Evaluation of dynamic hardening models for BCC, FCC, and HCP metals at a wide range of strain rates

This paper is concerned with dynamic hardening models of metallic materials for various crystalline structures. The dynamic response of metallic materials is indispensable for the analysis of deformation in the high-speed condition. The description of the dynamic behavior, however, can be hardly suggested with a unique model that is capable of representing the dynamic hardening characteristics of all types of materials because the dynamic hardening behavior of a material is inherent characteristics which are different in materials. It is important to select the most adequate model that is capable of representing the dynamic hardening characteristics of a material accurately. In this paper, the fitting characteristics of several well-known models are investigated and verified by experiments at a wide range of strain rates. By comparing the characteristics of the models with experimental results, the effective selecting of the most adequate model has been carried out to apply experimental stress-strain curves to the numerical analysis accurately and effectively. Several hardening models reported have been investigated and evaluated using the dynamic hardening characteristics of three kinds of materials: 4340Steel (BCC); OFHC (FCC); and Ti6Al4V (HCP). Three well-known models have been constructed and evaluated for the Johnson-Cook model, the Zerilli-Armstrong model, and the Preston-Tonks-Waliace model using the test results of three materials. Several models suggested by the authors have also been compared for the modified Johnson-Cook model and the modified Khan-Huang model. Another novel dynamic hardening model is newly proposed and compared to the other models. The changes in the strain rate and the temperature during the deformation process were considered for the accurate application of the hardening models. The most applicable model for each material has been suggested by comparison of results investigated. (C) 2014 Elsevier B.V. All rights reserved.