Residual stress improved by Water Jet Peening for small-diameter pipe inner surfaces

As one of degradation conditions on components used in water, overlapping environment, material and stress might cause stress corrosion cracking (SCC). Especially, for the tensile residual stress produced by welding, it is particularly effective to reduce the tensile residual stress on the material surface to prevent SCC. In this paper, the residual stress improvement method using cavitation impact generated by a water jet, called Water Jet Peening, has been developed for the maintenance technology for the inner surfaces of small diameter Alloy 600 pipes. As the results, for the inner surfaces of Alloy 600 pipe (ID:10-15 mm), we confirmed to be able to reduce to compressive stress on surface by about 350 MPa and in depth by about 0.5 mm.