F0工作辊断辊的失效分析

Fracture failure analysis of F0 work roll

热连轧精轧机组F0工作辊发生爆裂、断辊事故。检查了该辊首次使用前的检测情况,观察了断辊的断口形貌,对残留辊面、剥落碎块各部位进行了硬度、金相、电镜检测,结果表明,轧辊的断裂经历了短周期的轧制、裂纹扩展的循环过程,轧辊表面产生大量异常热疲劳龟裂;轧辊的硬度均匀性差;工作层碳化物由表及里呈鱼骨状生长,会助长表层龟裂沿径向扩展;结合层组织异常、铸造缺陷促使裂纹萌生、加速裂纹扩展,导致工作层的剥落、爆裂。

F0 work roll was exploded and fractured in a hot rolling mill.The primal inspection of the roll before first application was checked,and the fractured roll surface and the residual fragments were observed,and the hardness test,microstructure and electron microscope analysis were carried out on the fractured roll.The results show that the fracture of the roll suffers from a short cycle rolling and crack propagation period,large amounts of abnormal heat fatigue cracks appear on the roll surface,the uniformity of hardness of the roll is poor,growth direction of fish bone shape carbide in outside working layer is inclined to the roll center.As a result,the cracks are propitious to expand to the center,and the abnormal microstructure and casting defects appear in the transition layer of the roll,which form primal cracks and accelerate the cracks to propagate,finally,parts of the outside working layer are flaked away and the roll explodes.