PRODUCTION OF HIGH STRENGTH AND HIGH TOUGHNESS MARTENSITIC STAINLESS WELDED STEEL PIPE EXCELLENT IN CORROSION RESISTANCE

摘要

PURPOSE: To obtain a high strength stainless welded steel pipe having good corrosion resistance in a corrosive environment contg. chlorides, CO₂, and a trace amt. of H₂S and in the air and furthermore excellent in weldability, workability and ductility-toughness. ;CONSTITUTION: A welded steel pipe produced from a steel sheet having the following compsn. and in which the compsn. of weld metal is furthermore constituted of O≤0.035% is heated to the temp. range of 850 to 1000°C and is thereafter cooled to the temp. range of the M_f point or below at ≥3°C/min cooling rate: the compsn. contg., by weight, C≤0.03, Si≤1.0, Mn≤1.0, Cu:0.05/1.0, Ni:5.0/7.0, Cr:13.0/17.0, Mo≤2.0 and N≤0.02 and satisfying the inequalities of (1) to (3), and the balance Fe with inevitable impurities: C+N≤0.03-(1), 12×Cr+15×Mo+20×Si-9×Ni-2×Cu-190×C-160×N≤154-(2) and Cr+1.3×Mo+1.5×Si+2×Ni+0.7×Cu+68×C+54×N≥27.6-(3).;COPYRIGHT: (C)1995,JPO