Achieve a trade-off between corrosion and wear performance of Al-Zn-Mg-Cu alloy by controlling the shot peening intensity: Linking microstructural tailoring to surface degradation behaviors

This work reveals a non-monotonic relationship between shot peening (SP) intensity and the corrosion-wear performance of an Al-Zn-Mg-Cu alloy, uncovering a critical trade-off governed by competing microstructural mechanisms. An favorable intermediate intensity of 0.2 mmA was identified, achieving a superior balance between corrosion and wear resistance, exhibiting a 28.8% reduction in corrosion current density ( I _corr ) to 1.21 μA/cm², a 59.5% mitigation in intergranular corrosion (IGC) susceptibility, and a wear volume reduction of up to 39.9% compared with the untreated condition. Beyond this peak, further increases in peening intensity degrade corrosion resistance sharply, while wear resistance only plateaus. The trade-off originates from competing microstructural responses, while synergistic grain refinement and compressive residual stresses create a coherent and damage-tolerant surface barrier at the favorable intermediate intensity. Insufficient peening (0.1 mmA) yields an underdeveloped layer with limited protection, whereas excessive peening (0.3 mmA) introduces micro-cracks and severe surface roughening, which override the benefits of increased hardness and accelerate corrosion degradation. This understanding of the strength-degradation balance provides a microstructure-guided framework for tuning SP intensity to achieve superior surface durability in high-strength aluminum alloys.