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In order to investigate the correlation between irradiation-assisted stress corrosion cracking (IASCC) susceptibility and the magnetic properties of austenitic stainless steel after ion irradiation, the magnetic properties and phase transformation were studied using a vibrating sample magnetometer and synchrotron radiation grazing incidence X-ray diffraction (GIXRD) on an irradiated specimen up to 25 displacements per atom. GIXRD indicated that the body-centered-cubic (BCC) phase was introduced in austenitic stainless steel by ion irradiation. Then, magnetic hysteresis loop analysis was conducted to give a quantitative analysis on the BCC magnetic phase under different irradiation damage and annealing temperature conditions. Based on the fact that postirradiation annealing will eliminate IASCC susceptibility at 550°C for 1 h, a correlation between IASCC susceptibility and magnetic properties was discussed, and a corresponding IASCC evaluation method was developed. [ABSTRACT FROM AUTHOR]

Nitrogen ion implantation can be used to improve the surface mechanical properties of austenitic stainless steel. In this study, austenitic stainless steel was irradiated with 1.1 MeV N ions at room temperature up to 15 displacements per atom. Then the microstructural and mechanical properties were studied by grazing incidence X-ray diffraction and nano-indenter. A finer synchrotron radiation diffraction pattern is obtained compared with traditional X-ray diffraction, indicating an expanded austenite phase γN and CrN phase after being irradiated to several damage levels. An irradiation-induced martensite phase appears first and then disappears with increased damage. The enrichment of the nitrogen supply in austenitic stainless steel can explain this phenomenon. The hardness data show an irradiation hardening phenomenon. Two different inflexion points hc1 and hc2 in H2 versus 1/h curves are observed, and the real hardness of the irradiation damaged layer can be obtained from the H2 versus 1/h curve between hc1 and hc2. [ABSTRACT FROM AUTHOR]

Specimens of austenitic stainless steel were compressively deformed or irradiated with Xe ions at room temperature. The characterization of the magnetic properties and microstructural variations were done by vibrating sample magnetometer, grazing incidence X-ray diffraction and TEM. The results indicated that higher deformation or irradiation damage causes more significant magnetization phenomenon. The amount of ferromagnetic phase can be deduced from M s and increases with deformation and irradiation. The stress relief after deformation or irradiation may be responsible for the ferromagnetic phase formation. H c increases first and then decreases continuously with a turning point at deformed to 40% or irradiated to 2dpa. The different contributions of dislocation density and ferromagnetic precipitates on H c can explain this variation. [ABSTRACT FROM AUTHOR]

Specimens of austenitic stainless steel (ASS) were irradiated with H, Fe and Xe ions at room temperature. The vibrating sample magnetometer (VSM) and grazing incidence X-ray diffraction (GIXRD) were used to analyze the magnetic properties and martensite formation. The magnetic hysteresis loops indicated that higher irradiation damage causes more significant magnetization phenomenon. Under the same damage level, Xe irradiation causes the most significant magnetization, Fe irradiation is the second, and H irradiation is the least. A similar martensite amount variation with irradiation can be obtained. The coercivity H c increases first to 2 dpa and then decreases continuously with irradiation damage for Xe irradiation. At the same damage lever, H irradiation causes a largest H c and Xe irradiation causes a minimal one. [ABSTRACT FROM AUTHOR]

Specimens of austenitic stainless steel were irradiated with 6 MeV Xe ions at room temperature to 2, 7, 15 and 25 dpa. The vibrating sample magnetometer (VSM), grazing incidence X-ray diffraction (GIXRD) and positron annihilation lifetime spectroscopy (PLS) were carried out to analysis the magnetic properties and microstructural variations. The magnetic hysteresis loops indicated that higher irradiation damage causes more significant magnetization phenomenon. The equivalent saturated magnetization M es and coercive force H c were obtained from magnetic hysteresis loops. It is indicated that the M es increases with irradiation damage. While H c increases first to 2 dpa and then decreases continuously with irradiation damage. The different contributions of irradiation defects and ferrite precipitates on M es and H c can explain these phenomena. [ABSTRACT FROM AUTHOR]

Specimens of stainless steel reactor internals were irradiated with 240 keV protons and 6 MeV Xe ions up to 15 dpa. The positron annihilation lifetime spectroscopy (PLS) was carried out to study the development of vacancy-type defects. It is indicated that positrons are trapped by vacancies, vacancy clusters and other defects (precipitate, dislocations). The short lifetime parameter τ 1 decreases when specimens are irradiated to 2 dpa by proton, whereas in the case of Xe irradiation, τ 1 decreases when specimens are irradiated to 7 dpa. The positron annihilation at small cluster with H atoms (for H irradiation) and precipitated phase (for Xe irradiation) may explain this transition. The long lifetime parameter τ 2 increases continuously with damage increase. Compared with Xe irradiated specimens, a larger τ 2 is obtained in proton irradiated specimens at the same damage. The gas atoms-vacancies, which are expected to be the early state of H bubbles, will develop into small bubbles with the increase of irradiation damage and thus cause long lifetime parameter increase. [ABSTRACT FROM AUTHOR]

Specimens of reactor internals stainless steel were irradiated with 6 MeV Xe ions to peak displacement damage 2, 7 and 15 dpa. The grazing incidence X-ray diffraction (GIXRD), positron annihilation lifetime spectroscopy (PALS) and doppler broadening spectroscopy (DBS) were carried out to study the phase transition and vacancy-type defects variations after irradiation. A new ferrite phase diffraction peak α (1 1 0) after irradiated to 7 dpa and another two ferrite phase diffraction peak α (2 0 0) and α (2 1 1) after irradiated to 15 dpa were observed by GIXRD. The results of PLAS indicate that the mono-vacancies, dislocations and vacancy clusters were introduced by Xe irradiation. It is observed that the short lifetime parameter τ 1 increases from 2 to 7 dpa and then decreases at 15 dpa. Meanwhile, a small increment of S parameter after irradiated to 2 and 7 dpa and a remarkable increase after irradiated to 15 dpa are observed. The ultrafine ferrite particles formed at 15 dpa, which may trap the migrating vacancies and decrease the recombination of vacancies and interstitials, may explain this phenomenon. [ABSTRACT FROM AUTHOR]

Highlights: [•] High density dislocation loops were introduced in RPV steel by protons irradiation. [•] Increasing fluence will increase the estimated radius of vacancy clusters. [•] The experimental hardness results were higher than that predicted by Orowan model. [ABSTRACT FROM AUTHOR]