30CrMnSiA钢退火组织低速加热时奥氏体的形成

Formation of Austenite in a Annealed Structure of Steel 30CrMnSiA during Heating at Slow Speed

对钢加热时奥氏体的形核位置及形态已进行过大量细致的研究[1～5]。但对于低速(<50℃/min)加热条件下,ΔT(T-Ac1)较小时,奥氏体核的形成及生长,尚未见报道。本文研究亚共析钢退火组织低速加热、ΔT较小时奥氏体的形核及生长的特点。

The paper deals with the nucleation and growth of austenite after heating just above A c1 at a rate of 0.5℃/min in a annealed structure of steel 30CrMnSiA,obtained by furnace cooled from 1250℃.The results showed that austenite could nucleate at all of the ferrite/cementite interfaces and grow along the interface in the form of plate,into ferrite with acicular shape or/ into pearlite to form long axial allotriomorphy.It was also observed that austenite could be nucleated and grown within a ferrite grain in the shape of aciculum,parallelogram or regular hexagon,and some acicular austenites which were parallel to or at certain angles.It was thought that acicular austenite within a ferrite grain could consist of subunites which were formed by sympathetic nucleation,then growed by diffusion and finally merged togather.