《9_Ni钢焊接热影响区组织及残余应力分析》》-毕业论文.doc

9 Ni钢焊接热影响区组织及残余应力分析 摘要：本文首先对焊接残余应力的测试方法和有限元分析的基本原理进行了阐述。在对钢板焊接残余应力模拟分析过程中，本文采用ANSYS软件的热一结构耦合功能，利用改变单元属性法、生死单元法对对接焊缝在焊接过程的残余应力进行了模拟分析，通过ANSYS软件实现焊接热源的移动加载。最后通过后处理，得出了不同时刻焊缝处各点的温度分布曲线及焊缝部位残余应力的大小及分布规律。 通过研究和实例验证，本文建立了可行的对接焊缝的三维温度场、残余应力的动态模拟分析方法，为复杂的焊接钢结构进行三维焊接温度场、残余应力的分析提供了理论和指导，促进了有限元分析方法在焊接力学在实际工程中的作用 通过对大型LNG低温储罐用9Ni钢的焊接性能的研究，掌握国产两种9Ni钢的两种焊接工艺，主要包括手工电弧焊和埋弧自动焊对所得的焊接接头进行质量检测，并进行硬度试验、金相试验.并观察两种工艺下的金相组织。综合研究此两种焊接工艺所得的两种9Ni钢焊接接头的综合性能，获得合适的焊接工艺。本文经过上述两种焊接工艺对国产9Ni钢和适用的焊接工艺进行了详细研究，取得进展。研究表明了，国产9Ni钢在两种焊接工艺都能获合格的焊接接头，对焊接工艺的研究获得了成功。 关键词：9Ni钢；焊接工艺；数值模拟 Subject：9Ni steel welding heat affected zone and residual stress analysis Abstract ：The paper firstly describes the testing methods of welding residual stress and the basic theories of finite element analysis．In the processing of numerical simulation of the steel plate welding residual stress，with the thermal—structure coupling function of Ansys software and the method of changing elements type or“Birth and Death”．This paper deals with simulation analysis of the residual stress for the welding process of the butt welding．It uses Ansys to apply moving heat source load．Finally temperature distribution curve of each point and the size and distributed rules of the welding residual stress in welding line． Through the research and practical verification,this paper establishes a feasible dynamic simulation method on 3-D welding temperature field and residual stress field of butt welding plane，providing the theoretic analysis of residual stress and instruction, promoting the application of Finite Element Method on welding mechanics analysis and engineering． Through to the large—scale LNG low temperature storage tank with the 9Ni steel welding performance research，grasps the domestically produced two kind of 9Ni steel and four kinds of welding processes，mainly including shielded metal arc welding、argon tungsten—arc welding union melt carries on the quality examination to the obtained weld joint，and carries on the hardness test，the me