MEASUREMENT FOR CCT CURVE OF 22Mn2SiVBS STEEL BY DIFFERENTIAL SCANNING CALORIMETER

Transformation point and microstructure of self-designed low carbon air cooling bainite steel 22Mn2SiVBS was tested using differential scanning calorimeter on STA-409PC synchronism thermal analyzer,and by contrast and analysis for theoretical transformation point formula,the CCT curve was drawn,and the correctness of theoretical formula was validated.The result show that the beginning temperature of the austenite transformation is 732℃,the ending temperature of the austenite transformation is 836℃;the critical cooling rate of pearlite(vP) is 0.667℃ /s,the critical cooling rate of ferrite(vF)is 1.16℃/s,it accords with theoretical value commendably;When the air cooling rate is controlled as vF≤vture＜vB ,it can obtain the microstructure consisting mostly of granular bainite,the steel has the combination of excellent strength and toughness .