Assessment of synergistic cavitation and silt erosion performance of hydraulic turbine steel

Abstract Hydraulic turbines endure degradation from cavitation erosion, silt erosion, corrosion, and fatigue, with combined silt and cavitation erosion exacerbating machinery deterioration, increasing repair costs, and reducing lifespan. While standardised tests for silt and cavitation erosion exist, they do not fully assess material suitability for such conditions. This study presents an accelerated testing methodology for 13Cr-4Ni Martensitic Stainless Steel, commonly used in hydraulic turbines, by comparing the effects of cavitation erosion, silt erosion, and combined cavitation and silt erosion. Experimental conditions include a submerged cavitating jet and two symmetrically placed submerged silt jets at a 30° impingement angle. Mass loss measurements are recorded to quantify performance under cavitation erosion, silt erosion, and combined cavitation and silt erosion. SEM imaging reveals distinct failure modes induced by these erosive modes. Results indicate that combined cavitation and silt erosion accelerate material degradation significantly, causing approximately 37 times more mass loss than the sum of their individual effects.