加热速率对逆转变奥氏体微观组织的影响

Effects of heating rate on microstructure of reverted austenite

为了研究连续加热过程中加热速率对逆转变奥氏体微观组织的影响,通过热膨胀仪和EBSD研究了不同加热速率下部分逆相变和完全逆相变后的微观组织。结果表明,高加热速率促进了块状奥氏体的形成,而低加热速率有利于针状奥氏体的形成,且加热速率越大,最终逆转变完成时奥氏体晶粒尺寸越微细。高加热速率使得奥氏体形核和长大被推向高温区进行,高温区块状奥氏体为置换性合金元素非配分长大模式,长大速率极快。因此,高加热速率促进了块状奥氏体的形成。

In order to investigate the effects of heating rate on the reverted austenite structure,the microstructures after partial or complete reversion was studied by thermal dilatometer and Electron backscatter diffraction(EBSD). It was found that high heating rate promotes the formation of globular austenite,while low heating rate favors the formation of acicular austenite. Meanwhile,higher heating rate leads to finer austenite structures after reversion. High heating rate makes the nucleation and growth of the reverted austenite occurred at high temperatures,at which the growth of the globular austenite is substitutional alloying elements partitioning- less and grows very fast. Therefore,high heating rate enhances the formation of globular austenite.