DP590钢连续冷却过程中的相变规律

Phase Transformation Rules of DP590 Steel during Continuous Cooling

通过热膨胀试验、显微组织观察等研究了DP590钢的静态CCT曲线以及加热温度对连续冷却相变规律的影响。结果表明:随着加热温度的升高,奥氏体转变量呈多速增加的趋势;其静态CCT曲线可分为三个区域,冷速在0.5～15℃·s-1范围内获得铁素体和珠光体组织,冷速超过15℃·s-1时出现贝氏体组织,冷速较高时(约30℃·s-1)出现马氏体组织;当加热温度降低时,珠光体区右移,贝氏体转变孕育期延长,马氏体开始转变温度降低,马氏体与贝氏体相变区域分离,马氏体开始转变温度随着冷速的增加而升高;随着冷速增加,铁素体、珠光体的析出被抑制,马氏体析出动力得以增加;随着加热温度升高,相同冷却速率下的铁素体含量增多,马氏体板条变细。

The static CCT curve and the effect of heating temperature on continuous cooling transformation rule of DP590 steel were researched by thermal dilation experiment and microstructure observation.The results show that,the amount of austenite increased more and more with heating temperature increasing;the CCT curve of the steel could was divided into three regions,the F+P microstructure was obtained at cooling rate of 0.5-15℃·s-1,banite appeared at cooling rate over 15℃·s-1,and martensite emerged at cooling rate higher than 30℃·s-1.The pearlite region shifted to the right,incubation period of banite prolonged, martensite starting transformation temperature decreased,and the phase transformation region of martensite and banite seperated and martensite starting transformation temperature increased with the increase of the cooling rate.The ferrite and pearlite precipitation were depressed and martensite precipitation power increased with cooling rate increasing.The ferrite content increased and martensite panel become refine with heating temperature increasing.