Modelling of the diffusional austenite-ferrite transformation

Abstract

The austenite-ferrite transformation is the key metallurgical tool to tailor properties of low alloyed steels and remains an active area of research. Models have yet to be developed with truly predictive capabilities for phase transformations in multi-component commercial steels. This review provides a critical analysis of the various austenite-to-ferrite diffusional transformation model approaches that have been significantly broadened over the past decade by modelling at different length scales, i.e. classical macro-scale models have been augmented with simulations at the meso-scale and atomistic scale. Both semi-empirical and fundamental models are reviewed with an emphasis on polygonal ferrite formation in low and medium carbon steels. Formation of ferrite with more complex morphologies (i.e. irregular/bainitic/Widmanstätten ferrite) is also discussed. In particular, approaches to describe the interaction of alloying elements with the austenite-ferrite interface are critically analysed. The paper concludes with an outlook on the proposed austenite-ferrite transformation modelling work for the next decade.

Progress in elemental segregation and solute drag effect at the austenite/ferrite interface

“…通常, 铁素体的形成包括形核和 长大两个阶段. 形核过程较为复杂且难以准确观测, 经典形核理论涉及诸多不可测定参数(如界面能、频 率因子、形核位点密度等), 限制了对新相形核过程 的定量描述, 因此研究进展缓慢 [1][2][3] ；相比之下, 铁素 体长大(更准确的说是 α/γ 界面的迁移)占据了相变 的主要进程, 故备受学术界关注 [4][5][6][7][8][9][10] . 铁素体长大伴 随着两个重要的物理过程, 即合金元素的配分和界 面偏聚.…”