Ashish Dawari

Abstract:

During high strain rate deformation, some of the plastic work is transformed into heat. The lower thermal conductivity of Ti-6Al-4V alloys does not let the generated heat to escape easily thus producing an adiabatic system. Therefore, during deformation of Ti-6Al-4V alloy temperature increases called 'Adiabatic Heating'. Adiabatic heating contributes to flow softening in the stress-strain response of the material. Adiabatic heat rise and volume fraction of a phase in this two phase alloy has a strong influence on its hot deformation behavior. Hot compression tests were conducted on Gleeble 3500 thermo-mechanical simulator with cylindrical specimens in the temperature range of 700 - 1000 °C and strain rate range of 1 - 100 s-1 up to a true strain of 0.7. Experimental results show that the flow stress of Ti-6Al-4V alloy decreases with the increase in temperature and decrease in strain rate. Temperature rise due to adiabatic heating has been measured through K-type thermocouple. Adiabatic temperature rise contributes to increase in the volume fraction of a phase. Maximum temperature rise is observed to be 103 °C at strain rate of 100 s -1 and test temperature of 700 °C. Fraction increase in a phase due to adiabatic heating has been analyzed and an attempt has been made to co-relate it with Zener- Hollomon parameter (Z). The a volume fraction increases with temperature and strain rate. Z parameter and a volume fraction relation fits well by exponential relation for a given strain rate.