Microhardness and corrosion resistance behaviour of Ti–6Al–4V alloy-coloured surface under WEDM-HS process

In this work, the reaction films were generated on the Ti–6Al–4V alloy by means of high-speed wire electrical discharge machining (WEDM-HS) technology in order to improve its microhardness and corrosion resistance. The microhardness was evaluated by using a nanoindentation tester. The corrosion behaviour was studied using measurements of potentiodynamic polarisation and electrochemical impedance spectroscopy. The experimental results showed that the processed alloys presented a higher microhardness than the matrix, and the thicker film on the surface had a greater microhardness. Additionally, the corrosion resistances of the processed alloys were superior, which could have been due to the lower corrosion current densities and the higher impedance values. Furthermore, the corrosion current densities of the processed alloys would decrease with thicker reaction films. This research provides important insights into the surface modification of titanium alloys.