Fracture characterization of the TLP welding specimen of a single crystal superalloy DD3

In order to study the welding characteristics of single crystal superalloy DD3, the fracture mechanism of the TLP welding specimen of single crystal superalloy DD3 and original DD3 specimen is studied with the three-point bending tests and SEM. Based on the single crystallographic theory, the distributing of the Mises stress and the maximum of resolved shear stress is analyzed by the FEM. The results showed that the welding specimen of single crystal superalloy DD3 changed more brittle than the original DD3 specimen and therefore the welding specimen had nearly half of the bending strength of original DD3 alloy. The numerical results of the Mises stress and the maximum of resolved shear stress proved that the welding line played an important role in the models. Because of the material difference, the stress distribution changed near the welding region, and the resolved shear stress concentrated very evidently near the welding line. Consequently, the brittleness of the single crystal welding specimen increased, the bending strength reduced.