Abstract
Electron beam melting (EBM) is a rapidly-developing metal additive manufacturing process that holds significant interest in the aerospace and biomedical industries for the high-strength titanium alloy, Ti-6Al-4V. These industries have fatigue-limited applications, but a lack of understanding of the EBM process-microstructure-fatigue relationships limit widespread use and presents challenges for certification. In this review, uniaxial fatigue data was collected and the effects of build orientation, surface roughness, and hot-isostatic pressing are linked to the fatigue properties highlighting microstructure, defects, and failure mechanisms. The observations and conclusions are supported by statistical analysis using the mean fatigue life obtained by the Statistical Fatigue-Limit Model. Both EBM-process and post-process structure relationships are discussed in order to identify the best-practice for fatigue-resistant design. The performance of the EBM material is compared to conventionally manufactured Ti-6Al-4V and possible methods to increase the fatigue resistance are discussed. Anisotropic fatigue behavior was observed in as-fabricated parts and no statistical distinction was found in the fatigue performance of HIPed and as-fabricated material provided the same as-fabricated rough surface condition. However, comparable fatigue life to traditionally manufactured lamellar Ti-6Al-4V is achieved when both post-process HIP and machining are applied to EBM-fabricated parts.
| Original language | English |
|---|---|
| Pages (from-to) | 173-184 |
| Number of pages | 12 |
| Journal | International Journal of Fatigue |
| Volume | 119 |
| DOIs | |
| State | Published - Feb 2019 |
Funding
This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. Research was sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office , under contract DE-AC05-00OR22725 with UT-Battelle, LLC.
| Funders | Funder number |
|---|---|
| U.S. Department of Energy | |
| Advanced Manufacturing Office | DE-AC05-00OR22725 |
| Office of Energy Efficiency and Renewable Energy |
Keywords
- Defects
- Electron beam melting
- Fatigue crack initiation
- Fatigue strength
- High cycle fatigue
- S-N curves
- Surface roughness
- Titanium
