture problem in production process of hot galvanizing steel wire for overhead stranded conductors. 65 steel carbon content is high, composition segregation produced easily after rolling, network cementite occurred in grain boundary, wire rod produced huge stress concentration in cementite grain boundary and caused microcracks because of drawing force. Surface treatment adopted mechanical descaling, scale was removed un- clean. In drawing process, pass compression ratio was too big, temperature couldn＇t drop effectively after wire drawn. Dif- ferent diameter hot galvanizing steel wire adopted different diameter and material wire rod. The mechanical descaling is replaced by adopting pickling and phosphating, hydrochloric acid mass fraction is 15% - 20%, pickling time is about 10 minutes, ferrous ion mass concentration is no more than 200 g/L, in phosphating process, medium temperature phosphating is adopted, acid ratio is 10 - 15, phosphating film is no less than 9 μm. The straight wire drawing machine is replaced by a- dopting water tank, to improve die matching process. To control degrease temperature, tensile strength of finished steel wire is controlled no higher than 150 MPa of standard value.