The effects of specimens geometry on solidification conditions and microstructure formation in laser powder bed fusion fabricated Ti–6Al–4V alloys
Laser powder bed fusion (LPBF) excels at creating intricately shaped parts, which will result in variations in solidification conditions, microstructure formation and mechanical properties. To address this issue, three distinct shapes: cubic, pyramidal and inversed pyramidal Ti–6Al–4V alloy specimen...
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Elsevier
2024-11-01
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| Series: | Journal of Materials Research and Technology |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785424023652 |
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| author | Rijie Zhao Ronghui Kou Haoliang Wang Chenghao Song Chuan Li Zhenzhong Sun |
| author_facet | Rijie Zhao Ronghui Kou Haoliang Wang Chenghao Song Chuan Li Zhenzhong Sun |
| author_sort | Rijie Zhao |
| collection | DOAJ |
| description | Laser powder bed fusion (LPBF) excels at creating intricately shaped parts, which will result in variations in solidification conditions, microstructure formation and mechanical properties. To address this issue, three distinct shapes: cubic, pyramidal and inversed pyramidal Ti–6Al–4V alloy specimens were fabricated using LPBF technology. The effects of specimen geometry on microstructure formation, transformation as well as its effects on mechanical properties were investigated in the present study. Our results show that specimen geometry significantly affects the thermal gradient, influencing nucleation and growth during fabrication. EBSD (Electron Backscatter Diffraction) characterization reveals that the primary β-phase grows in columnar grains in cubic specimens, coarse columnar grains along lateral faces in pyramidal specimens, and nearly equiaxed grains in inverted pyramidal specimens, leading to a significant reduction in texture. Nanoindentation tests show higher nanohardness in the top parts of cubic and pyramidal specimens compared to the bottom parts, while inverted pyramidal specimens have consistent nanohardness throughout. This variation is due to differences in solid solute concentration, melt pool undercooling, and thermal histories during and post solidification processes respectively. TEM results indicate that the fine lath phase on the top parts has transformed into β-phase, while the bottom parts remain as α′ phase, highlighting a disparity due to different thermal cycling times and temperatures. |
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| id | doaj-art-f7c8c101ef1d4d73b596e2bde15e36c8 |
| institution | OA Journals |
| issn | 2238-7854 |
| language | English |
| publishDate | 2024-11-01 |
| publisher | Elsevier |
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| series | Journal of Materials Research and Technology |
| spelling | doaj-art-f7c8c101ef1d4d73b596e2bde15e36c82025-08-20T02:35:29ZengElsevierJournal of Materials Research and Technology2238-78542024-11-01335030503910.1016/j.jmrt.2024.10.095The effects of specimens geometry on solidification conditions and microstructure formation in laser powder bed fusion fabricated Ti–6Al–4V alloysRijie Zhao0Ronghui Kou1Haoliang Wang2Chenghao Song3Chuan Li4Zhenzhong Sun5Neutron Scattering Technical Engineering Research Center, School of Mechanical Engineering, Dongguan University of Technology, Dongguan, 523808, ChinaSchool of Mechanical Engineering, Shenyang University, Shenyang, 110003, China; Corresponding author.Neutron Scattering Technical Engineering Research Center, School of Mechanical Engineering, Dongguan University of Technology, Dongguan, 523808, ChinaNeutron Scattering Technical Engineering Research Center, School of Mechanical Engineering, Dongguan University of Technology, Dongguan, 523808, ChinaNeutron Scattering Technical Engineering Research Center, School of Mechanical Engineering, Dongguan University of Technology, Dongguan, 523808, ChinaNeutron Scattering Technical Engineering Research Center, School of Mechanical Engineering, Dongguan University of Technology, Dongguan, 523808, China; Corresponding author.Laser powder bed fusion (LPBF) excels at creating intricately shaped parts, which will result in variations in solidification conditions, microstructure formation and mechanical properties. To address this issue, three distinct shapes: cubic, pyramidal and inversed pyramidal Ti–6Al–4V alloy specimens were fabricated using LPBF technology. The effects of specimen geometry on microstructure formation, transformation as well as its effects on mechanical properties were investigated in the present study. Our results show that specimen geometry significantly affects the thermal gradient, influencing nucleation and growth during fabrication. EBSD (Electron Backscatter Diffraction) characterization reveals that the primary β-phase grows in columnar grains in cubic specimens, coarse columnar grains along lateral faces in pyramidal specimens, and nearly equiaxed grains in inverted pyramidal specimens, leading to a significant reduction in texture. Nanoindentation tests show higher nanohardness in the top parts of cubic and pyramidal specimens compared to the bottom parts, while inverted pyramidal specimens have consistent nanohardness throughout. This variation is due to differences in solid solute concentration, melt pool undercooling, and thermal histories during and post solidification processes respectively. TEM results indicate that the fine lath phase on the top parts has transformed into β-phase, while the bottom parts remain as α′ phase, highlighting a disparity due to different thermal cycling times and temperatures.http://www.sciencedirect.com/science/article/pii/S2238785424023652Ti−6Al–4V alloysLaser powder bed fusionSolidification conditionsThermal historyMicrostructure formation |
| spellingShingle | Rijie Zhao Ronghui Kou Haoliang Wang Chenghao Song Chuan Li Zhenzhong Sun The effects of specimens geometry on solidification conditions and microstructure formation in laser powder bed fusion fabricated Ti–6Al–4V alloys Journal of Materials Research and Technology Ti−6Al–4V alloys Laser powder bed fusion Solidification conditions Thermal history Microstructure formation |
| title | The effects of specimens geometry on solidification conditions and microstructure formation in laser powder bed fusion fabricated Ti–6Al–4V alloys |
| title_full | The effects of specimens geometry on solidification conditions and microstructure formation in laser powder bed fusion fabricated Ti–6Al–4V alloys |
| title_fullStr | The effects of specimens geometry on solidification conditions and microstructure formation in laser powder bed fusion fabricated Ti–6Al–4V alloys |
| title_full_unstemmed | The effects of specimens geometry on solidification conditions and microstructure formation in laser powder bed fusion fabricated Ti–6Al–4V alloys |
| title_short | The effects of specimens geometry on solidification conditions and microstructure formation in laser powder bed fusion fabricated Ti–6Al–4V alloys |
| title_sort | effects of specimens geometry on solidification conditions and microstructure formation in laser powder bed fusion fabricated ti 6al 4v alloys |
| topic | Ti−6Al–4V alloys Laser powder bed fusion Solidification conditions Thermal history Microstructure formation |
| url | http://www.sciencedirect.com/science/article/pii/S2238785424023652 |
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