Patent ID: 8021502
Filing Date: 2011-09-20
Classification: C21D

Abstract:
1. A method for producing a high-strength martensitic stainless steel pipe which comprises: heating the steel pipe, which is made by use of the martensitic steel, having a chemical composition comprising by mass percent, C: 0.18 to 0.22%, Si: 0.1 to 0.5%, Mn: 0.40 to 1.00%, P: 0.011 to 0.018%, S: 0.003% or less, Cr: 11.50 to 13.50%, Ni: 0.5% or less, Al: 0.0005 to 0.003%, N: 0.012 to 0.040%, Cu: 0.25% or less, Ti: 0.05% or less, V: 0.02 to 0.18%, Mo: 0 to 0.05%, Nb: 0 to 0.009%, B: 0.0010% or less, and Ca: 0.0050% or less, with the balance being Fe and impurities, as the material and cooled to room temperature by atmospheric cooling or air cooling, at a temperature T then cooling the steel pipe from the temperature T successively cooling the steel pipe from the temperature T performing a bend straightening treatment at a straightener outlet temperature of 510 degrees C. or higher successively to tempering treatment at 610 to 750 degrees C.