Abstract
The present study investigates the synergistic influence of fatigue and corrosion damage in a simulated recycled 6082 Al-alloy with high content of trace elements like Fe, Cu and Zn through carrying out high cycle fatigue (HCF) tests after prior accelerated intergranular corrosion at different durations viz. 1, 4, 12 and 24 h- in as-extruded and glass-bead blasted condition. Maximum corrosion depth is found to show an increasing trend for all corrosion durations barring between 4 and 12 h. On the contrary, fatigue life is found to reduce with consecutive levels of increasing corrosion duration, but the reduction is significant only at shorter corrosion duration like 1 or 4 h. This depicts an inverse relationship between fatigue life and corrosion depth, indicating the possibility of a critical corrosion depth beyond which corrosion attack does not affect the fatigue life significantly. Detailed fractographic investigation revealed that this phenomenon is attributed to significant curtailing of the crack-initiation phase even at smaller corrosion durations, on account of extensive intergranular corrosion emanating from corrosion pits in the surface grains. Although glass-bead blasting leads to significant improvement in fatigue life in controlled condition, the extent of such improvement is significantly curtailed in pre-corroded condition owing to the presence of intergranular corrosion extending to the interior grains, which offsets to a great extent the effect of compressive residual stresses present in the surface layer.