Separate Contributions of Corrosion-Product Induced and Roughness-Induced Crack Closure to the Fatigue Threshold of Al Alloys

A comparison of nominal and effective fatigue threshold values, ΔKth and ΔKeff th, obtained for different Al alloys with different tempers, tested in inert and in aggressive or moist environments, allowed to estimate the contributions to the non-effective portion of ΔKth arising from roughness-induced as well as from corrosion-product induced crack closure. These results demonstrated that the corrosion-product induced crack closure is a function of the roughness of the fracture surface and tends to be less important for rougher fracture surfaces.