镀锌钢丝钢绞线拉拔断裂原因分析

Analysis on the Causes of Fracture of Galvanized Steel Wire and Strand during Drawing

首钢水钢研发镀锌钢丝钢绞线用盘条在拉拔加工时发生严重断裂,对断裂样品进行了化学成分分析,利用扫描电镜、电子探针和金相显微镜分析了断裂样品的断口形貌、夹杂物、显微组织。结果表明:盘条拉拔时发生脆断的主要原因是产生了网状渗碳体组织和马氏体等不易变形的异常组织。通过原因分析发现,在冶炼、连铸过程中不稳定操作,铸坯中溶质元素锰和铬偏析、富集现象,提高了过冷奥氏体在转变区尤其是低温转变区的稳定性,大大推迟了过冷奥氏体向珠光体的转变时间,使连续冷却曲线右移,以及冷却速率低于临界冷速速率等原因,产生低温马氏体和渗碳体组织。

The wire rod for galvanized steel wire and strand developed by Shougang Shuigang Compa ny experienced severe fracture during drawing processing.The chemical composition of the fractured sample was analyzed,and the fracture morphology,inclusions,and microstructure of the fractured sample were analyzed using scanning electron microscopy,electron probe,and metallographic mi croscopy.The results show that the main reason for brittle fracture of wire rod during drawing is the formation of reticular cementite and Martensite and other abnormal structures that are not easy to de form.Through cause analysis,it is found that unstable operation during smelting and continuous cast ing,segregation and enrichment of solute elements manganese and chromium in the slab have im proved the stability of undercooled austenite in the transformation zone,especially in the low-temper ature transformation zone,greatly delayed the transformation time of undercooled austenite to pearlite,shifted the continuous Cooling curve to the right,and the cooling rate was lower than the critical cool ing rate,As a result,low-temperature Martensite and cementite are produced.