超声冲击对球笼-法兰焊缝残余应力场的影响

Effect of Ultrasonic Impact Treatment on Residual Stress Field of Cage-Flange Weld

为研究超声冲击处理对传动轴总成球笼-法兰焊缝表面残余应力的影响,采用超声冲击强化对球笼-法兰激光焊接焊缝进行了焊趾冲击和全覆盖冲击试验。分析了超声冲击前后裂纹产生原因,测试了焊趾冲击和全覆盖冲击前后残余应力值。残余应力测量结果表明,采用冲击工艺,可以在焊缝表面一定深度下产生压应力,最高测得-237MPa。全覆盖冲击后焊缝整体处于压应力状态下,焊缝中心残余压应力进一步增大;焊趾冲击后,焊缝中心应力值没有较大变化,焊趾处压应力值增大。经超声冲击后,组织发生塑性变形形成了高位错密度的包状结构,这个高位错密度的表面层能够有效阻碍表面应变层底部的晶体在交变应力作用下向表层滑移,抑制表面裂纹产生。

In order to study the effect of ultrasonic impact treatment for cage-flange of drive shaft assembly on residual stress of weld surface, the ultrasonic treatment was used to the laser weld in the way Of part UIT and full UIT. The reason of the cracks before and after ultrasonic treatment was analyzed, and the residual stress of the weld which was shocked in the way of part UIT and full UIT was tested. The results show that the residual compressive stress can be increased after the shock process, and the maximum value is -237 MPa.The whole weld is in the stress state after full UIT, and the stress in the weld center is further increased; the stress value in the weld center is not changed, but the stress value of the weld toe is increased after part UIT. After the UIT, the structure occurs plastic deformation and forms high dislocation density, which can effectively prevent the crystals on the bottom of the surface strain layer from moving to the surface layer under the stress field and inhibiting the surface cracks.