某热电厂锅炉用螺纹型紧固件螺栓和销轴失效原因分析  

Failure analysis of screw fasteners ina thermal power plant

作　　者：梁宝琦 车鹏程 刘青 程义[2] LIANG Baoqi;CHE Pengcheng;LIU Qing;CHENG Yi(Institute for Special Steels,China Iron and Steel Research Institute,Beijing 100081,China;State Key Laboratory of Efficient and Clean Coal-fired Utility Boilers(Harbin Boiler Company Limited),Harbin 150046,China;Harbin Energy Innovation Digital Technology Co.,Ltd.,Harbin 150028,China;Harbin Institute of Technology,Harbin 150006,China)

机构地区：[1]钢铁研究总院有限公司特殊钢研究院,北京100081 [2]高效清洁燃煤电站锅炉国家重点实验室(哈尔滨锅炉厂有限责任公司),黑龙江哈尔滨150046 [3]哈尔滨能创数字科技有限公司,黑龙江哈尔滨150028 [4]哈尔滨工业大学材料科学与工程学院,黑龙江哈尔滨150006

出　　处：《锅炉制造》2023年第4期31-34,共4页Boiler Manufacturing

摘　　要：某热电厂燃煤锅炉螺纹型紧固件发生失效现象,包括M22型20MnTiB高强螺栓和M24型45^(#)钢销轴。20MnTiB高强螺栓(M22)端头存在边缘开裂现象,通过对失效的7根高强螺栓进行微观金相分析,并选取其中4根具有代表性的以确定其端头裂纹扩展机理及失效原因。20MnTiB高强螺栓为锻造制造,尖端锻造裂纹发生M型扩展增加了尖端裂纹扩展通道,增大失效风险,同时比对GB/T5779.1-2000标准确认其合规性。同时,该电厂45^(#)钢销轴(M24)运行时发生断裂,为烟囱挡板连接销轴。通过对45^(#)钢销轴断口进行SEM分析,断裂形式为运行过程中连接杆施加给旋转销轴的旋转载荷造成的疲劳断裂,销轴裂纹源区为疲劳纹区域(区域1)。由此得出该两种螺旋形紧固件在制造过程中和运行过程中的失效现象进行预防和改进措施:加强45^(#)钢销轴调质处理的控制,适当降低淬火速率,增加销轴屈服强度并降低脆性;加强20MnTiB高强螺栓在锻造过程中的消应力退火监控,避免由于锻造应力造成的端头裂纹产生。Some Screw fasteners were found ineffective in a certain power plant,including 20MnTiB high-strength bolt(M22)and 45^(#)axis pin(M24).Microstructure analysis were conducted in tips of 7 bolts,and 4 of the 7 were further studied to conform the extension mechanism of crack and failure cause.The forging crack extended in M-shape increased the path number of the propagation and the risk of failure.Finally conformed the compliance in accordance with GB/T 5779.1-2000.In the meanwhile,a axis pin was rotary fatigue fracture in service,which is the connection pin of baffle.The fracture reason was conformed through SEM analysis,the failure was conducted by the rotating load of joint lever,crack source was in area 1.The precautionary measures are as follows:Strengthen the supervision of thermal refining of 45^(#)axis pin,reduce the quenching rate in order to improve the yield strength and avoid the brittleness.Pay attention to the stress relief annealing of 20MnTiB highstrength bolt,aiming at avoiding the crack caused by foring stress.

关 键 词：高强螺栓 销轴 锻造裂纹 旋转载荷 疲劳断裂 

分 类 号：TU391[建筑科学—结构工程]