High Temperature Flow Response Modeling of Ultra-Fine Grained Titanium
This work presents the mechanical behavior modeling of commercial purity titanium subjected to severe plastic deformation (SPD) during post-SPD compression, at temperatures of 600-900 °C and at strain rates of 0.001-0.1 s−1. The flow response of the ultra-fine grained microstructure is modeled using the modified Johnson-Cook model as a predictive tool, aiding high temperature forming applications. It was seen that the model was satisfactory at all deformation conditions except for the deformation temperature of 600 °C. In order to improve the predictive capability, the model was extended with a corrective term for predictions at temperatures below 700 °C. The accuracy of the model was displayed with reasonable agreement, resulting in error levels of less than 5% at all deformation temperatures.
An experiment study of the lubrication behavior of graphite in hot compression tests of Ti–6Al–4V alloy
Abstract The compression test has been used widely in obtaining flow stress data at hot working temperatures. In order to obtain reliable data, uniform deformation must be ensured by having adequate lubrication throughout testing. In this paper, the lubrication behavior of graphite was investigated by ring compression tests of Ti–6Al–4V alloy at temperatures from 750 to 1000°C and constant strain rates from 0.05 to 15 s −1 . It was found that the friction factor m increases with the increase of temperature and with the decrease of strain rate. At temperatures below 800°C, the friction factor m is less than 0.3, so that graphite can be used effectively as a lubricant in this range of temperature for compression tests.
SCIENCE AND EMPIRICISM IN PILE FOUNDATION DESIGN
Scientific approaches to pile design have advanced enormously in recent decades and yet, still, the most fundamental aspect of pile design—that of estimating the axial capacity—relies heavily upon ...