Hot water jet erosion characteristics of Ti-Ni shape memory alloys

Abstract

The Co-free materials with high erosion resistance are anticipated for parts of equipment in nuclear power plants. The erosion resistance of Ti-Ni shape memory alloys (SMAs) against the impact of hot water jet onto the specimen surface was investigated experimentally and by finite element method (FEM). The results are compared with that of an existing Co-based alloy (Stellite). Both of the erosion damaged cross-sectional area and the maximum damaged depth increased linearly with the elongated exposure time. The damaged areas of SMAs were extremely small compared to those of Stellite. However, no significant difference in the maximum damaged depth was found between the two materials. From the FEM results, larger values of the maximum shear stress and the mean stress were found to distribute in the specimens in testing. It is estimated that the essential erosion damage mechanism of Ti-Ni SMAs is cavitation. In Stellite a combination of the shear stress and the cavitation controls erosion. The erosion resistance of the Ti-Ni SMAs is superior to that of Stellite. It is suggested that the Ti-Ni SMAs will be one of the promising alternative materials for Stellite.