Acoustic emission and optimized CO₂ laser welding of steel sheets Available to Purchase

Studies of spectrally resolved acoustic emission (AE) over the 0-20 kHz frequency range during a CO₂ laser welding of steel has been carried out to try to find the signature of optimized welding conditions. An analysis was performed using real-time fast Fourier Transform on the AE signal over the 6-17 kHz range. In the keyhole penetration welding mode, integrated acoustic emission is a strong function of welding speed at constant laser intensity and exhibits a minimum at some critical speed. Weldment cross-sections show that welding at the critical speed yields an optimum condition of penetration and small heat affected zone. This suggests that physical processes within the laser-generated keyhole are closely related to the emission of acoustic energy. Possible mechanisms for the generation of AE from the keyhole will be discussed.