Study Of High Temperature Mechanical Properties Of Fast Reactor Cladding ODS Materials After Irradiation

Oxide Dispersion Strengthened Steel(ODS)is an important candidate material for fast reactor cladding because of its excellent high temperature mechanical properties and resistance to irradiation swelling.Due to the extreme environment of high temperature,high dose neutron irradiation and corrosion for a long time,the mechanical properties of the fuel cladding material are degraded.The cladding structure materials that meet the service requirements need to ensure the service life of fuel assemblies and avoid sudden mechanical failure in the high temperature and high dose irradiation environment to ensure the safe operation of nuclear reactors.Therefore,the evaluation of high-temperature mechanical properties of candidate materials before and after irradiation provides important technical support for material evaluation and screening as well as preparation process optimization,and has important engineering application value.Ion irradiation experiments have many advantages such as controllable experimental parameters,high irradiation damage rate,short cycle time,and nonradioactive irradiation,etc.The use of ion irradiation to simulate neutron irradiation to evaluate the anti-irradiation properties of materials has become an important tool for material screening.In this paper,12Cr-ODS was irradiated at 580℃ with 40 MeV Fe4+ions,and 12Cr ferritic/martensitic steel was irradiated at a peak dose of 40 dpa,and the surface indentation morphology was observed by SEM in situ nanoindentation test and SEM.The high-temperature mechanical properties of the material under different irradiation conditions were systematically investigated by electron microscopy in situ nano indentation tests and scanning electron microscopy surface indentation.The microstructural information of the sample materials before and after irradiation was also investigated by transmission electron microscopy.The results of the work obtained in this paper are as follows:1.The hardness values of the 12Cr reference sample after using ion irradiation are significantly larger than those of the unirradiated sample,indicating that the irradiation damage(vacancies and interstitial atoms,etc.)produced by irradiation causes hardening of the material.The irradiation hardening phenomenon decreases with increasing temperature when the irradiation dose is certain.2.The comparison of 12Cr-ODS before and after irradiation shows that the hardening phenomenon of ODS samples is not obvious,indicating that the high density of defect traps introduced in the material can inhibit irradiation hardening,indicating that ODS samples have excellent resistance to irradiation hardening.3.The hardness of both steels decreased with the increase of temperature after the high-temperature nanoindentation test,but overall,the decrease of ODS samples was lower,indicating that the high-temperature mechanical properties of ODS samples were good.500℃,550℃,600℃ nanoindentation experiments in the load-holding section could be seen the occurrence of creep phenomenon,and the creep amount increases with the increase of temperature and depth.By calculating the creep amount at high stress,could found that the temperature creep phenomenon of ODS samples to be less than that of HT9 samples.4.Low-stress nanoindentation creep tests of ODS steel at high temperature were carried out,and the test results showed that the difference in creep stress index before and after irradiation of 12Cr-ODS samples was not significant.