Characterization of CO2 and diode laser welding of high carbon steels

Abstract

Deep penetration welding with a high power CO2 and diode laser may offer an attractive means to join metal for certain applications, for instance: welding car drive shafts and gear plant. The rapid cooling rate of laser welding results in high hardness discontinuities across the welded joint; however, this leads to brittle weld and fatigue failure. To avoid this critical problem, it is useful to optimize the laser operating parameters in order to improve the mechanical properties of the weld. In this study, an experimental analysis was used to predict the significant effect of the weld quality using CO2 and high power diode laser (HPDL) laser welding, operating at 10.6 μm and 810 nm, respectively. Investigations into the weld quality were done to quantify the effect of different welding velocities by examining the hardness profiles, tensile strength, aspect, weld volume formation rate, and microstructure formation. In all cases, the results showed that for the HPDL weld configurations, cracking was observed in the fusion zone, whereas, for a CO2 laser weld, a greater weld strength and wider weld width were observed. For HPDL welding, center-line cracking was found along the fusion zone at higher welding velocities.