Cavitation erosion resistance of AISI 420 martensitic stainless steel laser-clad with nickel aluminide intermetallic composites and matrix composites with TiC reinforcement

The cavitation erosion behaviour of AISI 420 Martensitic stainless steel laser clad with NiAl–Ni3Al intermetallic composites (IC) and intermetallic matrix composites (IMC) with TiC reinforcement was investigated using a vibratory cavitation tester. The erosion resistance of IC and IMC coating was 3.3 and 3.6 times that of the as-received specimen and 2.4 and 2.6 times that of the heat treated specimen, respectively. The increase in cavitation erosion resistance was attributed to the high work hardening ability of the nickel aluminide IC coatings. The resistance was further improved by strengthening the matrix with TiC reinforcement. No correlation was found between erosion resistance and hardness, over the range of process parameters investigated, indicating that the hardness alone cannot improve the erosion resistance. Micrographs of the surface and cross-sections of the eroded specimens were characterised by optical microscopy (OM) and scanning electron microscopy (SEM) in order to identify the mechanism of erosion. Both the IC and IMC coatings failed due to brittle fracture with varying severity.