It was found that hydrogen induced delayed failure could occur in 308L and 347L weld metals,and the threshold stress intensities of 308L and 347L welds were lower than that of 304L austenitic stainless steel.When dyn...It was found that hydrogen induced delayed failure could occur in 308L and 347L weld metals,and the threshold stress intensities of 308L and 347L welds were lower than that of 304L austenitic stainless steel.When dynamically charged under load on a single edge notched specimen,the threshold stress intensities of 308L,347L and 304L decrease with the increase in the diffusible hydrogen content C 0 and the experimental results are as follows:K ⅠH =85.2-10.7 ln C 0 (308L),K ⅠH =76.1-9.3 ln C 0 (347L),K ⅠH =91.7-10.1 ln C 0 (304L).The morphology of the hydrogen induced delayed fracture in the three materials are correlated with the K Ⅰ and C 0 values.展开更多
The valence electron structure of alloying austenite of 3C-15Cr high chromium white cast iron with different Mn contents from 1% to 6% is analyzed by BLD method and EET. Results show that the addition of Mn has major ...The valence electron structure of alloying austenite of 3C-15Cr high chromium white cast iron with different Mn contents from 1% to 6% is analyzed by BLD method and EET. Results show that the addition of Mn has major influence on the valence electron structure of the alloying austenite, especially on that of Fe-C, Fe-C-Cr and Fe-C-Cr-Mn unit cells of it. The effect becomes weak when Mn content is over 4%. Based on the effect of n~, F~~, the weighting of each unit cell and the degree of undercooling on phase transition of the aus- tenite, we can calculate the retained austenite content of as-cast structure of the high chromium white cast iron. The calculation results coincide well with those of the experiment. The phase transition characters of the austenite in high chromium white cast iron can be forecasted through valence electron structure analysis of alloying austenite by BLD method and EET on the basis of Fe-C-Cr equilibrium phase diagram.展开更多
Three different NiTi-based alloys,whose nominal compositions were Ni50Ti50,Ni49Ti49Fe2,Ni45Ti51.8Fe3.2(molefraction,%),respectively,were used in the current research to understand the influence of Fe addition on phase...Three different NiTi-based alloys,whose nominal compositions were Ni50Ti50,Ni49Ti49Fe2,Ni45Ti51.8Fe3.2(molefraction,%),respectively,were used in the current research to understand the influence of Fe addition on phase transformationbehavior in NiTi shape memory alloy(SMA).The microstructure and phase transformation behavior of the alloys were investigatedby optical microscopy(OM),transmission electron microscopy(TEM),X-ray diffraction(XRD)and differential scanningcalorimetry(DSC)analysis.The results show that the matrix of the Ni50Ti50alloy consists of both B19′(martensite)phase and B2(austenite)phase.Moreover,the substructures of twins could be observed in the B19′phase.However,the ternary alloys of NiTiFeexhibit B2phase in the microstructures.Such microstructures were also characterized by large presence of Ti2Ni precipitatesdispersed homogenously in the matrix of the two kinds of alloys.The addition of Fe to the NiTi SMA results in the decrease in phasetransformation temperatures in the ternary alloys.Based on mechanism analysis,it can be concluded that this phenomenon isprimarily attributed to atom relaxation of the distorted lattice induced by Ni-antisite defects and Fe substitutions during phasetransformation,which enables stabilization of B2phase during phase transformation.展开更多
An attempt was made to optimize friction welding parameters to attain a minimum hardness at the interface and a maximum tensile strength of the dissimilar joints of AISI 304 austenitic stainless steel （ASS） and copp...An attempt was made to optimize friction welding parameters to attain a minimum hardness at the interface and a maximum tensile strength of the dissimilar joints of AISI 304 austenitic stainless steel （ASS） and copper （Cu） alloy using response surface methodology （RSM）. Three-factor, five-level central composite design matrix was used to specify experimental conditions. Twenty joints were fabricated using ASS and Cu alloy. Tensile strength and interface hardness were measured experimentally. Analysis of variance （ANOVA） method was used to find out significant main and interaction parameters and empirical relationships were developed using regression analysis. The friction welding parameters were optimized by constructing response graphs and contour plots using design expert software. The developed empirical relationships can be effectively used to predict tensile strength and interface hardness of friction welded ASS-Cu joints at 95% confidence level. The developed contour plots can be used to attain required level of optimum conditions to join ASS-Cu alloy by friction welding process.展开更多
