在第四代先进反应堆钍基熔盐堆(Thorium Molten Salt Reactor,TMSR)中,高温含缺陷构件的寿命预测是结构完整性评估的重要环节。在该研究中,首先基于随时间变化的蠕变断裂力学,采用有限元分析(Finite Element Analysis,FEA)软件的围线积...在第四代先进反应堆钍基熔盐堆(Thorium Molten Salt Reactor,TMSR)中,高温含缺陷构件的寿命预测是结构完整性评估的重要环节。在该研究中,首先基于随时间变化的蠕变断裂力学,采用有限元分析(Finite Element Analysis,FEA)软件的围线积分方法计算蠕变断裂参量C^(*),结合Python语言编写的自动化分析程序,预测了GH3535合金紧凑拉伸试样C(T)的蠕变裂纹扩展(Creep Crack Propagation,CCP)。将FEA数值计算结果和蠕变裂纹扩展试验的结果进行对比验证,分析了数值模拟计算中的不确定性来源。然后按照规范,建立了GH3535合金的时间相关失效评定图(Time-dependent Failure Assessment Diagram,TDFAD),并从FEA计算结果提取并计算裂纹扩展过程中的应力强度因子K和参考应力σ_(ref),最后对缺陷试样进行了寿命评估。在蠕变裂纹扩展数值模拟中,蠕变断裂参量C^(*)仅能描述裂纹扩展阶段,而裂纹萌生阶段采用试验数据拟合的裂纹萌生时间进行描述。高温含缺陷结构的寿命跟缺陷的尺寸、载荷、裂纹扩展速率等因素相关,通过数值模拟方法可获取这些因素的影响。该研究结果解释了GH3535合金的蠕变裂纹行为,为TMSR高温含缺陷结构的寿命预测提供了工程指导。展开更多
The hot deformation behavior of GH3535 superalloy was investigated by hot compression tests in the temperature range of 1000-1200 °C and strain rate range of 0.01-50 s-1. The activation energy is about 356.3 k J/...The hot deformation behavior of GH3535 superalloy was investigated by hot compression tests in the temperature range of 1000-1200 °C and strain rate range of 0.01-50 s-1. The activation energy is about 356.3 k J/mol, and the flow curves and processing map were developed on the basis of experimental data. The processing map exhibits a stable domain which occurs in the strain rate range of 0.01-1 s-1 at all the temperatures and a instable domain which occurs in the strain rate range of 1-50 s-1. Microstructural observations reveal that the full dynamic recrystallization（DRX） occurs in the conditions of（1150 °C, 0.01 s-1）,（1200 °C, 0.01 s-1） and（1200 °C, 0.1 s-1） with different grain sizes and undissolved carbides. The flow localization and cracks occur in the regime of flow instability.展开更多
In this study,pure Ni was demonstrated to protect the GH3535 alloy from Te vapor corrosion because of its strong absorption capacity.Severe Te corrosion of a single GH3535 alloy sample occurred in Te vapor at 700C,whi...In this study,pure Ni was demonstrated to protect the GH3535 alloy from Te vapor corrosion because of its strong absorption capacity.Severe Te corrosion of a single GH3535 alloy sample occurred in Te vapor at 700C,which manifested as complex surface corrosion products and deep intergranular cracks.However,when pure Ni and the GH3535 alloy were put together in the vessel,the GH3535 alloy was completely protected from Te corrosion at the expense of the pure Ni.Thermodynamic calculations proved that the preferential reaction between pure Ni and Te vapor reduced the activity of Te vapor considerably,preventing the corrosion of the GH3535 alloy.Our study reveals one potential approach for protecting the alloys used in molten-salt reactors from Te corrosion.展开更多
The evolution of microstructure and the stress rupture properties of long term thermally exposed GH3535 alloy have been investigated. It was found that M6 C carbides presented in the solid solution heat treated sample...The evolution of microstructure and the stress rupture properties of long term thermally exposed GH3535 alloy have been investigated. It was found that M6 C carbides presented in the solid solution heat treated samples. During long term thermal exposure at 700 C, fine M12 C carbides precipitated preferentially at grain boundaries. These carbides coexisted with the pre-exiting M6 C. The stress rupture life of700 C/1000 h exposed sample under creep testing at 650 C/324 MPa is 93 h. It is much longer than that of the solid solution samples. No noticeable changes could be detected in both the microstructure and stress rupture lives when the samples were exposed for time longer than 1000 h M12 C carbides were found to be beneficial to the creep properties. The cracks initiated at the interface of M6 C carbides and matrix, which led to a lower creep rupture life.展开更多
As a primary material of the thorium molten salt reactor（TMSR） that is a suitable candidate reactor of the Generation IV nuclear reactors, GH3535 superalloy was successfully welded. The effect of laser beam welding...As a primary material of the thorium molten salt reactor（TMSR） that is a suitable candidate reactor of the Generation IV nuclear reactors, GH3535 superalloy was successfully welded. The effect of laser beam welding（LBW） on microstructure evolution of fusion zone（FZ） and heat affected zone（HAZ）, such as element segregation, precipitate behavior and grain evolution, was investigated. The microhardness and tensile properties were tested and discussed. The results of microstructure evolution showed that a number of fine M6C-y eutectic phases precipitated at solidification grain boundaries and interdendritic region in FZ. Compared to base metal zone（BMZ）, the grain size of HAZ has no obvious change. While a few of M6C-y eutectic phases were observed in partially melted zone（PMZ） of HAZ. The results of microhardness indicated that the hardness of FZ was higher than that of HAZ and BMZ. The results of tensile test showed that the ultimate tensile strength of joints at room temperature, 650 and 700？C were98%, 97% and 99% of that of BM, respectively. All the tensile specimens of joints failed in BMZ rather than in PMZ where M6 C carbides had been transformed into M6C-y eutectic phases.展开更多
