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采用不同焊接速度焊接7A04铝合金板材,并对搅拌摩擦焊接头进行微观组织和力学性能分析研究。结果表明,接头焊核区由于搅拌头的搅拌作用及发生动态再结晶,形成细小等轴晶,尺寸远小于母材;机械热影响区处于搅拌头外缘,在搅拌头搅拌作用下发生明显的拉伸变形;热影响区晶粒发生明显粗化。不同焊接速度下焊缝区的硬度分布整体上呈“W”形分布,接头软化,焊缝区硬度低于母材,硬度最高值出现焊核区,最低值出现在热影响区。当旋转速度为800 r/min,焊接速度为120 mm/min时,接头成型性最佳,其抗拉强度为410 MPa,达母材强度的75%。
7A04 aluminum alloy plates were welded by different welding speeds, and the microstructure and mechanical properties of the friction stir welded joints were analyzed. The results show that the weld nugget zone is formed with fine equiaxed grains due to the stirring effect and dynamic recrystallization. The size of the HAZ is much smaller than that of the base metal. The HAZ is at the outer edge of the stirrer head. Tensile deformation; heat affected zone significantly coarsened grains. The hardness distribution of the weld zone showed a “W” shape distribution at different welding speeds. The joints softened. The hardness of the weld zone was lower than that of the base metal. The highest hardness appeared in the weld zone, and the lowest appeared in the heat affected zone. When the rotation speed is 800 r / min and the welding speed is 120 mm / min, the joint has the best formability and the tensile strength is 410 MPa, which is 75% of the strength of the base metal.