张力减径辊断裂原因及改进措施研究

某公司张力减径辊在轧制T91材质钢管时发生断裂。为研究断裂原因及改进措施,对张力减径辊的化学成分、微观组织、力学性能、使用过程和制造过程等进行检测与分析。研究结果表明:Mn、Cr、Ni和Mo元素含量偏低,基体抗拉强度不足,是引起断裂的内部原因;热处理温度和冷却速度控制不当,使张力减径辊心部出现珠光体和牛眼状石墨,也导致基体强度降低;使用过程中应力异常增大是张力减径辊断裂的直接原因。将改进措施固化为制造、使用、维护标准,避免了断裂的再次发生。

Study on Reasons for Fracture of Stretch-reducing Roll and Related Countermeasures

The reasons for fracture of the stretch-reducing roll being used to make the T91 steel tube at a certain domestic company are investigated,involving testing,inspection and analysis of such elements of the roll as chemical composition,microstructure,mechanical property,operation process and manufacturing process,etc.Relative countermeasures are also studied.As a result,it is revealed that in the material of the roll,the contents of chemical elements Mn,Cr,Ni and Mo are rather low,which leads to tensile strength deficiency of the basal body,and this is the internal reason for the said fracture;due to improper control of the heat treatment temperature and the cooling rate,pearlite and bull*s-eye graphite structure occur in the core part of the roll,which also causes strength reduction of the basal body;and the unusual growth of the stress during the operation process,and this is just the direct reason for the fracture.The countermeasures are regularized as criteria for manufacture,operation and maintenance so as to prevent recurrence of the said fracture.