Q235碳素钢超细铁素体在奥氏体内的形核

利用扫描电镜观察了Q235碳素钢形变强化相变过程中超细铁素体在奥氏体内部的形核;使用背散射电子衍射(EBSD)技术分析了析出的铁素体取向.结果表明,随内、外界条件不同,奥氏体内有两类典型的铁素体形核地点:形变带及奥氏体晶界附近的形变不均匀区.原始奥氏体晶粒尺寸的增加,形变温度的降低有利于铁素体的形变带形核.在的超细铁素体最佳形成温度区间,靠近形变可使铁素体及第2组织均匀分布.形变带形核造成带状分布的铁素体及第2相,不仅形貌上出现方向性,铁素体取向也出现择优.

Nucleation of Ultra-fine Ferrite in Austenite of A Q235 Low Carbon Steel

The nucleation of ultra-fine ferrite inside austenite was followed during deformation-enh- anced transformation in a Q235 low carbon steel. EBSD technique was applied to reveal the orientation fea- tures of ferrite formed at different places. Results indicate that there are two typical nucleation sites inside aus- tenite, namely, deformation bands and deformation inhomogeneities near austenite grain boundaries. Increas- ing austenite grain size and decreasing deformation temperature favor to the ferrite formation at deformation bands. In the suitable deformation temperatures of A3-Ar3 for ultra-fine ferrite, the deformation near A, leads to a uniform distribution of ferrite as well as second phases. The band-like ferrite and second phases caused by the nucleation at deformation bands gives rise to not only the anisotropy in microstructure but also in ferrite orientation.