Ultrasonic-assisted laser welding on AISI 321 stainless steel

• Published in: Welding in the world 2019-05, Vol.63 (3), p.875-886
• Main Authors: Tarasov, S. Yu, Vorontsov, A. V., Fortuna, S. V., Rubtsov, V. E., Krasnoveikin, V. A., Kolubaev, E. A.
• Format: Article
• Language: English
• Subjects: Austenitic stainless steels; Base metal; Chemistry and Materials Science; Dislocations; Finite element method; Laser beam welding; Lasers; Materials Science; Metallic Materials; Microhardness; Microstructure; Research Paper; Solid Mechanics; Stainless steel; Tensile strength; Theoretical and Applied Mechanics; Waveguides; Weld metal; Welded joints; Workpieces
• ISSN: 0043-2288; 1878-6669
• DOI: 10.1007/s40194-019-00716-1

Ultrasonic-assisted laser welding on 321 stainless steel has been carried out to find out the effect of ultrasonic energy input on the microstructure and strength of the weld metal. Ultrasonic energy was transmitted from a transducer, via two waveguides and hard alloy indenter fixed perpendicularly on the workpiece surface. Real-time ultrasonic oscillation amplitude distributions over the workpiece surface and in the bulk of the workpiece have been obtained using the laser Doppler vibrometry and finite element simulation which allowed estimating the close to reality ultrasonic energy input values. The real energy input was at least two orders of magnitude less than that calculated from the nominal ultrasonic source power. The welded joints have been characterized for microstructure, microhardness, and tensile strength. It was shown using TEM that higher microhardness of the sonicated welded joint is due to high concentration of split dislocations induced by ultrasonics. The tensile strength of the ultrasonic-assisted-welded joint depended on the ultrasonic energy input and was higher than that of the base metal in case of sonication by 600 W output power.