Multi-pass narrow-gap (MPNG) laser welding process for the low-distortion and hot-crack-free joining of thick plates made of aluminium alloys

With the multi-pass narrow-gap laser welding process, aluminium plates can be welded with a very low laser beam power (less than 3 kW) down to a depth of 50 mm with low distortion. It could be shown that lack of fusion can be prevented and the number of pores in the weld metal reduced to a minimum. For the first time, this makes it possible to generate very deep aluminium welds in conformity with the applicable quality standards with a moderate laser beam power.