焊接残余应力对高频机械冲击处理焊接结构疲劳行为的影响

Effect of welding residual stress on fatigue behavior of welded structures treated by high-frequency mechanical impact

利用高频机械冲击处理装置对Q355钢纵向角接接头进行处理,研究了残余应力对焊接接头疲劳性能的影响。结果发现:高频机械冲击处理可显著提高接头的疲劳寿命,而消应力+高频机械冲击复合处理则会大幅度改善焊接接头的疲劳性能。对比焊态接头特征疲劳强度(FAT),在含焊接残余应力条件下直接进行冲击处理,接头的FAT提高了143.9%,而复合处理的FAT提高了210.3%。焊态和高频机械冲击态接头的疲劳裂纹源位于焊趾,而经过焊后消应力+高频机械冲击复合处理的接头,其断裂位置转移至母材。

The influence of residual stress on the fatigue properties of the welded joint is studied by treating the longitudinal corner joint of Q355 steel with a high-frequency mechanical impact(HFMI)device.The results show that HFMI treatment can significantly improve the fatigue life of welded joints and that a combined treatment of stress relief and HFMI can considerably improve their fatigue properties.In terms of the characteristic fatigue strength(FAT)of as-welded joints,in comparison,the FAT of joints directly treated with HFMI under the condition of welding residual stress increased by 143.9%,while FAT of joints with a combined treatment increased by 210.3%.While fatigue crack of as-welded and HFMI joints initially occurred at the weld toes,the location changed to the base material for welded joints treated with combined treatment.