超声冲击法提高焊接接头疲劳强度的机理分析

Mechanism Analysis of Fatigue Strength Improvement of Welded Joints by Ultrasonic Peening Method

使用工具显微镜和维氏硬度计测量了超声冲击处理前后焊趾区的几何形状与硬度的变化,并应用疲劳缺口系数的概念及Dang Van准则,对超声冲击造成的焊趾区几何形状的变化及残余压缩应力对接头疲劳性能改善的影响行为进行了研究.结果表明,对于低中强钢来说,超声冲击处理焊接接头疲劳性能的改善主要是由焊趾部位形成的残余压应力及改善焊趾几何外形这两个因素引起的,硬化的作用相比次之.研究还证明,冲击处理对焊接接头应力集中程度的降低,主要是通过增加焊趾区过渡半径来实现的.

The variation of weld toe geometric shape and hardness was measured before and after ultrasonic peening treatment with toolmaker＇s microscope and Vickers hardness tester. And the influence of their variation and residual compressive stress on fatigue improvement performance of welded joints was researched by the concept of fatigue gap coefficient and Dang Van criterion. The results are as follows： to the middle and low-strength steel, residual compressive stress and weld toe geometric shape have larger contribution to the fatigue strength improvement than material hardening; the reduction of stress concentration by ultrasonic peening treatment is mainly achieved by increasing weld toe transition radius.