Effects of Surface Treatment on the Cavitation Erosion–Corrosion Performance of 17-4PH Stainless Steel in Sodium Chloride Solution

Two different surface treatments are applied on 17-4PH stainless steel with laser techniques to improve mechanical properties and cavitation erosion–corrosion resistance. One involves laser precipitation hardening and the other implements laser cladding of Stellite 6 powder. The mechanical properties of the laser-treated surfaces are determined using nanoindentation test, and the cavitation erosion behavior of 17-4PH stainless steel with the laser-treated surface is investigated in 3.5 wt.% NaCl solution. The eroded surfaces are studied using SEM, and the depth data of the pits generated in the specimen surface are fitted into the extreme value analysis model to predict the maximum pit depth that may occur in the material surface with a given service life. Untreated 17-4PH stainless steel is also tested under the same conditions for comparison. It is shown that both surface treatments improve the mechanical and cavitation erosion–corrosion performance of 17-4PH stainless steel and laser cladding Stellite 6 treatment is even better.