This study involves thermal, metallurgical and mechanical analysis during tungsten inert gas welding of Ti–6Al–4V alloy aiming at optimizing the welding current to enhance the mechanical properties. Firstly, a 3D transient FEM simulation of TIG Ti–6Al–4V weld using ABAQUS software, based on a Gaussian distribution of power density in space, has been built to predict the effect of welding current on the heat input, weld bead geometry, temperature and residual stresses distribution across the welding line. Secondly, a validation of FEM with the experimentally measured temperature distribution and welding bead geometries has been presented. Finally, experimental study of the effect of TIG welding current, the suitable range predicted from FEM, on the microstructure, hardness and tensile strength of 12-mm-thick alloy plate is discussed. Using FEM, the suitable range of welding current was predicted to be 130–170 A. There was a close agreement among the experimental results and the FEM simulation data. It has been found that low welding current of 130 A results in high tensile strength and hardness of the welding joint. This is attributed to low heat input, high cooling rate and the formation of a fine grain structure containing martensite-phase with low values of residual stresses.

中文翻译：

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使用 FEM 模拟和实验表征的 Ti-6Al-4V TIG 焊缝分析

本研究涉及 Ti-6Al-4V 合金钨惰性气体焊接过程中的热、冶金和机械分析，旨在优化焊接电流以提高机械性能。首先，基于空间功率密度的高斯分布，使用 ABAQUS 软件对 TIG Ti-6Al-4V 焊缝进行 3D 瞬态 FEM 模拟，以预测焊接电流对热输入、焊道几何形状、温度的影响以及整个焊缝的残余应力分布。其次，通过实验测量的温度分布和焊道几何形状对 FEM 进行了验证。最后，讨论了 TIG 焊接电流（FEM 预测的合适范围）对 12 毫米厚合金板的显微组织、硬度和抗拉强度影响的实验研究。使用有限元法，焊接电流的合适范围预计为 130-170 A。实验结果与有限元模拟数据非常吻合。已经发现，130A的低焊接电流导致焊接接头的高抗拉强度和硬度。这归因于低热输入、高冷却速率以及形成含有低残余应力值的马氏体相的细晶粒结构。