| 摘要 |
PROBLEM TO BE SOLVED: To provide steel for a member with a steel-frame structure capable of attaining the increase of the toughness in the heat-treated parts as well as the strength therein by performing partial heat treatment to a member with a steel-frame structure in a construction site without performing special working such as a thickening process, to provide a method for using the steel for a member with a steel-frame structure, and to provide a steel-frame structure obtained by using the steel for a member with a steel-frame structure. SOLUTION: In the member 1 with a steel-frame structure having a composition comprising 0.04 to 0.18% C, 0.02 to 0.50% Si, 0.5 to 2.0% Mn,≤0.06% sol.Al, 0.003 to 0.030% Ti and≤0.008% N, and satisfying 2Nb+3Ti+Al:≥0.05%, and further having a weld cracking parameter (Pcm) of 0.12 to 0.27, the edge faces including dangerous cross-sections are partially subjected to heat treatment so as to be heated to≥800°C and to be cooled from 800 to 500°C at the average cooling rate of≥3°C/s, thus the heat-treated parts 4 are allowed to have a structure essentially composed of fine bainite giving the 0°C Charpy absorbed energy of≥70 J. COPYRIGHT: (C)2006,JPO&NCIPI
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