Development of 780MPa Grade Steel Plate by Microstructural Control Containing M-A through the On-Line Heating Process

Abstract:

High strength steel plates with 780MPa in tensile strength, suitable for building construction use, have been developed. The steel plates provide excellent combination of high strength, toughness, deformability and weldability. The key technology to obtain the excellent combination in mechanical properties of the steel is the microstructural control of M-A (martensite-austenite constituent) and the bainitic ferrite dual-phase structure, through the on-line heat treatment immediately after the accelerated cooling in Thermo-mechanical control process (TMCP). The developed steel plates have microstructure of fine M-A dispersed in the bainitic ferrite matrix. Basic metallurgical research revealed that the transformation behavior and microstructural morphologies were varied with the cooling stop temperature before the on-line heating, and the on-line heating temperature itself. Trial production of the developed 780MPa grade steel plates was also carried out with the plate mill. The obtained plates showed the satisfactory combination of high strength, low yield ratio, toughness.

• Periodical: Materials Science Forum (Volumes 638-642)
• Pages: 3555-3560
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.638-642.3555
• Online since: January 2010
• Authors: Keiji Ueda, Shinichi Suzuki, Shinji Mitao, Nobuo Shikanai, Takayuki Ito
• Keywords: Dual Phase Microstructure, Martensite-Austenite Constituent (MA), Strength, Yield Ratio

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