Fremgangsmåte for lasersveising av stålrör og innretning for gjennomföring av fremgangsmåten

摘要

A laser welded steel pipe having a weld zone containing a steel pipe containing 0.01 to 0.2 weight % C, 1 weight % or less S, 0.05 to 2 weight % Mn and 6 weight % or less Mn. The weld zone has a melted and solidified metal structure containing carbon and oxygen which satisfy the following equations:(carbon weight %)(oxygen weight %)/=0.02.A method for manufacturing a laser-welded steel pipe including producing an open pipe made from a hot-rolled steel strip with opposing edge portions facing each other by employing a formal roll, preheating the two edge portions, pressing the two edge portions to butt against each other by using squeeze rolls and welding the butted edge portions by irradiation with a laser beam to heat and melt the two edge portions.