Prediction of mechanical performance of Ti6Al4V cast alloy based on microCT-based load simulation

Abstract

The effect of porosity on the mechanical properties of cast titanium alloy was investigated in this work, specifically for investment-cast Ti6Al4V. X-ray micro computed tomography (microCT) was used to non-destructively analyse pores in 10 samples prior to mechanical testing. A finite element analysis was done on the microCT data providing a 3D view and quantitative values for maximum stress areas. All 10 samples were again analysed by X-ray microCT after physical testing. This allowed the location of failure to be correlated to pores and regions of high stress from the calculations. All samples showed high tensile strength with little effect of the pore size or simulated stress, most likely due to the simplified casting geometry. Irrespective of the microstructure, it was found that an increasing pore size results in increasing simulated stresses around the pores, which correlate strongly with a decrease in the measured ductility of the samples. This result indicates that induced stresses when a sample is put under load affects the ductility, since ductility depends on stress state of the material. Moderate correlation of the simulated stresses with ultimate tensile strength was found for samples with homogeneous microstructure.