Assessing thermal properties of multipass weld beads using active thermography: microstructural variations and anisotropy analysis

Abstract In the present paper, results of a research focused on microstructure investigation steel welded joints by means non destructive thermographic technique are presented. particular, two rough obtained irregular manual welding analyzed. Active lock in thermography phase analysis is applied, basing evidence that thermal diffusivity related to diffusion length, using contrast trend as function distance from laser spot. Diffusivity expected be dependent local and vary through different directions. By variation diffusivity, it possible investigate level anisotropy.The compared with micrographic analysis. The proposed method provides an active lock-in infrared camera exciting head evaluate diffusivity.