Abstract
Shear localization is often a failure mechanism in materials subjected to high strain rate deformation. It is generally accepted that the microstructure evolution during deformation and the resulting heterogeneities strongly influence the development of these shear bands. Information regarding the development of local mechanical heterogeneities during deformation is difficult to characterize and as such, constitute is a critical missing piece in current crystal plasticity models. With the recent advances in spherical nanoindentation data analysis, there is now an unprecedented opportunity to obtain insights into the change in local mechanical properties during deformation in materials at sub-micron length scales. In this work, we quantify the evolution of microstructure and local mechanical properties in tantalum under dynamic loading conditions (split Hopkinson pressure bar), to capture the structure- property correlations at the sub-micron length scale. Relevant information is obtained by combining local mechanical property information captured using spherical nanoindentation with complimentary structure information at the indentation site measured using EBSD. The aim is to gain insight into the role of these microstructural features during macroscopic deformation, particularly their influence on the development of mechanical heterogeneities that lead to failure.
Highlights
Shear localization is often a failure mechanism in materials subjected to high strain rate deformation
The position of grains A and B on the Inverse pole figure (IPF) map represent the crystal direction in the grain that is parallel to the indentation direction
A novel approach to characterize the percentage increase in the slip resistance during dynamic deformation of tantalum is presented in this work
Summary
Shear localization is often a failure mechanism in materials subjected to high strain rate deformation. A brief summary of the same is provided here This procedure follows a two-step approach consisting of (i) the determination of an effective zero point followed by (ii) the calculation of the contact radius used for computing the indentation stress and strain values. Hertz’s theory is recast in the following set of equations to calculate the contact radius, a, and indentation stress, σind , and indentation strain, εind , values: a= S 2Eef f σind = Ee f f εind , He is the elastic indentation depth, S is the elastic stiffness described earlier, a, the radius of the contact boundary at the indentation load P, the effective radius and the effective stiffness of the indenter and the specimen system, Ref f and Eef f respectively are given by the following equations:. These test conditions were utilized in all of the measurements reported here
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