1：Experimental Design and Method Selection:

Laser welding experiments were conducted using a single-mode fiber laser source with high-speed X-ray radiography combined with AE measurements. Four categories of laser welding processes were defined based on X-ray imaging.

2：Sample Selection and Data Sources:

An aluminum-magnesium alloy was chosen for its relative low Z-number. Samples had dimensions 50 x 20 x 2 mm

3：List of Experimental Equipment and Materials:

StarFiber 150 P fiber laser, piezo acoustic sensor Pico, data acquisition unit and software from Vallen, high-speed X-ray imaging at the beamline ID19 of the ESRF.

4：Experimental Procedures and Operational Workflow:

The acoustic signals were recorded and synchronized with the video sequences from X-ray imaging. The signals were preprocessed using wavelet packet transform and analyzed using gradient boost with two learners: classifications and regression trees CART, and trees based on independent component analysis (ICA).

5：Data Analysis Methods:

The classification of the AE signals into the four predefined categories was performed using gradient boost with both ICA and CART.