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1

Creep rupture properties of a nickel-base heat-resistant alloy Hastelloy XR under varying stress condition  

International Nuclear Information System (INIS)

A series of constant load and temperature creep rupture tests and varying stress creep rupture tests was carried out on a nickel-base heat-resistant alloy Hastelloy XR, which was developed for applications in the High-Temperature Engineering Test Reactor, at temperatures ranging from 850 to 1000 degC in order to examine the applicability of the conventional creep damage rules, i.e., the life fraction, the strain fraction and their mixed rules. Among these three criteria, the life fraction rule showed the best applicability. The good applicability of the rule was considered to result from the fact that the creep strength of Hastelloy XR was not strongly affected by the change of the chemical composition and/or the microstructure during exposure to the high-temperature simulated HTGR helium environment. In conclusion the life fraction rule is applicable in engineering design of high-temperature components made of Hastelloy XR. (author)

2

Creep rupture properties of a nickel-base heat-resistant alloy Hastelloy XR under varying temperature/stress condition  

International Nuclear Information System (INIS)

A series of constant temperature and load creep rupture tests and varying temperature and/or load creep rupture tests was carried out on a nickel-base heat-resistant alloy Hastelloy XR, which was developed for applications in the High-Temperature Engineering Test Reactor, at 850 to 1000degC in the simulated HTGR helium gas. This report describes the applicability of the conventional creep damage rules, i.e., the life fraction, the strain fraction and their mixed rules, to the alloy. The applicability was examined using the data under varying both temperature and load conditions as well as those, which were obtained in the previous work, under constant temperature and varying load conditions. The life fraction rule showed the best applicability of these three criteria. The good applicability of the rule was considered to show that the change of the chemical composition and/or the microstructure during exposure to the high-temperature simulated HTGR helium environment was not appreciable to affect the creep strength of Hastelloy XR. Though the life fraction rule under varying both temperature and load conditions is slightly less applicable than that under constant temperature and varying load conditions, it has been concluded that the rule is applicable in engineering design of high-temperature components made of Hastelloy XR. (author)

3

Multiaxial creep behavior of nickel-base heat-resistant alloys Hastelloy XR and Ni-Cr-W superalloy at elevated temperatures  

International Nuclear Information System (INIS)

A series of uniaxial and multiaxial creep tests was carried out on Hastelloy XR and Ni-Cr-W superalloy, which were developed as the high temperature structural materials for nuclear application at the JAERI, in order to investigate multiaxial creep behavior of these materials. Norton's creep law and von Mises' flow rule were applied to the prediction of multiaxial creep behavior of a tube under some significant loading conditions. In most cases the multiaxial creep behavior of these materials were successfully described with the constitutive equations based on the material parameter fitting uniaxial creep test results, though a few exceptional cases were observed. The present study has revealed that the method based on Norton's creep law and von Mises' flow rule are basically applicable for the description of the multiaxial creep behavior for Hastelloy XR and Ni-Cr-W superalloy as the conventional design method. (author)

4

Heat resistant cast aluminium alloys with iron  

International Nuclear Information System (INIS)

On the base of structural approach principal possibility of development of cheaper high-iron cast heat resisting aluminium alloys is proved. Perspective Al-Fe-Ce-Zr-Cr and Al-Fe-Ni-Zr-Cr compositions are proposed. The alloys proposed have high heat resistance, mechanical and casting properties

5

Studies on neutron irradiation effects of iron alloys and nickel-base heat resistant alloys  

International Nuclear Information System (INIS)

The present paper describes the results of neutron irradiation effects on iron alloys and nickel-base heat resistant alloys. As for the iron alloys, irradiation hardening and embrittlement were investigated using internal friction measurement, electron microscopy and tensile testings. The role of alloying elements was also investigated to understand the irradiation behavior of iron alloys. The essential factors affecting irradiation hardening and embrittlement were thus clarified. On the other hand, postirradiation tensile and creep properties were measured of Hastelloy X alloy. Irradiation behavior at elevated temperatures is discussed. (author)

6

Electron beam welding of dissimilar heat resistant alloys  

International Nuclear Information System (INIS)

To the welding of the different heat resistant materials for high temperature gas-cooled reactors, electron beam welding was applied, and the high temperature strength of the weld metal was examined as it is necessary for evaluating the welded joints. As the results, the high temperature strength of the weld metal of Hastelloy X and 2.25 Cr-1Mo steel at 500 degC and that of Hastelloy X and SUS316 at 600 degC showed the nearly intermediate values of both parent materials in both cases. Accordingly, when the high temperature strength of electron beam welded metals is evaluated, it is considered that by evaluating at least with the value of a lower strength parent metal, sufficient safety is ensured. In this study, the electron beam welded joints of typical different heat resistant alloys were made, and the tesile strength, creep rupture strength and low cycle fatique strength of the weld metals at high temperature were determined to compare with those of parent alloys. The tested alloys, welding method and high temperature tests are reported. (Koko, I.)

