Effect of heat treatment on mechanical and stirring wear properties of low temperature bainite steels

One- step and two- step isothermal low temperature bainitic transformation were designed. The effects of heat treatments on the microstructures, mechanical properties and stirring wear resistance of low temperature bainite were discussed. The results show that the microstructures of samples under different heat treatments all consist of micro- and nano- scale bainite lath and austenite. The size of bainite lath decreases from 95 nm to 65 nm with the decrease of isothermal temperature from 300?? to 250?? under the one- step isothermal bainitic transformation. Moreover, the volume fraction of austenite likewise decreases from 28??1% to 19??9%. The unstable block austenite is apparently refined by the two- step isothermal bainitic transformation. The optimal balance between the tensile strength (1857MPa) and elongation (10??59%) is obtained in the sample treated by two- step isothermal bainitic transformation. Also, the V- notch impact absorbed energy of the sample treated by two- step isothermal bainitic transformation reaches 11J. Compared with the one- step isothermal bainitic transformation (300, 250??), the sample treated by two- step isothermal bainitic transformation shows the optimized wear resistance and increases by 11??8% and 31??4%, respectively, which is attributed to the better ductility and toughness.