Quantifying the mesoscopic shear strains in plane strain compressed polycrystalline zirconium

An algorithm is used to estimate mesoscopic strains in a deformed polycrystalline material. This requires comparison of microstructures before and after imposed macroscopic plastic deformations, in order to estimate the local/mesoscopic strains from the displacements of identifiable grain boundary segments. The algorithm was applied to lightly plane strain compressed (PSC) polycrystalline zirconium. Very large (up to 1.2) near-boundary mesoscopic shear strains were estimated. These were well above the estimated measurement uncertainties and remarkably larger than the extremely small (0.01-0.04) PSC strains imposed. Opposing local shears, on both sides of a grain boundary, appeared to compensate each other. Direct correlations were noted, in the same grain, between mesoscopic shear strains and (i) in-grain misorientations and (ii) subsequent grain fragmentation.