中文摘要：

通过对2219-T6铝合金搅拌摩擦焊对接接头进行金相观察、疲劳试验和显微硬度测量，对接头的不均匀性和疲劳性能进行分析。结果表明，接头最低硬度和疲劳源基本都在热影响区。基于接头各区的显微硬度、微观形貌及微拉伸试验测试，建立接头的弹塑性有限元模型，并在循环加载下模拟接头的应力和应变分布。利用Smith-Watson-Topper 损伤公式和性能薄弱区域的应力、应变数据对焊接接头进行疲劳寿命预测，预测结果与试验结果相比，寿命误差基本在两倍因子之内。

英文摘要：

The inhomogeneity and fatigue properties of the friction stir welded butt joints for 2219-T6 aluminum alloy were analyzed by metallographic observation of different zones, fatigue tests and micro-hardness measurement. The results show that the lowest hardness and fatigue crack initiation sites are mainly located in heat affected zone. The elastic-plastic FE model was established based on the micro-hardness, microstructure and the mechanical properties obtained from micro-tensile tests of every zone. The stress and strain distributions of joints were simulated under cyclic loading. According to the FE simulations results, the fatigue lives were estimated by using the damage equation of Smith-Watson-Topper and the stress-strain data of the weak area in the joints. The results of estimations are compared with the test results and the errors are less than two times of factors.