This study is about Eugene O＇Neill＇s use of ＂medusation＂ as an effective metatheatrical device and foremost achievement in his art. Occurring onstage as an unexpected ＂anagnorisis＂, the medusation is a traumatic...This study is about Eugene O＇Neill＇s use of ＂medusation＂ as an effective metatheatrical device and foremost achievement in his art. Occurring onstage as an unexpected ＂anagnorisis＂, the medusation is a traumatic experience that engenders ritual death. This author argues that the medusation is a quintessentially metatheatrical act, insomuch as here O＇Neill carries out a commentary on the function and functioning of theatre, through the consciously fictitious events that unfold on the stage. In the ＂Introduction＂, the author reviews its development in O＇Neill＇s plays, from the more traditional melodramatic situations of the early works to the subsequent portrayal of a self-defeating pattern calling for psychological violence and symbolic death. In the section called ＂Medusation＂, the author addresses the concept of medusation in order to account for the process whereby O＇Neill＇s people, annihilated by their sudden glimpses into the other within themselves, undergo major physical and spiritual change In ＂Case Studies＂, the author analyzes the chief correlatives of medusation： the dead-in-life, the death mask and the dead double. The author＇s point in this paper is, thus, to show how extensively and pervasively O＇Neill deploys medusation in order to signify a rite of passage that engenders metatheatrical death. Its outcome may either be the perpetuation of an endless spiral of violence and self-defeat, or a premise for rebirth arising from the characters＇ assumption of responsibility as to their share of guilt in the evil of the world, together with the renewed human sympathy and understanding that this awareness brings along展开更多
This paper focuses on work related to post irradiation examination of 300-series austenitic stainless steel taken from reactor vessel internals of PWR. High neutron irradiation dose in NNP＇s leads to a degradation of...This paper focuses on work related to post irradiation examination of 300-series austenitic stainless steel taken from reactor vessel internals of PWR. High neutron irradiation dose in NNP＇s leads to a degradation of microstructure of the material in a nano-metric scale. Hence, it is important to characterize the irradiated materials to understand the physical basis of the degradation mechanisms. Microstructural characterization of neutron-irradiated materials by TEM requires enhanced sample preparation methodologies, which commonly needs general improvements regarding particular experiment to be performed. In this study, the authors have developed methodology specialized in 1 mm TEM thin foil preparation from a deformed shank of a broken miniaturized tensile specimen. TEM foil size in current studies is smaller than standard because of the small shank diameter and high radioactivity of the studied material. The reduction of the TEM foil radioactivity to minimum is crucial to perform EDX chemical analysis and to increase the EDX detector lifetime. This paper describes whole process from bulk sample handling, including remote-controlled material cutting in shielded hot-cells and disc polishing in glow-boxes, up to the final procedure of electrolytic-polishing of electron transparent 1 mm TEM foils. Eventually, results of TEM microanalysis of radiation-induced defects were present.展开更多
The microstructure characteristies of the dual phase strueture of austenite and bamite obtained in a silicon high carbon low-alloy steel,isothermally transformed, have been inverstigated and compared witb that of the ...The microstructure characteristies of the dual phase strueture of austenite and bamite obtained in a silicon high carbon low-alloy steel,isothermally transformed, have been inverstigated and compared witb that of the conventionai types of mierostructure. The influence of the isothermal transformation temperatures on the mierostrueture and the mechanical properties of the steel bas been examined. Therefore, the strengthening meehanism of the new dual phase steel with ultra-high strength has been revealed.展开更多
基金Special Fund for the Major Basic Research Projects(No.G1 9990 650 )
文摘It was found that hydrogen induced delayed failure could occur in 308L and 347L weld metals,and the threshold stress intensities of 308L and 347L welds were lower than that of 304L austenitic stainless steel.When dynamically charged under load on a single edge notched specimen,the threshold stress intensities of 308L,347L and 304L decrease with the increase in the diffusible hydrogen content C 0 and the experimental results are as follows:K ⅠH =85.2-10.7 ln C 0 (308L),K ⅠH =76.1-9.3 ln C 0 (347L),K ⅠH =91.7-10.1 ln C 0 (304L).The morphology of the hydrogen induced delayed fracture in the three materials are correlated with the K Ⅰ and C 0 values.
文摘The valence electron structure of alloying austenite of 3C-15Cr high chromium white cast iron with different Mn contents from 1% to 6% is analyzed by BLD method and EET. Results show that the addition of Mn has major influence on the valence electron structure of the alloying austenite, especially on that of Fe-C, Fe-C-Cr and Fe-C-Cr-Mn unit cells of it. The effect becomes weak when Mn content is over 4%. Based on the effect of n~, F~~, the weighting of each unit cell and the degree of undercooling on phase transition of the aus- tenite, we can calculate the retained austenite content of as-cast structure of the high chromium white cast iron. The calculation results coincide well with those of the experiment. The phase transition characters of the austenite in high chromium white cast iron can be forecasted through valence electron structure analysis of alloying austenite by BLD method and EET on the basis of Fe-C-Cr equilibrium phase diagram.
