An ultra-high strength bainitic aging steel

Bainite has been recognized to have both high strength and good toughness. Therefore, the isothermal quenching treatment at 220 ºC was applied to conventional maraging steel with ultra-low carbon content. It was found that the bainitic microstructure was successfully achieved by isothermal quenching treatment for this maraging steel. After aging at 500 ºC for 3 h, the tensile strength of such bainitic aging steel reached 2.2 GPa, the room temperature Charpy V-notch impact energy 15 J, and fatigue strength 775 MPa.