Study on cavitation erosion and slurry erosion resistance of martensitic precipitation hardening stainless steel coatings fabricated by high power laser cladding

Abstract

The present study systematically compared the cavitation erosion (CE) and slurry erosion (SE) resistance of 0Cr12Ni9A and 0Cr17Ni4Cu4Nb coatings fabricated by high power laser cladding (HPLC) and the differences in CE and SE resistance were revealed by combining microstructure and mechanical properties. The experimental results indicated that the build rate of HPLC reached 256 mm³/s, which was much higher than that achieved by traditional low power laser cladding (154 mm³/s). Furthermore, the hardness (50 HRC), ultimate tensile strength (1370 MPa), yield strength (1349 MPa) and break elongation (11.5 %) of 0Cr12Ni9A coating were 1.11 times, 1.12 times, 1.25 times and 0.59 times that of 0Cr17Ni4Cu4Nb coating, respectively. The CE and SE resistance of the 0Cr12Ni9A coating were 9.51 times, 0.63 times (attack angle $\alpha$ = 45°) and 1.23 times (90°) than that of the 0Cr17Ni4Cu4Nb coating and 22.87 times, 1.32 times (45°), 1.91 times (90°) than that of the 0Cr13Ni5Mo substrate, respectively. The cladding layers with high hardness and strength exhibits enhanced CE and SE (90°) resistance due to the higher resistance to plastic deformation and failure when facing the vertical impact of cavitation bubble collapse or sand particles. However, the SE resistance (45°) is related to the unit volume fracture energy, with a higher value indicating more effective absorption of kinetic energy from impacting sand particles, resulting in reduced flaky peeling off for improved SE resistance. The high build rate of HPLC and the exceptional CE and SE resistance of 0Cr12Ni9A coating material provide a novel solution to extend the service life of Pelton turbines.