The effects of hydrogen charging time and pressure on the hydrogen embrittlement(HE)susceptibility of X52 pipeline steel material are studied by slow strain rate tensile tests.The fracture morphologies of the specimen...The effects of hydrogen charging time and pressure on the hydrogen embrittlement(HE)susceptibility of X52 pipeline steel material are studied by slow strain rate tensile tests.The fracture morphologies of the specimens are observed by scanning electron microscopy.The HE susceptibility of the X52 pipeline steel material increases with an increase in both hydrogen charging time and hydrogen pressure.At a charging time of 96 h,the HE susceptibility index reaches 45.86%,approximately 3.6 times that at a charging time of 0 h.Similarly,a charging pressure of 4 MPa results in a HE susceptibility index of 31.61%,approximately 2.5 times higher than that at a charging pressure of 0.3 MPa.展开更多
Austenitic stainless steels are usually chosen to make many components of nuclear power plants (NPPs). However, their microstructure in the heat-affected zone (HAZ) will change during the welding process. Some fai...Austenitic stainless steels are usually chosen to make many components of nuclear power plants (NPPs). However, their microstructure in the heat-affected zone (HAZ) will change during the welding process. Some failures of the weld joints, mainly stress corrosion cracking (SCC), have been found to be located in the HAZ. In this research, the microstructure, micro-hardness, residual strain and SCC behavior at different locations of the 316L HAZ cut from a safeend dissimilar metal weld joint were studied. However, traditional optical microscope observation could not find any microstructural difference between the HAZ and the base metal, higher residual strain and micro-hardness, and higher fraction of random high-angle grain boundaries were found in the HAZ than in the base metal when studied by using electron back-scattering diffraction scanning and micro-hardness test. What's more, the residual strain, the microhardness and the fraction of random grain boundaries decreased, while the fraction of coincidence site lattice grain boundaries increased with increasing the distance from the fusion boundary in 316L HAZ. Creviced bent beam test was applied to evaluate the SCC susceptibility at different locations of 316L HAZ and base metal. It was found that the HAZ had higher SCC susceptibility than the base metal and SCC resistance increased when increasing the distance from the fusion boundary in 316L HAZ.展开更多
In high-temperature and high-pressure water, traditional anticorrosion approaches are not suitable to be used to protect structural materials from oxidation and corrosion. In this study, monolayer graphene was explore...In high-temperature and high-pressure water, traditional anticorrosion approaches are not suitable to be used to protect structural materials from oxidation and corrosion. In this study, monolayer graphene was explored as a barrier to protect the materials from degradation. The oxidation and corrosion rate of the monolayer-graphene-coated copper is much lower than that of the bare copper, suggesting that the monolayer graphene can effectively protect the copper from oxidation and corrosion in the simulated primary water of pressurized water reactors.展开更多
In pressurized water reactor,fretting corrosion has become the main reason for the failure of 690TT heat exchanger tubes.The effect of temperature on the fretting corrosion behavior between 690TT tube and 405 stainles...In pressurized water reactor,fretting corrosion has become the main reason for the failure of 690TT heat exchanger tubes.The effect of temperature on the fretting corrosion behavior between 690TT tube and 405 stainless steel(SS)bar has been studied during 106 fretting cycles.The overall average coefficient of friction(COF)values descends with an increase in test temperature,while the width of worn scar becomes wider.The severest fretting corrosion happens when the test temperature is at 100℃.The wear mechanism differs at different test temperatures,from adhesive wear at room temperature to abrasive wear and delamination at 100℃,to abrasive wear at 200℃.Deformation slips,high residual strain concentration,and micro-cracks are found which are disadvantageous for the further service performance of the tubes.展开更多
基金This work was supported by the National Key R&D Program of China(2021YFB4001601)the Youth Innovation Promotion Association CAS(2022187).
文摘The effects of hydrogen charging time and pressure on the hydrogen embrittlement(HE)susceptibility of X52 pipeline steel material are studied by slow strain rate tensile tests.The fracture morphologies of the specimens are observed by scanning electron microscopy.The HE susceptibility of the X52 pipeline steel material increases with an increase in both hydrogen charging time and hydrogen pressure.At a charging time of 96 h,the HE susceptibility index reaches 45.86%,approximately 3.6 times that at a charging time of 0 h.Similarly,a charging pressure of 4 MPa results in a HE susceptibility index of 31.61%,approximately 2.5 times higher than that at a charging pressure of 0.3 MPa.
基金financially supported by the National Natural Science Foundation of China (No. 51301183)Science and Technology Commission of Shanghai Municipality under Grant No. 14DZ2250300, Shanghai, China
文摘Austenitic stainless steels are usually chosen to make many components of nuclear power plants (NPPs). However, their microstructure in the heat-affected zone (HAZ) will change during the welding process. Some failures of the weld joints, mainly stress corrosion cracking (SCC), have been found to be located in the HAZ. In this research, the microstructure, micro-hardness, residual strain and SCC behavior at different locations of the 316L HAZ cut from a safeend dissimilar metal weld joint were studied. However, traditional optical microscope observation could not find any microstructural difference between the HAZ and the base metal, higher residual strain and micro-hardness, and higher fraction of random high-angle grain boundaries were found in the HAZ than in the base metal when studied by using electron back-scattering diffraction scanning and micro-hardness test. What's more, the residual strain, the microhardness and the fraction of random grain boundaries decreased, while the fraction of coincidence site lattice grain boundaries increased with increasing the distance from the fusion boundary in 316L HAZ. Creviced bent beam test was applied to evaluate the SCC susceptibility at different locations of 316L HAZ and base metal. It was found that the HAZ had higher SCC susceptibility than the base metal and SCC resistance increased when increasing the distance from the fusion boundary in 316L HAZ.
基金financially supported by the National Basic Research Program of China(No.2011CB610502)the National Natural Science Fund for Distinguished Young Scholars (No.51025104)
文摘In high-temperature and high-pressure water, traditional anticorrosion approaches are not suitable to be used to protect structural materials from oxidation and corrosion. In this study, monolayer graphene was explored as a barrier to protect the materials from degradation. The oxidation and corrosion rate of the monolayer-graphene-coated copper is much lower than that of the bare copper, suggesting that the monolayer graphene can effectively protect the copper from oxidation and corrosion in the simulated primary water of pressurized water reactors.
基金supported by the National Natural Science Foundation of China (No.51771211)the Large-scale advanced PWR major projects (No.2017ZX06002006)+1 种基金the Liaoning Provincial Natural Science Foundation of China (No.20180540076)the open-ended fund of the CAS Key laboratory of Nuclear Materials and Safety Assessment (Institute of Metal Research,Chinese Academy of Sciences,China) (Nos.2019NMSAKF02 and 2017NMSAKF04)
文摘In pressurized water reactor,fretting corrosion has become the main reason for the failure of 690TT heat exchanger tubes.The effect of temperature on the fretting corrosion behavior between 690TT tube and 405 stainless steel(SS)bar has been studied during 106 fretting cycles.The overall average coefficient of friction(COF)values descends with an increase in test temperature,while the width of worn scar becomes wider.The severest fretting corrosion happens when the test temperature is at 100℃.The wear mechanism differs at different test temperatures,from adhesive wear at room temperature to abrasive wear and delamination at 100℃,to abrasive wear at 200℃.Deformation slips,high residual strain concentration,and micro-cracks are found which are disadvantageous for the further service performance of the tubes.