Study of CO2 laser welding to suppress the defects in thick steel plates welding bead

Probability characteristics of welding defects occurrence of thick steel plate, such as porosity and solidification cracks, have been investigated as functions of laser power and welding speed. The welding defects tend to be suppressed by increasing laser power and by decreasing welding speed. Sound bead, satisfying ISO13919-B level, is achieved when the penetration depth performance is set at about 120% of the welded sample thickness. Welding characteristics at various orientations, such as down-hand, overhead, vertically upward, have been investigated. Defects inclusion characteristics can be described by the aforementioned penetration condition at each welding orientation. These results will be useful for many fields of heavy-duty laser welding applications such like joint welding of pipeline construction.