PROCESS FOR PRODUCING LARGE DIAMETER, HIGH STRENGTH, CORROSION-RESISTANT WELDED PIPE AND PIPE MADE THEREBY

摘要

A method of roll-forming sheet or plate into a round hollow, welding the round hollow with a welding alloy that matches the alloy of the round hollow to form a welded pipe, annealing the welded pipe at a minimum of 1950°F to provide a carbide-free microstructure, ultrasonic inspecting to assure sound welds, and cold-working the annealed and inspected pipe via drawing or pilgering to the desired tensile strength. The compositional range alloys suitable for use in the method of the present invention in weight % is: 25.0-65.0% Ni, 15.0-30.0% Cr, 0-18.0% Mo, 2.5-48.0% Fe, 0-5.0% Cu, 0-5.0% Mn, 0-5.0% Nb, 0-2.0 Ti, 0-5.0% W, 0-1.0% Si, and 0.005-0.1% C. The process has been most preferably optimized for an alloy range consisting of 32.0-46% Ni, 19.5-28.0% Cr, 18.0-40.0% Fe, 3.0-8.0% Mo, 1.0-3.0%Cu, 0.6-1.2% Ti, 0.5-2.0% Mn, 0.1-0.5% Si, 0.01-0.08% C. The present invention also includes the pipe made thereby.