实时超声冲击消减焊接残余应力

为了消减焊接残余应力,在焊接时对熔池后方焊缝的背面进行超声冲击.结果表明,实时超声冲击能够有效地消减焊接残余应力,其消减焊缝纵向残余应力比消减横向残余应力的效果显著.当在弹塑性转变温度区进行冲击,且冲击头直径较小、形状为球冠形时,消减焊接残余应力的效果更好.实时超声冲击消减焊接残余应力的机理是:在焊缝背面施加超声冲击能使焊缝正面产生拉伸塑性变形,抵消更多升温膨胀时所产生的压缩塑性变形,从而消减焊后的残余应力.

Reduction of welding residual stress by in-situ ultrasonic impact treatment

In order to reduce welding residual stress, ultrasonic impact was applied on the back of the weld bead during welding process. The results show that, the in-situ treatment of ultrasonic impact can reduce residual stress effectively, the reduction effect of longitudinal residual stress is more obvious than that of transverse residual stress. When the ultrasonic impact is applied in the elastic-plastic transition temperature zone of the weld, the impact head diameter is relatively small and the impact head shape is spherical shape, the effect of reducing welding residual stress is better. The mechanism of in-situ ultrasonic impact is that, when the impact is applied on the back of the weld bead, tensile plastic deformation is produced at the face side of the weld bead. It counteracts more compressive plastic deformation that was generated during the heating expansion stage and finally leads to the reduction of the residual stress.