PROBLEM TO BE SOLVED: To provide a steel for high heat input welding used for various structures of shipbuilding or the like, having excellent weld heat affected zone toughness by high heat input welding in which heat input exceeds 300 kJ/cm, and having a yield strength of ≥460 N/mm2.;SOLUTION: The steel has a componential composition containing, by mass, 0.03 to 0.1% C, 0.01 to 0.5% Si, 2.0 to 3.0 Mn, ≤0.02% P, ≤0.0050% S, 0.005 to 0.1% Al, 0.004 to 0.03% Ti, 0.01 to 0.05% Nb, 0.0003 to 0.0025% B and 0.0060 to 0.0100% N, and at needed, one or more selected from V, Cu, Ni, Cr, Mo, Ca, Mg, Zr and REM, and the balance Fe with inevitable impurities, and satisfying (Ti+0.5×Nb)/N≤3.40, wherein precipitates containing Ti, Nb and N with the grain size of 0.01 to 0.10 μm are present by 1.0×105 pieces/mm2 when heated to 1,400°C to the temperature of (a melting point-10°C).;COPYRIGHT: (C)2011,JPO&INPIT
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机译：解决的问题：提供一种用于造船业等各种结构的高热输入焊接用钢，其通过热输入超过300kJ / cm的高热输入焊接而具有优异的焊接热影响区韧性。强度：≥460N / mm 2 。;解决方案：该钢的成分组成按质量计为0.03至0.1％C，0.01至0.5％Si，2.0至3.0 Mn。 0.02％P，0.0050％S，0.005至0.1％Al，0.004至0.03％Ti，0.01至0.05％Nb，0.0003至0.0025％B和0.0060至0.0100％N，并在需要时从V中选择一种或多种，Cu，Ni，Cr，Mo，Ca，Mg，Zr和REM，余量的Fe具有不可避免的杂质，并满足（Ti + 0.5×Nb）/N≤3.40，其中，含Ti，Nb和N的析出物与当加热到1400°C至（熔点）温度时，晶粒尺寸为0.01至0.10μm的比例为1.0×10 5 个/ mm 2 -10°C）.;版权：（C）2011，JPO＆INPIT
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