Constitutive modelling and microscopic analysis of TC4 alloy sheet at elevated temperature

Tensile tests of TC4 alloy sheet were performed at elevated temperatures to explore the deformation behaviors under different conditions. The deformation conditions were determined by four temperatures 600 degrees C, 650 degrees C, 700 degrees C and 750 degrees C, and each temperature corresponds to four strain rates (i. e. 0.005 s(-1), 0.01 s(-1), 0.05 s(-1) and 0.1 s(-1)), respectively. Based on the obtained deformation behaviors, two constitutive models were established. It was found that although the two models both showed good prediction accuracy, the modified Johnson-Cook (JC) model was more accurate than the strain compensated Arrhenius model. The effect of the forming conditions on the deformation behavior of TC4 alloy sheet was studied by means of microscopic analysis. The microstructure analysis showed that the content of beta phase played an important role in the thermoplastic deformation of TC4 alloy. The fracture morphology of the specimen was also affected by the forming conditions. The high temperature and low strain rate contributed to the increase of number and depth of dimples.