Modeling the Thermal History–Microstructure Links in Equal Channel Angular Extrusion

Author(s):

Philip E. Goins and Kristopher A. Darling

Abstract:

The development of cutting-edge materials requires ever more precise control of processing conditions to obtain windows of optimal performance, especially controlling temperature and pressure where islands of performance can be very narrow and sensitive to fluctuations or error, particularly in larger specimens produced by methods under extreme conditions. Detailed awareness of the precise conditions of operations is necessary, especially when attempting to engineer microstructure in complex alloys. In this work, a microstructure model is coupled to a process model that captures the heat transport in the emerging processing approach of equal channel angular extrusion (ECAE), which is a process of severe plastic deformation under shear that is often performed with samples preheated to high temperatures. The precise thermal history may deviate significantly from idealized conditions as heat is lost in contact with the ECAE system and is also generated at points by plastic strain, and that deviation will lead to error in engineering materials for optimal performance, especially during scale-up efforts. This thermal history model is coupled with a microstructure model based on ferrous systems to highlight the coupling of models and create a holistic approach to precisely engineer materials in alignment with current and future experimental and data-driven efforts.