TRIP780钢贝氏体区等温转变的规律

采用 DIL805L 型淬火膨胀仪测定了 C-Si-Mn 系 TRIP780钢贝氏体区等温转变曲线。依据膨胀量-时间曲线，计算出相变过程中的组织转变率，分别统计不同工艺下的转变率以及对应的时间关系。研究了 TRIP 钢在等温转变时的相变规律。结果表明：加热温度相同时，贝氏体转变速率随着等温温度的升高而提高，但总转变率降低；在等温温度相同时，加热温度越高，转变率也相应增大。在贝氏体等温转变图上，转变终了线为 C 形，即存在一个鼻尖，对应于最短的转变时间。

Transformation rule of TRIP780 steel in isothermal bainite area

The isothermal bainite transformation curve of TRIP780 steel was measured by DIL805L quenching dilatometer.The change rate of microstructure during phase transformation was calculated by using expansion vol-ume-time curve,and the relationship between the rates of the change of microstructure under different processes and the corresponding time was studied.The rule of isothermal transformation of TRIP steel was researched.The results show that under the same heating temperature,the higher the isothermal temperature,the higher the transformation speed of bainite,while the total rate of transformation decreases at the same time.When the iso-thermal temperature is the same,the rate of transformation increases with the increase of the heating temperature. The tip of the nose on transition ending line with C shape at the right of bainite isothermal transformation diagram corresponds to the shortest transformation time.