Step loading corrosion fatigue testing of 7075-T6 WC/C coated specimens in air and methanol

The 7075-T6 aluminum alloy, despite its outstanding mechanical qualities, has shown critical issues due to its sensitivity to corrosion. In the present work, a Tungsten Carbide/Carbon (WC/C) thin hard coating has been evaluated for its effects on corrosion fatigue behavior on a 7075-T6 substrate, by means of rotating bending (R = 1) step-loading tests at 2 105 cycles, in laboratory air and methanol, with different surface finishing. A corrosion fatigue protection effect was found for the smoothest coated specimens, along with detrimental fatigue effects caused by the high applied stresses and the coating process thermal effects. SEM analysis has been performed to characterize the fracture surfaces.