超声冲击对Q370qE钢焊接接头性能的影响

Effects of Ultrasonic Impact Treatment on Properties of Q370qE Welded Joints

采用超声冲击技术对Q370qE桥梁钢对接接头进行了全覆盖超声冲击处理(UIT),并通过XRD、显微硬度计、Olympus金相显微镜等对UIT前后Q370qE焊接接头的残余应力、显微硬度、焊趾应力集中系数等性能的变化进行了测试和分析。结果表明,UIT使左焊趾附近的残余压应力由25.6 MPa增高达240.8MPa,使右焊趾附近17.2 MPa的残余拉应力转变为196.3MPa的残余压应力;使焊接接头300μm深度内次表层的显微硬度由100HV0.5提高到206HV0.5,提高了1倍多;使焊趾区平均过渡半径从1.58 mm增加到2.63 mm,焊缝过渡角由38°减小到27°,这有效改善了接头的几何形状,降低了疲劳应力集中系数。这些性能的变化均有利于提高Q370qE焊接接头的抗疲劳性能。

Specimens of Q370qE steel plate welded joints were treated by ultrasonic impact treatment（UIT） method.The influence of UIT treatment on residual stresses,microhardness,geometry morphology of the weld toes and section corrosion morphology of the joints was investigated.Results of tests showed that： because of UIT,the 25.6 MPa compressive residual stress of the left weld toe was advanced to 240.8 MPa and the 17.2 MPa tensile residual stress of the right weld toe was changed to 196.3 MPa compressive residual stress;The microhardness of the 300 μm layer from the surface wad advanced to HV0.5206 from HV0.5100;The transition radius of the weld toe was advanced to 2.63 mm from 1.58 mm and transition angle was reduced to 27°from 38°,which improved the geometry morphology of the weld joint and reduced its fatigue stress concentration factor.These varieties of the properties improved the fatigue resistance of the Q370qE steel welded joints.