Corrosion Behavior of Ti-6Al-4V with Different Thermomechanical Treatments and Microstructures

The corrosion behavior of four different microstructures of Ti-6Al-4V with varying volume fractions of primary α (0, 10%∼20%, 40%∼50%, and ∼90%) was investigated in sodium chloride (NaCl) and hydrochloric acid (HCl) solutions. The microstructure constituent morphologies and distributions were charac...

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Bibliographic Details
Published in:Corrosion (Houston, Tex.) Tex.), 2010-06, Vol.66 (6), p.65004-65004-9
Main Authors: ATAPOUR, M, PILCHAK, A, FRANKEL, G. S, WILLIAMS, J. C, FATHI, M. H, SHAMANIAN, M
Format: Article
Language:English
Subjects:
Analysis
Applied sciences
Beta phase
Composition
Constituents
Corrosion
Corrosion environments
Corrosion rate
Electron microscopy
Exact sciences and technology
Heat treatment
Heat treatments
Hydrochloric acid
Hydrogen chloride
Lamellar structure
Metals. Metallurgy
Microstructure
Morphology
Scanning electron microscopy
Sodium
Sodium chloride
Submerging
Thermomechanical treatment
Titanium base alloys
Vanadium
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Summary:The corrosion behavior of four different microstructures of Ti-6Al-4V with varying volume fractions of primary α (0, 10%∼20%, 40%∼50%, and ∼90%) was investigated in sodium chloride (NaCl) and hydrochloric acid (HCl) solutions. The microstructure constituent morphologies and distributions were characterized with optical and scanning electron microscopy (SEM) while constituent compositions were determined with energy-dispersive x-ray (EDX) analysis. All four microstructures exhibited spontaneous passivity in 0.9% NaCl at 37°C and active/passive transitions in 1.5 M HCl at 37°C. Very little difference in corrosion rate was observed using potentiodynamic polarization curves and weight-loss tests. However, SEM analysis of corroded surfaces indicated that the fully lamellar structure (0% primary α) exhibited the worst attack. Analysis of surfaces after 48 h immersion in 3.5 M HCl revealed that α/β phase boundaries were preferential sites for corrosion attack. Also, β phase in lamellar structures exhibited preferential dissolution in comparison to α phase. The corrosion results are discussed in terms of microstructure and constituent composition. In particular, the extent of partitioning of vanadium to the β phase during heat treatment varies with the volume fractions of primary α and transform β, which affects the corrosion performance in aggressive environments.
ISSN:0010-9312
1938-159X
DOI:10.5006/1.3452400