Laser-welded steel pipe

Abstract

A laser-welded steel pipe includes: a steel pipe consisting essentially of C in an amount of 0.01 to 0.5 wt. %, Si in an amount of 1 wt. % or less, Mn in an amount of 0.05 to 2 wt. % and Cr in an amount of 6 wt. % or less; and a weld zone having a melted and solidified metal structure containing carbon and oxygen. The carbon content, ›C wt. %!, and the oxygen content, ›O wt. %!, in the melted and solidified metal structure satisfies the following equations: ›C wt. %!.times.›O wt. %!.ltoreq.0.006, for the steel pipe containing C in an amount of less than 0.2 wt. %, ›O wt. %!.ltoreq.0.03, for the steel pipe containing C in an amount of 0.2 wt. % or more.

Dependencies are inferred from the claim text.