Influence of Cooling Process Routes after Intercritical Annealing on Impact Toughness of Duplex Type Medium Mn Steel

To apply the duplex type low-carbon medium-manganese steel to hot/warm-forging and -stamping products, influence of cooling process routes immediately after intercritical annealing such as air-cooling (AC) isothermal transformation (IT) processes on impact toughness 0.2%C-1.5%Si-5%Mn (in mass %) medium-Mn (D-MMn) was investigated. Moreover microstructural tensile properties were also The AC increased volume fraction reverted austenite but decreased thermal mechanical stability in D-MMn steel, compared IT process. strength total elongation. Charpy V-notch value ductile-brittle transition temperature deteriorated by process, This deterioration mainly related characteristics fracture mode.