Electrochemical properties and dissolved behavior of laser solid formed Ti6Al4V alloy in NaCl solution with different current densities

Abstract

The hybrid manufacturing process of additive manufacturing (AM) and electrochemical machining (ECM) is a new approach to advanced manufacturing technology. The feasibility of using ECM to machine an as-deposited Ti6Al4V alloy fabricated by the laser solid forming (LSF) method of AM was investigated in 15 wt.% NaCl solution. As the machining current density increased, the material removal rate increased linearly, and the current efficiency dropped from 140% to 93%. The current efficiency over 100% at low current densities was attributed to the electrochemical reactions of atoms in lower valence states. The microdissolved grooves, resulting from selective preferential dissolution of the α phase, were shallowed when machined at a higher current density (>3 A cm −2 ) and are attributed to the weakening of the galvanic effect at higher machining voltages. Additionally, the dissolved surface topography exhibited the worst waviness at the delimited current density of 10 A cm −2 , and the surface waviness decreased rapidly as the current density increased in the positive delimited range. Considering the machining efficiency and the surface quality of ECM, the as-deposited Ti6Al4V machined at a current density of 40 A cm −2 will be the preferred ECM current parameter.