It is of great significance to reveal the microevolution mechanism of welded structures during thermo-mechanical coupling to improve the welding quality. In this paper, a random microcrystalline structure model for welds is established by the Voronoi tessellation method. According to the nanoindentation results, heterogeneous grains are produced. A welding workpiece model with statistical significance is established. On this basis, the Python script and the birth and death element method are used to realize the transient growth of a weld, and a thermo-mechanical coupling model for the SUS301L-HT stainless steel metal inert gas welding process is established. The temperature field and thermal stress field are calculated. The calculation shows that the thermal stresses along the growth direction of the weld area are in the form of a “trapezoid,” and the stresses at both ends are small. The stress in the vertical direction of the weld has a single peak, and the peak appears in the center of the weld. The stress distribution of the model that considers heterogeneous grains is obviously inhomogeneous compared with that of the traditional model. The thermal stress distribution in the weldment is obviously inhomogeneous due to the heterogeneous grains, the stresses at the boundaries of the adjacent grains in the weldment change abruptly. It is found that the greater the difference in the mechanical properties between grains is, the more obvious the change.

中文翻译：

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考虑晶粒异质性的金属惰性气体焊接过程数值模拟

揭示热力耦合过程中焊接结构的微观演化机制对提高焊接质量具有重要意义。本文采用Voronoi镶嵌法建立了焊缝随机微晶结构模型。根据纳米压痕结果，产生了异质晶粒。建立了具有统计显着性的焊接工件模型。在此基础上，利用Python脚本和生死元法实现了焊缝的瞬态生长，建立了SUS301L-HT不锈钢金属惰性气体焊接工艺的热-机耦合模型。计算温度场和热应力场。计算表明，沿焊缝区生长方向的热应力呈“梯形，”，而且两端的应力很小。焊缝垂直方向的应力有一个峰值，峰值出现在焊缝中心。考虑异质晶粒的模型应力分布与传统模型相比明显不均匀。由于晶粒不均匀，焊件中的热应力分布明显不均匀，焊件中相邻晶粒边界处的应力发生突变。发现晶粒间力学性能差异越大，变化越明显。考虑异质晶粒的模型应力分布与传统模型相比明显不均匀。由于晶粒不均匀，焊件中的热应力分布明显不均匀，焊件中相邻晶粒边界处的应力发生突变。发现晶粒间力学性能差异越大，变化越明显。考虑异质晶粒的模型应力分布与传统模型相比明显不均匀。由于晶粒不均匀，焊件中的热应力分布明显不均匀，焊件中相邻晶粒边界处的应力发生突变。发现晶粒间力学性能差异越大，变化越明显。