基金Projects(51305091,51305092,51475101)supported by the National Natural Science Foundation of ChinaProject(20132304120025)supported by Specialized Research Fund for the Doctoral Program of Higher Education,China
文摘Three different NiTi-based alloys,whose nominal compositions were Ni50Ti50,Ni49Ti49Fe2,Ni45Ti51.8Fe3.2(molefraction,%),respectively,were used in the current research to understand the influence of Fe addition on phase transformationbehavior in NiTi shape memory alloy(SMA).The microstructure and phase transformation behavior of the alloys were investigatedby optical microscopy(OM),transmission electron microscopy(TEM),X-ray diffraction(XRD)and differential scanningcalorimetry(DSC)analysis.The results show that the matrix of the Ni50Ti50alloy consists of both B19′(martensite)phase and B2(austenite)phase.Moreover,the substructures of twins could be observed in the B19′phase.However,the ternary alloys of NiTiFeexhibit B2phase in the microstructures.Such microstructures were also characterized by large presence of Ti2Ni precipitatesdispersed homogenously in the matrix of the two kinds of alloys.The addition of Fe to the NiTi SMA results in the decrease in phasetransformation temperatures in the ternary alloys.Based on mechanism analysis,it can be concluded that this phenomenon isprimarily attributed to atom relaxation of the distorted lattice induced by Ni-antisite defects and Fe substitutions during phasetransformation,which enables stabilization of B2phase during phase transformation.
文摘An attempt was made to optimize friction welding parameters to attain a minimum hardness at the interface and a maximum tensile strength of the dissimilar joints of AISI 304 austenitic stainless steel （ASS） and copper （Cu） alloy using response surface methodology （RSM）. Three-factor, five-level central composite design matrix was used to specify experimental conditions. Twenty joints were fabricated using ASS and Cu alloy. Tensile strength and interface hardness were measured experimentally. Analysis of variance （ANOVA） method was used to find out significant main and interaction parameters and empirical relationships were developed using regression analysis. The friction welding parameters were optimized by constructing response graphs and contour plots using design expert software. The developed empirical relationships can be effectively used to predict tensile strength and interface hardness of friction welded ASS-Cu joints at 95% confidence level. The developed contour plots can be used to attain required level of optimum conditions to join ASS-Cu alloy by friction welding process.
文摘This study is about Eugene O＇Neill＇s use of ＂medusation＂ as an effective metatheatrical device and foremost achievement in his art. Occurring onstage as an unexpected ＂anagnorisis＂, the medusation is a traumatic experience that engenders ritual death. This author argues that the medusation is a quintessentially metatheatrical act, insomuch as here O＇Neill carries out a commentary on the function and functioning of theatre, through the consciously fictitious events that unfold on the stage. In the ＂Introduction＂, the author reviews its development in O＇Neill＇s plays, from the more traditional melodramatic situations of the early works to the subsequent portrayal of a self-defeating pattern calling for psychological violence and symbolic death. In the section called ＂Medusation＂, the author addresses the concept of medusation in order to account for the process whereby O＇Neill＇s people, annihilated by their sudden glimpses into the other within themselves, undergo major physical and spiritual change In ＂Case Studies＂, the author analyzes the chief correlatives of medusation： the dead-in-life, the death mask and the dead double. The author＇s point in this paper is, thus, to show how extensively and pervasively O＇Neill deploys medusation in order to signify a rite of passage that engenders metatheatrical death. Its outcome may either be the perpetuation of an endless spiral of violence and self-defeat, or a premise for rebirth arising from the characters＇ assumption of responsibility as to their share of guilt in the evil of the world, together with the renewed human sympathy and understanding that this awareness brings along
文摘This paper focuses on work related to post irradiation examination of 300-series austenitic stainless steel taken from reactor vessel internals of PWR. High neutron irradiation dose in NNP＇s leads to a degradation of microstructure of the material in a nano-metric scale. Hence, it is important to characterize the irradiated materials to understand the physical basis of the degradation mechanisms. Microstructural characterization of neutron-irradiated materials by TEM requires enhanced sample preparation methodologies, which commonly needs general improvements regarding particular experiment to be performed. In this study, the authors have developed methodology specialized in 1 mm TEM thin foil preparation from a deformed shank of a broken miniaturized tensile specimen. TEM foil size in current studies is smaller than standard because of the small shank diameter and high radioactivity of the studied material. The reduction of the TEM foil radioactivity to minimum is crucial to perform EDX chemical analysis and to increase the EDX detector lifetime. This paper describes whole process from bulk sample handling, including remote-controlled material cutting in shielded hot-cells and disc polishing in glow-boxes, up to the final procedure of electrolytic-polishing of electron transparent 1 mm TEM foils. Eventually, results of TEM microanalysis of radiation-induced defects were present.
文摘The microstructure characteristies of the dual phase strueture of austenite and bamite obtained in a silicon high carbon low-alloy steel,isothermally transformed, have been inverstigated and compared witb that of the conventionai types of mierostructure. The influence of the isothermal transformation temperatures on the mierostrueture and the mechanical properties of the steel bas been examined. Therefore, the strengthening meehanism of the new dual phase steel with ultra-high strength has been revealed.
