9. Finishing: non-destructive testing, machining, welding

9.1 Non-destructive testing

Non-destructive testing (NDT) is a set of methods for characterizing the integrity of structures or materials, without damaging them, either during production, use or maintenance. When it comes to superalloys, one of the difficulties lies in controlling the cleanliness of alloys, i.e. the level of inclusions (oxides, nitrides, carbonitrides) or defects generated by these inclusions during manufacturing processes (vacuum induction furnace + remelting or vacuum atomization + consolidation). These inclusions, whose existence is inherent to manufacturing processes, are in fact sources of crack initiation during cyclic loading (fatigue).