Fatigue failure: A Structure study

Abstract

Fatigue failure in copper has been studied using X-ray back reflection and metallographic techniques. In the safe range below the endurance limit the structural changes are noticed up to a certain number of researchers, depending on the magnitude of stress. In the unsafe range there is a progressive change till at fracture it becomes . Metallographic observations show that in the unsafe range, the slip lines intensify with increased stress cycles and that the cracks follow either slip bands or grain boundaries. The presences of crystallites at the root of a fatigue crack and the branching of cracks along crystallite boundaries have also been demonstrated. It is possible that outside the scope of the X-ray and microscope, viz., in dislocations and that these may throw only indirect evidences towards that direction.