High thickness Nd:YAG laser welding of construction steel

Abstract

Recent development of high power Nd:YAG CW laser and the possibility to easily couple such lasers through optical fibers on a focusing head offer today the possibility to dispose up to 8 kW power on parts to be manufactured. Such a power allows us to realize applications were the use of high power CO2 laser was initially considered; the main advantages of Nd:YAG laser versus CO2 Laser, being here the easiness of use of optical fibers, compared to the use of a CO2 laser with a gantry. The aim of this study is to study the weldability of carbon steel, under these conditions, with samples thickness greater than 12 mm, the final application being the welding of tubes (and more precisely the welding of pipe-tubes). This process is very difficult to achieve with a CO2 laser, due to the high complexity for realizing an Orbital Laser Welding Device. The availability of rather large Nd:YAG laser power allows us to realize the welding of a 13mm thickness tube in a maximum of 2 passes. This paper will present the main results we have obtained during this study. The effect of the main several operating parameters used during the root and the filling passes will be discussed in detail: They concern the welding and filler wire speeds and the geometry of the initial groove.Recent development of high power Nd:YAG CW laser and the possibility to easily couple such lasers through optical fibers on a focusing head offer today the possibility to dispose up to 8 kW power on parts to be manufactured. Such a power allows us to realize applications were the use of high power CO2 laser was initially considered; the main advantages of Nd:YAG laser versus CO2 Laser, being here the easiness of use of optical fibers, compared to the use of a CO2 laser with a gantry. The aim of this study is to study the weldability of carbon steel, under these conditions, with samples thickness greater than 12 mm, the final application being the welding of tubes (and more precisely the welding of pipe-tubes). This process is very difficult to achieve with a CO2 laser, due to the high complexity for realizing an Orbital Laser Welding Device. The availability of rather large Nd:YAG laser power allows us to realize the welding of a 13mm thickness tube in a maximum of 2 passes. This paper will present the ma...