| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for advantageously producing steel for weld structure, which has yield stress exceeding 390 MPa and has a weld heat-affected zone excellent in toughness even when large-heat input welding is performed with weld input heat exceeding 200 kJ/cm. <P>SOLUTION: A steel material is provided, which contains, by mass: 0.03-0.12% C; 0.02-0.22% Si; 1.4-2.5% Mn; ≤0.010% P; 0.0005-0.0040% S; 0.005-0.06% Al; 0.005-0.025% Ti; 0.0030-0.0070% N; and the balance Fe with inevitable impurities. After being held for 3-10 hours at a temperature where a two-phase area of ferrite and austenite exists with a ferrite area fraction of 30-70 vol% in an equilibrium state, the steel material is reheated and hot-rolled. <P>COPYRIGHT: (C)2013,JPO&INPIT |
