Simulation and experimental study on the quality evaluation of laser welds based on ultrasonic test

An evaluating method for the laser weld quality of a stainless steel lap joint is studied herein, based on an ultrasonic testing simulation and an experimental study. A laser weld model is established for the simulation focusing on the analysis of the transient distribution of the acoustic waves and the A-scan signal during the ultrasonic test process. According to the simulation and the experimental study on the scanning process, particularly the scanning direction vertical to the weld, the weld centre is confirmed by the characteristic of the first echo from the bottom of the upper sheet, where an echo amplitude increase occurs. A mathematical model calculating the welding pool width is established based on the position of the weld centre. The results show that the mathematical model has a higher accuracy when the probe is located on the weld centre. The error of the mathematical model is within 0.05 mm, and the accuracy can completely meet the engineering application requirements.