7

Structure effect on niobium alloy heat resistance  

International Nuclear Information System (INIS)

Stusied are the possibilities to increase alloy heat resistance due to obtaining structure with optimum grain size. The effect of the grain size on physical and mechanical properties and on heat resistance is studied. The physical nature of this effect is understood. It is established that heat resistance dependence on grain size is nonmonotonous, i.e. the rate of secondary creep of the alloy decreases at first, reaches minimum, and then decreases. It is shown that dependences of X-ray line width, electric resistivity and hardness on grain size are of the same character, that evidences the changes occurring in the structure of the grain itself. Determined are the values of effective energy of recrystallization process activation which agree with views of the controlling role of diffusion processes of different types. The complex of investigations carried out permitted to establish the optimum grain size (100-120 ?m) for alloy providing its maximum level of heat resistance

8

Filler metal development for hastelloy alloy XR  

International Nuclear Information System (INIS)

A method of alloy designing has been proposed and validated to develop the filler metal for Hastelloy alloy XR(nuclear reactor grade of Hastelloy alloy X), which is the candidate material for high temperature structure of High-Temperature Engineering Test Reactor (HTTR). In the filler metal development for Hastelloy alloy XR, materials of two heats were melted and fabricated with special emphasis placed on manufacturing process. One is the trial products (alloy termed 'C') designed by using multiple regression analysis in the range of the chemical composition specified as Hastelloy alloy X. The other is filler metal (alloy termed 'D') with optimum boron content in the same chemical composition as Hastelloy alloy XR. The results of the tests on several key items may be summarized as follows: (1) Weldments with alloy'C' showed higher strength and ductility at elevated temperatures than those of alloy'D'. (2) Weldments with alloy'D' had more excellent strength characteristics at elevated temperatures than those of the other conventional filler metals. (3) As for weldability, the crater cracks were slightly observed in the FISCO cracking test, but those were out of the problem in the degree of cracking from the viewpoint of practical application. The results of qualification tests on weldability showed good performance for all welding conditions of the present experiments. On the other hand, the mechanism of hot cracking initiation and the controlling factors in hot cracking susceptibility with relation to boron content have been clarified for Hastelloy alloy XR base metal. (author)

9

Dendritic liquiation in nickel heat resisting alloys  

International Nuclear Information System (INIS)

Dendrite and phase heterogeneity in the casting heat-resistant nickel alloys of the Ni-Ci-W-Al-Ti system is determined. It is shown that hafnium possesses the maximum coefficient of liquation in the nickel alloys under investigation. Molybdenum in the presence of hafnium changes its liquation sign for the opposite one. Vanadium is gradually distributed in the axes and interaxis parts, its liquation being insignificant

10

Filler metal development for Hastelloy alloy XR  

International Nuclear Information System (INIS)

In order to develop the filler metal for Hastelloy alloy XR structure with thick wall, the weldability and high temperature strength properties of Hastelloy alloy XR weldment were investigated using the filler metals, which were alloy-designed on the basis of multiple regression analysis. The former was examined through the chemical analysis in the deposited metal, bend test, FISCO cracking test, optical microscopy and hardness measurement. The latter was investigated by means of tensile and creep test. It was found from these results that the crack susceptibility in the weldment was apparent to be lowered without degrading the high temperature strength properties. Therefore, it is concluded that these filler metals possess excellent performance as the filler metal for Hastelloy alloy XR structure with thick wall. (author)

11

Filler metal development for Hastelloy alloy XR  

International Nuclear Information System (INIS)

