Constitutive modelling of thermomechanical abnormalities due to dynamic strain aging in commercially pure titanium

Abstract

Dynamic Strain Aging (DSA) is the irregular increase in metal strength that results from the diffusion of impurity atoms and their interactions with dislocations during plastic deformation at specific strain rates and temperatures. Commercially Pure Titanium (CP–Ti) has been reported to exhibit DSA over a broad range of temperature and strain rates during plastic deformation owing to the impurity atoms diffusion. The current work focuses on the modification of the physical-based Voyiadjis Abed (VA) model by introducing an additional term, based on the concentration and diffusion kinetics of different impurities, to capture DSA in CP-Ti. The analysis of diffusion parameters indicates that the hydrogen impurity diffuse into the dislocation core and interact with the mobile dislocations, thus defining the temperature range for the activation of DSA at low and high strain rates. The results show that the modified VA model could capture DSA in CP-Ti over a wide range of strain rates and temperatures when the recommended novel modification based on physical and microstructural parameters was introduced.

Keywords

• Dynamic strain aging
• Impurity concentration
• VA model
• Constitutive model
• Commercially pure titanium
• Impurity-dislocation interactions