Microstructure and mechanical properties of dissimilar welded joints of Inconel 718 alloy and 316L stainless steel thin sheets produced using ultrasonic vibration-assisted gas tungsten arc and fiber laser welding technologies

• Published in: Archives of Civil and Mechanical Engineering Vol. 25; no. 4; p. 192
• Main Authors: Tu, Hao, Xie, Weifeng, Nian, Keyu, Fu, Rui, Zhang, Xiaobin
• Format: Journal Article
• Language: English
• Published: London Springer London 05.06.2025; Springer Nature B.V
• Subjects: Alloys; Austenitic stainless steel; Austenitic stainless steels; Butt joints; Butt welding; Civil Engineering; Comparative studies; Cooling; Crack initiation; Crystal defects; Dissimilar material joining; Dissimilar metals; Electric vehicles; Engineering; Fiber lasers; Friction stir welding; Gas tungsten arc welding; Grain boundaries; Grain size; Laser beam welding; Lasers; Mechanical Engineering; Mechanical properties; Metal sheets; Metals; Microstructural analysis; Microstructure; Molybdenum; Nickel alloys; Nickel base alloys; Original Article; Stainless steel; Structural Materials; Superalloys; Tensile strength; Ultimate tensile strength; Ultrasonic imaging; Ultrasonic vibration; Welded joints; Mechanical properties; UV-GTA welding; Microstructure; Laser welding; Dissimilar metals
• ISSN: 2083-3318; 1644-9665; 2083-3318
• DOI: 10.1007/s43452-025-01248-w

The increasing demand for lightweight electric vehicles necessitates reliable dissimilar joints between materials, yet systematic comparative studies on arc and laser welding of thin-sheet welded joints remain insufficient. This present study delved into the analysis of microstructure and mechanical properties of butt welded joints of Inconel 718 alloys and 316L stainless steel sheets by ultrasonic vibration-assisted gas tungsten arc (UV-GTA) and fiber laser welding, respectively. The results indicated that with an increase in ultrasonic power during UV-GTA welding, the area of the weld zone (WZ) decreased, and the ultrasonic vibration can also more effectively suppress the occurrence of concave defects in welded joints to a certain extent. However, for the UV-GTA joint with an ultrasonic power of 140W, the proportion of low-angle grain boundaries (LAGBs) in the weld center reached 25.5%, and its average grain size at the center of this weld was also only 40.7 μm. Both of these values were the smallest among all UV-GTA joints, and this refined grain, which was 24% smaller than the 53.3 μm grains observed in laser-welded joints. In addition, at this ultrasonic power level, the UV-GTA-welded joints exhibited the highest average hardness of 232.3 HV. In terms of ultimate tensile strength (UTS), the UTS of the laser-welded joints reached 321 MPa, while the UTS of the UV-GTA-welded joints increased significantly by 118% to 700 MPa, which has reached 84% of the Inconel 718 alloy. These findings highlighted a considerable potential of the UV-GTA welding method as a cost-efficient alternative to laser welding for joining of thin dissimilar metal sheets.