Indicating the limits of metals to receive surface engineering treatments in order to improve their fatigue resistance

摘要

In this work,the limits of metals to receive Surface Engineering Treatments in order to improve their fatigue resistance are investigated.Ultrasonic Impact Treatment (UIT) of four different conditions has been performed on Aluminum alloy 2024-T351.Specimens were then fatigue tested and the respective S-N curves were derived.The investigation was supported by microhardness and dislocation density measurements prior to and after the surface treatments,as well as fracto-graphy.The results indicate that excessive amount of cold work can cause loss of ductility leading to multiple surface cracking.Consequently,the material can experience significant reduction of its fatigue resistance at both,the low and high cycle fatigue region despite the appreciable magnitude of residual stresses caused by the UIT treatment.Therefore,care should be given prior to any surface engineering treatment in order to reveal its maximum potential.