PRODUCTION OF SEAWATER CORROSION RESISTING STEEL FOR USE IN HIGH TEMPERATURE AND HIGH HUMIDITY ENVIRONMENT, EXCELLENT IN TOUGHNESS IN WELD HEAT-AFFECTED ZONE

摘要

PURPOSE: To produce a steel material excellent in seawater corrosion resistance as well as in toughness in a weld heat-affected zone by rolling a steel, containing specific amounts of C, Si, Mn, Al, Cr, Ti, N, and Fe, under specific conditions. ;CONSTITUTION: A steel, having a composition consisting of, by weight, ≤0.1% C, 0.1-0.8% Si, ≤1.5% Mn, 0.005-0.05% Al, 1-3% Cr, 0.005-0.03% Ti, 0.002-0.012% Ni, and the balance essentially Fe, is used. This steel is heated to 950-1250°C and rolled under the conditions of ≥30% cumulative rolling reduction at ≤950°C and 650-850°C rolling finishing temp. When the steel is heated to 1250°C, γ-grains become remarkably coarse. When cumulative rolling reduction is 30%, the elongation of γ-structure becomes insufficient and fine ferrite cannot be formed. When rolling finishing temp. is 850°C, fine ferrite grains cannot be formed, and on the other hand, when it is 650°C, rolling becomes that in two phase region and toughness at low temp. becomes deteriorated.;COPYRIGHT: (C)1996,JPO