Surface modification of Ti-6Al-4 V by gas–liquid mixed EDM

Ti-6Al-4 V alloy is widely used in many fields due to its excellent properties. However, its further applications are limited by its low hardness and poor wear resistance. In this paper, gas–liquid mixed electrical discharge machining (G-LEDM) process was applied to investigate the machining performance and surface modification Ti-6Al-4 V alloy. The effect of peak current and pulse duration on surface morphology, surface roughness, cross section morphology, micro hardness, and wear resistance were investigated using nitrogen mixed special oil dielectric. The results indicated that the G-LEDM process has better performance with fewer pores, shallower and larger craters on smoother surface. A continuous and thicker recast layer was obtained on G-LEDM process. The X-ray diffraction results demonstrated that TiN phase was formed on the sample surface. The micro hardness of G-LEDM process was about 1329.5 HV, which is about 3 times that of the matrix, and the wear resistance is improved accordingly. The surface of Ti-6Al-4 V alloy was modified by G-LEDM process.