6005A-T6铝合金高频脉冲MIG焊补新工艺

High frequency pulsed MIG welding and repairing of 6005A-T6 aluminum alloy by new technology

采用快速热启动工艺RTS(Rapid Thermal Start),对轨道车辆用6005A-T6铝合金(6 mm板)对接接头进行一次焊补,研究焊补后接头的组织和性能。试验结果表明,与传统焊补工艺相比,焊前经80℃的RTS,可以较明显地减少常规补焊所产生的气孔等缺陷;加热(起始)区域的焊趾处焊接残余应力会降低10%左右,而在其他区域的焊趾处焊接残余应力下降5%左右;在焊补后的新老焊缝交界区域,晶粒粗化现象不太明显,其微观组织优于常规焊补的; RTS一次焊补接头的强度系数达到了0. 6,且RTS一次焊补、常规的一次焊补接头的弯曲试验的弯曲角度为180°时,弯曲试样均无裂纹,接头塑性良好;经RTS一次焊补后,焊接接头的疲劳强度为77. 4 MPa,比常规的一次焊补的接头疲劳强度提高约为17%。

Welding and repairing was carried out on the butt joint of 6005A-T6 aluminum alloy(6 mm plate)for rail vehicle with the rapid thermal start-up technology(RTS),and the microstructures and properties of the welded joint were studied.The test results show that,compared with the traditional welding and repairing process,the RTS with 80℃before welding can significantly reduce the porosity defect that produces in the conventional welding and repairing.The welding residual stress in the weld toe of the heating(starting)zone decreases by about 10%,while the residual stress in the weld toe of the other zone decreases by about 5%.In the junction zone of new and original weld metal,the phenomenon of grain coarsening is not obvious,and its microstructure is better than that of the conventional welding and repairing.The strength coefficient of the welded joint by RTS is 0.6,and when the bending angle is 180°,the bending specimen has no crack and the joint has good plasticity.After once welding and repairing,the fatigue strength of the welded joint is 77.4 MPa,which is about 17%higher than that of the conventional one.