Influence of pre-precipitation on the multi-stage hot deformation behavior of an Al-Cu-Mg-Zr alloy: Experiments and integrated modeling

Abstract

Most industrial hot working operations of heat treatable Al alloys are frequently comprised of several successive deformation stages, and therefore the in-depth understanding and better prediction of flow stress evolution during multi-stage thermomechanical processing are required in modern aluminum industries. In this work, the effects of pre-precipitation microstructures on the complicated flow stress behaviors of an Al-Cu-Mg-Zr alloy during multi-stage hot deformation were first investigated. Further, a new integrated model was developed to predict the multi-stage flow stress behaviors. Concretely, by considering dynamic microstructural evolution, a microstructure-based constitutive KM + Avrami model in which the parameters could be well described by the empirical relationship with the Zener-Hollomon parameter was developed to predict the whole flow stress evolutions of single-stage deformation. Then, a novel approach was proposed to describe the whole flow behaviors during multi-stage hot deformation by integrating the microstructure-based constitutive approaches and a physically-based recovery model for static softening. A good modeling capability and agreement between the modeled and experimental flow stress results was found for the studied alloy with three types of pre-precipitation microstructures. In addition, the in-depth dynamic and static softening mechanisms with the influences of pre-precipitation were also discussed based on modeling analysis and microstructural observations.

Keywords

• Al alloy
• Hot deformation
• Model
• Flow stress
• Microstructure