Correlating Manufacturing Strategies to Material Performance in Laser Powder Bed Fusion of Titanium 6Al-4V
Abstract
An investigation into the links between manufacturing and fatigue performance for laser powder bed fusion Ti-6Al-4V has been performed. Given the reliance of the project (and much literature data) on X-ray computed tomography a study into the detection limits and repeatability of this technique was performed. Variation between users was greater than the differences reported in samples. When we tried to replicate literature results, we found that we were unable to reproduce published data. Some of this is due to inherent scatter in the process, and some due to measurement errors. We were able to demonstrate certain pore types were associated with high or low energies, and near the surface of parts. Fatigue testing of samples manufactured with a variety of melt strategies showed that we were able to manufacture samples with a better fatigue life than manufacturer recommended settings. Efforts were made to understand why some settings produced better samples than others based on the pore population. It was found that the proximity of the pore to the surface was important, and the data scatter could be reduced by using the sixth root of the pore size (m^1/6) to normalize the stress. Artificial pores introduced into wrought and LPBF material, showed that for a given defect size, the LPBF tended to have a longer fatigue life but that life was more scattered. This suggests that we cannot fully explain the scatter in fatigue data using pore data alone.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 11, 2023
- Accession Number
- AD1224949
Entities
People
- Samuel Tammas-williams
Organizations
- Liverpool John Moores University