Page 43 - MSAM-2-2

Materials Science in Additive Manufacturing Tensile and fatigue properties of Ti6Al4V SLM parts

10 million cycles were indeed close to the fatigue limit. may also be a factor of the large variation in fatigue
For experiment 18, a new specimen was tested under 30% testing results.
yield strength to confirm that the quality of the grinding For future development, all tests need to be repeated
has improved from the initial specimens. The number of multiple times for repeatability and reliability. For tensile
cycles from experiment 9 versus those from experiment testing, Taguchi orthogonal arrays should be implemented
18 improved from 60,136 to 321,199, showing that the in future. This, however, would require 48 sets of samples
quality of specimen has improved. Eventually, the S/N and experiments. In addition, more work needs to be done
curve of the fabricated Ti6Al4V samples was plotted and on the part of parameter optimization.
shown in Figure 7.
In the future, specimens should be arranged in a Acknowledgments
diamond shape, as shown in Figure 8, instead of being all The authors acknowledge the support from Singapore
parallel to each other on the plate. This is to prevent the Centre for 3D Printing (SC3DP) and School of
base plate itself from warping. Heat treatment should also Mechanical and Aerospace Engineering (MAE), Nanyang
be done before separating specimens from the base plate to Technological University (NTU) Singapore, for the use
reduce the stress-concentrations. of the testing and characterization facilities. The authors
would also acknowledge the support from SLM Solutions
4.3.2. Fracture analysis Singapore Ptd. Ltd., in fabricating the Ti6Al4V samples
By analyzing the surface of the fractured surface that is using SLM280 Twin 700W AM machine.
captured from the various forms of microscopy, we can
identify areas of significance such as crack initiation sites, Funding
beach lines, fatigue region, and overload region as shown None.
in Figure 9. This will help us understand where the weakest
point comes from if it is from a surface defect or if the Conflict of interest
failure stems purely from material fatigue. Further process The authors declared no potential conflict of interest with
parameter improvements can be developed based on the respect to the research, authorship, and/or publication of
analysis of these fracture pictures. this article.

5. Conclusion Author contributions
Good relative density of Ti6Al4V samples was achieved Conceptualization: Zhen Lu
in both 30- and 130-μm layer thicknesses (99.97 ± 0.02 % Formal analysis: Zhen Lu and Sandra Leong Lai San
[n = 8] for 30-μm and 99.96 ± 0.02 % [n = 4] for 130-μm). Investigation: Zhen Lu and Sandra Leong Lai San
Tensile strength like UTS of Ti6Al4V samples showed Methodology: Zhen Lu and Sandra Leong Lai San
insignificant difference with a p-value of 0.0422. Possible Project administration: Zhen Lu and Ming Jen Tan
factors impacting the tensile properties of SLM-produced Resources: Zhen Lu, Ming Jen Tan, and Chee Kai Chua
parts, such as layer thickness, build orientation, and post- Supervision: Ming Jen Tan, Jia An, Yi Zhang, and Chee Kai
processing, are discussed in this paper. We also obtained Chua
S/N curve of the fatigue performance of Ti6Al4V samples Validation: Zhen Lu and Sandra Leong Lai San
printed with 30-μm layer thickness. Visualization: Zhen Lu and Sandra Leong Lai San
Based on the tensile testing results, specimens with Writing – original draft: Zhen Lu and Sandra Leong Lai San
30- and 130-μm layer thicknesses have similar tensile Writing – review & editing: Zhen Lu and Jia An
strength. Factors such as layer thickness and post-
processing condition may not have significant impact on Ethics approval and consent to participate
the tensile properties of built samples with proper process Not applicable.
optimization.
The fatigue properties of the specimens produced Consent for publication
in this study are not up to the industry standard yet. Not applicable.
Therefore, further research is required to improve not
only the microstructures but also the post-processing Availability of data
and handling of specimens to achieve a good surface Current raw data can be shared with readers on reasonable
finish. Inconsistencies with the warpage of specimens request.

Volume 2 Issue 2 (2023) 10 https://doi.org/10.36922/msam.0912