The efficacy of plasma electrolytic nitrocarburizing (PENC) in enhancing the surface hardness and wear resistance of the surface of Ti6Al4V alloy additively manufactured by selective laser melting (SLM) and electron beam melting (EBM) was assessed in comparison with the surface of the alloy obtained by the traditional method (TM) of vacuum casting and subsequent hot rolling. The surface of TM, SLM and EBM samples after PENC without pre-treatment have the same structural-phase composition and consist of TiN nitride and TiC, Ti8C5 titanium carbides in a martensitic matrix with an oxide layer on the surface. Such a structure leads to an increase in microhardness to 1170 ± 180 HV for SLM samples, 1050 ± 40 HV for TM samples and 1025 ± 130 HV for EBM samples. Significant differences in the morphological features of the surface are associated with the presence of unmelted and semi-melted particles of raw materials after additive manufacturing, which causes predominant anodic dissolution along the contours of these particles and high-temperature oxidation of depressions during plasma electrolytic treatment. The most significant increase in wear resistance (a factor of 14.4) was observed in EBM samples, concomitant with a change in the dominant friction mechanism from microcutting to plastic displacement. For SLM samples, fatigue wear was observed both before and after treatment. Nitrocarburizing increased the wear resistance of these samples by a factor of 5.2. For TM samples, the treatment increased wear resistance by a factor of 3.2. The reduction in weight wear of the samples following PENC is attributed to the combined effect of increased titanium surface microhardness, oxidation, an increased bearing capacity of the rough profile (Kragelsky-Kombalov criterion), and a softer friction condition. For industrial application, a significant simplification of post-processing is the primary technological effect of plasma electrolytic processing of the additively manufactured titanium. • PENC can be effectively applied to additively manufactured parts. • Structure and composition of surface is similar to traditionally manufactured parts. • The granule contours dissolve and the depressions oxidize with PENC. • Microhardness of SLM and EBM surfaces after PENC increases to 1170 and 1025 HV. • Wear of SLM and EBM samples after PENC is reduced by 5.2 and 14.4 times.
Ludin et al. (2026) studied this question.