The present report describes the results of cooperative research in order to evaluate the weldability and properties of Hastelloy alloy XR weldment with the filler metal fabricated on the industrial scale. A series of qualification test was performed using the filler metal, of which the content of the minor elements such as boron was optimized on the basis of the results so far obtained by the filler metal development for Hastelloy alloy XR structure with thin wall. The boron diffusion behavior, weldability, and the properties such as corrosion, aging embrittlement and high temperature strength were examined on the Hastelloy alloy XR weldment by means of tungsten inert gas arc welding procedure. Based on the excellent weldability and weldment properties as well as the mass production possibility for the filler metal, it is concluded that the filler metals possessing the required performance has been developed. (author)

12

A View of Compatible Heat-Resistant Alloy and Coating Systems at High-Temperatures  

International Nuclear Information System (INIS)

Conventional and advanced coatings were reviewed, and it was pointed out that the coated Ni-base superalloys decreased their creep rupture life significantly at higher temperatures, and the advanced high strength superalloy became more remarkably. Concept of diffusion barrier coating system (DBC system) and their formation process was introduced, and the results obtained for several heat-resistant alloys, stainless steel (SUS310S), Ni-Mo base alloy (Hastelloy-X), and 4th generation single crystal superalloy (TMS-138) were given. It was noted that creep-rupture life of the SUS310S and Hastelloy-X with the DBC system became longer than those of the bare alloys with or without conventional ?-NiAl coatings. This is due to slow creep-deformation of the Re-base alloy layer as the diffusion barrier. A novel concept based on combination of superalloys and coatings was proposed, by taking both the materials science and corrosion science into consideration.

13

Machining of high alloy steels and heat resistant alloys  

International Nuclear Information System (INIS)

The peculiarities of machining high alloy steels and heat resistant alloys on the base of nickel by cutting are described. The factors worsening the machining of heat resistant materials, namely, the low heat conductivity, strong reverting and high wearing capability, are pointed out. The resign and materials of cutting instruments, providing for high quality machining of heat resistant steels and alloys, are considered. The necessity of regulating thermal processes during cutting with cutting fluids and other coolants (e.g. air with a negative temperature) is noted. The recommended modes of cutting are presented. The efficiency of the conveyer-type method for sawing products and forged intermediate articles is demonstrated by the example of 5KhNM steel

14

Diffusion welding of molybdenum to hastelloy alloy X  

International Nuclear Information System (INIS)

Diffusion welding between pure molybdenum and heat-resisting alloy Hastelloy X has been performed in vacuum at the temperature range of 7500C-12000C. Two steps welding technique including a short time annealing at high temperature (1 minute at 12000C) increases the real metal-contact between molybdenum and Hastelloy alloy X, and takes the improvements in joint strength. Furthermore, this technique is useful not to enlarge the deformation at weld joint. Application of Ni insert-metal suppresses the formation of brittle intermetallic compound, P phase, and increases the joint strength. However, the formation of binary compound, delta-MoNi, was observed at bonding interface. Fracture of the weld joints by the tensile strength tests at room temperature has occured always through the intermetallic compounds and also along the grain boundaries of molybdenum base metal. After the welding procedure, the voids and MoO2 were found out at the grain boundaries of molybdenum using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. (auth.)

15

Diffusion welding of molybdenum to hastelloy alloy X  

International Nuclear Information System (INIS)

Diffusion welding between pure molybdenum and heat-resisting alloy hastelloy X has been performed in vacuum at the temperature range of 7500C -- 12000C. Tensile strength of the weld joint at room temperature is discussed on the effects of methods in welding technique and a use of Ni insert-metal. The use of two steps welding technique and a Ni insert-metal is appreciable to improve the tensile strength of weld joint, but the fracture had occured always near weld bond. Metallographical investigations using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction analysis and electron probe X-ray microanalysis have been performed in order to clarify the effects of two steps welding technique and a use of Ni insert-metal on the microstructure near the bonding interface. Results obtained are summarized as follows; (1) Two steps welding technique including a short time annealing at high temperature (1 minute at 12000C) increases the real metal-contact between molybdenum and hastelloy X, and takes the improvement of the joint strength. Furthermore, this technique is useful not to enlarge the deformation by welding procedure. (2) Application of the Ni insert-metal suppresses the formation of the brittle intermetallic compound, P phase, and increases the tensile strength. However the formation of binary compound, delta-MoNi, was observed at the bonding interface. (3) Fracture of the weld joints by the tensile strength tests has occurred always through the intermetallic compounds and also along the grain boundaries of molybdenum base metal. (4) After the welding procedure, the voids and MoO2 were found out at the grain boundaries of molybdenum using SEM and TEM techniques. (auth.)

