热处理加超声冲击复合处理对Q345B钢焊接接头疲劳性能的影响

By comparing and analyzing the effects of direct ultrasonic impact, common heat treatment plus ultrasonic impact, and vacuum heat treatment plus ultrasonic impact on the fatigue life of Q345B steel welded joints, the mechanism of the effect of heat treatment plus ultrasonic impact composite treatment on the fatigue performance of welded joints was explored. The results show that compared with direct ultrasonic impact, although the welding residual stress of the welded joint is somewhat eliminated by common heat treatment plus ultrasonic impact, due to the reduction of the compressive stress generated by the impact caused by material softening and the increase in the risk of forming laminated defects due to surface oxidation, the fatigue performance is reduced, and the longer the heat treatment holding time, the more obvious the reduction in fatigue performance; although there is also material softening in the welded joint with vacuum heat treatment plus ultrasonic impact, due to the absence of surface oxidation and the elimination of residual tensile stress, compared with the welded joint with direct ultrasonic impact, the fatigue life is increased, and the fatigue failure location is transferred from the weld toe to the base metal or the weld root.

通过对比分析直接超声冲击、普通热处理加超声冲击及真空热处理加超声冲击对Q345B钢焊接接头疲劳寿命的影响,探讨了热处理加超声冲击复合处理对焊接接头疲劳性能的作用机制.结果表明,普通热处理加超声冲击相较于直接超声冲击,焊接接头的焊接残余应力虽然有所消除,但由于材料软化使冲击产生的压应力降低及表面氧化使形成叠型缺陷的风险提高,疲劳性能有所降低,且随热处理保温时间延长,疲劳性能降低得越明显;真空热处理加超声冲击焊接接头虽然也存在材料软化,但由于不发生表面氧化加上残余拉应力消除,相较于直接超声冲击焊接接头的疲劳寿命有所提高,且疲劳破坏位置由焊趾转移到母材或焊根.