Heat-Conduction-Type and Keyhole-Type Laser Welding of Ti–Ni Shape-Memory Alloys Processed by Spark-Plasma Sintering

Bahador, Abdollah and Hamzah, Esah and Kondoh, Katsuyoshi and Tsutsumi, Seiichiro and Umeda, Junko and Abu Bakar, Tuty Asma and Yusof, Farazila (2018) Heat-Conduction-Type and Keyhole-Type Laser Welding of Ti–Ni Shape-Memory Alloys Processed by Spark-Plasma Sintering. Materials transactions, 59 (5). pp. 835-842. ISSN 1347-5320

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Official URL: https://doi.org/10.2320/matertrans.M2017387

Abstract

High-brightness and high-power laser welding with different welding speeds and laser powers was applied to join Ti51 at%Ni shape-memory alloy, which was fabricated from the elemental pure Ti and pure Ni powders by spark-plasma sintering. Dendritic microstructures were observed in all the welds except the heat-conduction-type weld with the minimum welding parameters. In addition, the weld seam consisted of equiaxial grains surrounded by a narrow dendritic region. Based on the micro-X-ray diffraction pattern, in the keyhole-type welding, the martensite phase declined on increasing laser power and welding speed. Abnormal peak intensities were detected for (211) in the heat-conduction weld and (200) in the keyhole weld. Differential scanning calorimetry results revealed that phase transformation peaks of the conduction-type weld seam were similar to the base metal of Ti51 at%Ni SMA, whereas the corresponding peaks of the phase transformation in the other weld seams shifted towards lower temperatures due to Ni depletion in the matrix, grain coarsening and residual stress. Therefore, the findings suggest that heat-conduction-type can be a promising method for surface treatment of TiNi SMAs with minimum effect on the microstructure and shape memory properties.

Item Type: Article
Uncontrolled Keywords: shape-memory alloys; spark-plasma sintering; heat-conduction-type welding; keyhole-type welding
Subjects: T Technology > TJ Mechanical engineering and machinery
Divisions: Faculty of Engineering
Depositing User: Ms. Juhaida Abd Rahim
Date Deposited: 17 Sep 2019 06:41
Last Modified: 17 Sep 2019 06:41
URI: http://eprints.um.edu.my/id/eprint/22374

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