Investigation of grain-scale surface deformation of a pure Aluminium polycrystal through kinematic-thermal full-field coupling measurement

This is a study of plastic strain localization, temperature evolution, surface roughening and of the origin of these phenomena in polycrystals. First, a review on different techniques of coupled kinematic-thermal measurements is given, and the two-face set-up, after several technical improvements, was employed in our work. Thanks to this integrated optical system, the full-field strain and temperature of the aluminium oligocrystal specimen were measured simultaneously during a tensile test. And the coupled data was further proceeded by following some particular methodologies, namely the Lagrangian thermography and the crystallography-based field projection. The surface profile of the deformed specimen was measured by interferometric profilometer, which showed clearly that the specimen had been suffered a strong out-of-plane deformation during the test. This out-of-plane effect was highlighted in the temperature field as well as in the strain field, which brought considerable affections on the measurement precisions of temperature and in-plane strain. Further data analysis shows that the heterogeneity of the out-of-plane deformation is closely associated with the crystallographic structure of the material, and reveals that the grain boundaries and grain interactions during the deformation play an important role in the process of deformation, temperature and surface profile evolutions.