In-situ high-energy X-ray diffraction and crystal plasticity modeling to predict the evolution of texture, twinning, lattice strains and strength during loading and reloading of beryllium. (March 2022)

• Record Type: Journal Article
• Authors: Ferreri, Nicholas C.; Feng, Zhangxi; Savage, Daniel J.; Brown, Donald W.; Clausen, Bjørn; Sisneros, Thomas A.; Knezevic, Marko
• Is Part Of: International journal of plasticity. Volume 150(2022)
• Publication Date: 2022-03
• Subjects: Texture -- Twinning -- Lattice strains -- Crystal plasticity -- HEDM -- Beryllium; Plasticity -- Periodicals; Plasticité -- Périodiques; Plasticity; Periodicals; 620.11233
• DOI: 10.1016/j.ijplas.2022.103217
• Languages: English
• ISSNs: 0749-6419

Abstract

Highlights: In-situ high energy synchrotron X-ray diffraction is used to characterize the evolution of texture, twinning, lattice strains, and flow stress for Be. Compressive loading and cross-reloading tests are performed to observe transients in the flow stress and microstructure. An advanced elastic-plastic self-consistent crystal plasticity model is used to predict and interpret the data. Shifts in active deformation mechanisms are responsible for the transients from one deformation path to another and hardening. Role of twinning/de-twinning along with slip during compressive deformation of beryllium as a function of strain rate is discussed. Abstract: Deformation behavior of beryllium during compressive loading and cross-reloading is studied using in-situ high energy synchrotron X-ray diffraction microscopy and crystal plasticity modeling. The evolution of texture, twinning, elastic lattice strains, and flow stress are measured and compared with the predictions of an advanced elastic-plastic self-consistent (EPSC) crystal plasticity model. The model is initialized with the experimentally measured texture and residual stress produced by a simulation of cooling and calibrated to establish a set of model parameters using a portion of the measured data. The rest of the measured data is used for validation of the model. It is shown that the model is sufficiently flexible to reproduce the particularities pertaining to the complex strain-path-change and strain rate sensitive deformation of the material including the evolution of texture, twinning, lattice strains, transients in the stress-strain response, and anisotropic hardening with great accuracy using a single set of model parameters. From the comparison of the experimental data and predictions, we infer that the shifts in active deformation mechanisms between the slip systems from soft to hard and vice versa as well as between twinning to de-twinning are primarily responsible for drastic changes in the flow stress from one path to another. In particular, deformation twins form during compressive in-plane loading followed either by de-twinning during compressive cross-reloading in the through-thickness direction or by forming additional twin variants with some de-twinning of the existing variants during a compressive cross-reloading in another in-plane direction. The shifts in active deformation mechanisms are a consequence of changes in texture relative to the compression direction mediated with the deformation history and strain rate dependent dislocation density evolution governing hardening. The secondary effects improving the predictions come from accounting for residual stress, slip system-level backstress, and latent hardening.