Further development of the car lightweight in automotive industry significantly depends on the reliability of the Al/steel dissimilar joint, since more and more Al alloy parts are used in the car manufacturing. It has been proved that the Al/steel dissimilar joint strength can be effectively increased when the intermetallic compound (IMC) growth, especially the Fe₂Al₅ layer thickness, is controlled at certain level. Because the Fe₂Al₅ is the dominant phase of the entire IMC layer in the Al/steel dissimilar joint, and cracks usually initiate at this location when damage is conducted. Therefore, for the automotive industry assembly line, the prediction model monitoring the Fe₂Al₅ layer thickness of each Al/steel weld seam is desired to ensure the dissimilar joint quality and reliability. In the present research, a numerical dynamic growth model based on element diffusion laws is established to calculate the IMC layer thickness of Fe₂Al₅ phase during the variable polarity cold metal transfer (VP-CMT) welding of aluminum to steel in the function of welding heat input and location. To build up effective connection between the welding heat input and the actual temperature history of Al/steel interface, a finite element analysis (FEA) model is customized for the present VP-CMT process. The Fe₂Al₅ layer thickness calculation results are further validated using electron back-scattered diffraction (EBSD) characterization under scanning electron microscopy (SEM), confirming a 2.3 % deviation between the model prediction and actual layer thickness.

汽车轻量化在汽车行业的进一步发展很大程度上取决于铝/钢异种接头的可靠性，因为越来越多的铝合金零件用于汽车制造。实践证明，当金属间化合物(IMC)生长，特别是Fe ₂ Al ₅层厚度控制在一定水平时，可以有效提高Al/钢异种接头强度。因为 Fe ₂ Al ₅是铝/钢异种接头中整个 IMC 层的主要相，当进行损伤时，裂纹通常在该位置开始。因此，对于汽车工业装配线，预测模型监测 Fe ₂ Al ₅每个铝/钢焊缝的层厚是需要的，以确保不同的接头质量和可靠性。本研究建立了基于元素扩散规律的数值动态生长模型，计算了铝钢变极性冷金属转移（VP-CMT）焊接过程中Fe ₂ Al ₅相的IMC层厚度，其函数为焊接热输入和位置。为了在焊接热输入和铝/钢界面的实际温度历史之间建立有效的联系，为当前的 VP-CMT 工艺定制了有限元分析 (FEA) 模型。Fe ₂ Al ₅ 在扫描电子显微镜 (SEM) 下使用电子背散射衍射 (EBSD) 表征进一步验证层厚度计算结果，确认模型预测与实际层厚度之间存在 2.3% 的偏差。