Numerical Simulation and Modeling of the Trielectrode-Coupled Corrosion Mechanism at the Laser-Welded Interface of N80 Steel

Abstract

Laser welding, a prevalent technique in automotive structure manufacturing, can introduce compositional disparities and stresses within the weld zone, exacerbating corrosion complexity at the weld interface. This paper develops a three-electro-couple corrosion model for N80 steel welds under stress conditions, leveraging the COMSOL software for simulations. The findings demonstrate that, within the elastic stress range, an elevation in stress intensifies the overall electrode surface potential, ultimately transitioning into plastic stress and fostering a more negative potential. This, in turn, amplifies the cathode-anode potential difference, rendering the material more susceptible to corrosion. The deeper the depression between the weld zone and the heat-affected zone, the higher this potential difference becomes, exacerbating the corrosion risk. Under stress, the corrosion rate markedly surpasses that observed in unstressed conditions. Over a 160-day corrosion period, the weld and heat-affected zones transition from predominantly plastic to elastic strains, while the base metal zone exhibits a mixed state of plastic and elastic strains. This dynamic strain evolution leads to temporal variations in the stress-induced cathode-anode potential differences. In comparison to stress-free corrosion scenarios, the impact of stress on the cathode-anode potential difference initially intensifies, yet this effect tapers off over time.

Keywords: laser welding, galvanic corrosion, COMSOL, stress coupling