Patent ID: 7157672
Filing Date: 2007-01-02
Classification: B21C,Y10T

Abstract:
1. A method of manufacturing a heavy walled welded pipe formed of corrosion/erosion resistant stainless steel, the method comprising the steps of: providing as a starting material a selected one of a finished plate or coil, the selected plate or coil being formed of a corrosion/erosion resistant metal which is itself selected from the group consisting of stainless steels of the chromium, molybdenum and carbon families and mixtures thereof; passing the starting material through a continuous high speed forming mill to produce a formed body having a longitudinal seam region and a wall thickness; welding the formed body along the longitudinal seam region to achieve an autogenous electric resistance weld with induction high frequency welder to thereby produce a welded pipe; wherein the starting material is selected from a corrosion/erosion resistant stainless steel characterized as having less than about 0.080% maximum content by weight carbon and from about 10.5 to 14% content by weight chromium; wherein the corrosion/erosion resistant stainless steel is a low carbon dual phase (ferrite plus martensite) stainless steel; and wherein the corrosion/erosion resistant stainless steel starting material has a specifically defined microstructure as determined by the Kaltenhauser Factor's formula: where Km=the Kaltenhauser Factor; and wherein Km is in the range of 8 to 10.7.