针对某贮箱焊点渗漏处X射线检测出现白斑影像的现象,采用几组表面阳极氧化试样进行电阻点焊模拟试验,发现部分试样X射线底片上焊核区存在与产品类似的白斑影像.通过对点焊试样上的焊点进行剖切后,通过低倍观察、金相检验、显微硬度测试及能谱分析,发现点焊前铝板表面的阳极氧化膜层未能被彻底去除,焊接时铜电极与铝板之间形成了较大的接触电阻,导致该侧母材出现熔透现象,致使铜电极中的铜扩散至熔核区,形成高密度高铜铝相,导致X射线底片显示为白斑影像.

To study the light spot appearance on X-ray detection image for leak place on welding spot of storage tank, several groups of resistance spot welding simulation experiments were carried out on some specimens with anodic oxidized surface.Similar light spots were observed on the X-ray detection image of the specimens.By means of low magnification observation, metallographic examination, microhardness testing and energy spectrum analysis on the section of welding spot on specimens, it was found that the residual anodic oxidation film on the Al plate led to a large contact resistance between the Al plate and the Cu electrode, resulting in a metal penetration phenomenon.The Cu in electrode diffused to nugget zone forming a Cu-rich Al phase, which produced a light spot on the X-ray detection image.