扭紧力矩对SWRM10K螺栓疲劳性能影响的研究  

Study on Effect of Tightening Torque on Fatigue Properties of SWRM10K Steel Bolts

作　　者：张艳斌 沈诚 孙东洋 张继旺[2] ZHANG Yanbin;SHEN Cheng;SUN Dongyang;ZHANG Jiwang(School of Mechanical Engineering,Southwest Jiaotong University,Chengdu 610031,China;State Key Laboratory of Traction Power,Southwest Jiaotong University,Chengdu 610031,China;Western Superconducting Materials Technology Co.,Ltd.,Xi'an 710018,China)

机构地区：[1]西南交通大学机械工程学院,四川成都610031 [2]西南交通大学牵引动力国家重点实验室,四川成都610031 [3]西部超导材料科技股份有限公司,陕西西安710018

出　　处：《机械制造与自动化》2024年第5期27-32,共6页Machine Building & Automation

基　　金：四川省国际科技创新合作项目(2019YFH0045)。

摘　　要：对扭紧力矩分别为0、12.5、22.0、29.5和35.0 Nm的SWRM10K钢螺栓进行轴向加载疲劳实验,获取螺栓的疲劳S-N数据。对比不同扭紧力矩下螺栓疲劳S-N特性,分析扭紧力矩对螺栓疲劳性能的影响。采用SEM观察螺栓试样的断口形貌,结合EDS分析裂纹萌生区元素分布,揭示螺栓疲劳断裂的规律。研究结果表明:增加扭紧力矩能有效提升该螺栓疲劳极限,但增加到一定程度提升效果明显下降,扭紧力矩值接近29.5 Nm较为合理。在该扭紧力矩下,螺栓疲劳极限为141 MPa,与未施加扭紧力矩相比提升了62.1%。螺栓疲劳断口分为3个区域:裂纹萌生区、扩展区和瞬间断裂区。在高应力幅下,裂纹萌生于试样表面,由晶体滑移引起;在低应力幅下,裂纹同样萌生于试样表面,但由晶体滑移或夹杂物引起。Axial loading fatigue tests were carried out on SWRM10K steel bolts with tightening torque of 0,12.5,22.0,29.5 and 35.0 Nm respectively,and the fatigue S-N data of the bolts were obtained.By comparing the S-N characteristics under different tightening torque,the fatigue performance of bolts was analyzed.The fracture morphology of the bolt sample was observed by SEM,and the element distribution in the crack initiation zone was analyzed by EDS,revealing the rule of fatigue fracture of the bolt.The research results show that increasing the tightening torque can effectively improve the fatigue limit of the bolt,but as the increase goes to a certain extent,the lifting effect obviously deminishes,and the tightening torque value close to 29.5 Nm is more reasonable.Under this tightening torque,the fatigue limit of the bolt is 141 MPa,which is 62.1%higher than that without tightening torque.Fatigue fracture surfaces of the bolts are divided into three regions:crack initiation region,crack propagation region and instant fracture region.Under high stress amplitude,crack initiation occurs on the specimen surface caused by crystal slip,while under low stress amplitude,crack initiation occurs on the surface caused by crystal slip or inclusions.

关 键 词：扭紧力矩 螺栓 疲劳 S-N特性 断口形 

分 类 号：TG115.57[金属学及工艺—物理冶金] TH131.3[金属学及工艺—金属学]