Bridging the gap - a new generation process model for steels by modelling across different length scales

UBC-McMaster联合项目汇集了一群加拿大领先的计算材料科学家，目标是基于计算机建模技术开发新的过程模型，从原子到宏观材料的长度尺度。具体而言，该项目涉及钢中的铁素体到铁素体的转变。这种转变构成了用于产生复杂微观结构的主要冶金工具，从而提供先进高强度钢的上级性能。这些新型钢材主要对汽车应用具有重要意义，它们可以设计出轻量化，因此更省油的车辆。在管道和建筑领域，开发新钢种的进展也类似。这些新的钢需要增加的合金添加水平（例如Mn、Cr）以定制相变，并且作为增值产品，与常规钢相比，它们需要显著增加的加工窗口控制（例如在热轧机中）。因此，工艺模型对于减少性能变化和提高加拿大钢铁生产商和用户保持全球竞争力的生产率至关重要。为这些新钢开发可靠的工艺模型的一个特殊挑战是，从基本的角度来看，合金元素对贝氏体到铁素体转变的影响知之甚少。因此，拟议的建模方法采用了一种创新的方法，在不同的长度尺度建模。过程模型是在宏观长度尺度上制定的，而基本的物理参数则来自原子尺度上的现象。因此，将结合涵盖不同长度尺度的建模工具，即从合金元素与移动转变前沿的相互作用的从头原子建模开始，建模长度尺度将通过微观结构的尺度（即所谓的介观尺度）逐渐增加到工业产品的宏观尺度。所提出的方法的一个组成部分是验证模型的实验和工业数据。

This joint UBC-McMaster project brings together a group of Canada's leading Computational Materials Scientists with the goal of developing new process models based on computer modelling techniques spanning the atomistic to the macroscopic materials length-scales. Specifically, this project deals with the austenite-to-ferrite transformation in steels. This transformation constitutes the primary metallurgical tool used to generate the complex microstructures giving the superior properties of advanced high-strength steels. These new steels are primarily of significance for automotive applications where they enable the design of light-weight and, therefore, more fuel efficient vehicles. Similar developments in developing new steel grades are seen for pipelines and in the construction sector. These new steels require an increased level of alloying addition (e.g. Mn, Cr) to tailor the phase transformation and, as a value-added product, they require a significantly increased control of processing windows (e.g. in a hot mill) as compared to conventional steels. Thus, process models are critical to reduce property variability and to increase productivity that Canada's steel producers and users remain globally competitive. A particular challenge in developing a reliable process model for these new steels is that the effect of alloying elements on the austenite-to-ferrite transformation is poorly understood from a fundamental perspective. Thus, the proposed modelling approach employs an innovative methodology by modelling across different length scales. Process models are formulated on a macroscopic length scale while underlying physical parameters result from phenomena on the atomistic scale. Thus, modelling tools will be combined that cover different length scales, i.e. starting from ab-initio atomistic modelling of the interaction of alloying elements with the moving transformation front the modelling length scale will be gradually increased via the scale of the microstructure (i.e. so-called meso-scale) to the macro-scale of the industrial product. An integral part of the proposed approach is to validate the models with experimental and industrial data.