含稀土元素的对接接头焊接残余应力数值模拟

发布时间：2018-04-28 12:23

本文选题：镧、氧化铈 + 多层多道焊接　；参考：《江苏师范大学》2017年硕士论文

【摘要】：焊接是现代制造技术中重要的金属连接方法。在焊条中添加稀土元素镧(La)、氧化铈(CeO_2),可以有效地细化熔敷金属的微观组织,提高其力学性能。同时,数值模拟是一种低成本、可靠性较高的确定焊接工艺参数的方法。本文基于Visual Environment软件,对含稀土元素La/Ce的对接接头多层多道焊接过程中产生的温度场、应力场、微观组织、变形及焊后残余应力进行了数值模拟,并对提取的结果进行了相关的研究。设计了12组模拟方案,每个方案在焊条组分与焊接速度上各有区别。利用Visual Mesh软件完成了V型坡口对接接头的有限元模型的建立,然后在Visual Weld软件工艺向导中对此12组方案的工艺参数进行设置。模拟得到了第六组方案产生的变形最小,第六组方案中添加了质量分数为0.5%的La及0.1%的CeO_2。利用Visual Viewer软件,提取了特征点的热循环曲线及焊接过程中温度分布云图,总结了温度场的变化规律。根据热循环曲线可知,多层多道焊的温度场变化更加复杂,已经完成的焊道的温度场会受到后续焊道焊接的影响。通过分析焊接过程中应力场分布云图及特征路径的残余应力趋势图,发现在焊缝两侧的热影响区以及夹持点附近区域处的残余应力最大。通过对产生最小变形的第六组方案与没有添加稀土元素的第一组方案进行比较,发现添加稀土元素后,整体构件的残余应力数值有所降低。根据模拟得到的相比例曲线图可知,熔敷金属中主要有铁素体及珠光体。利用BX51M金相分析系统对第六组方案的熔敷金属进行观察,测量计算出铁素体及珠光体的比例关系,发现其与模拟结果一致,同时进一步分析了稀土元素对于熔敷金属组织的影响。
[Abstract]:Welding is an important method of metal joining in modern manufacturing technology. The addition of La _ 2O _ 3 and ce _ 2O _ 2 into the electrode can effectively refine the microstructure and improve the mechanical properties of the deposited metal. At the same time, numerical simulation is a low cost and high reliability method to determine welding parameters. Based on Visual Environment software, the temperature field, stress field, microstructure, deformation and residual stress of butt joint with rare earth element (La/Ce) during multilayer and multi-pass welding are numerically simulated. The results of extraction were studied. Twelve groups of simulation schemes are designed, each of which is different in composition of electrode and welding speed. The finite element model of V-groove butt joint is established by using Visual Mesh software, and then the process parameters of the 12 groups are set up in the Visual Weld software process guide. The simulation results show that the sixth group has the smallest deformation, and the sixth group has 0.5% La and 0.1% CEO _ 2s added to the sixth group. By using Visual Viewer software, the thermal cycle curve of characteristic points and the temperature distribution cloud diagram during welding are extracted, and the variation law of temperature field is summarized. According to the thermal cycle curve, the temperature field of multi-layer and multi-pass welding is more complicated, and the temperature field of the completed welding pipe will be affected by the subsequent welding. By analyzing the distribution of the stress field and the trend of residual stress in the characteristic path during welding, it is found that the residual stress is the largest in the heat affected zone on both sides of the weld and the area near the clamping point. By comparing the sixth group of schemes with the first group without rare earth elements, it is found that the residual stress of the whole member decreases after the addition of rare earth elements. According to the simulated phase ratio curves, ferrite and pearlite are the main elements in the deposited metal. The BX51M metallographic analysis system was used to observe the deposited metals of the sixth group. The proportion of ferrite and pearlite was measured and calculated. It was found that the results were consistent with the simulation results. The effect of rare earth elements on the microstructure of deposited metal was also analyzed.
【学位授予单位】：江苏师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG404

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