A unified physically based constitutive model for describing strain hardening effect and dynamic recovery behavior of a
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Dong-Xu Wen School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, Hunan Province, China; and State Key Laboratory of High Performance Complex Manufacturing, Changsha 410083, Hunan Province, China
Yuan-Chun Huang School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, Hunan Province, China; Light Alloy Research Institute of Central South University, Changsha 410083, Hunan Province, China; and State Key Laboratory of High Performance Complex Manufacturing, Changsha 410083, Hunan Province, China
Xiao-Min Chen School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, Hunan Province, China; and State Key Laboratory of High Performance Complex Manufacturing, Changsha 410083, Hunan Province, China
Xue-Wen Chen School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471003, Henan Province, China (Received 8 October 2015; accepted 13 November 2015)
The strain hardening effect and dynamic recovery behavior of a Ni-based superalloy are studied by isothermal compressive tests. A new unified dislocation-density based constitutive model is developed to characterize the strain hardening effect and dynamic recovery behavior of the studied superalloy. In the developed constitutive model, some material parameters (yield stress, strain hardening coefficient, and dynamic recovery coefficient) are assumed as functions of initial grain size, deformation temperature, and strain rate. An iterative algorithm is designed to predict the high-temperature deformation behaviors under time-variant hot working conditions. The hot deformation parameters and material parameters can be updated in each strain increment. Comparisons between the experimental and calculated flow stresses indicate that the developed constitutive model can accurately describe the high-temperature deformation behavior of the studied superalloy. Furthermore, the developed constitutive model is also successfully used for analyzing time-variant hot working processes.
I. INTRODUCTION
Contributing Editor: Jürgen Eckert a) Address all correspondence to this author. e-mail: [email protected] or [email protected] DOI: 10.1557/jmr.2015.368
complex deformation mechanisms (strain hardening, dynamic recovery, dynamic recrystallization, etc.) further affect the final mechanical properties of materials.46 The constitutive models are often used to analyze the hightemperature deformation behavior and predict flow stress.1 Therefore, the establishment of accurate constitutive models to predict the high-temperature deformation behavior is very important for optimizing hot forming parameters. In recent years, considerable constitutive models have been developed to describe the high-temperature deformation behavior of metals or alloys. Lin and Chen1 presented a critical review on some experimental findings and constitutive models for metals or alloys under hot working. The constitutive models were mainly composed
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