Investigation of Endurance Limits and Analysis of Electric Discharge Machined Surface of Aluminum Alloy 2024 T6

Abstract

Electric discharge machining (EDM) removes the workpiece material by the electro-thermal energy followed by flushing of the molten pool. A portion of this molten material is not removed but resolidifies on the surface of base material and alters the mechanical properties of the material. In this study the endurance limits are investigated for the electric dischrage machined (EDMed) aerospace grade Aluminum alloy 2024T6 for the discharge currents of 3 and 12 amperes. The fatigue tests were performed on 4-point rotating bending machine at the frequency of 50Hz and ambient temperature. These tests were carried out according to the modified stair case method. It is found that the obtained endurance limit for the EDMed specimens at 3 ampere discharge current level is 21% greater than that of 12 ampere. Some surface and subsurface defects are highlighted that can cause high stress concentration.