Variable-parameter NiTi ultrasonic spot welding with Cu interlayer

ABSTRACT

NiTi thin sheets were ultrasonic spot welded with a Cu interlayer, where different welding vibration amplitudes were applied to study the influence on the surface and interface microstructural characteristics, phase transformation behavior and mechanical response of the joints, which aimed to enhance the joint performance by proper optimization of the process parameters. An excellent bonding interface was achieved when an optimized vibration amplitude was applied, with a recrystallized microstructure formed in the Cu foil side near the bonding interface, which helped to improve the mechanical performance of the joints. Joints made with vibration amplitude of 55 μm had an improved strength compared to the NiTi base material.

KEYWORDS:

• Ultrasonic
• welding
• NiTi
• interlayer
• parameter
• microstructure
• performance
• fracture

Acknowledgments

JPO acknowledges the Fundação para a Ciência e Tecnologia (FCT) for its support via the project UID/00667/2020 (UNIDEMI).

Additional information

Funding

This work was supported byThe Chinese Civil Aviation Administration [No. U1933129], The Chinese National Key Program [No.2018YFB1107900], Natural Science Foundation of Tianjin City [No. 18JCQNJC04100, No.19JCZDJC39000, and 19YFFCYS00090].