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，目标是基于跨越原子到宏观材料长度尺度的计算机建模技术开发新的过程模型。具体地说，这个项目涉及钢中奥氏体到铁素体的转变。这种转变构成了用于产生复杂组织的主要冶金工具，使先进的高强度钢具有优越的性能。这些新钢材主要对汽车应用具有重要意义，在汽车应用中，它们能够设计出更轻的、因此更省油的汽车。管道和建筑行业在开发新钢种方面也出现了类似的发展。与传统钢材相比，这些新钢材需要更多的合金化添加剂(如：锰、铬)来调整相变，并且作为一种附加值产品，它们需要显著增加对加工窗口的控制(例如，在热轧中)。因此，流程模型对于降低资产变异性和提高生产率至关重要，这样加拿大的钢铁生产商和用户才能保持全球竞争力。为这些新型钢开发可靠的工艺模型的一个特别挑战是，从根本上很难理解合金化元素对奥氏体铁素体转变的影响。因此，拟议的建模方法采用了一种创新的方法，通过跨不同的长度尺度进行建模。过程模型是在宏观长度尺度上形成的，而潜在的物理参数是由原子尺度上的现象产生的。因此，将组合覆盖不同长度尺度的建模工具，即从从头开始对合金元素与移动相变前沿的相互作用进行原子模拟，建模长度尺度将通过微观尺度(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用实验和工业数据来验证模型。

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.