STEEL FOR BUILDING USED AFTER THICKENING WORKING

摘要

PROBLEM TO BE SOLVED: To provide a steel for building, of which the thickening worked part has the same toughness as before being worked, without being subjected to post-heat treatment.;SOLUTION: The steel has a chemical composition comprising 0.001-0.25% C, 0.003-2.0% Si, 0.003-3.0% Mn, 0.005-2.0% sol.Al, 0.15% or less P, 0.020% or less S, 0.005% or less O (oxygen), 0.015% or less N, such Ti as to satisfy Ti/N=0.5-5.0, and the balance substantially Fe, and has a mean diameter of a microstructure unit in a principal phase of the structure in a size of 500 μm or less and an aspect ratio of 3 or less, in a state with no post-heat treatment.;COPYRIGHT: (C)2004,JPO