Abstract: A high manganese steel with high strength and impact absorbed energy was obtained by Nb-alloying, and its microstructure evolution and properties under different water toughening temperatures and time were studied to explore the best water toughening condition. The results show that with the increase of water toughening temperature or time, the carbides in the steel are dissolved in the austenite matrix constantly, while the grains are growing, and the strength and impact absorbed energy of the steel increase firstly and then decrease. When the water toughening temperature is 1100 ℃ and the time is 1.5 h, the strength and impact absorbed energy of the steel reaches the peak value, as the tensile strength, yield strength, elongation, impact absorbed energy and hardness are 957.7 MPa, 415.3 MPa, 57.2%, 298 J and 222 HBW, respectively, showing the optimum mechanical properties.

Key words: Nb-alloying, water toughening, high manganese steel, impact absorbed energy, austenite