Damage detection in hot‐dip galvanized structural steel using AC potential drop method

This study presents an experimental investigation for the detection of fatigue damage in hot‐dip galvanized structural steel using the alternating current potential drop (ACPD) method. Through cyclic bending and tension tests on samples subjected to different galvanizing processes, the method was established as a sensitive instrument for recording micro‐ and macro‐crack formation. The analysis of the voltage gradient (d u /dN) showed characteristic changes long before macroscopically visible damage occurred, enabling the time‐resolved differentiation between coating and substrate damage. Differences between normal‐temperature (NTV) and high‐temperature galvanizing (HTV) were analyzed, revealing that normal‐temperature galvanized samples exhibited significantly faster crack propagation in the coating and a greater reduction in fatigue life. The results were validated using microscopic cross‐sections and computed tomography. The method offers considerable potential for condition‐based life‐cycle monitoring of steel structures.