中文摘要：

采用Linseie L78 RITA淬火/相变热膨胀仪测定了试验低碳钢的相转变温度,利用金相显微镜（OM）及扫描电镜（SEM）研究了等温处理对试验钢中铁素体形核及形态的影响。结果表明：试验低碳钢Ac3、Ar1和Ar3分别为880、530和750℃。730~600℃等温处理时,随着等温温度的降低,晶内铁素体形貌由多边形转变为针状,同时伴随着轴比的升高,各向异性的增加。随转变温度降低和等温时间延长在夹杂物上形成晶内铁素体,晶内铁素体的形成总是滞后于晶界铁素体的形成。

英文摘要：

Phase transition temperature of low carbon steel was measured by L78 RITA Linseie quenching/phase change thermal expansion instrument,effect of isothermal treatment on the nucleation and morphology of ferrite was studied by optical microscope（ OM） and scanning electron microscope（ SEM）. The results show that the Ac3,Ar1 and Ar3of the tested steel are 880,530 and 750 ℃,respectively. With the decrease of the transformation temperature,the morphology of intragranular ferrite changes from idiomorphic one to acicular one in the isothermal treatment at 730-600 ℃. At the same time,with the increase of axial ratio,the anisotropy increases. With the decrease of the transition temperature and the extension of isothermal time,the intragranular ferrite nucleated on the inclusion,and the formation of intragranular ferrite is always lagging behind the formation of grain boundary ferrite.