典型焊接参数对铝锂合金FSW对接接头疲劳性能的影响

采用疲劳试验机对3种不同对接工艺的Al-Li-S4铝锂合金FSW对接接头及母材进行了疲劳性能测试,并采用光学显微镜和扫描电镜对组织和断口进行了分析。结果表明:在210MPa应力水平下,Al-Li-S4-T8铝锂合金母材在疲劳寿命达到200万次;在600/400、800/80、800/2003种典型FSW工艺条件下,800/200参数接头疲劳性能最优,在170MPa应力水平下,接头疲劳寿命可达200万次;Al-Li-S4合金FSW接头疲劳断裂大部分从焊缝表面起裂,这可能与FSW过程中金属材料的周期性流动和周期性微观组织使焊缝内部出现强度薄弱区或应力集中有关。

Influence of Typical Welding Parameters Process on Fatigue Properties of Al-Li Alloy FSW Butt Joint

The fatigue properties of butt joints of Al-Li-S4 Al-Li alloy under different FSW Parameters is inspected by fatigue-testing machine microstructures and fractures are analyzed by OM and SEM. The result shows that, the fatigue life of Al-Li-S4 base metal is 2 million times under 210MPa stress level. For 600/400, 800/80, 800/200 processes, the fatigue property of butt joints under 800/200 is better than others, under 170MPa stress level, the fatigue life of 800/200 joint is about 2 million times. In the fatigue experiment, fatigue cracks of FSW joints initiate at the surface of joint mostly, this may be associated with low strength areas or stress concentration which appear in the joint because of the metal material cyclical flows and periodic microstructures in FSW process.