Fatigue performance and alternate coupling mechanism of ZL114A aluminum alloy under corrosion-fatigue alternating

Abstract

This paper investigates the fatigue performance of ZL114A cast aluminum alloy through laboratory corrosion-fatigue alternating test conducted under simulated tropical marine humid-hot atmosphere. The study examines the impact of different alternating frequency on the fatigue properties of the aluminum alloy. At the same time, the micro morphology of the specimen surface and fatigue fracture were observed, and the damage mechanism under the alternating action of corrosion-fatigue was analyzed. The concept of ‘fatigue impact factor’ in alternating test was proposed to reflect the effect of fatigue on corrosion in alternating process. The results show that the increase of alternating frequency leads to an extended fatigue life for the alloy, following a power function relationship. Pitting is identified as the primary form of corrosion damage on specimen surfaces, with multi-crack initiation observed in fatigue fractures. It is found that the fatigue impact factor exponentially increases with each alternating cycle during testing. In early alternating cycles of test, the presence of fatigue inhibits corrosion by promoting passivation of corrosion pits; however, in later alternating cycles, propagation of fatigue cracks accelerates growth in size for these corrosion pits which subsequently promotes further corrosion.