Molecular dynamics simulation of crack growth in pure titanium under uniaxial tension

Abstract

The analysis of crack growth in titanium was performed using molecular dynamics simulation with Embedded Atom Method potentials. The effect of temperature and strain rate on the mechanism of crack growth and the change of microstructure were discussed. After setting an initial crack, the specimen was subjected to uniaxial tension strain up to the total strain level of 0.2 with a constant strain rate. During the period, the shape and the microstructure of crack tip as well as the stress–strain curves were monitored. In the simulation, the gather of voids and stress concentration leading to the crack growth occurred, which are in agreement with experimental results observed by transmission electron microscopy. The transformation from HCP to BCC also occurred at crack tip. The remarkable effect of temperature and strain rate on the growth direction and rate of stacking fault of crack tip was observed. Moreover, initial crack greatly lowered the tension yield point of pure titanium. In the stage of deformation, simulation results showed that loading strain rate and temperature strongly influenced peak stress point, which was increased by the low temperature and high strain, whereas the initial slope of the stress strain curve was independent of loading strain rate.