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.
