Quantification of intermetallic compound layer morphology in aluminum-steel arc welding

In this work, we investigate the complex morphology of the intermetallic compound (IMC) layer forming at the interface during aluminum-steel welding. This layer is often summarized in the literature as a single “IMC thickness” scalar. In Fe-Al welds, the IMC exhibits significant irregularity at both the microscopic and macroscopic scales. At the microscopic scale, this irregularity is due to anisotropic growth. At the macroscopic scale, it is due to the inhomogeneous temperature field imposed by welding. Here, we focus on Fe-Al arc welding and propose an automated method to thoroughly analyze IMC morphology at both scales. We introduce a series of scalar descriptors that quantify uneven IMC thickness, continuity, curvature, and roughness along the interface with the base metals. We then investigate the evolution of IMC morphology with respect to welding current and speed and reveal that the former has a remarkably greater influence. The proposed quantification procedure is general and could be applied beyond Fe-Al welding to characterize any irregular interlayer. • Automated method to analyze the intermetallic compound layer morphology in Al-Fe welds. • Quantification of thickness distribution, interface roughness and discontinuities. • Welding current has more influence on morphology than welding speed.