搅拌摩擦焊接的传热和力学计算模型

搅拌摩擦焊接（Ｆｒｉｃｔｉｏｎ Ｓｔｉｒ Ｗｅｌｄｉｎｇ）是最近发展起来的一种新的固态连接技术。它主要用于铝合金，可以得到小变形、低成本和高质量的焊接接头。本文提出一个基于三维热弹塑性有限元分析的传热和力学计算模型。利用该模型可以了解搅拌摩擦焊接过程中的温度分布和循环，并预测焊后的残余应力和变形。对６０６１－Ｔ６铝合金搅拌摩擦焊接进行了实例分析。传热分析表明，铝合金搅拌摩擦焊接时的最高温度不超过材料熔点的８０％，因而属固态连接，同时为预测焊接接头的组织性能提供依据。力学计算结果表明，搅拌摩擦焊接的残余应力与变形要比传统的熔化焊接方法小得多。工件中最大的残余应力大约只有母材屈服极限的２５％～３０％。计算结果与试验数据相近，可作为进一步研究搅拌摩擦焊接过程和优化焊接参数的有效工具。

Thermal and Thermo-mechanical Modeling of Friction Stir Welding

Friction stir welding (FSW) is a new solid-stats joining technique that has been invented recently. This process produces low-distortion, high-quality, low-cost welds on aluminum alloys even for those difficult to the traditional fusion welding, In this paper,a three-dimensional finite element modeling of FSW process is presented. The modeling effort includes a de-coupled heat transfer and a subsequent thermo-mechanical analysis. The temperature fields during welding, the residual stress distribution and distortion of the workpiece after FSW process are studied for aluminum alloy 6061-T6. The heat transfer analysis shows that the maximum temperature during FSW is not higher than 80% of the melting point. It provides possibility for predicting the microstructure of the joint made by FSW technique. The thermo-mechanical analysis shows that the residual stress and distortion after FSW are much lower than that after traditional fusion welding. The maximum residual stress is only about 25%-30% of the yield stress of base metal. The results from the modeling are consistent with the available experimental data and trends.