焊趾TIG熔修跟随超声冲击处理对焊接接头残余应力及疲劳强度的影响

Influence of ultrasonic impact following TIG remelting at weld toe on residual stress and fatigue strength of welding joints

采用焊趾TIG熔修跟随超声冲击处理工艺对SMA490BW钢超微弧焊接头进行处理,对超声冲击前后焊趾熔修区残余应力以及接头4点弯曲疲劳性能进行研究。结果表明:超声冲击后,焊趾熔修区残余应力由拉应力转变为对疲劳强度有利的双向压应力,纵向与横向残余应力平均消除率分别达到116%和158%;超声冲击通过增大焊趾角与焊趾半径,使焊趾熔修区应力集中程度降低22%;超声冲击可使接头疲劳强度提高70%。

The SMA490 BW steel joints welded by forceArc welding process were treated by ultrasonic impact following TIGremelting at weld toe. The four-point bending fatigue performance of joints and the residual stress of remelting zone before andafter ultrasonic impact were investigated. The results indicate that the residual stress is transformed to biaxial compress stresswhich is beneficial to the improvement of fatigue strength after the ultrasonic impact of remelting zone. The average eliminationrate of longitudinal and horizontal stress is 116% and 158%,respectively. The level of the stress concentration of weld toe isdeclined by 22% for the reason that both the weld toe angle and the weld toe radius are increased by ultrasonic impact. The four-point bending fatigue strength of joints is raised by 70% because of ultrasonic impact.