Hybrid laser Arc Welding for The Production of Longitudinally Welded Pipes

The aim of the present work is to investigate the possibilities of the hybrid laser arc welding regarding the reliable and cost effective production of longitudinal welds on the high strength pipeline steels X80 and X120 and to evaluate the achievable mechanical properties of the laser hybrid welds. The study focused on the investigations of the weld seam toughness in the low temperature range (-60 °C and -40 °C). Suitable filler materials have been identified in the context of this task. It could be shown that the metal powder filler wires, micro alloyed with Ni and partly with Cr and Mo, guaranteed sufficient Charpy impact toughness at low temperature for the both investigated materials (average value 190 J for X80 at -60 °C and 53 J for X120 at -40 °C). The modern arc technologies such as modified pulsed spray arc have been used to promote the deeper penetration of the filler material in the narrow laser weld. The edge preparation with a root face of 14 mm has been proposed as optimum, because no penetration of the filler material could be detected over this depth limit and therefor any metallurgical influences on the properties of the weld metal through the welding wire are not possible.