摘要
对新型980MPa深海用高强钢TIG焊接接头5种不同缺口位置的试样进行了原位拉伸试验,通过试验观察了每个试样的动态断裂过程,并对其断裂机理进行了详细研究和分析,最终确定焊接接头的薄弱环节。试验结果表明:直缺口试样的微观断裂经历了塑性变形、缺口处起裂、裂纹扩展、裂纹尖端钝化,直至试样断裂的过程,并且在裂纹扩展过程中,裂纹尖端重复钝化、扩展、新裂纹产生、再钝化、再扩展的过程;圆弧试样和平板试样在剪切力的作用下经历塑性变形、颈缩、出现微裂纹、微裂纹扩展,直至试样瞬间断裂的过程,并且圆弧试样和平板试样的起裂应力和断裂应力十分接近,表现为突发形式;平板试样中发现最后断裂在焊缝金属处,这说明其薄弱环节为焊缝金属处。
In-situ tensile tests of welding joints of bainite high strength steels with notch specimens were studied.Fracture processes of welding joints of this high strength steel were observed by in-situ tensile tests,and fracture mechanism was also analyzed.By these studies,the weak link of welding joints was determined.It is found that：plastic deformation is produced at notch tips with applied load increasing.For slight notch specimens,plastic deformation appears at the notch root,a short plastic crack is initiated,propagated,blunted and repeated process are done,finally,the specimens are fractured along notch root.For the specimens with a large arc,at the action of shear stress,plastic deformation appears firstly,and necking are produced,then microcracks are initiated and propagated.The processes are repeated until the specimen fracture.Initiated stress and fracture stress are almost the same for large arc specimens and smooth specimens,so sudden fracture are produced.In the smooth tensile specimens,fracture is produced at weld metals zone,so weld metals are the weak link of welding joints.
出处
《中国机械工程》
EI
CAS
CSCD
北大核心
2010年第22期2746-2750,共5页
China Mechanical Engineering
基金
国家自然科学基金资助项目(50905081
50671047)
国家高科技研究发展计划(863计划)资助项目(2006AA03206)
西安交通大学金属材料强度国家重点实验室开放研究项目(201011001)
