超声冲击对焊接接头表面质量的影响

焊接是船舶、飞机、汽车、火车、压力容器、起重设备等大结构、复杂结构的重要加工方法。焊接结构的失效尤其是疲劳失效大多起始于焊接接头表面,因此对焊接接头表面质量的优化可改善焊接结构的性能,延长使用寿命。综述了超声冲击在焊接接头表面质量改进中的研究现状。分析了超声冲击对焊接接头表面几何形状的影响,指出超声冲击增大焊趾处圆弧过渡半径、降低应力集中系数和减小缺口效应的作用。总结了超声冲击对焊接接头表面残余应力的影响,指出超声冲击通过宏观塑性变形引发微观位错运动和增殖的机制,由此在焊接接头表面和次表面产生有益的残余压应力。阐述了超声冲击对焊接接头表面组织形态的影响,指出超声冲击在产生宏观织构和细化晶粒方面的作用。简述了超声冲击对提高焊接接头显微硬度和消除表面缺陷等方面的有利影响,同时指出合理的超声冲击参数才能降低焊接接头的表面粗糙度。最后,分析了目前研究存在的问题并对未来研究方向进行了展望。

Effect of Ultrasonic Impact on the Surface Quality of Welded Joint

Welding is an important processing method for ships, aircraft, automobiles, trains, pressure vessels, lifting equipment, and other large structures and complex structures. The failure of welded structure, especially the fatigue failure, starts from the surface of welded joint, so the optimization of surface quality of welded joint can improve the performance of welded structure and prolong its service life. The research status of ultrasonic impact treatment on the surface quality improvement of welded joint was reviewed. The influence of ultrasonic impact treatment on the surface geometry of welded joint was analyzed, and the effect of ultrasonic impact on the increase of arc transition radius, the decline of stress concentration factor and the reduction of notch effect were pointed out. The effect of ultrasonic impact treatment on surface residual stress was summarized. It was found that ultrasonic impact treatment caused microscopic dislocation motion and proliferation through macroscopic plastic deformation, resulting in beneficial compressive residual stress in the welding joint surface and sub surface. The influence of ultrasonic impact treatment on the surface micro structure of welded joint was described. The effect of ultrasonic impact on the macro texture and grain size was proposed. The advantages of ultrasonic impact on improving the micro hardness of welded joint and eliminating the surface defects were put forward, and the reasonable ultrasonic impact parameters were pointed out to reduce the surface roughness of the welded joint. Finally, the existing problems were analyzed and the future research directions were prospected.