16

Heat resistant magnesium alloys for automotive powertrain applications  

Energy Technology Data Exchange (ETDEWEB)

The suitability of new Mg-Zn-Al-Ca-RE alloys for automotive power train applications are evaluated. Zinc and aluminum contents of the alloys were systematically varied in order to determine alloys with a combination of good diecasting characteristics and high heat resistance. Addition of large amounts of zinc to the alloys results in the formation of intermetallic compounds that crystallize at lower temperatures relative to the matrix, and consequently, fluidity is improved, but hot tearing occurs during diecasting. However, one of the new alloys, Mg-0.5%Zn-6%Al-1%Ca-3%RE alloy is found to exhibit good diecastability and comparable heat resistance with the conventional aluminum alloy, ADC12 that is currently used for diecasting of automotive powertrain parts. (orig.)

Anyanwu, I.A.; Gokan, Y.; Nozawa, S.; Kamado, S.; Kojima, Y. [Dept. of Mechanical Engineering, Nagaoka Univ. of Technology, Nagaoka, Niigata (Japan); Takeda, S.; Ishida, T. [Ahresty Corp., Magnesium Products Mfg. Div., Tochigi (Japan)

2003-07-01

17

Compatibility of heat resistant alloys with boron carbide  

International Nuclear Information System (INIS)

The solid state compatibility of Hastelloy X and Incoloy 800 with boron carbide (B4C) were investigated at 850 - 10500C for periods of 20 - 2000 hrs for potential control rod application for Very High Temperature Gas-cooled Reactor (VHTR). These studies have shown both the alloys were incompatible with nearly stoichiometric B4C or B4C+C (70 wt% carbon) and they were less compatible with nearly stoichiometric B4C than with B4C over the temperature range 850 to 10000C. At 10500C for 100 hrs both of the alloys reacted with nearly stoichiometric B4C or B4C+C were melt by producing eutectic alloys. It was observed that boron and carbon penetration in the alloy is dominated by the grain boundary penetration. And some had a uniform reaction layer near the surface as a result of volume penetration. In general Incoloy 800 was more compatible than Hastelloy X and it was clearly seen by comparing the volume penetration depth reacted with nearly stoichiometric B4C at 9500C for 100 hrs. In Hastelloy X the depth was 225 ?m but in Incoloy 800 it was 117 ?m. The phases formed on alloys were identified to be Fe2B, Cr2B and Ni2B by X-ray diffraction. By the tensile test of reacted Hastelloy X material, it was found that the ultimate tensile strength was reduced due to the reaction of alloy with boron carbide but there was no change on the yield strength. (author)

18

New iron base heat resisting alloys for application in high temperature gas-cooled reactor  

International Nuclear Information System (INIS)

Heat resisting steels with relatively low nickel content have been designed and tested, which showed creep strength and corrosion resistance equivalent or superior to the present prime candidate nickel base alloys. The materials are expected to substitute nickel base alloys in the applications to the components in reactor core, e.g. neutron absorber sheathing, for which most nickel rich alloys are not suited because of their susceptibility to the loss of ductility caused by thermal neutron irradiation. 12Cr-12Ni-5Mo-5Cu-iron base alloys were designed and several similar versions were prepared. Tests at high temperatures were conducted on tensile properties at up to 10000C, creep rupture properties at 700 -- 9000C, toughness after aging at 700 and 8000C and corrosion resistance in the impure helium gas at 9000C. The helium environment was prepared simulating the impurity contents in the coolant of high temperature gas-cooled reactor. After exposure test to the impure helium, changes in weight and carbon content were measured, and metallurgical analysis was made by optical microscopy, EPMA analysis and X-ray diffraction. It was found that creep rupture strength of a heat of 12Cr-12Ni-5Mo-5Cu steel with small amounts of niobium was superior to the prime candidate material, Hastelloy alloy XR and was comparable to Inconel alloy 617, although some significant decrease in toughness occurred after aging at intermediate temperatures. Weight gain due to oxidation and carbon increase due to carburization of this steel in the simulated impure helium gas were lower than those of Hastelloy alloy XR. In conclusion this alloy, with appropriate modification, can be a potential substitutional material as the structural material to be used under thermal neutron exposure. The material may also be potential for general structural applications for high temperature gas-cooled reactors, substituting the commonly used material like Incoloy alloy 800H. (author)

19

Metal Dusting of Heat-Resistant Alloys  

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Metal dusting leads to disintegration of such alloys as iron and nickel-based into a “dust” of particulate metal, metal carbide, carbon, and/or oxide. It occurs in strongly carburising environments at 400-900°C. Literature survey has shown that alloys behave differently in metal dusting conditions based on their composition and the environment. Metal dusting mechanisms for iron and nickel-based alloys have been proposed but, nevertheless, have not been agreed upon and numerous modificati...

