Numerical simulation and modeling of the trielectrode-coupled corrosion mechanism at the laser-welded interface of N80 steel

•Plastic stresses increase the cathode-anode potential difference and decrease the overall electrode potentials.•The deeper the depression in the weld and heat affected zones, the greater the cathode-anode potential difference.•In comparison to stress-free corrosion, the impact of stress on the cathode-anode potential difference initially intensifies but subsequently diminishes. 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 triple galvanic 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. During the 160 day corrosion period, the weld seam and heat affected zone undergo a transition from plastic strain to elastic strain, while the base metal zone experiences both plastic strain and elastic strain simultaneously. 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. [Display omitted] The schematic diagram of the triboelectric couple corrosion coupling model under stress (left), and the influence of stress on the cathode potential difference as corrosion progresses.