A precise machining surface obtained electrolyte plasma polishing on Ti–6Al–4V alloy: Microstructure and in-situ mechanical behaviors

As an innovative finishing technique, electrolytic plasma polishing (EPP) is effective in improving the surface quality of Ti-6Al-4V alloy. In this paper, the microstructural evolution of Ti-6Al-4V alloy at different polishing voltages was investigated by means scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM). Furthermore, the in-situ tensile test was performed via SEM to systematically characterize the mechanical properties and fracture behaviors. According to the research results, EPP significantly reduced scratches and crests on the surface at 300 V, reducing the average surface roughness to 1/24 of its original value. Subsequent to EPP treatment at 300 V, the ultimate tensile strength (UTS) of the Ti-6Al-4V alloy peaked at 1094.5 ± 25.2 MPa, with an elongation increase of approximately 16 % compared to the untreated sample. Finally, fracture modeling was performed through finite element simulation and in-situ tensile test. Initiated in surface microcracks, the crack developed rapidly along slip lines. The tensile damage caused by axial stresses extended from surface microcracks to the entire fracture, thus causing the material to fracture.