7029铝合金YAG激光焊接接头的组织与性能研究

Microstructure and Mechanical Properties of Welded Joint of 7029 Alloy by YAG Laser Welding

采用YAG激光焊接方法对2衄厚挤压态7029合金板进行拼焊，并对焊接接头的微观组织及力学性能进行了观察分析和测试。结果表明：其焊接接头由三个区域（近缝区母材、焊核区、热影响区）组成；焊核区中心组织由尺寸约8~15μm的等轴晶组成，析出相在晶界析出；热影响区析出相发生回溶，晶粒未明显粗化；随着焊接热输入的增大，焊核区生长，析出相数量减少。从焊缝中心到母材，显微硬度先迅速增加达到峰值后逐渐下降，在热影响区达到峰值，焊缝区硬度值略低于母材约10HV；拉伸实验表明，焊接接头强度约为母材的81％。

The welding experiment was conducted for 7029 alloy with 2 mm thickness by YAG laser Welding. The microstructure and mechanical properties of the welded joint were investigated using optical microscope,scanning electron microscope, tensile test,microhardness etc. The results indicate that the welded joint is composed of three zones, such as the basemetals,nugget and heat affected zone.The weld nugget zone consists of fine equiaxed dendritic grains with the size of 8-15μm, and the lesser second phases are mainly distributed on the grain boundaries. The grains have not grown up in the heat affected zone, and the second phase diffuses into the grains. With the heat input increasing, the grains in fuse zone get coarser and the number of the second phases becomes less. The microhardness declines from the welding line to base metal, and the microhardness of the welding line is about 10 lower than that of base metal. The tensile strength of the welded joint is 81% of the base metal.