Solidification characterization and its correlation with the mechanical properties and functional response of NiTi shape memory alloy manufactured by electron beam freeform fabrication

Li, Binqiang; Wang, Liang; Wang, Binbin; Li, Donghai; Cui, Ran; Su, Baoxian; Yao, Longhui; Luo, Laihui; Chen, Ruirun; Guo, Jingjie; Fu, Hengzhi

doi:10.1016/j.addma.2021.102468

Cited by 15 publications

(7 citation statements)

References 73 publications

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“…More recently, Xue et al [42] obtained tensile pseudoelasticity values up to 6% in the asbuilt state by tailoring process parameters and by a strict control of the oxygen content within the building chamber. We also note that other additive manufacturing technologies applied to NiTi have shown promising tensile properties, such as Electron Beam Freeform [43] and Wire Arc Manufacturing [44].…”

Section: Introductionmentioning

confidence: 85%

Building Orientation and Heat Treatments Effect on the Pseudoelastic Properties of NiTi Produced by LPBF

Carlucci

Patriarca

Demir

et al. 2022

Shap. Mem. Superelasticity

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NiTi dominates the market of shape memory materials due to its optimal combination of mechanical, functional, and biocompatibility properties, which enabled its use for several applications, in particular for the biomedical and the aerospace sectors. However, due to its poor machinability, NiTi is a challenging material from the manufacturing standpoint. Therefore, in the last years, researchers have focused on the production of NiTi components by additive manufacturing processes, which also enable the manufacturing of complex shape parts that cannot be produced with conventional methods. The aim of this study is to provide insights on the optimization of the functional performances of NiTi produced by Laser Powder Bed Fusion, leveraging on the building orientation and post-processing heat treatments. Uniaxial mechanical tests have been performed in tension and compression, and the influence of heat treatments and building orientation on the mechanical behavior of pseudoelastic NiTi has been evaluated. Different heat treatment schedules have been evaluated, leading to transformation strains up to 2.7% in tension and 4.6% in compression. This study confirms that Laser Powder Bed Fusion is a promising additive manufacturing technology for the production of net-shape and near defect-free NiTi components, exhibiting remarkable functional properties.

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Section: Introductionmentioning

confidence: 85%

Building Orientation and Heat Treatments Effect on the Pseudoelastic Properties of NiTi Produced by LPBF

Carlucci

Patriarca

Demir

et al. 2022

Shap. Mem. Superelasticity

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“…These techniques are wire-arc additive manufacturing 10,11 and electron beam freeform fabrication (EBF3). [12][13][14][15][16][17][18] The first work on EBF3 of NiTi was published by Dutkiewicz et al 12 The authors compared the physical properties, microstructural features and superelastic behaviour of Ni50.97Ti (at. %) NiTi alloy fabricated by both EBF3 and laser-engineered net shape (LENS).…”

Section: Introductionmentioning

confidence: 99%

“…The authors showed better superelastic compression behaviour of the LENS samples compared to EBF3 in the as-built condition. In contrast, the EBF3 samples presented higher superelastic recovery after ageing at 500 °C for 2 h. Li et al 13 produced wall-structured parts with Ni50.7Ti depositing it over a commercially pure Ti plate, an alternative to reduce the use of expensive NiTi substrates. A stable region composed of austenite was formed above the transition Ti-NiTi layer.…”

Section: Introductionmentioning

confidence: 99%

“…19,20 These microstructural characteristics have implications on the strain recovery, as well as on the phase TTs. 13,18,21 Apart from the work of Dutkiewicz et al 12 and Pu et al, 14 there is not enough information in the literature about the impact of the post-heat treatment on the compressive superelastic behaviour of EBF3-fabricated parts.…”

Section: Introductionmentioning

confidence: 99%

“…These techniques are wire-arc additive manufacturing 10,11 and electron beam freeform fabrication (EBF3). 12–18…”

Section: Introductionmentioning

confidence: 99%

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The electron beam freeform fabrication of NiTi shape memory alloys. Part II: Influence of the heat treatment on the superelastic behaviour

Guimarães,

Rauchdobler,

Pixner

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part L:

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In a previous study (part I), the deposition of functional single-track and multi-layer Ni-rich NiTi using the electron beam freeform fabrication (EBF3) technique was demonstrated. The processed microstructure consists of columnar millimetre range grains that grow parallel to the build direction. Based on the same parameters of part I, this work successfully deposited a stable multi-track and multi-layer NiTi block. Different heat treatments were applied to modify the superelastic properties of the deposited material. Initially, the solution treatment reduces the chemical inhomogeneity and the thermal stresses that originated during the deposition and cooling. Subsequently, due to ageing, Ni4Ti3 particles precipitate at 350 °C and 450 °C for 1, 6 and 12 h, modified the superelastic behaviour of the deposited NiTi. The differential scanning calorimetry results did not reveal any difference in the martensitic starting temperature between as-built and solution-treated samples. However, a remarkable influence of the ageing temperature was detected: while ageing at 350 °C impacted R-phase starting temperatures, 450 °C altered the martensitic starting one. The superelastic behaviour was evaluated by cycling compression. As-built and solution heat-treated samples presented poor mechanical performance, with about 40% of strain recovered after 10 cycles. The ageing at 350 °C for 1 h led to a maximum measured strain recovery of 72.5% after 10 uniaxial compression cycles up to 860 MPa. This condition also resulted in 3.3% permanent deformation out of 11.3% of the total. This study addressed for the first time the fabrication by the EBF3 technique of a stable multi-track and multi-layer NiTi block besides the importance of heat treating it, demonstrating that this post-treatment improves the superelastic performance of EBF3 fabricated parts.

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Review on Fatigue of Additive Manufactured Metallic Alloys: Microstructure, Performance, Enhancement, and Assessment Methods

Liu,

Yu,

Guo

et al. 2023

Advanced Materials

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Additive manufacturing (AM), which is a process of building objects in a layer‐upon‐layer fashion from designed models, has received unprecedented attention from research and industry because it offers outstanding merits of flexibility, customization, reduced buy‐to‐fly ratio, and cost‐effectiveness. However, the fatigue performance of safety‐critical industrial components fabricated by AM is still far below that obtained from conventional methods. This review discusses the microstructural heterogeneities, randomly dispersed defects, poor surface quality, and complex residual stress generated during the AM process that can negatively impact the fatigue performance of as‐printed parts. The difference in microstructural origin of fatigue failure between conventionally manufactured and printed metals is reviewed with particular attention to the effects of the trans‐scale microstructures on AM fatigue failure mechanisms. Various methods for mitigating the fatigue issue, including pre‐process, inter‐process and post‐process treatments, are illustrated. Empirical, semi‐empirical and microstructure‐sensitive models are presented to predict fatigue strength and lifetime. Summary and outlooks for future development of the fatigue performance of AM materials are provided.This article is protected by copyright. All rights reserved

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Solidification characterization and its correlation with the mechanical properties and functional response of NiTi shape memory alloy manufactured by electron beam freeform fabrication

Cited by 15 publications

References 73 publications

Building Orientation and Heat Treatments Effect on the Pseudoelastic Properties of NiTi Produced by LPBF

Building Orientation and Heat Treatments Effect on the Pseudoelastic Properties of NiTi Produced by LPBF

The electron beam freeform fabrication of NiTi shape memory alloys. Part II: Influence of the heat treatment on the superelastic behaviour

Review on Fatigue of Additive Manufactured Metallic Alloys: Microstructure, Performance, Enhancement, and Assessment Methods

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