Low-Cycle Fatigue Behavior of Wire and Arc Additively Manufactured Ti-6Al-4V Material
Additive manufacturing (AM) techniques, such as wire arc additive manufacturing (WAAM), offer unique advantages in producing large, complex structures with reduced lead time and material waste. However, their application in fatigue-critical applications requires a thorough understanding of the mater...
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MDPI AG
2023-09-01
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Online Access: | https://www.mdpi.com/1996-1944/16/18/6083 |
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author | Sebastian Springer Martin Leitner Thomas Gruber Bernd Oberwinkler Michael Lasnik Florian Grün |
author_facet | Sebastian Springer Martin Leitner Thomas Gruber Bernd Oberwinkler Michael Lasnik Florian Grün |
author_sort | Sebastian Springer |
collection | DOAJ |
description | Additive manufacturing (AM) techniques, such as wire arc additive manufacturing (WAAM), offer unique advantages in producing large, complex structures with reduced lead time and material waste. However, their application in fatigue-critical applications requires a thorough understanding of the material properties and behavior. Due to the layered nature of the manufacturing process, WAAM structures have different microstructures and mechanical properties compared to their substrate counterparts. This study investigated the mechanical behavior and fatigue performance of Ti-6Al-4V fabricated using WAAM compared to the substrate material. Tensile and low-cycle fatigue (LCF) tests were conducted on both materials, and the microstructure was analyzed using optical microscopy and scanning electron microscopy (SEM). The results showed that the WAAM material has a coarser and more heterogeneous grain structure, an increased amount of defects, and lower ultimate tensile strength and smaller elongation at fracture. Furthermore, strain-controlled LCF tests revealed a lower fatigue strength of the WAAM material compared to the substrate, with crack initiation occurring at pores in the specimen rather than microstructural features. Experimental data were used to fit the Ramberg–Osgood model for cyclic deformation behavior and the Manson–Coffin–Basquin model for strain-life curves. The fitted models were subsequently used to compare the two material conditions with other AM processes. In general, the quasi-static properties of WAAM material were found to be lower than those of powder-based processes like selective laser melting or electron beam melting due to smaller cooling rates within the WAAM process. Finally, two simplified estimation models for the strain-life relationship were compared to the experimentally fitted Manson–Coffin–Basquin parameters. The results showed that the simple “universal material law” is applicable and can be used for a quick and simple estimation of the material behavior in cyclic loading conditions. Overall, this study highlights the importance of understanding the mechanical behavior and fatigue performance of WAAM structures compared to their substrate counterparts, as well as the need for further research to improve the understanding of the effects of WAAM process parameters on the mechanical properties and fatigue performance of the fabricated structures. |
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institution | Directory Open Access Journal |
issn | 1996-1944 |
language | English |
last_indexed | 2024-03-10T22:30:33Z |
publishDate | 2023-09-01 |
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series | Materials |
spelling | doaj.art-005b3eac4d424275ad4caaa65d66f9ae2023-11-19T11:42:38ZengMDPI AGMaterials1996-19442023-09-011618608310.3390/ma16186083Low-Cycle Fatigue Behavior of Wire and Arc Additively Manufactured Ti-6Al-4V MaterialSebastian Springer0Martin Leitner1Thomas Gruber2Bernd Oberwinkler3Michael Lasnik4Florian Grün5Chair of Mechanical Engineering, Montanuniversität Leoben, 8700 Leoben, AustriaInstitute of Structural Durability and Railway Technology, Graz University of Technology, 8010 Graz, AustriaVoestalpine BÖHLER Aerospace GmbH & Co KG, 8605 Kapfenberg, AustriaVoestalpine BÖHLER Aerospace GmbH & Co KG, 8605 Kapfenberg, AustriaVoestalpine BÖHLER Aerospace GmbH & Co KG, 8605 Kapfenberg, AustriaChair of Mechanical Engineering, Montanuniversität Leoben, 8700 Leoben, AustriaAdditive manufacturing (AM) techniques, such as wire arc additive manufacturing (WAAM), offer unique advantages in producing large, complex structures with reduced lead time and material waste. However, their application in fatigue-critical applications requires a thorough understanding of the material properties and behavior. Due to the layered nature of the manufacturing process, WAAM structures have different microstructures and mechanical properties compared to their substrate counterparts. This study investigated the mechanical behavior and fatigue performance of Ti-6Al-4V fabricated using WAAM compared to the substrate material. Tensile and low-cycle fatigue (LCF) tests were conducted on both materials, and the microstructure was analyzed using optical microscopy and scanning electron microscopy (SEM). The results showed that the WAAM material has a coarser and more heterogeneous grain structure, an increased amount of defects, and lower ultimate tensile strength and smaller elongation at fracture. Furthermore, strain-controlled LCF tests revealed a lower fatigue strength of the WAAM material compared to the substrate, with crack initiation occurring at pores in the specimen rather than microstructural features. Experimental data were used to fit the Ramberg–Osgood model for cyclic deformation behavior and the Manson–Coffin–Basquin model for strain-life curves. The fitted models were subsequently used to compare the two material conditions with other AM processes. In general, the quasi-static properties of WAAM material were found to be lower than those of powder-based processes like selective laser melting or electron beam melting due to smaller cooling rates within the WAAM process. Finally, two simplified estimation models for the strain-life relationship were compared to the experimentally fitted Manson–Coffin–Basquin parameters. The results showed that the simple “universal material law” is applicable and can be used for a quick and simple estimation of the material behavior in cyclic loading conditions. Overall, this study highlights the importance of understanding the mechanical behavior and fatigue performance of WAAM structures compared to their substrate counterparts, as well as the need for further research to improve the understanding of the effects of WAAM process parameters on the mechanical properties and fatigue performance of the fabricated structures.https://www.mdpi.com/1996-1944/16/18/6083wire arc additive manufacturinglow-cycle fatigueTi-6Al-4VRamberg–Osgood modelManson–Coffin–Basquincyclic deformation |
spellingShingle | Sebastian Springer Martin Leitner Thomas Gruber Bernd Oberwinkler Michael Lasnik Florian Grün Low-Cycle Fatigue Behavior of Wire and Arc Additively Manufactured Ti-6Al-4V Material Materials wire arc additive manufacturing low-cycle fatigue Ti-6Al-4V Ramberg–Osgood model Manson–Coffin–Basquin cyclic deformation |
title | Low-Cycle Fatigue Behavior of Wire and Arc Additively Manufactured Ti-6Al-4V Material |
title_full | Low-Cycle Fatigue Behavior of Wire and Arc Additively Manufactured Ti-6Al-4V Material |
title_fullStr | Low-Cycle Fatigue Behavior of Wire and Arc Additively Manufactured Ti-6Al-4V Material |
title_full_unstemmed | Low-Cycle Fatigue Behavior of Wire and Arc Additively Manufactured Ti-6Al-4V Material |
title_short | Low-Cycle Fatigue Behavior of Wire and Arc Additively Manufactured Ti-6Al-4V Material |
title_sort | low cycle fatigue behavior of wire and arc additively manufactured ti 6al 4v material |
topic | wire arc additive manufacturing low-cycle fatigue Ti-6Al-4V Ramberg–Osgood model Manson–Coffin–Basquin cyclic deformation |
url | https://www.mdpi.com/1996-1944/16/18/6083 |
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