HIGH-STRENGTH, HIGH-TOUGHNESS ROLLED SHAPE STEEL AND PRODUCTION METHOD THEREOF

摘要

A high-strength, high-toughness rolled shape steel of 590 Mpa class used for building structural members and a method of producing the high-tension rolled shape steel. The shape steel has mechanical characteristics including a tensile strength of 590 Mpa or higher, a yielding strength or a 0.2 % proof stress of 440 Mpa or higher and a Charpy impact absorption energy at 0 DEG C of 47 J or larger, all of which are obtained by microstructuring provided by higher strength of alloys to improve a quenching property and by fine dispersion of Ti oxides and TiN by the addition of Ti, by precipitation strengthening by the addition of Cu, and by fine bainite structuring by temperature-controlled rolling or cooling control.