550 and 610 MPa Class High-strength Steel Plates with Excellent Toughness for Tanks and Penstocks Produced Using Carbide Morphology Controlling Technology

JFE Steel has developed 550 and 610 MPa class high strength steel plates with superior toughness and excellent weldability produced by JFE Steel's latest on-line heat-treatment technology. Excellent properties of the plates and their weldments are obtained by micro-alloving technology, and direct-quenching and on-line tempering process using Super-OLAC® (On-Line Accelerated Cooling) and HOP® (Heat-treatment On-line Process), while including low C, low weld cracking parameter (P CM ) value and free of B additive. Especially, rapid heating and tempering using on-line HOP temper process achieved both improvement of toughness and the extension of heat treated high-performance steel plates' production capacity. They have actual application results to many plants.