Deep penetration laser welding of austenitic stainless steel thick-plates using a 20 kW fiber laser

The deep penetration laser welding of a thick section of austenitic stainless steel by a 20 kW laser is systematically evaluated. The welding phenomena of bead-on-plate and butt-welding of 20 and 30 mm thick steel plates are examined. The results show that the penetration depth of bead-on-plate welding can reach 32 mm and that wide processing windows exist to obtain defect-free butt-welding of 20 mm thick plates, but not for 30 mm thick plates. When the welding position is changed from a flat welding position (1G) to a horizontal welding position (2G), butt-welding of 30 mm thick plates can be penetrated successfully to obtain defect-free welds. The weld joint maintains the full austenite microstructure, which is composed of mostly directional columnar and cellular grains, while there are some equiaxed grains at the weld center.