Characterisation of microstructural damage evolution during tensile deformation of a near-α titanium alloy: Effects of microtexture

The evolution of microstructural damage during tensile deformation of a near-α titanium alloy has been characterised using nonlinear ultrasonic (NLU) parameters. Evolution of the damage state in the interrupted tensile specimens at different strain levels has been correlated with the second-order (NLU) parameter. It is shown that the second-order ultrasonic parameter does not change monotonically with increasing strain. The variation in (NLU) parameters is shown to be a function of both the density of dislocation substructure and the preferred crystallographic orientations that evolve during tensile deformation. The presence of microtexture predominantly affects the harmonics generation from the dislocation substructure. A physical basis for the above observation has been established using a dislocation string vibration model. Infrared thermal imaging has been used to map the evolution of damage along the gauge length of the specimens to take into account the in-homogeneities of deformation.