Al-meshari, Abdulaziz I.

2008-01-01

20

Hydrogen permeation through iron, nickel, and heat resisting alloys at elevated temperatures  

International Nuclear Information System (INIS)

Hydrogen permeability of several metals and alloys was measured in the temperature range between 2000 and 10000C and some factors affecting the hydrogen permeability were discussed. Materials studied were iron, nickel, 80Ni-20Cr alloy, 50Fe-30Ni-20Cr alloy, HK 40, Incoloy 800, Hastelloy X, and Inconel 600. The hydrogen permeability of nickel was proportional to the square root of the pressure and inversely proportional to the membrane thickness. The activation energy and pre-exponential factor for the hydrogen permeation through these metals and alloys were derived from the temperature coefficient. The hydrogen permeability of nickel was larger than that of iron (?), and the permeabilities of the heat resisting alloys were between those of nickel and iron (?). There was a close correlation between the hydrogen permeability and nickel content in the alloys, that is, the permeability increased with the increase of the nickel content in the alloys. The formation of the oxide film on the alloy surface in wet hydrogen resulted in a remarkable reduction of the hydrogen permeability at elevated temperatures. (author)

 
 
 
 
21

Hydrogen permeation through iron, nickel, and heat resisting alloys at elevated temperatures  

International Nuclear Information System (INIS)

Hydrogen permeabilities of several metals and alloys were measured over the temperature range of 200 - 10000C and some factors affecting the hydrogen permeability were discussed. Materials studied were iron, nickel, 80Ni-20Cr alloy, 50Fe-30Ni-20Cr alloy, HK 40, Incoloy 800, Hastelloy X, and Inconel 600. The hydrogen permeability of nickel was proportional to the square root of the pressure and inversely proportional to the membrane thickness. The activation energy and pre-exponential factor for the hydrogen permeation through these metals and alloys were derived from the temperature coefficient. The hydrogen permeability of nickel was larger than that of iron (?), and the permeabilities of the heat resisting alloys were between those of nickel and iron (?). There was a close correlation between the hydrogen permeability and nickel content in the alloys, that is, the permeability increased with the increase of the nickel content in the alloys. The formation of the oxide film on the alloy surface in wet hydrogen resulted in a remarkable reduction of the hydrogen permeability at elevated temperatures. (auth.)

22

Study of creep and rupture behavior for a Ni-base heat resistant alloy improved for high temperature gas-cooled reactor  

International Nuclear Information System (INIS)

Creep-rupture tests of Hastelloy XR-II, a Ni-base heat resistant alloy modified for HTGR environment, were carried out in air and simulated HTGR helium at 700-1000degC up to 26,733 hours in the longest rupture time and about 207,000 hours in total testing times. The data was evaluated for high-temperature structural design using time-temperature parameter method. The boron content of Hastelloy XR-II (about 0.005 mass%) has been increased within the specification of Hastelloy XR. Experimental data and evaluated results were compared with the previous results for Hastelloy XR with low boron content (0.00028 mass%). Followings are a summary of the major findings. 1) Larger ductility is observed for Hastelloy XR-II than Hastelloy XR at higher temperatures. 2) The 100,000 h strength of Hastelloy XR-II is approximately twice of Hastelloy XR at 800 and 900degC. 3) The microstructural observation of creep-ruptured specimens showed a few macrocracks at 700degC, but round-type cavities at grain boundaries were pronounced with increasing temperatures. 4) With regard to the effect of the product forms, the creep-rupture strength of specimens sampled from tubes is slightly higher at 1000degC than that from plates. 5) The creep curves above 900degC were predominantly nonclassical. 6) The allowable stresses of So, Sm and St were computed using similar procedure employed for the previous data on Hastelloy XR with lower boron content. The significant increase in the So and St for Hastelloy XR-II over Hastelloy XR is recognized due to the improvement of both creep strength and creep-rupture ductility. (J.P.N.)

