| 摘要 |
PROBLEM TO BE SOLVED: To provide a high strength H-shaped steel excellent in strength and toughness by air cooling while rolling. ! SOLUTION: There is provided a high strength H-shaped steel excellent in toughness containing, by mass%, C: 0.01% or more and less than 0.05%, Mn: 0.8 to 2.0%, S: 0.002 to 0.02%, Cu: 0.3 to 1.2%, Ni: 0.1 to 1.0%, Mg: 0.0005 to 0.005%, B: 0.0003 to 0.0030% and O: limited to 0.0035% or less and having an area ratio of bainite in a micro structure of 40 to 100%, an old austenite grain size at 1/2 position from a surface in a length direction of a flange and 3/4 position from the surface in a thickness direction in a steel material structure of 150 μm or less on average, (Mg, Mn)S having a particle diameter of 0.005 to 0.5 μm of 1.0×105 to 1.0×107/mm2 and a web thickness or a flange thickness of 40 to 150 nm. One or more of V, Mo, Cr, Zr, Hf, REM, and Ca can be contained. ! COPYRIGHT: (C)2015,JPO&INPIT |
