加热速率对铸态60Si2Mn钢奥氏体化的影响

Effect of heating rate on austenitization of as-cast 60Si2Mn steel

利用DIL805A热膨胀仪记录了铸态60Si2Mn钢在不同的加热速率下(0.2、1、3、10、50℃/s)的线膨胀系数,获得了各自的热膨胀曲线和奥氏体体积转变分数曲线,研究了加热速率对奥氏体化的影响。采用高温金相显微镜对该钢在连续加热过程中的奥氏体转变过程进行了观察分析。结果表明:60Si2Mn钢在连续加热过程中的奥氏体转变可分为三个阶段:珠光体向奥氏体的转变、(Mn,Fe)_(3)C向奥氏体中的溶解和奥氏体的成分均匀化。随着加热速率提高,相变临界温度提高,相变速率提高。通过高温金相可以观察到,在连续加热过程中,铸态60Si2Mn钢的A转变是一个形核和长大交替进行的过程,并且由于Si元素含量的不同,导致这个过程是不连续的。

The linear expansion coefficient of as-cast 60Si2Mn steel at different heating rates(0.2,1,3,10,50℃/s)was recorded using the thermal dilatometer DIL805A.The corresponding thermal expansion curves and volume transformation fraction curves(austenite)were obtained to study the effect of heating rate on austenitization.A high-temperature metallurgical microscope was used to observe and analyze the austenite transformation process of the steel during continuous heating.Studies have shown that the austenite transformation of 60Si2Mn steel during continuous heating can be divided into three stages:the transformation of pearlite to austenite,the dissolution of(Mn,Fe)_(3)C into austenite and the composition of austenite homogenizing.And as the heating rate increases,the critical temperature of phase transition increases,and the rate of phase transition increases.In addition,high-temperature metallography shows that the A transformation of the as-cast 60Si2Mn steel during the continuous heating process is an alternate nucleation and growth process.This process is discontinuous due to the difference in Si element content.