Changes in High Temperature Deformation Behavior by Differences in Energy Dissipation Efficiency of Ti–6Al–4V Alloy

Abstract

Ti–6Al–4V alloy is widely used as a system material in high temperature and high pressure environments in various industrial fields and is difficult to mechanically machine. Thus, high temperature processing methods such as hot forging, rolling, and hot forming are usually applied. Among various methods for deriving optimal molding conditions during high-temperature processing, the dynamic material model suggests energy dissipation efficiency according to the flow stress of the material. However, the energy dissipation efficiency merely numerically represents the change in flow stress, not the metallurgical behavior of the material. Therefore, it is necessary to understand the difference in energy dissipation efficiency in relation to the high-temperature deformation mechanism. In this study, high temperature compression tests were performed on the Ti–6Al–4V alloy. The temperature range was set at 800°C∼1200°C at intervals of 50°C, and the strain rate was set at 1 × 10⁰/sec∼1 × 10⁻³/sec at intervals of 10⁻¹/sec. Based on the results of the experiments, flow stress and processing maps were derived, and the high temperature plastic deformation behaviors of Ti–6Al–4V alloy were analyzed in correlation with the microstructural changes and mechanical properties according to temperature and strain rate. And the prior beta grain size according to the difference in energy dissipation efficiency was explained for each condition.