Accessing the accuracy of full-field crystal plasticity models using in situ high energy x-ray diffraction microscopy

Crystal Plasticity (CP) modeling is well-known for the accurate prediction of averaged quantities such as the stress-strain response and the evolution of crystallographic texture. It is, however, less established to which extent full-field CP models can correctly predict the local deformation behavior at grain scale. In this study, the capabilities of CP models in predicting the local behavior are assessed by experimental results from a tensile test of a Mg-3Y(Wt.%) polycrystal characterized in situ by far-field high energy x-ray diffraction microscopy. To this end, the deformation of 955 grains near the Gauge center was simulated using a fast Fourier transformation based CP framework. From undeformed state to elasto-plastic transition stage, the simulation reasonably forecasts the stress-strain response of individual grains while the crystallographic re-orientations are not correctly predicted. Small discrepancies in type III stress tensors, which lead to the activation of different slip systems, are identified as one important reason. Possible sources for the discrepancy between simulated and experimental type III stress tensors are discussed.