This paper describes an experimental study in which a traditional resistance spot weld process with Multi-Ring Domed (MRD) welding electrodes was used to join AA5754-O to low carbon steel sheets in a coach peel configuration. A linear relationship was identified for the resistance spot weld C-gun stationary arm deflection with force applied by the movable gun arm. Due to the relative rotation of the electrodes during deflection, the point of electrode/coupon surface contact moved away from the original centerline to a point inboard towards the C-gun arm. This led to asymmetric features in aluminum/steel resistance spot weld morphology, intermetallic compound (IMC) characteristics, weld defect distribution, and aluminum hardness. The aluminum weld nugget solidified closer to the weld gun with respect to the centerline of the MRD electrode imprint and exhibited a softer thermo-mechanically affected zone (TMAZ) and expulsion which produced a thinner IMC layer and fewer oxide film defects. This in turn resulted in strong button pull-out strength and the welds were able to absorb 36% more energy under an applied directional load in comparison to aluminum weld nuggets that solidified further away from the weld gun with respect to the electrode imprint centerline. The mechanism responsible for these weld asymmetries was further revealed through analysis of the variation in contact condition between electrodes and workpieces due to weld gun deflection.

本文介绍了一项实验研究，其中使用带有多环圆顶 (MRD) 焊条的传统电阻点焊工艺将 AA5754-O 连接到采用教练剥离配置的低碳钢板。确定了电阻点焊 C 型枪固定臂偏转与可移动枪臂施加的力的线性关系。由于偏转期间电极的相对旋转，电极/试样表面接触点从原始中心线移向内侧朝向 C 型枪臂的点。这导致铝/钢电阻点焊形态、金属间化合物 (IMC) 特性、焊接缺陷分布和铝硬度的不对称特征。相对于 MRD 电极印记的中心线，铝焊核在更靠近焊枪的地方凝固，并表现出更软的热机械影响区 (TMAZ) 和排出，从而产生更薄的 IMC 层和更少的氧化膜缺陷。这反过来又产生了强大的按钮拔出强度，并且与相对于电极压印中心线在远离焊枪更远的地方固化的铝焊点相比，在施加的定向载荷下，焊缝能够多吸收 36% 的能量。通过分析由于焊枪偏转引起的电极和工件之间接触条件的变化，进一步揭示了造成这些焊接不对称的机制。