Mechanistic Understanding of the Corrosion Behaviors of AZ31 Finished by Wire Electric Discharge Machining

Metallic contamination that occurs during machining is extremely hard to avoid, which may cause an irretrievable effect on the performance of materials. Unfortunately, this point is chronically neglected in practice. The present study focused on investigating the influence of wire electric discharge machining (WEDM), one of the most common techniques for magnesium implant manufacturing, on the morphology and corrosion behaviors of AZ31. The results show that the surface roughness increased after machining due to the presence of overlapped craters and scattered micro-cracks. Deposition of tool electrode materials was found throughout the recast layer in the form of Cu-rich particles (CuRPs), and increasing the energy input escalates this deposition process. The corrosion resistance of WEDM machined AZ31 was significantly deteriorated due to the galvanic coupling between CuRPs and Mg matrix. The corrosion mechanism of AZ31 alloy with CuRPs deposition was elucidated.