Experimental and theoretical characterization of deep penetration welding threshold induced by 1-μm laser

- The experiment shows that P/d is more suitable than P/S for characterizing the DPWT.
- The evaporation of the molten pool is produced during thermal conduction welding.
- The total intensity of plume's spectra has a transition with the change of welding mode.
- The self-focusing of molten pool facilitates the change of welding mode.
- The theoretical analysis further confirmed the experimental results.