| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a rolled H-section steel, which is excellent in toughness of a fillet, and has a YP of ≥325 MPa, and a method of advantageously manufacturing the same. <P>SOLUTION: A steel material of the rolled H-section steel has a component composition containing, by mass%, 0.01-0.20% C, 0.01-1.0% Si, 0.5-2.0% Mn, 0.030% or less P, 0.030% or less S and 0.003-0.1% Al, and containing one or two selected from 0.0001-0.01% Ca and 0.001-0.03% REM, and has carbon equivalent Ceq of 0.36-0.46 mass%. The steel material is subjected to preliminary heating treatment of heating the steel material for 1 to 50 hours at the temperature of 1,200 to 1,350°C and then cooling it to (Ar<SB POS="POST">3</SB>transformation point-100)°C or lower, then reheated to 1,200 to 1,350°C, and hot-rolled to the H-section steel, in which a ferrite average particle size of a fillet part is turned to 30 μm or smaller and an Mn segregation degree is turned to 1.7 or lower. <P>COPYRIGHT: (C)2012,JPO&INPIT |
