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对大型轧机支承辊进行断裂失效分析,发现心部偏析和组织不均匀以及由此造成的残余应力是支承辊断裂的主要原因。利用Deform有限元软件对该支承辊锻后热处理工艺进行数值模拟,分析原锻后热处理工艺中支承辊的温度场、应力场和组织场,发现支承辊心部热处理过程中奥氏体化保温时间少、空冷后入炉温度低,正火后残余应力过大。提出降低加热速度为10℃·h~(-1),提高完全奥氏体保温温度为930℃和延长保温时间至30 h,提高入炉温度的优化锻后热处理工艺。研究结果表明:采用优化工艺可以解决支承辊心部完全奥氏体化保温时间不足,并降低了热处理残余应力和断裂风险。
Fracture failure analysis of the back-up roll of large rolling mill found that the core segregation and the microstructure are not uniform and the residual stress is the main reason for the backup roll breaking. Deform finite element software was used to simulate the heat treatment process of the backup roll after forging. The temperature field, stress field and microstructure field of the backup roll in the post-forging heat treatment process were analyzed. It was found that austenitic holding time during the heat treatment of the backup roll core Few, air-cooled furnace temperature is low, the residual stress after normalizing is too large. The optimized forging heat treatment process is proposed to reduce the heating rate to 10 ℃ · h ~ (-1), increase the complete austenite holding temperature to 930 ℃ and extend the holding time to 30 h, and increase the temperature of the furnace. The results show that the optimization process can solve the problem of insufficient austenitizing holding time in the center of the backup roll core and reduce the residual stress and fracture risk of heat treatment.