2A12铝合金焊接接头超声冲击处理前后拉伸性能分析

Property Analysis of 2A12 Aluminum Alloy Welded Joints with and without Ultrasonic Impact Treatment

为克服铝合金薄板焊接接头强度偏低、韧性不足的缺点,用ER5356焊丝对不同厚度的2A12铝合金板材进行了手工氩弧焊接,并采用超声冲击处理对焊接接头进行全覆盖强化处理。采用金相显微镜观察了处理和未处理焊接接头的显微组织结构,对接头的力学性能进行了测试分析,分析了超声冲击处理改善2A12铝合金焊接接头力学性能的机理。结果表明：铝合金焊接接头经超声冲击强化处理后,6 mm和4 mm厚板材对接接头的抗拉强度分别提高了17.4%和23.7%,延伸率分别提高了28%和44%,焊缝表层组织得到明显细化。分析认为：晶粒大幅细化、组织致密化和缺陷减少,是超声冲击处理改善铝合金焊接接头抗拉伸性能的主要原因。

In order to improve the disadvantages of aluminum welded joint such as lower strength and weaker toughness. Aluminum alloy 2A12 plates with different thicknesses are welded with Tungsten Inert Gas （TIG） using ER5356 welding wire. The welded joint is full coverage strengthened by Ultrasonic Impact Treatment （UIT）. The mierostructure and mechanical properties of the welded joint with and without UIT are studied by means of optical microscopy and tensile test, respectively. The strengthening mechanism of UIT on aluminum alloy welded joint is discussed finally. Results show that the mechanical properties of the aluminum alloy welded joints are greatly improved after full coverage of UIT. As compared with the samples without UIT, the average tensile strength of the welded joint of 6 mm and 4 mm thickness aluminum plates after UIT is increased by about 17.4% and 23.7% , and the elongation to failure of the specimens after UIT is increased by about 28% and 44% , respectively. The grain refinement behavior near the surface of the weld zone is observed. Furthermore, more compacted microstructure and reduction of welding defects in the welded joints after UIT are also the main mechanisms for the improvement of mechanical properties of the aluminum alloy welded joint.