基于数值模拟的Ti-6Al-4V合金接头等效残余应力及缺陷分析

Equivalent residual stress and defect analysis of Ti-6Al-4V alloy joint based on numerical simulation

  • 摘要:
    目的 旨在探究钨极惰性气体保护焊(Tungsten inert gas arc welding, TIG)焊接Ti-6Al-4V钛合金过程中热输入对等效残余应力的影响。
    方法 选用3 mm厚Ti-6Al-4V钛合金作为研究对象,进行焊接过程模拟仿真,预测不同参数下模型等效残余应力分布。
    结果 结果表明,3 mm厚Ti-6Al-4V模型焊后等效残余应力大小与焊接热输入成正比关系。模型横向等效残余应力最大值位于焊缝区及近焊缝区,并沿两侧逐渐递减。纵向等效残余应力呈现中部大、两端小的“山峰”状分布。选取不同参数下所得模型的焊缝视图切片表明,横向应力集中于中部及两端。同时,切片分析中可发现,部分焊接参数下焊缝剖面位置出现特殊异常斑点,其类似一种由于焊接热输入过大引起的焊接缺陷。
    结论 通过选用双椭球模型作为热源,并通过添加生死单元实现焊缝区域填充,使得等效残余应力预测精度均达到85%以上,可为实际焊接优化提供有效思路。

     

    Abstract: Objective The aim is to explore the influence of heat input on the equivalent residual stress during the welding process of Ti-6Al-4V titanium alloy by tungsten inert gas arc welding (TIG). Methods 3 mm thick Ti-6Al-4V titanium alloy is selected as the research object to conduct simulation and modeling of the welding process and predict the equivalent residual stress distribution of the model under different parameters. Results The results show that the post-weld equivalent residual stress of the 3 mm thick Ti-6Al-4V model is correlated with the welding heat input. The maximum transverse equivalent residual stress of the model is located in the weld area and near the weld area, and gradually decreases along both sides. Longitudinal equivalent residual stress shows “mountain” distribution with large middle and small ends. A slice view of the weld of the resulting model under different parameters is selected, which indicates that the transverse stress is concentrated in the middle and at both ends. At the same time, special abnormal spots can be found in the section analysis of some welding parameters, which are similar to a welding defect caused by excessive welding heat input. Conclusion By selecting the double ellipsoid model as the heat source and realizing the filling of the weld area by adding the life and death units, the numerical prediction accuracy of the equivalent residual stress reaches more than 85%, which can provide an effective idea for the actual welding optimization.

     

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