Constitutive Analysis of High-Temperature Deformation Behavior of Fine- and Coarse-Grained Two-Phase Titanium Alloys
Abstract
The present work investigated high-temperature deformation behavior (flow curve, strain rate sensitivity, deformation mode) in Ti-5Al-4V alloys using both Strain Rate Jump (SRJT) and Load Relaxation (LRT) Tests. The disparity in high temperature plasticity was observed by directly comparing two groups of results, and elucidated on the basis of microstructural evolution and semi-constitutive and quantitative analysis called internal-variable analysis. Stress-strain rate plots determined from SRJT and LRT were in good agreement with theoretical predictions considering the activation of grain-matrix deformation and particle/grain-boundary sliding. The relative contribution of the two mechanisms varied with the microstructure, temperature, strain rate, which affected the flow stress and strain rate sensitivity of the Ti-6Al-4V. A clear difference in strain rate sensitivity was observed depending on the experimental method; SRJT values were higher than those from the LRT in all cases. Such a discrepancy could be attributed to a variation in pre-strain between the two methods. This variation resulted in microstructural differences, such as the fraction of alpha/beta interfaces and the misorientation of alpha grain boundaries, and hence affected the contribution of particle/grain-boundary sliding to the overall deformation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 15, 2012
- Accession Number
- ADA567118
Entities
People
- Chong S. Lee
- Taekyung Lee
Organizations
- Pohang University of Science and Technology