Effect of wobble parameters on microwelding bead formation of AISI 316L stainless steel

Abstract

This study examines the impact of wobble movement on a laser beam’s behavior while moving over an AISI 316L stainless steel sample of 1.2 mm thickness during welding. The laser beam oscillatory movement is superimposed on linear movement, using a 400 W fiber laser installed on an experimental bench equipped with a scanner and worktable. Mathematical modeling estimates instantaneous beam speed values, predicting thermal influence on weld bead aspects. Microwelding experiments use autogenous processing with lateral beam oscillation. Two forms of overlapping transverse wobble are tested: one with a circular path and the other describing the mathematical symbol “infinity.” Correlations are evidenced between the input parameters and results obtained in the microwelds, including penetration and width of the beads. Results show that the frequency of movement in a circle and in “infinity” for frequencies from 200 to 400 Hz has no significant influence on the result. Increasing the amplitude of the wobble movement from 0.5 to 2 mm significantly influences the width and depth of the strands generated. The wobble technique is effective in preventing discontinuities in the process, such as porosities. A bead obtained with 300 W, 50 mm/s, 0.5 mm overlapping wobble movement, and 300 Hz circular rotation frequency showed the highest relationship between width and depth.