The Study of Laser-Acoustic Method of Spot Heating of Thin Sheet of AISI 316L Steel

Abstract—A laser-acoustic method of spot heating of thin-sheet AISI 316L steel is presented. Using 3D printing, a special snap-in for carrying out experiments with and without the application of ultrasonic vibrations with a frequency of 40 kHz and a power of 100 W is developed. The quality of the obtained weld spots is analyzed. A defect of the burn-through type in weld spots obtained using the laser-acoustic method is detected. The influence of ultrasonic vibrations on the geometry of the melt bath is shown. It is found that, owing to the intensification of flows in the melt bath, the melting trough depth increases with the introduction of ultrasonic vibrations. A comparative analysis of the surface area of the weld spots is carried out using a semiautomatic method. The formation of microstructure during spot heating is investigated. It is shown that ultrasonic impact provides a fine-grained structure tending towards a globular shape.