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通过金相显微镜观察、硬度测试、拉伸试验和扫描电镜观察等试验手段研究分析了6061-T651铝合金搅拌摩擦焊接头的微观组织与力学性能。结果表明,接头处焊核区因剧烈塑性变形和高温循环而发生了动态再结晶,形成细小的等轴晶组织,而热影响区晶粒组织和第二相颗粒均发生一定的粗化。接头的硬度沿着垂直于焊接方向基本呈W形分布,热影响区由于晶粒粗化以及第二相颗粒的聚集长大,其硬度值最低。沿垂直于焊接方向和平行于焊接方向的接头试样强度都比母材低,沿垂直于焊接方向的接头试样伸长率低于母材,而平行于焊接方向的伸长率比母材的高;断口形貌表明断裂方式为典型的韧性断裂。
The microstructure and mechanical properties of 6061-T651 aluminum alloy friction stir welded joint were studied by means of metallographic microscope, hardness test, tensile test and scanning electron microscope observation. The results show that the dynamic recrystallization occurs in the weld nugget zone at the joint due to severe plastic deformation and high temperature cycling, resulting in the formation of fine equiaxed grains. However, both the grain size of the heat affected zone and the secondary phase grains are coarsened. The hardness of the joint is basically W-shaped along the direction perpendicular to the welding direction. The HAZ has the lowest hardness value due to the coarsening of grains and the aggregation of the second-phase particles. The joint specimens along the direction perpendicular to the welding direction and parallel to the welding direction had lower strength than the base material and the specimen elongation along the direction perpendicular to the welding direction was lower than that of the base material while the elongation parallel to the welding direction was lower than that of the base material Of the high; fracture morphology shows that the fracture mode is a typical ductile fracture.