坡口形式对SUS304奥氏体不锈钢对接接头残余应力和变形的影响

发布时间：2019-02-16 16:23

【摘要】：SUS304奥氏体不锈钢由于具有良好的综合力学性能和加工性能,适用于制造各种要求耐腐蚀抗氧化、耐高温及超低温的零部件及设备,因而被广泛应用到工业生产当中。焊接过程中,由于存在不均匀温度场,被焊工件不可避免会产生残余应力和焊接变形。奥氏体不锈钢具有较大的线膨胀系数和相对较低的热导率,因而具有产生较大焊接残余应力和变形的倾向。焊接残余应力对不锈钢接头的静载强度、疲劳强度和抗腐蚀性能等都有着非常不利的影响;焊接变形不仅会影响接头的外观质量、降低结构的承载能力,而且矫正焊接变形还会增加制造成本和延误工期。因此,在设计制造过程中控制不锈钢结构的焊接残余应力与变形是个非常值得重视的问题。近年来,如何控制和减小焊接结构的残余应力和变形已成为越来越受重视的研究课题。随着计算机技术的快速发展和计算焊接力学理论的日臻成熟,数值模拟技术被广泛地用于预测实际工程结构中的焊接残余应力和变形。作为基础研究,本文以ABAQUS软件为平台,开发了用于模拟多层多道焊接过程的热-弹-塑性有限元计算方法。利用所开发的计算方法,对板厚10 mm的V形坡口、K形坡口和X形坡口的SUS304不锈钢平板对接接头的温度场、应力场和变形进行数值模拟,并通过试验方法验证了数值模拟结果的准确性。采用数值和试验的方法研究了坡口形式对SUS304不锈钢接头残余应力分布和变形的影响。为改善焊接结构的焊接工艺、控制和减小奥氏体不锈钢焊接残余应力与变形提供理论基础。实验研究表明:坡口形式对接头的残余应力和角变形有显著的影响:V形坡口的高拉伸残余应力区和角变形均明显大于K形坡口和X形坡口,而K形坡口则略大于X形坡口;坡口形式对纵向残余应力的峰值影响较小。另外,我们通过开发有限元计算方法模拟了奥氏体不锈钢SUS304在多层多道焊时的温度场和应力场,探讨了加工硬化和退火软化对焊接残余应力计算结果的影响。
[Abstract]:SUS304 austenitic stainless steel has been widely used in industrial production due to its good comprehensive mechanical properties and processing properties. In the welding process, the residual stress and welding deformation will inevitably occur due to the existence of uneven temperature field. Austenitic stainless steel has a high linear expansion coefficient and a relatively low thermal conductivity, so it tends to produce large welding residual stress and deformation. Welding residual stress has a very negative effect on the static load strength, fatigue strength and corrosion resistance of stainless steel joints. Welding deformation will not only affect the appearance quality of the joint and reduce the bearing capacity of the structure, but also increase the manufacturing cost and delay the construction period. Therefore, controlling welding residual stress and deformation of stainless steel structure is a very important problem in the process of design and manufacture. In recent years, how to control and reduce the residual stress and deformation of welded structures has become a more and more important research topic. With the rapid development of computer technology and the maturation of computational welding mechanics theory, numerical simulation technology has been widely used to predict welding residual stress and deformation in practical engineering structures. Based on the ABAQUS software, a thermo-elastic-plastic finite element method is developed to simulate the multilayer and multi-pass welding process. Using the developed method, the temperature field, stress field and deformation of SUS304 stainless steel butt joint with 10 mm thickness V-groove, K-shaped groove and X-shaped groove are numerically simulated. The accuracy of the numerical simulation results is verified by the experimental method. The effect of groove shape on residual stress distribution and deformation of SUS304 stainless steel joint was studied by numerical and experimental methods. It provides a theoretical basis for improving welding process of welding structure and controlling and reducing welding residual stress and deformation of austenitic stainless steel. The experimental results show that the groove form has a significant effect on the residual stress and angular deformation of the joint: the high tensile residual stress zone and angular deformation of the V-shaped groove are obviously larger than those of the K-shaped groove and the X-shaped groove, while the K-shaped groove is slightly larger than the X-shaped groove; The groove form has little effect on the peak value of longitudinal residual stress. In addition, the temperature field and stress field of austenitic stainless steel SUS304 during multi-layer and multi-pass welding are simulated by using finite element method, and the effects of work hardening and annealing softening on the calculation results of welding residual stress are discussed.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG457.11

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