基于同步辐射衍射技术的5A06铝合金焊接残余应力的测量研究

Research on Measurement of Residual Stress of Welded 5A06 Aluminum Alloy Based on Synchrotron Radiation Diffraction Technology

利用同步辐射X射线衍射技术测量了变极性等离子弧(VPPA)焊接5A06铝合金试样表面的残余应力,获得了该试样表面残余应力的分布规律,结合金相组织观察、EBSD、显微硬度测试等方法,分析了焊缝区、热影响区、母材区残余应力的产生及演化机制。结果表明:VPPA焊接5A06板材焊缝区晶粒粗大,热影响区晶粒细小,残余应力呈现出焊缝区域为压应力,热影响区为拉应力的"M"形状;在垂直于焊缝(TD)方向上存在75.79MPa的最大拉应力和159.34 MPa的最大压应力;在平行于焊缝(LD)方向上存在132.33 MPa的最大拉应力和89.38 MPa的最大压应力。相比于传统X射线仪器测量获得的残余应力变化趋势,同步辐射衍射测量的残余应力分布趋势与试样不同焊接区域显微硬度的变化趋势更加吻合。实验结果表明,相比于传统的X射线仪器测量残余应力,同步辐射X射线衍射测量的残余应力数据一致性更好。

The residual stress on surface of variable polarity plasma arc (VPPA)welded 5A06 aluminium alloy sample was measured by synchrotron radiation X-ray diffraction,and the distribution of residual stress on the surface of the sample was obtained.The generation and evolution mechanisms of weld zone,heat affected zone and base metal area were analyzed in combination with metallurgical structure observation,EBSD and microhardness tester.The results indicate that the weld zone of VPPA welded 5A06 plate shows coarse grains, while the grains in the heat affected zone are small;the residual stress presents an "M"shape:the weld zone is compressive stress,and the heat affected zone is tensile stress.There is a maximum tensile stress of 75.79 MPa and a maximum compressive stress of 159.34 MPa in the direction vertical weld (TD)and a maximum tensile stress of 132.33 MPa and a maximum compressive stress of 89.38 MPa in the direction parallel to the weld (LD).Compared with the trend of the residual stress measured by traditional X-ray instrument,the distribution trend of the residual stress of the synchrotron radiation diffraction measurement is more consistent with the variation trend of the microhardness of the sample in different welding areas.The experimental results show that the synchrotron radiation X-ray diffraction measurement has better consistency in residual stress data than the traditional X-ray instrument.