MANUFACTURE OF WELDED STEEL STRUCTURE AND WELDED STEEL STRUCTURE

摘要

PROBLEM TO BE SOLVED: To obtain a steel structure of superior tenacity satisfying a specific index TSp as well as Al/O by carrying out a submerged arc welding with a usage of a steel base material having a specific tensile strength, a welding wire for high tensile steel of specific composition and a flux of specific basicity. ;SOLUTION: A steel base having a tensile strength 800-1,100 Mpa, a welding wire for high tensile steel containing, 0.005-0.2 wt.% Al, 0.02 wt.% or less O, and a high basicity flux, a basicity of which shown by a formula III is 1.0-3.0 are used so that an index TSp shown by a formula I is 800-1,000, and Al/O satisfies a formula II. Symbols of elements in the formula I and II represent percentage of each element contained in the steel (weight%), chemical formulas in the formula III represent percentage of chemical compound contained in a flux (weight%). Thus, a steel structure, especially a welded steel pipe is obtainable, wherein an acicular ferrite acts as a main phase of set-up by correctly controlling Al/O, a welding metal is of high strength and tenancy, and a tension strength is 800-1,100 Mpa.;COPYRIGHT: (C)1999,JPO