Yee Ng, Xian Yi Tan, Tzee Luai Meng, Chen-Nan Sun, Zhaohong Huang, Andrew Chun Yong Ngo, Hongfei Liu,
Material removal and surface finishing of additively manufactured Ti-6Al-4V coupons by cyclic process of plasma electrolytic polishing,
Surface and Coatings Technology,
Volume 498,
2025,
131872,
ISSN 0257-8972,
https://doi.org/10.1016/j.surfcoat.2025.131872.
Abstract:
A cyclic plasma electrolytic polishing (PEP) process was applied to Ti-6Al-4V coupons fabricated by laser powder
bed fusion (LPBF). In the initial stage of each cycle, the anode (i.e., the workpiece) was slowly immersed (~2.5
mm/s) into the electrolyte with the applied voltage (300 V) turned on. By introducing process interruptions
between adjacent cycles, the electrolyte temperature was able to be maintained between 75 and 94 ◦C, which, in
turn, reduced electrolyte evaporations during the PEP process. The slow immersion lowered the current density
threshold required to form vapor-gaseous envelope (VGE) and to initiate microarc discharge and plasma in the
VGE layer surrounding the coupon. The shortened processing time (2 min) in each cycle shifted the PEP operation from a stable to an initiation-transition stage. Material removal (in terms of volume and weight) and
surface roughness reduction (from Ra > 10 μm to Ra ≈ 1.0 μm) were strongly correlated with each other, both
increasing with the number of PEP cycles. Microstructural and surface chemical analyses provided valuable
insights into the plasma electrochemical reaction on the coupon surface, revealing its relationship with material
removal and localized strain relaxation as the processing cycles increased.
License type:
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
Funding Info:
This research / project is supported by the A*STAR - Singapore Aerospace Programme
Grant Reference no. : M2315a0084