Microstructure and Phase Transformation Evolution in the SBHS500 Steel During TMCP Process

by Wei-Chih Chung, Tze-Ching Yang, Ching-Yuan Huang

Publisher - China Steel Corporation

Category - General Novel

The SBHS500 high-performance bridge steel plates produced by thermo-mechanical control process (TMCP) were developed in China Steel Corporation (CSC). This SBHS500 steel is designed as the low carbon bainitic (LCB) microstructure to satisfy the requirement of high yield strength, toughness and weldability. In this research, the TMCP thermal cycles of the SBHS500 steel with various accelerated cooling (ACC) rates and finish cooling temperatures were simulated in the quenching and deformation dilatometer to study the phase transformation evolution of the LCB steel. The result indicated that the lath and sheaf sizes of bainite would be refined using higher ACC rates. Also, the change of ACC finish cooling temperatures led to different morphologies of the micro-phases. The fully bainitic microstructure can be produced under the unique TMCP thermal cycles. The SBHS500 high-performance bridge steel plates were developed successfully by CSC.

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