23

Ignition and combustion of heat resisting alloy in oxygen  

International Nuclear Information System (INIS)

Phenomenological investigation into the processes of ignition and combustion of heat resisting alloy with increased nickel content in gaseous oxygen at the pressures of up to 130 atm is conducted. Under ohmic heating it is obtained that samples of cylindrical configuration are ignited at the temperatures lower than the alloy melting point. Dependences of sample surface temperature at which ignition tukes place, on oxygen pressure and sample diameter are obtained, the rate of flame propagation over the sample under its different orientation in space measured

24

Corrosion of nickel-base heat resistant alloys in simulated VHTR coolant helium at very high temperatures  

International Nuclear Information System (INIS)

A comparative evaluation was made on three commercial nickel-base heat resistant alloys exposed to helium-base atmosphere at 10000C, which contained several impurities in simulating the helium cooled very high temperature nuclear reactor (VHTR) environment. The choice of alloys was made so that the effect of elements commonly found in commercial alloys were typically examined. The corrosion in helium at 10000C was characterized by the sharp selection of thermodynamically unstable elements in the oxidizing process and the resultant intergranular penetration and internal oxidation. Ni-Cr-Mo-W type solution hardened alloy such as Hastelloy-X showed comparatively good resistance. The alloy containing Al and Ti such as Inconel-617 suffered adverse effect in contrast to its good resistance to air oxidation. The alloy nominally composed only of noble elements, Ni, Fe and Mo, such as Hastelloy-B showed least apparent corrosion, while suffered internal oxidation due to small amount of active impurities commonly existing in commercial heats. The results were discussed in terms of selection and improvement of alloys for uses in VHTR and the similar systems. (auth.)

25

Physicochemical fundamentals of designing heat resistant silicide coatings on niobium and its alloys  

International Nuclear Information System (INIS)

Processes of structure formation of multicomponent protective coatings made of silicide heat resistant alloys on niobium and its heat resistant alloys (Nb-Ti-Al) by the method of gas-thermal spraying and regularities of hiqh-temperature reaction procedure in the system of these coatings in interaction with elements of a protected substrate and with air are analysed. Principles of development of heat resistant silicide alloys intended for formation of high-temperature protective coatings on refractory metals are formulated

26

Investigation of EDM characteristics of Nickel-based heat resistant alloy  

International Nuclear Information System (INIS)

The EDM processing characteristics of one of the nickel-based heat resistant alloys, Hastelloy-X, were investigated under the various EDM conditions and analyzed in terms of surface integrity. This alloy is commonly used as a material for the hot gas path component of gas turbines and it is difficult to machine by conventional machining methods. The primary EDM parameter which was varied in this study were the pulse-on time. Since the pulse-on time is one of the main factors that determines the intensity of the electrical discharge energy, it was expected that the machining ratio and the surface integrity of the specimens would be proportionally dependent on the pulse-on duration. However, experimental results showed that MRR (Material Removal Rate) and EWR (Electrode Wear Rate) behaved nonlinearly with respect to the pulse duration, whereas the morphological and metallurgical features showed rather a constant trend of change by the pulse duration. In addition the heat treating process affected the recast layer and HAZ to be recrystallized but softening occurred in recast layer only. A metallurgical evaluation of the microstructure for the altered material zone was also conducted

27

Investigation of EDM characteristics of Nickel-based heat resistant alloy  

Energy Technology Data Exchange (ETDEWEB)

The EDM processing characteristics of one of the nickel-based heat resistant alloys, Hastelloy-X, were investigated under the various EDM conditions and analyzed in terms of surface integrity. This alloy is commonly used as a material for the hot gas path component of gas turbines and it is difficult to machine by conventional machining methods. The primary EDM parameter which was varied in this study were the pulse-on time. Since the pulse-on time is one of the main factors that determines the intensity of the electrical discharge energy, it was expected that the machining ratio and the surface integrity of the specimens would be proportionally dependent on the pulse-on duration. However, experimental results showed that MRR (Material Removal Rate) and EWR (Electrode Wear Rate) behaved nonlinearly with respect to the pulse duration, whereas the morphological and metallurgical features showed rather a constant trend of change by the pulse duration. In addition the heat treating process affected the recast layer and HAZ to be recrystallized but softening occurred in recast layer only. A metallurgical evaluation of the microstructure for the altered material zone was also conducted.

