Removal of Recast Layer in Laser-Ablated Titanium Alloy Surface by Electrochemical Machining Process

Recast layer formed in the laser-machined surface is usually fragile and composes of residual stress and micro cracks. The removal of recast layer is therefore necessary to prevent the contamination of broken off recast particles that could deteriorate the functionality and service life of manufactured parts. Electrochemical machining process can be employed to remove the recast structure from the work surface. In this study, the recast of titanium alloy (Ti-6Al-4V) produced by laser milling process was to be removed by using electrochemical-machining process. The surface, subsurface and dimensions of laser-milled cavity were investigated before and after the electrochemical dissolution. It was found that most recast can be removed by the electrochemical machining process and the cavity depth was increased with the processing time. The use of high laser power not only increased the amount of recast, but also raised surface imperfections to the workpiece such as micro holes and cracks. These imperfections can be reproduced by the electrochemical dissolution, thus enlarging the micro holes and cracks as well as roughening the work surface. In addition, the electrochemical machining process can facilitate the removal of heat-affected zone by 21% after being dissolved for 5,400 seconds. The implication of this study could provide a guideline for the recast removal and the deburring of laser-cut surface.