Patent ID: 6648209
Filing Date: 2003-11-18
Classification: C21D

Abstract:
A process for producing welded steel pipes by the UOE-process, comprising the steps of:providing a steel sheet having a composition by wt. % of 0.02 to 0.20% carbon, 0.05 to 0.50% silicon, 0.50 to 2.50% manganese, and 0.003 to 0.06% aluminum, up to 0.02% phosphorus, up to 0.06% titanium, up to 0.20% chromium, up to 0.50% molybdenum, up to 0.30% nickel, up to 0.10% niobium, up to 0.08% vanadium, up to 0.50% copper, up to 0.030% nitrogen, and up to 0.005% boron, the remainder being iron containing production-related impurities; cold-forming, welding and sizing the sheet to a desired diameter to thereby form a pipe; subjecting the pipe to a heat treatment at a temperature in the range of 100-300Â° C., while holding the pipe at that temperature for a time suited to a wall thickness of the pipe; and cooling the pipe with at least one of air cooling and forced cooling to thereby realize a finished steel pipe.