Patent ID: 6565682
Filing Date: 2003-05-20
Classification: C21D,C22C

Abstract:
A process for producing a high-strength heat-resistant pipe, the process comprising the steps of:normalizing a steel at a temperature in the range of 1100 to 1250Â° C., the steel comprising C in an amount of 0.06 to 0.15% by weight, Si in an amount of 1.5% by weight or less, Mn in an amount of 0.5 to 1.5% by weight, V in an amount of 0.05 to 0.3% by weight, and at least one of Nb, Ti, Ta, Hf, and Zr, in an amount of 0.01 to 0.1% by weight, the balance being Fe and unavoidable impurities, piercing the steel to produce a pierced product, and cooling the pierced product to room temperature or to a temperature lower than the temperature at which transformation to bainite is completed, wherein after the cooling the pierced product has microstructure consisting of bainite and at least one carbide of V, Nb, Ti, Ta, Hf or Zr.