The Influence of Strain Rate and Various Temperatures on the Quasi-Static Deformation Behavior and Microstructure of Ti-12Mo-6Zr-2Fe

Abstract

In this thesis the quasi-static compression properties and microstructure of the Ti-12Mo-6Zr-2Fe biomedical titanium alloy were studied at different temperatures of 25 °C 450 °C 900 °C and low strain rate from 0 000s-1 to 1s-1 using the universal testing machine The high temperatures of 450° C 900° C were obtained by using the deformation dilatometer The results indicate that under the same temperature conditions the flow stress work hardening rate strain rate sensitivity coefficient and theoretical temperature rise of Ti-12Mo-6Zr-2Fe all increase with the increasing strain rate but decrease with the increasing temperature However the thermal activation volume and the activation energy have completely opposite tendency The Combined Johnson-Cook & Zerilli- Armstrong model on Ti-12Mo-6Zr-2F can be used to describe the deformation behavior The optical microstructure shows that the Ti-12Mo-6Zr-2Fe has a pure β type titanium alloy at room temperature The appear on the microstructure as the temperature is increased precipitated fine alpha and omega phases However as the temperature were higher than the beta transus temperature of 754°C a pure β type titanium alloy is found The transmission electron microscop observations indicate that the dislocation density decreases as the temperature is increased or the strain rate is decreased The relationship between the stress and the dislocation density can be explained by using the Bailey-Hirsch equation accurately

Date of Award	2019
Original language	English
Supervisor	Woei-Shyan Lee (Supervisor)