ROLLED H-SECTION STEEL HAVING SUPERIOR TOUGHNESS AT FILLET PART AND NO RESTRICTION IN INTERPASS TEMPERATURE IN MULTILAYER WELDING, AND MANUFACTURING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a rolled H-section steel having superior toughness at a fillet part and no restriction in an interpass temperature in multilayer welding.;SOLUTION: The rolled H-section steel has a composition comprising, by mass%, 0.01-0.20% C, 0.05-1.0% Si, 0.1-3.0% Mn, 0.05-1.6% Al, 0.030% or less P, 0.030% or less S, and such C and Al as to satisfy the following expressions (1) and (2): for the case of (%Al)≤0.8, 0.1-0.125×(%Al)≤(%C)≤0.09+0.13×(%Al) --- (1); and for the case of (%Al)0.8, -0.20+0.25×(%Al)≤(%C)≤0.09+0.13×(%Al) --- (2) (wherein (%M) is a content (mass %) of an element M); and has a steel structure comprising ferrite as a primary phase structure, and a bainitic structure and/or a martensitic structure as a secondary phase structure.;COPYRIGHT: (C)2004,JPO&NCIPI