Modeling the Role of Epitaxial Grain Structure of the Prior β Phase and Associated Fiber Texture on the Strength Characteristics of Ti-6Al-4V Produced via Additive Manufacturing
| Autor: | John S. Madsen, Michael D. Sangid, Eric Fodran, Andrea Nicolas, Kartik Kapoor |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Diffraction
Morphology (linguistics) Materials science 02 engineering and technology Epitaxy lcsh:Technology 01 natural sciences crystal plasticity modeling Article titanium alloys 0103 physical sciences General Materials Science Fiber Texture (crystalline) Composite material lcsh:Microscopy lcsh:QC120-168.85 010302 applied physics electron beam melting lcsh:QH201-278.5 Burgers orientation relationship lcsh:T Titanium alloy 021001 nanoscience & nanotechnology Microstructure microstructure characterization Grain growth lcsh:TA1-2040 lcsh:Descriptive and experimental mechanics lcsh:Electrical engineering. Electronics. Nuclear engineering lcsh:Engineering (General). Civil engineering (General) 0210 nano-technology elasto-viscoplastic fast Fourier transform modeling lcsh:TK1-9971 |
| Zdroj: | Materials Volume 13 Issue 10 Materials, Vol 13, Iss 2308, p 2308 (2020) |
| ISSN: | 1996-1944 |
| Popis: | Due to the rapid cooling and directional heat flow inherent in metal-based additive manufacturing, Ti-6Al-4V results in epitaxial grain growth and a fiber texture of the prior &beta phase. While Ti-6Al-4V produced via powder bed, electron beam melted processing can exhibit a range of strength characteristics, recent studies have shown superior strength properties, compared to similar orientations, of conventional plate material (AMS 4911) across a range of elevated temperatures (204 to 371 ° C). To investigate this phenomenon, a series of crystal plasticity models was developed for the representative grain structures of Ti-6Al-4V to rationalize if the columnar, fiber texture produced by additive manufacturing (AM) was sufficient to explain the observed strength attributes. As a first step towards understanding this behavior, the grain structure was characterized via electron backscattering diffraction for AM material taken from four specimens (with different build directions), as well as material taken from baseline plate material (along and transverse to the rolling direction), and the resulting microstructures were modeled via a crystal plasticity framework. As expected, the results showed the AM material accounting for only the &alpha grain structure was stronger in the vertical builds and weaker in the horizontal builds compared to the conventional plate counterparts. This suggested that grain morphology and &alpha grain orientation alone provided some information about the relative strengths, but did not explain the overall trends observed from the experiments. To account for the role of texture, the characterized &alpha phase was converted, via variant selection, to its prior &beta phase for use in the simulations. The results showed that each simulation of the AM prior &beta phase exhibited a higher strength compared to the baseline plate material, except for one specimen (horizontally built), which had large colonies of soft microtextured regions for the prior &beta structure. This suggests that some variability was experienced (as anticipated), but the texture (especially of the prior &beta macrozones) was a key contributor for the unusually high strength observed of the AM Ti-6Al-4V material. |
| Databáze: | OpenAIRE |
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