2219铝合金薄板拉延件与锻件焊接接头的组织和性能分析

Microstructure and Performance Analysis of Welded Joint of 2219 Aluminum Alloy Sheet Drawing Part and Forging Part

针对2219铝合金薄板拉延件与锻件的对接,采用TIG焊接工艺进行焊接,分析了接头的组织形貌、硬度分布特点、力学性能和断裂特征。研究结果表明,拉延件和锻件焊接接头靠近熔合线的焊缝区组织基本相同,均是由柱状枝晶和等轴晶组成,靠近熔合线的热影响区组织不同,拉延件一侧的板条状组织呈现组织和性能上互不相同的若干小区,锻件一侧的晶粒形状不规则,比拉延件一侧更粗大,晶界边更长。焊接接头的焊缝区硬度最低,两边热影响区的硬度呈波浪式上升并最终上升至母材硬度,拉延件比锻件的接头软化区更宽,塑性更好。焊接接头抗拉强度平均值可达到305.58 MPa,δ5伸长率平均值可达到5.21%。接头通常断裂在锻件一侧熔合线处,断口的大、小韧窝交错排列,一部分韧窝较深,撕裂棱较多,一部分韧窝较浅,具有层状撕裂形貌。

For the butt of drawing parts and forgings of 2219 aluminum sheet alloy, the TIG welding process was used for welding, and the microstructure, hardness distribution, mechanical properties and fracture characteristics of the joint were analyzed. The research results show that the microstructure is basically the same in the weld zone near the fusion line of the welded joint of the drawn part and the forging, which are composed of columnar dendrites and equiaxed crystals, and the microstructure of the heat affected zone near the fusion line is different. The slat-like microstructure on one side of drawing part presents several cells with different structures and properties. The grain on one side of the forging part is coarsened and the shape is irregular. The edge of the grain boundary is longer than those of drawn part. The hardness of the seam area is the lowest, the hardness of the heat affected zone on both sides rises in the wave form and finally rises to the hardness of the base metal. The soften zone of drawn part is wider than that of the forging part, and the plasticity is better. The average tensile strength of the welded joint can reach 305.58 MPa. The average elongation of δ5 can reach 5.21%. The joint is broken at the fusion line on forging part, the large and small dimples of the fracture are staggered, some dimples are deep, the tearing ribs are more, and some are shallow, whicn has layered tearing appearance.