Investigation of mechanical properties and proton irradiation behaviors of SA-738 Gr.B steel used as reactor containment

Application of Positron Annihilation Spectroscopy in Accelerator-Based Irradiation Experiments

Positron annihilation spectroscopy (PAS) is widely recognized as a powerful characterization technique in all types of radiation damage studies in nuclear materials. In the past, fission reactor irradiation of reactor pressure vessel (RPV) steels was a primary aim in most studies, while today's applications of PAS in this field are centered around ion implantation experiments in advanced structural materials. These experiments use hydrogen, helium, heavy ions, and their combination to simulate various radiation environments of future nuclear reactors or nuclear research facilities. The spectrum of ion energies used ranges from a few tens of keV to tens or even hundreds of MeV in proton irradiation or spallation neutron source irradiation experiments. The variety of ion energies, irradiation temperatures, and other experimental conditions poses a major challenge to researchers, who often fail to successfully incorporate the lessons learned from their research. In this paper, we review and supplement recent PAS studies in which structural materials irradiated under a variety of irradiation conditions were investigated using positron annihilation spectroscopy. It summarizes the most important conclusions and lessons learned from the application of PAS in accelerator-based irradiation experiments.

Microstructure evolution and mechanical properties of tempered 5140 alloy steel after proton irradiation at different temperatures

: This article introduces the effect of tempered 5140 alloy steel commonly used in engineering on its structure and mechanical properties under the action of proton irradiation. In the present study, the irradiation energy of 160 keV is applied to experimentally investigate the proton irradiation with different cumulative fluences on the tempered 5140 alloy steel. The effect of the cumulative fluence of the proton irradiation on the microstructure evolution of tempered 5140 alloy steel is studied through transmission electron microscopy. Moreover, the morphology of the tensile fracture is analyzed by scanning electron microscope. The effect of the cumulative fluence of the proton irradiation on the nanomechanical properties of tempered 5140 alloy steel is investigated with a nanomechanical tester. It is found that the surface hardening effect formed by the proton irradiation damage causes the dislocation density in the structure near the tempered 5140 alloy steel surface layer and such effect increases as the proton irradiation cumulative fluence increases. The results obtained show that the yield and tensile strength of the tempered 5140 alloy steel increase slightly as the cumulative fluence of the proton irradiation increases. However, the corresponding elongation decreases. For a stable pressure load of the nanoindentation, the hardness of the nanoindentation of the tempered 5140 alloy steel increases as the proton irradiation fluence increases. However, the corresponding indentation depth decreases. Based on the obtained results, it is concluded that proton irradiation has no significant effect on the macro- and nanomechanical properties of the tempered 5140 alloy steel. This may be attributed to the low energy of the proton irradiation, and the resulting radiation damage only acts on the thin layer of the tempered 5140 alloy steel surface.