Arc discharge behavior of corroded surface and electrochemical corrosion characteristics of recast layer of Ti6Al4V titanium alloy

In this study, recast layer and dissolved surface of titanium alloy were prepared, the morphology, metallographic and electrochemical behaviors of both surfaces were characterized in detail. Based on the characterization results, a plasma heat transfer model of the corroded surface and an electrochemical dissolution model of the recast layer were constructed, and relevant validation experiments were carried out. The results show that the titanium alloy undergoes oxidation and carbonization during the dissolution process, with a slight increase in impedance, which induces a slight local electric field concentration and additional discharges. The degree of oxidation and carbonization of the recast layer is low, the concave and convex structure of its surface also increases the corrosion tendency, but the refinement of the internal tissue grain improves the corrosion resistance. To improve the dissolution efficiency of the recast layer, the mass transfer mechanism of electric arc electrochemical machining (EAECM) was investigated. It was found that EAECM could accelerate the corrosion of the recast layer by utilizing the electrothermal effect and maintain good machining accuracy.