Effect of ultrasonic spot welding on the mechanical behaviour of NiTi shape memory alloys

Zhang, Wei; Ao, Sansan; Oliveira, J.P.; Zeng, Zhi; Luo, Zhen; Hao, Zhitao

doi:10.1088/1361-665x/aacfeb

Cited by 27 publications

(15 citation statements)

References 23 publications

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“…Both properties occur due to a thermodynamic and crystallographic reversible martensitic transformation [2]. Although NiTi SMA research has taken place for nearly six decades now, and has been implemented in several applications, SMAs applications are still limited to simple geometries processed by laser [3][4][5], Tungsten Inert Gas (TIG) [6], electrical resistance [7] or ultrasounds [8].…”

Section: Introductionmentioning

confidence: 99%

Wire and arc additive manufacturing of a Ni-rich NiTi shape memory alloy: Microstructure and mechanical properties

Zeng

Cong

Oliveira

et al. 2020

Additive Manufacturing

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Wire and Arc Additive Manufacturing (WAAM) was used for fabrication of NiTi parts using a commercialy available Ni-rich NiTi wire as the feedstock material. The as-built parts are near fully austenitic at room temperature as confirmed by differential scanning calorimetry, X-ray diffraction and superelastic cycling. The as-built microstructure changed from collumnar, in the first deposited layers, to equiaxed in the last deposited ones as a result of the different thermal cycle conditions. This is the 2 first work where WAAM NiTi parts exhibit superelastic behavior under tensile conditions, highlighting the potential use of the technique for the creation of parts shaped in a complex manner based on this material and process. The potential to use WAAM for deposition of advanced functional materials is demonstrated.

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Section: Introductionmentioning

confidence: 99%

Wire and arc additive manufacturing of a Ni-rich NiTi shape memory alloy: Microstructure and mechanical properties

Zeng

Cong

Oliveira

et al. 2020

Additive Manufacturing

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“…It further indicates that the weld joint with welding energy of 1000 J has the good load capacity, which can be used in distinct engineering fields. Furthermore, the use of the Cu interlayer can improve the mechanical properties of the welded joint: when no Cu interlayer is used the fracture load of the 1000 J weld is of approximately 200 N [ 45 ], which is significantly lower than the 520 N obtained when the Cu interlayer was used.…”

Section: Resultsmentioning

confidence: 99%

Microstructural Characterization and Mechanical Behavior of NiTi Shape Memory Alloys Ultrasonic Joints Using Cu Interlayer

Zhang

Oliveira

et al. 2018

Materials

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NiTi shape memory alloys (SMAs) are a class of functional materials which can be significantly deformed and recover their original shape via a reversible martensitic phase transformation. Developing effective joining techniques can expand the application of SMAs in the medical and engineering fields. In this study, ultrasonic spot welding (USW), a solid-state joining technique, was used to join NiTi sheets using a Cu interlayer in between the two joining sheets. The influence of USW process on the microstructural characteristics and mechanical behavior of the NiTi joints was investigated. Compared with conventional fusion welding techniques, no intermetallic compounds formed in the joints, which is extreme importance for this particular class of alloys. The joining mechanisms involve a combination of shear plastic deformation, mechanical interlocking and formation of micro-welds. A better bonding interface was obtained with higher welding energy levels, which contributed to a higher tensile load. An interfacial fracture mode occurred and the fracture surfaces exhibited both brittle and ductile-like characteristics with the existence of tear ridges and dimples. The fracture initiated at the weak region of the joint border and then propagated through it, leading to tearing of Cu foil at the fracture interface.

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“…Furthermore, a large number of intermetallic compounds are formed during fusion welding, which is difficult to control [5,6]. Conversely, the UMW process is simple and advantageous owing to its low dependence on materials [7,8], and because it allows wide welds in a short period by minimizing the formation of the intermetallic compounds and energy loss at the contact part [9,10]. Therefore, this process has gained widespread interest as a suitable technology for battery cell welding.…”

Section: Introductionmentioning

confidence: 99%

Ultrasonic Metal Welding of Multilayered Copper Foils to Nickel-Plated Copper Sheet in Lithium-Ion Battery Cell

Shin¹,

Nam

et al. 2021

Metals

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The battery performance of electric vehicles depends on the density and capacity of the battery; thus, the battery cells must be assembled in as many layers as possible. Electric vehicle batteries are typically composed of several cells which form modules connected by busbars, with dozens of modules manufactured as battery packs. The ultrasonic metal welding (UMW) technology is applied to such multilayered foil welding. This study analyzed UMW to ensure the weldability of multilayered Cu foils and a Ni-plated Cu strip in lithium-ion battery cells through various approaches. In UMW, the effect of the alignment on weld production and quality were examined through the energy and mechanical performance of the weld by conducting comparative experiments on the alignment of the horn and anvil. Additionally, the effects of UMW process parameters, such as the welding pressure, amplitude, and welding time, were statistically analyzed. The weldability evaluation and characteristic analysis were performed based on these variables. Furthermore, the cross-sectional shapes and microstructure behavior of the Ni layers were analyzed based on the weld quality.

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Effect of ultrasonic spot welding on the mechanical behaviour of NiTi shape memory alloys

Cited by 27 publications

References 23 publications

Wire and arc additive manufacturing of a Ni-rich NiTi shape memory alloy: Microstructure and mechanical properties

Wire and arc additive manufacturing of a Ni-rich NiTi shape memory alloy: Microstructure and mechanical properties

Microstructural Characterization and Mechanical Behavior of NiTi Shape Memory Alloys Ultrasonic Joints Using Cu Interlayer

Ultrasonic Metal Welding of Multilayered Copper Foils to Nickel-Plated Copper Sheet in Lithium-Ion Battery Cell

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