Nd:YAG laser welding of 60 mm thickness 316L parts using multiple passes

Abstract

The welding of very high thickness with a high level of quality is up to date still dedicated to conventional TIG welding with very slow welding speed, low level of deposition at every pass an of course a very important number of passes. The use of robotic system and Nd:Yag laser, combined with filler wire device allows to define a process rather similar to the TIG process but with a much better efficiency, higher level of deposition of material and higher welding speed. This multi-kilowatt process was tested for the welding of 60-mm thick parts. The achievement of the root pass welding, the firsts 20 mm, is not discussed here. We just consider in this study the problem of filling the upper 40 mm. Various welding conditions were tested (focused an unfocused beams), the efficiency of gas shield protection was measured, and finally the optimum parameters to get filling with seven passes were obtained. In position welding, vertical up at 45° was also tested. These are first trials in order to prepare final application, which will need welding from standard 1G position to on top position, with all intermediate positions.