We developed a new strength evaluation technique applicable to impellers manufactured using a new laser slot-welding process. The welding process uses laser light to join blades to a shroud. In this process, first, slots are formed by machining on the shroud. Then, blades are welded to the opposite side of the shroud by the laser beam coming through those slots. Finally, the slots are filled with powder of the same material, welded, and closed. We experimentally examined the strength of the welded parts and found their strength was almost equal to that of the base material. During this welding process, fillet welds are formed between the blades and the shroud. We then focused on finding an effective method to evaluate their fatigue strength. After theoretical and experimental consideration, we reached the conclusion that total strain calculated using elastic and elastic-plastic stress analysis is suitable for evaluating the fatigue strength of a stress concentration region produced by the laser-welding process.
