| 摘要 |
PROBLEM TO BE SOLVED: To provide steel for building structures which has high plastic deformation capacity and can yield high joint performance even when short bead welding is performed or interpass temperature is made high and to provide a production method therefor. SOLUTION: The steel has a composition containing, by mass, 0.01 to 0.07% C, <=0.6% Si, 0.6 to 1.6% Mn, <=0.030% P, <=0.030% S, <=0.1% Al, 0.005 to 0.05% Nb, 0.003 to 0.020% Ti, 0.0010 to 0.0030% B and 0.0030 to 0.0070% N, and the balance Fe with inevitable impurities, and satisfying the inequalities (1) and (2), and also has a yield ratio of <=72%: 1.0<=Ti/N<=3.0 (1), and 0.0005<=B-0.785(N-Ti/3.4)<=0.0025 (2).
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