Abstract
The mechanical behaviour of heterogeneous regions like weldings is strongly affected by the local response, depending on the microstructural characteristics and the presence of defects. In this experimental work, 5083 H111 plates are welded by MIG method and DIC measurements were performed during uniaxial tensile tests to investigate the local mechanical behaviour in the area of interest. Digital Image Correlation (DIC) is a measuring technique capable of estimating the full displacement and strain field of an object through image acquisition and processing. The DIC techniques relates the intensity distribution of a small sub-set of pixel from a reference image and the image of the deformed specimen in order to estimate the full displacement field. The strain field is obtained relying on the displacement data. Specific tests are performed on specimens characterized by the presence of defects and porosity in the welding, to investigate the potentiality of the method and the obtained results show that the method is able to predict the position from which the final crack starts its propagation, giving rise to the final rupture of the specimen. Moreover, the work shows the possibility of determining the deformation field of the welded zone and of the heat affected zone by the DIC analysis, thanks to the capability of this measuring technique to estimate the mechanical behaviour of the specific regions of a welded joint (base material, HAZ and weld).
