Technological Processes for Increasing the Cavitation Erosion Resistance of Nimonic 80A Superalloys.

Nickel-based superalloys are frequently used to manufacture the components that operate under cavitation erosion conditions, such as aircraft gas turbine construction, nuclear power systems, steam turbine power plants, and chemical and petrochemical industries. Their poor performance in terms of cavitation erosion leads to a significant reduction in service life. This paper compares four technological treatment methods to improve cavitation erosion resistance. The cavitation erosion experiments were carried out on a vibrating device with piezoceramic crystals in accordance with the prescriptions of the ASTM G32-2016 standard. The maximum depth of surface damage, the erosion rate, and the morphologies of the eroded surfaces during the cavitation erosion tests were characterized. The results indicate that the thermochemical plasma nitriding treatment can reduce mass losses and the erosion rate. The cavitation erosion resistance of the nitrided samples is approximately 2 times higher than that of the remelted TIG surfaces, approximately 2.4 times higher than that of the artificially aged hardened substrate, and 10.6 times higher than that of the solution heat-treated substrate. The improvement in cavitation erosion resistance for Nimonic 80A superalloy is attributed to the finishing of the surface microstructure, graining, and the presence of residual compressive stresses, factors that prevent crack initiation and propagation, thus blocking material removal during cavitation stresses.