Comparative Study of Direct and Alternating Currents on the Microstructure Evolution of Additively Manufactured Ti-6Al-4 V

Abstract Electric current treatment has recently emerged as a novel, ultrafast, and efficient post-processing technique for additively manufactured (AM) materials. However, the choice of current—whether direct current (DC) or alternating current (AC)—varies, and its specific influence on the microstructure remains unclear. Therefore, this study conducts the first comparative investigation of the effects of AC and DC on the microstructure of AM Ti-6Al-4V under the same energy conditions. The results indicate that AC and DC currents can enhance plasticity and reduce hardness by coarsening the α/α’ grains in AM Ti-6Al-4 V alloys, achieving a good balance between plasticity and strength. The primary difference between the two is their effect on the evolution of β phase grains during the current application. Based on finite element analysis, the athermal effect of DC is ~ 2.27 times that of AC due to its continuous unidirectional application. This result closely aligns with the experimental results, where the β grain migration velocity under DC conditions is about 2.25 times that of AC. This study provides guidance for applying electric current treatment to other AM materials and offers a reference for selecting optimal current types and strategies for processing dual- and multiphase materials. Graphical Abstract