High temperature forming of Ti-6Al-4V alloy considering microstructure evolution

The investigation of the high temperature deformation behavior of Ti-6Al-4V alloy and the prediction of the final microstructure under given forming conditions have been made. Equiaxed microstructure of Ti-6Al-4V alloy was prepared as starting micro structures. By performing the compression tests at high temperatures (700 degrees C similar to 1100 degrees C) and a wide range of strain rates (10(-4)/s similar to 10(2)/s), various parameters such as strain rate sensitivity (m) and activation energy (Q) were obtained and used to establish constitutive equations. When the specimens were deformed up to a strain of 0.6, equiaxed microstructure did not show any significant changes in morphology, while the average a grain size was varied with the variation of temperatures. Accordingly, constitutive equations were developed by use of internal state variables, and applied in the FEM analysis to predict the final microstructure after forming. The grain size and the volume fraction of a phase of deformed body are predicted and well agreed with the experimental results.