Constructive and Technological Solutions to Improve the Life of a Hydro Turbine’s Runner Blade

Runner blades of Kaplan turbines are elements subject to multiple mechanical and chemical stresses. For these reasons they suffer from pitting corrosion. Taking them out of production for repair involves relatively high costs, such actions can take up to 6 months. The identification of a technological or constructive solution for increasing pitting corrosion resistance is thus desirable. The paper proposes a combined technological and constructive solution for increasing corrosion resistance by pitting leading edges, the areas most affected by this type of corrosion. The experimental program highlighted the fact that the use of a similar material in terms of chemical composition and characteristics or a duplex stainless steel, deposited with linear energies lower than 1 kJ/mm, can lead to the generation of a layer that has good behaviour at pitting corrosion. The generated layer must have a thickness limited to 3 mm to avoid the appearance of additional vibrations at the blade level.