Abstract
Laser powder bed fusion (PBF-LB) additive manufacturing (AM) enables production of complex metal parts. The PBF-LB process is, however, prone to the formation of voids, that can compromise the mechanical properties of the final product. Advancements to in-situ sensing and data processing enables the detection of void formation mid-process. If sensing data can be processed efficiently and in real-time, there is the possibility to mitigate voids in-situ, without relying on post-process methods, such as hot isostatic pressing (HIP). Mitigating defects in-situ reduces energy and material expense, limits the need for post-processing, and improves process reliability and consistency. This study investigates two in-situ strategies for targeted void mitigation in PBF-LB of Ti-6Al-4V: (1) targeted intralayer re-melt mitigation (TIRM, re-processing void regions before powder recoating) and (2) targeted interlayer parameter adjustment (TIPA, adjusting the laser power when processing in the void region on the subsequent layer after a void). For each mitigation strategy, the size of the mitigation area relative to the size of the void and the laser power used for mitigation were varied. To systematically assess mitigation success, surrogate voids were programmatically induced during part fabrication at known locations by decreasing the laser power when processing within predetermined regions over sequential layers. This work provides insight into the proper mitigation parameters to effectively heal voids and understanding into the limits of in-situ void mitigation. For both mitigation strategies, optimal mitigation parameters resulted in complete elimination of voids or a significant reduction in void volume. These results indicate that voids detected during PBF-LB AM can be reduced in volume or eliminated in-situ.
| Original language | English |
|---|---|
| Pages (from-to) | 1545-1560 |
| Number of pages | 16 |
| Journal | International Journal of Advanced Manufacturing Technology |
| Volume | 136 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jan 2025 |
| Externally published | Yes |
Funding
This effort was performed through the National Center for Defense Manufacturing and Machining under the America Makes Program entitled “Open framework for real-time control and mitigation of defects in metal PBF” and is based on research sponsored by Air Force Research Laboratory under agreement FA8650-20-2-5700. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the Government. Distribution authorized to U.S. Government Agencies and America Makes Members. Other request for this document shall be referred to AFRL/RXMS, Wright-Patterson Air Force Base, OH 45433 − 7750. This work was supported in part by the Applied Research Laboratory through a Walker Fellowship. The authors would like to thank Anil Chaudhary from Applied Optimization for discussion of the project methods and Jan Petrich from the Applied Research Laboratory for discussion of the results. This effort was performed through the National Center for Defense Manufacturing and Machining under the America Makes Program entitled “Open framework for real-time control and mitigation of defects in metal PBF” and is based on research sponsored by Air Force Research Laboratory under agreement FA8650-20-2-5700. The authors declare that no funds, grants, or other support was received during the preparation of this manuscript.
Keywords
- Defect mitigation
- Porosity
- Process control
- Ti-6Al-4V
- X-ray computed tomography