• Forced cooling during friction stir welding significantly enhances the corrosion resistance of fine-grained Al7075 joints, with the stir zone exhibiting the highest resistance.
• The improvement is attributed to refined grain structure, increased Σ3 grain boundaries, and a denser oxide layer formation.
• Forced cooling reduces the precipitation and coarsening of anodic phases, lowering susceptibility to pitting corrosion.
• Lower recrystallization texture content decreases corrosion-active sites, further improving corrosion performance.