780N/mm² Grade Steel with a Decrement of Yield Ratio Produced through Heat-treatment On-line Process and its Local buckling Performance as a Structural member

Abstract

780N/mm² Grade strength steel plates designed for earthquake-proof buildings have been developed. They provide high strength, low yield ratio, weldability and excellent toughness in welded joints. Key technology to obtain an excellent combination of mechanical properties is microstructural control of M-A (Martensite-Austenite constituent) and granular bainitic ferrite dual-phase structure through HOP (Heat-treatment On-line Process) immediately after an accelerated cooling in TMCP(Thermo-Mechanical Control Process). The developed steel plates have shown satisfactory performance for local buckling.