Kang, Sin Ho; Kim, Dae Eun [Yonsei Univ., Seoul (Korea, Republic of)

2003-10-01

28

Creep behavior of Ni-base heat resistant alloys for high temperature gas-cooled reactors in decarburizing helium environment  

International Nuclear Information System (INIS)

Creep and corrosion tests of Ni-base heat resistant alloys (Hastelloy XR and XR-II) for high temperature gas-cooled reactors (HTGR) were conducted at 950 deg C in several kinds of helium environments with different impurity compositions in order to examine the effect of decarburizing environment on creep behavior. Creep and corrosion data were analyzed on the basis of theoretical consideration in corrosion to clarify the corrosion mechanism in impure helium. Both alloys were decarburized in helium environment with low partial pressure of oxygen and carbon activity. The decarburization induced degradation of creep properties such as lower creep rupture strength, higher creep rate and earlier start of accelerating creep. Problems of the decarburization of the Hastelloy XR and XR-II in the primary helium coolant of HTGR could be predicted by using a stability diagram for chromium. Controlling impurities to maintain higher partial pressure of oxygen and carbon activity in primary coolant of HTGR is proposed in order to prevent degradation of creep properties of the materials caused by decarburization. (author)

29

Structure and properties of Ni-Cr-Al plasma coating on heat resisting nickel alloys  

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Properties and structure of Ni-Cr-Al system powder plasma coatings on heat resisting nickel alloys, applied for protection from high-temperature corrosion, are studied. To increase corrosion resistance, the coatings were additionally densified by laser melting

30

Evaluation of creep and relaxation data for hastelloy alloy x sheet  

International Nuclear Information System (INIS)

Hastelloy alloy X has been a successful high-temperature structural material for more than two decades. Recently, Hastelloy alloy X sheet has been selected as a prime structural material for the proposed Brayton Isotope Power System (BIPS). The material also sees extensive application in the High-Temperature Gas-Cooled Reactor (HTGR). Design of these systems requires a detailed consideration of the high-temperature creep properties of this material. Therefore, available creep, creep-rupture, and relaxation data for Hastelloy alloy X were collected and analyzed to yield mathematical representations of the behavior for design use

31

Corrosion characteristics of Hastelloy N alloy after He+ ion irradiation  

International Nuclear Information System (INIS)

With the goal of understanding the invalidation problem of irradiated Hastelloy N alloy under the condition of intense irradiation and severe corrosion, the corrosion behavior of the alloy after He+ ion irradiation was investigated in molten fluoride salt at 700 °C for 500 h. The virgin samples were irradiated by 4.5 MeV He+ ions at room temperature. First, the virgin and irradiated samples were studied using positron annihilation lifetime spectroscopy (PALS) to analyze the influence of irradiation dose on the vacancies. The PALS results showed that He+ ion irradiation changed the size and concentration of the vacancies which seriously affected the corrosion resistance of the alloy. Second, the corroded samples were analyzed using synchrotron radiation micro-focused X-ray fluorescence, which indicated that the corrosion was mainly due to the dealloying of alloying element Cr in the matrix. Results from weight-loss measurement showed that the corrosion generally correlated with the irradiation dose of the alloy. (author)

32

Studies on thermal properties of some heat-resisting alloys for high temperature gas reactor  

International Nuclear Information System (INIS)

in ?-T, C sub(p)-T and lanbda-T curves. Average linear expansion coefficient ? was monotonously increased with the increase of temperature and the value of ? of Hastelloy X was the smallest among the three alloys. The hardness of alloys which were aging at 500 -- 8000C for 5 hours were larger than that of solution-treated alloys by about 20% and this hardening was caused by precipitation of carbides. (author)

33

Study of creep and rupture behavior for hastelloy alloy XR  

International Nuclear Information System (INIS)

