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

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.

Effect of heat treatment combined with ultrasonic impact on fatigue property of Q345B steel welded joint

Through comparative analysis the effect of direct ultrasonic impact, the conventional heat treatment plus ultrasonic impact and vacuum heat treatment plus ultrasonic impact on fatigue life of Q345B steel welded joint were studied, and the mechanism of heat treatment combined with ultrasonic impact on the fatigue property of welded joint was discussed. The results show that conventional heat treatment plus ultrasonic impact compared with ultrasonic impact directly, while the welding residual stress of welded joint is eliminated to some extent, but as a result of material softening lower the impact of compressive stress and surface oxidation raise the risk of forming fold defects, the fatigue performance is reduced, and with the extension of heat preservation time, the fatigue performance decreases more obviously. Although the materials were softened by vacuum heat treatment plus ultrasonic impact, the fatigue life of welded joint was improved compared with that by direct ultrasonic impact without surface oxidation plus residual tensile stress elimination, and the fatigue damage position was transferred from the welding toe to the base material or the welding root.