(华东交通大学 机电工程学院，南昌 330013)
摘 要: 本文对6082铝合金焊接接头分别进行超声冲击处理和磨平焊缝余高处理，研究残余应力和应力集中对焊接接头疲劳性能的影响。结果表明：经超声冲击处理后，接头焊趾及其附近区域表层晶粒明显细化；焊趾处由冲击前的残余拉应力转变为残余压应力，其疲劳寿命得到提高；超声冲击前后接头疲劳裂纹均萌生于焊趾部位，而磨平焊缝接头的疲劳裂纹大多萌生于母材圆弧过渡处。无论冲击与否，疲劳断裂机制均为准解理断裂。当超声冲击电流为1.0 A、冲击时间为2 min时，与未超声冲击试样相比，6082铝合金接头疲劳寿命提高11.18%，无余高接头相对焊接接头疲劳寿命提高30.71%。接头表层金属晶粒尺寸、残余应力以及应力集中是影响6082铝合金焊接接头疲劳性能的主要因素。
关键字: 超声冲击；焊缝余高；晶粒细化；残余应力；疲劳
（College of Mechanical and Electrical Engineering, East China Jiaotong University, Nanchang, 330013, China）
Abstract:The effects of residual stress and stress concentration on the welded joint of 6082 aluminum alloy welded joint were investigated by ultrasonic impact treatment(UIT) and polished weld reinforcement. The results indicate that, after UIT, the surface grain of the weld toe and its vicinity are obviously refined; the residual stress at weld toe is changed from residual tensile stress to residual compressive stress, and its fatigue life is improved. The fatigue fracture of the welded joint is located at the toe of the joint before and after the UIT, while the fatigue fracture of the welded joint is mostly broken away from the arc transition of the base metal, and the fracture mechanism is quasi-cleavage fracture. When the impact current is 1.0 A and the impact time is 2 min, compared with the specimens without UIT, the fatigue performance of the 6082 aluminum alloy joint after UIT increases by 11.18%, and the fatigue performance of the polished weld reinforcement joint increases by 30.71%. It can be concluded that the grain refinement, the residual stress and stress concentration are the main factors that affect the fatigue properties of the welded joint of 6082 aluminum alloy.
Key words: ultrasonic impact; weld reinforcement; grain refinement; residual stress; fatigue
