【摘要】 利用金相显微镜、扫描电镜分析了弹簧钢55SiCr拉拔钢丝延迟断裂的原因，发现钢丝表面存在高碳回火马氏体组织形成的硬化层，且存在细小裂纹；断口呈现脆性断裂特征，在表面异常组织区域存在含F的CaO-SiO₂-Al₂O₃-MgO-MnO-Na₂O大型复合夹杂和C成分夹杂。追溯此批材料的炼钢过程，发现连铸过程的非稳态控制是造成钢丝表面增碳和卷渣的原因，而夹渣部位形成的异常组织则是55SiCr拉拔钢丝延迟断裂的直接原因。通过稳定浇铸过程，细化操作规程及要求，55SiCr盘条再未发生延迟断裂问题。更多还原

【Abstract】 The causes of delayed fracture of spring steel 55SiCr drawn steel wire were analyzed by metallographic microscope and scanning electron microscope.It was found that there was a hardened layer formed by high carbon tempered martensite on the surface of the steel wire,and there were small cracks;the fracture presents brittle fracture characteristics,and there are large-scale composite inclusions of CaO-SiO₂-Al₂O₃-MgO-MnO-Na₂O containing F and C-component inclusions in the area of abnormal surface structure.Tracing back the steelmaking process of this batch of materials,it is found that the unsteady control of continuous casting process is the cause of carburization and slag curling on the steel wire surface,and the abnormal structure formed at the slag inclusion part is the direct cause of the delayed fracture of 55SiCr drawn steel wire.Through the stable casting process and refining the operation procedures and requirements,no delayed fracture of 55SiCr wire rod occurred again.更多还原