低碳硼钢过冷奥氏体分解早期α形核位置饱和现象

PREFERENTIAL SITE SATURATION FOR NUCLEATION AND GROWTH OF α-PHASE AT EARLY STAGE OF AUSTENITE DECOMPOSITION IN LOW CARBON STEEL BEARING BORON

借助经典体视学方法和“扩展组织”概念,定量研究了低碳硼钢620℃过冷奥氏体等温分解早期显微组织的演变路径。结果表明,母相晶界网络仍是低碳硼钢中α相形核长大的择优位置集合,择优顺序为晶粒棱(含隅)、晶界界面.棱集和隅集的位置饱和总是早于面集。钢中有效硼量对趋于饱和的路径和晶界面集的饱和迟早有显著影响。

The microstructural evolution path at early stages of austenite decom- position at 620℃ in low carbon steels bearing boron has been investigated by means of stereological metbods and the concept of 'extended structure'. The results show that the grain boundaries of austenite are still the preferential sites for nuc- leation and growth of α-phase in boron steels, with the edges and corners being more preferential than the surfaces. The site saturation at edges and corners always occurs earlier than that at surfaces. It has been also shown that the amount of ef- fective boron in steel has marked influence on the path to achieve the site satura- tion, and delays the surface site saturation.