10.7538/yzk.2021.youxian.0078

Abstract:
The thermal aging effect of 17-4 precipitation hardening (PH) stainless steel valve rods used in nuclear power plants is an important issue. The characterization of nano-precipitates in the material is essential to understand the thermal aging effect. By taking advantage of neutron scattering technique, such as magnetic sensitivity and deep penetration, we applied magnetic small-angle neutron scattering (SANS) technique to investigate the 17-4PH stainless steel samples from the valve rod which has been served for around 14 years in nuclear power plants. Anisotropic two directions using polydisperse sphere model, it is concluded that the increase of the contrast is helpful for accurately analyzing the size of the Cu nano-precipitates. This is because that the relative contribution of the scattering from the fluctuations of the composition in the vicinity of Cu nano-precipitates, which has been show by previous atom probe tomography experiment, can be largely reduced by the magnetic scattering.