AHSS: Multi-scale Modeling of Deformation Mechanism for Design of New Generation of Steels

该奖项的研究目标是开发合适的计算方法来模拟先进高强度钢(AHSS)的相变和变形机制。采用一系列新的扩展时间尺度模拟方法，如扩散分子动力学和自由端轻推弹性带，通过耦合形变和相变机制的量子化学、原子和介观性质的多尺度模拟方法，探索AHSS中新的微观结构特征和新的强化机制。扩散、位移以及扩散-位移耦合过程将在统一的数学框架下处理。每种新的强化机制都具有各自的速率依赖性(激活能和激活体积)和应变硬化规律。交付成果包括软件模块、参数公式和属性表、研究成果出版物和工程专业学生教育。如果成功，研究结果将有助于在不增加成本的情况下提高钢材的强延性围护结构，这是第三代AHSS设计的主要标准。开发的新材料概念和模型将向学术界和工业界提供。我们计划将我们的计算方法和模拟结果放在一个开放的网站上。我们还将把新的材料概念、建模方法和软件程序整合到宾夕法尼亚大学和俄亥俄州立大学的本科生和研究生课程中。特别是，在现有的本科生和研究生课程中，将引入新的模块，应用本课程中开发的原子论和相场方法来模拟钢的相变和塑性变形。

The research objective of this award is to develop appropriate computational methods for modeling phase transformation and deformation mechanisms in advanced high-strength steels (AHSS). A new family of extended-timescale simulation methods such as diffusive molecular dynamics and free-end nudged elastic band will be employed to probe the novel microstructural features and new strengthening mechanisms in AHSS through a multi-scale modeling approach that couples the quantum chemical, atomistic and mesoscopic nature of deformation and phase transformation mechanisms. Diffusive, displacive as well as coupled diffusive-displacive processes will be treated under a unified mathematical framework. Each new strengthening mechanism will be characterized by its own rate dependence (activation energy and activation volume) and strain-hardening law. Deliverables include software modules, parametric formulas and property tables, publications of research results and engineering student education. If successful, the results of this research will aid the efforts to enhance the strength - ductility envelop of steels without increasing the cost, the main criterion for the design of third generation AHSS. New material concepts and models developed will be made available to both academic and industrial communities. We plan to place our computational methods and simulation findings on an open web site. We will also integrate the new materials concepts, modeling methods, and software programs into undergraduate and graduate curricula at Penn and OSU. In particular, new modules on applying atomistic and phase field methods developed in this program for modeling phase transformation and plastic deformation in steels will be introduced to the existing undergraduate and graduate courses.