Using Plasma Electrolytic Polishing for Post-Processing of Additively Manufactured Ti6Al4V Alloy Products

One of the limitations of additive manufacturing technology is the high surface roughness of finished products caused by the layered structure of the deposition and the effect of adhesion of unfused powder particles. This worsens the fatigue characteristics, wear resistance, and functional properties of the parts, which are especially important for critical applications in medicine, aviation, and mechanical engineering. The paper presents the results of a study on the possibility of using plasma electrolytic polishing for post-processing of products made of additively manufactured Ti6Al4V alloy to form a homogeneous surface with reduced roughness. The morphology, roughness, and tribotechnical characteristics of the surface after processing in a fluoride electrolyte were studied with varying voltage and polishing time. A 90% reduction in surface roughness is achieved by polishing at 300 V for 20 min. The results of tribological tests revealed that after the polishing of the oxidative wear mechanism is maintained, the temperature in the tribological contact zone decreases, and the load-bearing capacity of the surface increases (the Kragelsky–Kombalov criterion decreases). The greatest decrease in the friction coefficient by 2.1 times was observed with minimal surface roughness, when the largest average radius of rounding of the microprotrusions of the friction track microtopology is formed with a low value of the Kragelsky–Kombalov criterion.