Microstructure and Electrochemical Behavior of a 3D-Printed Ti-6Al-4V Alloy
Zhijun Yu1, Zhuo Chen2, Dongdong Qu3
1School of Materials Science and Engineering, Tongji University, Shanghai 201804, China.
Additive manufacturing, including selective laser melting (SLM) and electron beam melting (EBM), shows lower corrosion resistance in Ti-6Al-4V than isothermal forging (ISF). Microstructure differences, particularly phase interfaces and martensitic twins, explain these varying corrosion behaviors.
Area of Science:
- Materials Science
- Corrosion Engineering
- Additive Manufacturing
Background:
- 3D printing, or additive manufacturing, offers advanced material properties for aerospace and medical applications.
- While mechanical properties of 3D-printed Ti-6Al-4V are studied, its corrosion resistance compared to conventionally manufactured parts remains unclear.
- Selective Laser Melting (SLM) and Electron Beam Melting (EBM) are key 3D printing techniques for Ti-6Al-4V.
Purpose of the Study:
- To compare the corrosion resistance of Ti-6Al-4V manufactured by SLM, EBM, and Isothermal Forging (ISF).
- To investigate the underlying corrosion mechanisms influenced by microstructural variations.
- To evaluate electrochemical corrosion behavior in a 3.5% NaCl solution.
Main Methods:
- Electrochemical corrosion tests were performed on Ti-6Al-4V samples produced via SLM, EBM, and ISF.
- Microstructural analysis focused on phase composition (α, β) and morphology (equiaxed, acicular, lamellar).
- Corrosion resistance was assessed by analyzing microgalvanic cell formation and anodic dissolution rates.
Main Results:
- Isothermal forged (ISF) Ti-6Al-4V exhibited superior corrosion resistance compared to SLM and EBM samples.
- The equiaxed α + β microstructure of ISF samples showed better performance than the acicular α' + β (SLM) and lamellar α + β (EBM) microstructures.
- Higher β phase content and fewer phase interfaces in ISF samples contributed to enhanced corrosion resistance, while SLM samples suffered from martensitic twins, increasing corrosion rates.
Conclusions:
- The microstructure significantly impacts the corrosion resistance of Ti-6Al-4V, with equiaxed α + β being the most resistant.
- Additive manufacturing techniques like SLM and EBM produce microstructures more susceptible to corrosion in 3.5% NaCl compared to ISF.
- Understanding these microstructural-corrosion relationships is crucial for selecting appropriate manufacturing methods for demanding applications.
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