Effect of laser welding parameters on the weld morphology and microstructure of stainless steel joints

Laser welding has been widely used in the joining of metal materials due to its advantages of high efficiency, precision, and a small heat-affected zone. This paper investigates the effects of different laser welding parameters on the weld joints of steel plates, focusing on the influence of oscillation mode, oscillation frequency, oscillation amplitude, and laser power on the weld morphology and the microstructure of the heat-affected zone. Experimental results show that as the oscillation frequency increases, the weld gradually narrows; as the oscillation amplitude increases, the weld gradually widens; however, in the “↕” mode, increasing the oscillation amplitude narrows the weld instead. Low oscillation frequency helps to improve the flatness of the weld surface. In the “○” oscillation mode, an increase in laser power widens the weld. The optimal welding conditions occur at an oscillation frequency of 150 Hz, an oscillation amplitude of 1.5 mm, and a laser power of 900 W, where the weld surface is the flattest under the “↔” mode. Analysis of the microstructure using a metallurgical microscope shows that different parameters significantly affect the grain size and the heat-affected zone characteristics of the weld joint. The research results provide a theoretical basis for optimizing the laser welding process of 304 stainless steel.