Optimization of resistance spot welding process parameters of dissimilar DP600/AISI304 joints using the infrared thermal image processing

This work shows a new, non-invasive methodology using infrared (IR) images to evaluate the behavior of the dissimilar DP600/AISI304 joints conducted by resistance spot welding (RSW) process. The processing and characterization of the IR images is conducted to establish their correlation with the mechanical strength and geometric parameters of the welded joints. The influence of the welding current (3, 4, and 5 kA) and the welding time (300, 400, and 500 ms) on the features of the infrared images is evaluated. Empirical models were obtained to associate the features of the IR images with the mechanical strength of the welded joint. The optimization of the process parameters is made from the diameter of the isotherms of the IR images using the response surface method. The results demonstrated a strong correlation between the IR thermal images and the mechanical strength. This new methodology can be used to characterize in real time the mechanical strength of the RSW welded joint based on a non-invasive method.