焊渣对镀锌汽车零件焊接缺陷的影响研究

Effect of Welding Slag on Welding Defects of Galvanized Automobile Parts

目的研究白车身点焊过程中凸包缺陷产生的可能原因。方法利用电镜分析了缺陷的形状特征,用能谱分析其化学成分。在此基础上,用金相显微镜观察缺陷处的截面,发现与正常的金相结果比较,晶粒明显长大。结果观察到缺陷本身多呈现为灰褐色疤形,且与正常表面形貌完全不同,其化学成分主要为铁锰的氧化物,区别于正常的锌层表面。点焊过程中焊渣飞溅附着在零件表面上,其虽与零件基体连接并不紧密,却导致与之相接触的钢板基体中的铁素体晶粒尺寸变大,造成零件局部凸包变形。结论通过及时清除附着在零件表面的氧化物焊渣,优化焊接工艺,可有效减少凸包缺陷的产生。

The paper aims to study the possible causes of convex hull defects during spot welding of BIW.The shape characteristics of the defects were analyzed by electron microscopy.It was observed that the defects were mostly grayish brown scar shape,which was completely different from the normal surface morphology.Its chemical composition was mainly Fe Mn oxide,which was different from the normal zinc layer.Although it was not tightly connected to the part's substrate,it caused the size of the ferrite grains in the substrate of the steel plates that were in contact with each other become larger,causing local convex hull deformation of the part.By removing oxide welding slag in time and optimizing the welding process,the occurrence of convex hull defects can be effectively reduced.