Effects of Electropolishing on Mechanical Properties and Bio-Corrosion of Ti6Al4V Fabricated by Electron Beam Melting Additive Manufacturing
Abstract
:1. Introduction
2. Material and Methods
3. Results and Discussions
3.1. Powder Analysis
3.2. Surface Roughness
3.3. Surface Morphology
3.4. Surface Compositions Analysis
3.5. Mechanical Response
3.6. Bio-Corrosion Electrochemical Response
3.7. Closing Remarks
4. Conclusions
- (1)
- The current spherical, smooth and non-broken shape of Ti6Al4V powders can result in good powder flow and uniform powder bed during EBM. But the as-EBMed surface would contain partially melted powders, forming a rougher surface with Ra ~ 24 μm.
- (2)
- The electropolishing treatment is able to achieve surface improvement from Ra over ~24 μm down to about 4.5 μm with proper EP solution, voltage, current density, temperature and duration time.
- (3)
- Via the proper EP, the stress concentration effect can be pronouncedly reduced, upgrading the subsequent tensile performance to raise the UTS by 6% and tensile elongation by 53%. With decreasing Ra values, the mechanical response is continuously upgraded in this study.
- (4)
- According to potentiodynamic polarization results, the as-EBMed sample with the highest Ra possesses the higher Ecorr, Icorr and Ipass values. With decreasing Ra, the bio-corrosion rate becomes much lower.
- (5)
- However, when the EP treatment is over-done, the tiny dots induced by EP would impose some negative effects on the bio-corrosion in SBF. Proper EP treatments should result in a flatter surface without tiny EP-induced defects.
Author Contributions
Funding
Conflicts of Interest
References
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Ra (µm) | Kt | Young’s Modulus (GPa) | Yield Stress (MPa) | Ultimate Tensile Stress (MPa) | Tensile Elongation (%) | |
---|---|---|---|---|---|---|
Unpolished | 24.1 ± 2.6 | 2.8 ± 0.3 | 100 ± 2 | 813 ± 3 | 995 ± 8 | 7.6 ± 0.4 |
Polished 1 | 15.1 ± 1.2 | 2.4 ± 0.1 | 103 ± 2 | 817 ± 2 | 1012 ± 13 | 8.7 ± 0.5 |
Polished 2 | 10.2 ± 0.9 | 2.0 ± 0.2 | 100 ± 1 | 809 ± 5 | 1025 ± 7 | 9.3 ± 0.4 |
Polished 3 | 4.5 ± 0.5 | 1.2 ± 0.1 | 102 ± 3 | 817 ± 2 | 1052 ± 8 | 11.6 ± 0.7 |
Ra (µm) | OCP E (V) | Ecorr (V) | Epit (V) | ΔE (V) | Icorr (nA/cm2) | Ipass (µA/cm2) |
---|---|---|---|---|---|---|
24.1 ± 2.6 | −0.25 | −0.270 ± 0.014 | 1.850 ± 0.034 | >2 | 54.36 ± 7.80 | 6.71 ± 0.16 |
19.0 ± 0.7 | −0.38 | −0.413 ± 0.007 | >2 | >2 | 29.38 ± 8.28 | 2.80 ± 0.08 |
15.1 ± 1.2 | −0.45 | −0.394 ± 0.025 | >2 | >2 | 22.19 ± 1.97 | 2.88 ± 0.06 |
10.2 ± 1.3 | −0.32 | −0.369 ± 0.008 | >2 | >2 | 15.47 ± 4.40 | 2.68 ± 0.42 |
4.5 ± 0.8 | −0.23 | −0.225 ± 0.020 | >2 | >2 | 27.24 ± 5.89 | 2.90 ± 0.32 |
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Wu, Y.-C.; Kuo, C.-N.; Chung, Y.-C.; Ng, C.-H.; Huang, J.C. Effects of Electropolishing on Mechanical Properties and Bio-Corrosion of Ti6Al4V Fabricated by Electron Beam Melting Additive Manufacturing. Materials 2019, 12, 1466. https://doi.org/10.3390/ma12091466
Wu Y-C, Kuo C-N, Chung Y-C, Ng C-H, Huang JC. Effects of Electropolishing on Mechanical Properties and Bio-Corrosion of Ti6Al4V Fabricated by Electron Beam Melting Additive Manufacturing. Materials. 2019; 12(9):1466. https://doi.org/10.3390/ma12091466
Chicago/Turabian StyleWu, Yao-Cheng, Che-Nan Kuo, Yueh-Chun Chung, Chee-How Ng, and Jacob C. Huang. 2019. "Effects of Electropolishing on Mechanical Properties and Bio-Corrosion of Ti6Al4V Fabricated by Electron Beam Melting Additive Manufacturing" Materials 12, no. 9: 1466. https://doi.org/10.3390/ma12091466