Effects of Rotational Speed on the Microstructure and Mechanical Properties of 2198-T8 Al-Li Alloy Processed by Friction Spot Welding

• Published in: Materials Vol. 16; no. 5; p. 1807
• Main Authors: Pang, Zheng, Yang, Jin, Cai, Yangchuan
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 22-02-2023; MDPI
• Subjects: Alloys; aluminum-lithium alloy; Aluminum-lithium alloys; Comparative analysis; Dislocation density; Ductile fracture; Ductile-brittle transition; Fracture mechanics; Friction stir welding; Friction welding; Grain size; Grains; Mechanical properties; microstructure; rotational speed; Shear strain; Specialty metals industry; Spot welding; Tensile properties; Tensile strength; Welded joints; Welding; aluminum-lithium alloy; microstructure; friction stir welding; mechanical properties; rotational speed
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16051807

The friction spot welding (FSpW) method was used to weld 2198-T8 Al-Li alloy at rotational speeds of 500 rpm, 1000 rpm, and 1800 rpm. It was shown that the grains in the FSpW joints were transformed from "pancake" grains to fine equiaxed grains by the heat input of welding, and the reinforcing phases of S' and θ were all redissolved into the Al matrix. This leads to a decrease in the tensile strength of the FsPW joint compared to the base material and a change in the fracture mechanism from mixed ductile-brittle fracture to ductile fracture. Finally, the tensile properties of the welded joint depend on the size and morphology of the grains and their dislocation density. At the rotational speed setting of 1000 rpm in this paper, the mechanical properties of welded joints consisting of fine and uniformly distributed equiaxed grains are best. Therefore, a reasonable set of the rotational speed of FSpW can improve the mechanical properties of the welded joints of 2198-T8 Al-Li alloy.