The high-temperature deformation behavior of metals and alloys undergoes complex mechanisms depending on the deformation conditions. The microstructure and mechanical properties after deformation are important factors that determine the strength and durability of the final product. Therefore, many studies to predict the microstructure and mechanical properties have been conducted. In this regard, numerous mathematical approaches for predicting microstructure and flow stress have been proposed over the past half century. Accordingly, many advances have been made in the field of material science. Nevertheless, there are limitations in the mathematical modeling method as there is a complex relationship between the deformation conditions and the mechanical properties. Therefore, in this study, flow stress prediction was performed by applying conventional constitutive equation and artificial intelligence technology, which is known to be effective in modeling complex relationships. As a result, it was confirmed that the flow stresses modeled by the artificial neural network showed a higher accuracy than the flow stresses modeled by the conventional Arrhenius hyperbolic sine equation.

Invar alloy possesses a uniquely low coefficient of thermal expansion, making it an ideal material for fine metal masks. To manufacture fine metal masks, Invar alloys are often cold-rolled, during which residual stress develops. Heat treatment is an effective means to control residual stress that develops within Invar sheets after cold rolling, but the treatment should be carried out with care. In this article, a comprehensive study on the effect of heat treatment on the residual stress, microstructure, and mechanical properties of a cold-rolled Invar sheet is reported. We show that while both recovery and recrystallization are effective means of reducing residual stress, substantial microstructural changes and, therefore, notable changes in mechanical properties and residual stress, occur after recrystallization. Moreover, residual stress release due to recrystallization can be affected by microstructure and texture prior to heat treatment as these factors play a significant role in recrystallization.