Finite element simulations on the relation of microstructural characteristics and the formation of different types of adiabatic shear bands in a v-titanium alloy

Deformation at high strain rates in combination with local thermal softening can lead to the formation of so-called adiabatic shear bands. These shear bands occur when the macroscopic deformation is concentrated in microscopic areas. The fundamental thermomechanical processes and micromechanical mechanisms acting during adiabatic shear band formation are not fully understood yet. In particular, the influence of different initial microstructures on shear band formation has not sufficiently clarified. In an earlier investigation, adiabatic shear bands formed in a v-titanium alloy with different initial microstructures were characterized in detail. It was shown that different volume fractions of the a-phase result in the formation of different types of shear bands. In the present study, a simple modeling approach based on the finite element (FE) method is used to investigate in a systematic parameter study (with a special focus on mechanical and thermal variables) how these different types of adiabatic shear bands can occur in the same material. The FE simulations clearly show that microstructural characteristics - such as size and volume fraction of the a-phase in the v-titanium alloy - have a strong influence on shear band formation. This study contributes to a more detailed understanding of the microstructural and thermomechanical mechanisms leading to the formation of different types of adiabatic shear bands in titanium alloys.