热处理工艺对低温贝氏体钢力学及搅拌磨损性能的影响

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

设计了一步和两步低温贝氏体转变热处理工艺,讨论了不同热处理工艺对低温贝氏体显微组织、力学及搅拌磨损性能的影响。结果表明,不同低温贝氏体热处理工艺后试验钢组织均由微纳尺度的贝氏体板条和奥氏体组成。其中,一步低温工艺中随着温度由300℃降至250℃,贝氏体板条尺寸由95nm降至65nm,奥氏体体积分数也由28.1%减少至19.9%;两步低温贝氏体转变工艺可显著细化不稳定块状奥氏体,具有优良的强韧性匹配,抗拉强度达到1857MPa,伸长率和V型缺口冲击功分别达到10.59%和11J。与一步低温工艺（300、250℃）相比,两步低温贝氏体转变工艺的搅拌磨损性能分别提高了11.8%和31.4%,表现出了更优的搅拌磨损性能,这主要与其更优异的塑韧性有关。

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（1857 MPa）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 11 J.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.