Improving fatigue life and toughness in electron beam welded Ti–6Al–4V achieved through beta heat treatment for microstructure uniformity
Electron beam welding (EBW) offers significant production efficiency advantages for Ti alloys in aerospace applications. However, the formation of martensitic α′ in the weld joint reduces toughness and fatigue properties, posing safety challenges. To address these issues, this study investigates the...
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2025-03-01
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| author | Seongji Seo A Ra Jo Hyun Wook Lee Sun Kwang Hwang Jeongho Han Jiyong Park |
| author_facet | Seongji Seo A Ra Jo Hyun Wook Lee Sun Kwang Hwang Jeongho Han Jiyong Park |
| author_sort | Seongji Seo |
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| description | Electron beam welding (EBW) offers significant production efficiency advantages for Ti alloys in aerospace applications. However, the formation of martensitic α′ in the weld joint reduces toughness and fatigue properties, posing safety challenges. To address these issues, this study investigates the effects of annealing below the β transus temperature (mill annealing, MA) and above the β transus temperature (beta annealing, BA) on the microstructure and mechanical properties of EBWed Ti–6Al–4V (Ti64). EBW produced α′ in both the fusion zone (FZ) and heat-affected zone due to rapid heating and cooling. MA transformed α′ into an α+β basketweave structure, but did not eliminate microstructural gradients. Conversely, BA produced a homogenized microstructure across all regions, characterized by a transformed β phase with a coarse α+β basketweave structure dominantly oriented with prismatic plane. Both annealing processes reduced the amount of low-angle grain boundaries in the FZ compared to the EBWed condition. BA achieved superior mechanical improvements, including a 20 % increase in tensile toughness, a 56 % improvement in fatigue life, and a 100 % improvement in impact toughness. These enhancements are attributed to uniform strain distribution and enhanced fracture resistance facilitated by the basketweave structure. Therefore, this study suggests that BA is the optimal heat treatment for Ti64 weld joint, significantly improving fatigue cycle and impact toughness, and is recommened for aerospace structural applications. |
| format | Article |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-03-01 |
| publisher | Elsevier |
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| series | Journal of Materials Research and Technology |
| spelling | doaj-art-b6ec4c13945846869ad338ca52bc27ec2025-01-17T04:49:33ZengElsevierJournal of Materials Research and Technology2238-78542025-03-0135869880Improving fatigue life and toughness in electron beam welded Ti–6Al–4V achieved through beta heat treatment for microstructure uniformitySeongji Seo0A Ra Jo1Hyun Wook Lee2Sun Kwang Hwang3Jeongho Han4Jiyong Park5Advanced Packaging Integration Center, Korea Institute of Industrial Technology, Incheon, 21999, Republic of Korea; Department of Materials Science and Engineering, Hanyang University, Seoul, 04763, Republic of KoreaSmart Manufacturing Technology R&D Group, Korea Institute of Industrial Technology, Daegu, 42994, Republic of KoreaDepartment of Materials Science and Engineering, Hanyang University, Seoul, 04763, Republic of KoreaSmart Manufacturing Technology R&D Group, Korea Institute of Industrial Technology, Daegu, 42994, Republic of KoreaDepartment of Materials Science and Engineering, Hanyang University, Seoul, 04763, Republic of Korea; Corresponding author.Advanced Packaging Integration Center, Korea Institute of Industrial Technology, Incheon, 21999, Republic of Korea; Department of Convergence Manufacturing System Engineering, Korea National University of Science and Technology (UST), Daejeon 34113, Republic of Korea; Corresponding author. Advanced Packaging Integration Center, Korea Institute of Industrial Technology, Incheon 21999, Republic of Korea.Electron beam welding (EBW) offers significant production efficiency advantages for Ti alloys in aerospace applications. However, the formation of martensitic α′ in the weld joint reduces toughness and fatigue properties, posing safety challenges. To address these issues, this study investigates the effects of annealing below the β transus temperature (mill annealing, MA) and above the β transus temperature (beta annealing, BA) on the microstructure and mechanical properties of EBWed Ti–6Al–4V (Ti64). EBW produced α′ in both the fusion zone (FZ) and heat-affected zone due to rapid heating and cooling. MA transformed α′ into an α+β basketweave structure, but did not eliminate microstructural gradients. Conversely, BA produced a homogenized microstructure across all regions, characterized by a transformed β phase with a coarse α+β basketweave structure dominantly oriented with prismatic plane. Both annealing processes reduced the amount of low-angle grain boundaries in the FZ compared to the EBWed condition. BA achieved superior mechanical improvements, including a 20 % increase in tensile toughness, a 56 % improvement in fatigue life, and a 100 % improvement in impact toughness. These enhancements are attributed to uniform strain distribution and enhanced fracture resistance facilitated by the basketweave structure. Therefore, this study suggests that BA is the optimal heat treatment for Ti64 weld joint, significantly improving fatigue cycle and impact toughness, and is recommened for aerospace structural applications.http://www.sciencedirect.com/science/article/pii/S2238785425000559Electron beam weldingTi alloyAnnealingMicrostructureFatigue lifeToughness |
| spellingShingle | Seongji Seo A Ra Jo Hyun Wook Lee Sun Kwang Hwang Jeongho Han Jiyong Park Improving fatigue life and toughness in electron beam welded Ti–6Al–4V achieved through beta heat treatment for microstructure uniformity Journal of Materials Research and Technology Electron beam welding Ti alloy Annealing Microstructure Fatigue life Toughness |
| title | Improving fatigue life and toughness in electron beam welded Ti–6Al–4V achieved through beta heat treatment for microstructure uniformity |
| title_full | Improving fatigue life and toughness in electron beam welded Ti–6Al–4V achieved through beta heat treatment for microstructure uniformity |
| title_fullStr | Improving fatigue life and toughness in electron beam welded Ti–6Al–4V achieved through beta heat treatment for microstructure uniformity |
| title_full_unstemmed | Improving fatigue life and toughness in electron beam welded Ti–6Al–4V achieved through beta heat treatment for microstructure uniformity |
| title_short | Improving fatigue life and toughness in electron beam welded Ti–6Al–4V achieved through beta heat treatment for microstructure uniformity |
| title_sort | improving fatigue life and toughness in electron beam welded ti 6al 4v achieved through beta heat treatment for microstructure uniformity |
| topic | Electron beam welding Ti alloy Annealing Microstructure Fatigue life Toughness |
| url | http://www.sciencedirect.com/science/article/pii/S2238785425000559 |
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