Application study of salt spray accelerated corrosion model for 6061-T6 aluminum alloy in marine atmospheric environment

To evaluate the effectiveness of the neutral salt spray (NSS) test in simulating the corrosion behavior of 6061-T6 aluminum alloy in marine atmospheric environments, corrosion kinetics, corrosion product characteristics, and electrochemical behavior were comparatively investigated for samples exposed to NSS for 96 h, 240 h, 480 h, 720 h, and 1008 h, as well as samples subjected to 21 months of outdoor exposure in the coastal atmospheric of Hainan. Based on the comparative analysis, a corrosion prediction model applicable to marine atmospheric conditions was established.The results indicate that the corrosion products of 6061-T6 aluminum alloy in both environments are mainly composed of Al(OH) 3 and Al 2 O 3 , and the corrosion kinetics follow a power-law relationship.Based on corrosion weight-loss data, the kinetic models for NSS and marine atmospheric exposure are ΔW =0.042 t 0.635 and ΔW =1.37 t 0.29 , respectively, corresponding to an acceleration factor expressed as K = 36.6 t 0.538 .From the perspective of maximum pit depth evolution, the pit growth models for NSS and marine atmospheric exposure are Y = 1.869 t 0.307 and Y = 62.046 t 0.222, respectively, with an acceleration factor of K = 0.0976 t 0.277 (K < 1).These results indicate that NSS testing can significantly accelerate the overall corrosion process but cannot effectively accelerate pit depth development, indicating that long-term outdoor corrosion behavior cannot be directly predicted using a constant acceleration factor.Therefore, a nonlinear time-dependent acceleration model is proposed to guide the selection of appropriate acceleration factors for different service times, providing a more reliable basis for evaluating the service life of 6xxx aluminum alloys in marine atmospheric environments using NSS testing.