热轧板带轧机高速钢复合轧辊断裂失效分析

针对热轧板带工作辊在轧制过程中发生的断辊事故,对其失效原因进行了分析。通过对轧辊断口宏观形貌,材质化学成分、显微组织、工作层残余奥氏体含量及断口形貌的分析,认为轧辊断裂属于应力断裂.而造成轧辊断裂的主要原因是工作层残余奥氏体含量过高,轧辊在使用过程中残余奥氏体发生马氏体相变,巨大的内应力导致裂纹的产生;同时轧辊工作层显微组织中网状碳化物,芯部C、Mn含量不足以及铸造孔洞缺陷加速了裂纹扩展而造成的。为此,对轧辊的制造工艺、使用及维护提出了相应的措施,确保了轧辊的正常使用。

Fracture failure analysis of high speed steel composite roll used in hot strip rolling mill

The failure mechanism of the work roll in the hot strip rolling mill were analyzed.The observation and analysis of macro-morphology of the fracture,chemical composition,microstructure,the content of the retained austenite and fracture surfaces were carried out.The results show that the work roll fracture is caused by stress,the main cause is that the content of retained austenite in working layer is too high,and it transforms into martensite during using,resulting in huge internal stress.At the same time,the network carbide in working layer,the insufficient content of C and Mn in the roll core and the holes defects of the casting accelerate the cracks growth.For this reason,corresponding measures were proposed for the manufacturing process,usage and maintenance of roll to ensure the normal use.