基金Project(XDA02040000)supported by the Strategic Priority Research Program of the Chinese Academy of Sciences
文摘The hot deformation behavior of GH3535 superalloy was investigated by hot compression tests in the temperature range of 1000-1200 °C and strain rate range of 0.01-50 s-1. The activation energy is about 356.3 k J/mol, and the flow curves and processing map were developed on the basis of experimental data. The processing map exhibits a stable domain which occurs in the strain rate range of 0.01-1 s-1 at all the temperatures and a instable domain which occurs in the strain rate range of 1-50 s-1. Microstructural observations reveal that the full dynamic recrystallization（DRX） occurs in the conditions of（1150 °C, 0.01 s-1）,（1200 °C, 0.01 s-1） and（1200 °C, 0.1 s-1） with different grain sizes and undissolved carbides. The flow localization and cracks occur in the regime of flow instability.
基金the National Natural Science Foundation of China(Nos.U2032205,52171023,51971238,and 52005492)Natural Science Foundation of Shanghai(Nos.20ZR1468600 and 19ZR1468200)+1 种基金Shanghai Sailing Program(No.19YF1458300)the Youth Innovation Promotion Association,Chinese Academy of Science(No.2019264)。
文摘In this study,pure Ni was demonstrated to protect the GH3535 alloy from Te vapor corrosion because of its strong absorption capacity.Severe Te corrosion of a single GH3535 alloy sample occurred in Te vapor at 700C,which manifested as complex surface corrosion products and deep intergranular cracks.However,when pure Ni and the GH3535 alloy were put together in the vessel,the GH3535 alloy was completely protected from Te corrosion at the expense of the pure Ni.Thermodynamic calculations proved that the preferential reaction between pure Ni and Te vapor reduced the activity of Te vapor considerably,preventing the corrosion of the GH3535 alloy.Our study reveals one potential approach for protecting the alloys used in molten-salt reactors from Te corrosion.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA020404040)the National High Technology Research and Development Program of China (Grant No. 2012AA03A511)
文摘The evolution of microstructure and the stress rupture properties of long term thermally exposed GH3535 alloy have been investigated. It was found that M6 C carbides presented in the solid solution heat treated samples. During long term thermal exposure at 700 C, fine M12 C carbides precipitated preferentially at grain boundaries. These carbides coexisted with the pre-exiting M6 C. The stress rupture life of700 C/1000 h exposed sample under creep testing at 650 C/324 MPa is 93 h. It is much longer than that of the solid solution samples. No noticeable changes could be detected in both the microstructure and stress rupture lives when the samples were exposed for time longer than 1000 h M12 C carbides were found to be beneficial to the creep properties. The cracks initiated at the interface of M6 C carbides and matrix, which led to a lower creep rupture life.
基金supported by National Key Research and Development Program of China (Grant No. 2016YFB0700404)the National Natural Science Foundation of China (Grant Nos. 51371188, 51671122, 51671154, 51501216, 51601213)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA02004210)
文摘As a primary material of the thorium molten salt reactor（TMSR） that is a suitable candidate reactor of the Generation IV nuclear reactors, GH3535 superalloy was successfully welded. The effect of laser beam welding（LBW） on microstructure evolution of fusion zone（FZ） and heat affected zone（HAZ）, such as element segregation, precipitate behavior and grain evolution, was investigated. The microhardness and tensile properties were tested and discussed. The results of microstructure evolution showed that a number of fine M6C-y eutectic phases precipitated at solidification grain boundaries and interdendritic region in FZ. Compared to base metal zone（BMZ）, the grain size of HAZ has no obvious change. While a few of M6C-y eutectic phases were observed in partially melted zone（PMZ） of HAZ. The results of microhardness indicated that the hardness of FZ was higher than that of HAZ and BMZ. The results of tensile test showed that the ultimate tensile strength of joints at room temperature, 650 and 700？C were98%, 97% and 99% of that of BM, respectively. All the tensile specimens of joints failed in BMZ rather than in PMZ where M6 C carbides had been transformed into M6C-y eutectic phases.
