2219铝合金变截面结构搅拌摩擦焊接工艺及组织特性

针对变截面结构产品,提出了一种变截面搭接结构搅拌摩擦焊接方法,通过加装辅助板将整条焊缝焊接方向上补偿为等厚度。焊接采用一次定位焊接+二次定位焊接+正式焊接的工艺方式,一次定位焊为预定位,二次定位焊保证辅助板与试片主体结构之间形成有效连接,正式焊保证形成完整的焊缝。焊缝表面成形良好,超声相控阵检测无超标缺陷。通过对力学性能的分析,变截面搭接结构处焊缝与非搭接处焊缝和常规对接焊缝的力学性能基本相同,平均抗拉强度均达到母材的70%以上,平均延伸率均在5.8%以上。变截面搭接焊缝焊核处晶粒形态为细小的等轴晶,靠近轴肩影响区部分的晶粒尺寸大于靠近焊缝根部的晶粒尺寸,受再结晶影响,焊缝两侧热机影响区处辅助板搭接界面消失。

Process and Microstructure Analysis of the Variable Cross-sectional Structure Friction Stir Welding of 2219 Aluminum Alloy

Aiming at the product with variable cross-section structure, a friction stir welding method for variable cross-section lap joint was proposed.By adding an auxiliary plate, the entire weld was compensated to equal thickness in the welding direction.Welding adopts frist-position welding + second-position welding + formal welding process,frist-position welding was pre-positioned, second-position welding ensured an effective connection between the auxiliary plate and the main structure of the test piece,and the formal welding ensured the formation of a complete weld. The surface of the weld is well formed,and the ultrasonic phased array detection has no defects beyond the standard.Through analysis of mechanical properties, the mechanical properties of the weld at the variable cross-section and the non-variable cross-section are basically the same,the average tensile strength reaches more than 70% of that of the base material,and the average elongation is above 5.8%.The morphology of the grains at the weld nugget of the variable cross-section weld is fine equiaxed grains. The grain size near the shoulder impact zone is larger than that near the weld root. The lap interface of the auxiliary plate at the heat engine affected area on both sides of the weld disappears because of recrystallization influence.