Incorporating grain-level residual stresses and validating a crystal plasticity model of a two-phase Ti-6Al-4 V alloy produced via additive manufacturing

•Explicitly modeled α and β phases of Ti-6Al-4 V with a realistic FE mesh.•Residual stresses initialized via GNDs, obtained from EBSD characterization.•TEM indicates higher amount of  dislocations than  type dislocations.•Good agreement between CPFE simulations and HR-DIC experiments.•Strain localiz...

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Bibliographic Details
Published in:Journal of the mechanics and physics of solids 2018-12, Vol.121, p.447-462
Main Authors: Kapoor, Kartik, Yoo, Yung Suk Jeremy, Book, Todd A., Kacher, Josh P., Sangid, Michael D.
Format: Article
Language:English
Subjects:
Additive manufacturing
Alloying additive
Computer simulation
Critical components
Crystal plasticity finite element modeling
Cyclic loads
Damage detection
Damage localization
Digital image correlation
Digital imaging
Dislocations
Electron backscatter diffraction
Electron imaging
Finite element method
Image resolution
Laser beam melting
Manufacturing
Materials fatigue
Nucleation
Plastic deformation
Plastic properties
Residual stress
Strain localization
Ti-6Al-4 V
Titanium alloys
Titanium base alloys
Transmission electron microscopy
Vanadium
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Summary:•Explicitly modeled α and β phases of Ti-6Al-4 V with a realistic FE mesh.•Residual stresses initialized via GNDs, obtained from EBSD characterization.•TEM indicates higher amount of  dislocations than  type dislocations.•Good agreement between CPFE simulations and HR-DIC experiments.•Strain localization predominantly takes place at prior β grain boundaries. Titanium alloys, produced via additive manufacturing techniques, offer tremendous benefits over conventional manufacturing processes. However, there is inherent uncertainty associated with their properties, often stemming from the variability in the manufacturing process itself along with the presence of residual stresses in the material, which prevents their use as critical components. This work investigates Ti-6Al-4 V produced via selective laser melting by carrying out crystal plasticity finite element (CPFE) simulations and high-resolution digital image correlation (HR-DIC) on samples subject to cyclic loading. This is preceded by detailed material characterization using electron backscatter diffraction, back-scattered electron imaging and transmission electron microscopy, whose results are utilized to inform the CPFE model. A method to incorporate the effect of grain-level residual stresses via geometrically necessary dislocations is developed and implemented within the CPFE framework. Using this approach, grain level information about residual stresses obtained spatially over the region of interest, directly from the experimental material characterization, is utilized as an input to the model. Simulation results match well with HR-DIC and indicate that prior β boundaries play an important role in strain localization. In addition, possible sites for damage nucleation are identified, which correspond to regions of high plastic strain accumulation. [Display omitted]
ISSN:0022-5096
1873-4782
DOI:10.1016/j.jmps.2018.07.025