钢中固溶稀土对过冷奥氏体转变的影响

Effect of Solid-solution Rare Earth in Steel on Transformation of Super-cooled Austenite

采用ICP-MS电感耦合等离子质谱仪、JEM-2100透射电镜及L78淬火热膨胀仪等设备,结合对La界面扩散系数的测定,研究了固溶稀土元素在钢中的存在及对过冷奥氏体转变的影响。结果表明,稀土在钢中有一定固溶量。微量的固溶稀土存在于晶界、位错等晶体缺陷处。固溶稀土元素可推迟过冷奥氏体的转变,使CCT曲线向右下方移动。固溶稀土原子塞集于晶界等缺陷处,阻碍扩散或热激活过程,延迟了新相的形核-长大,是推迟过冷奥氏体转变的主要原因。

Using ICP-MS inductively coupled plasma mass spectrometry, JEM-2100 transmission electron microscope and L78 quenching dilatometer, combined with the measurement of the interface diffusion coefficient of La, the effects of solid-solution rare earth existence in steel on super-cooled austenite transformation were studied. The results show that the rare earth has a certain amount of solid solution in steel. The trace amount of solid-solution rare earth can exist in the grain boundary, dislocation and other crystal defects. The solid-solution rare earth can defer the transformation of super-cooled austenite and make the CCT curves move to the bottom right. The solid-solution rare earth atoms block in the crystal defects and then hinder the process of diffusion or thermal activation, so the nucleation and growth of the new phase will be delayed. This is the main reason why the rare earth can postpone the transformation of super-cooled austenite.