Creep tests of Hastelloy alloy XR (a modified Hastelloy alloy X developed for VHTR application) were carried out at 800, 900 and 10000C up to 310,000 hours in total testing times. The effects of environment (air and simulated VHTR helium), specimen diameters, product forms of the material (tube, plate and bar) and the neutron irradiation were also investigated. The ASME allowable stresses (Ssub(o), Ssub(m), and Ssub(t) in Code Case N-47) required to establish the design limit on the primary system were calculated using the current data. A procedure was developed to calculate equations which represented lower limits of the prediction intervals and the simultaneous tolerance intervals of strength on the basis of regression analysis. Statistical analysis of the three time-temperature parameter methods showed that the Manson-Succop method was better than that of either Larson-Miller or Orr-Sherby-Dorn in respect of curve fitting to the present creep-rupture data. Application of the Garofalo equation to the strain-time data resulted in a creep constitutive equation (tentative version) which represented the average isochronous stress-strain curves. It was recognized that there was little difference between air and helium in the creep-rupture strength up to about 10,000 hours. In helium environment there appeared slight indication that carburization occured in the early stage of exposure but no further carbon intrusion was observed in the steady state creep range. Comparison of creep behaviors among three product forms of the same heat indicated that the bar had superior creep-strength to the tube. This was attributed to the banded precipitation of carbides in the tube. As a result of significant ductility loss due to the neutron irradiation up to 8.7 x 1020n/cm2(th) at 600C, the rupture times reduced below about 20% that of the unirradiated one. (author)

34

Putting into production of large-sized semiproducts of heat resistant nickel alloys  

International Nuclear Information System (INIS)

he process of manufacturing large-sized semiproducts of heat resistant nickel base alloys (ZhS26, ZhS32, EhK79-ID, EhK151-ID, EhK152-ID) is described. The process runs according to the following production schedule: induction-vacuum (or open) melting ? electroslag remelting ? preliminary machining ? hot forging and pressing ? heat treatment. The tests include chemical express-analysis of the alloys obtained using a computerized optical emission spectrometer. Heat resistant nickel alloys are used for manufacture of turbine blades and discs for GTE

35

Resistance of welded joints of heat resistant nickel alloys of Hastalloy type against hot cracking  

International Nuclear Information System (INIS)

The tendency of welded joints of heat resistant alloys of Hast-alloy tipe on the base of nickel of the system nickel-chromium-molybdenum to hot cracking is considered. The topography of occurence of cracks and possible mechanism of their formation have been found

36

Effects of aging and test temperature on tensile and fatigue properties of nickel-base heat-resistant alloy  

International Nuclear Information System (INIS)

A series of tensile and strain controlled low-cycle fatigue tests were conducted at the temperatures ranging from room temperature (RT) to 900 deg C on a nickel-base heat-resistant alloy, Hastelloy XR-II, which is one of the candidate alloys for applications in the process heating high-temperature gas-cooled reactor (HTGR). Materials were tested in the solution annealed as well as in the pre-aged condition where aging consisted of isothermal exposure at 900 deg C for the period of 1000 h. In those tests the effects of aging and test temperature on tensile and fatigue properties were investigated. The ductility minimum point was observed near 600 deg C in the solution annealed condition. On the other hand, the ductility of the aged materials was reduced excessively at RT, and increased with increasing test temperature. At and below 700 deg C, the fatigue lives of the aged materials were shorter than those of the solution annealed ones. The tendency was interpreted through the fractographic and metallographic features of the fatigued specimens. The fatigue lives estimated from tensile properties using the method proposed by Manson were compatible with the results of fatigue tests under the test conditions employed. (author)

37

New technology of manufacturing complex shape machine parts from powder heat resisting nickel alloys  

International Nuclear Information System (INIS)

The mathematical model of manufacturing turbine wheels of powder heat resistant nickel base alloys by hot isostatic pressing is developed. The model includes the stage of pressing tool design, powder behaviour simulation, pressing conditions, etc. Computer programs developed allow manufacturing machine parts of complicated shape with precise geometry and a high level of mechanical properties

38

Corrosion behaviours of heat resisting alloys in steam at 8000C and 40 atm pressure  

International Nuclear Information System (INIS)

The corrosion behaviours of 3 heat resisting alloys, Inconel 600, Inconel 617 and Incoloy 800, have been studied in steam at 8000C and 40 atm pressure. A protective Cr2O3-rich scale is formed initially on the 3 alloys. After this introductory stage, the formation of nodular oxides on Inconel 600 and Inconel 617 drastically increases the weight gain rate. No evidence is found for the formation of these nodular oxides on Incoloy 800. The effect of the alloy composition, especially the concentration of Cr, on the nucleation and the growth of the nodular oxides is discussed. (orig.)

39

Influence of crystal orientation on mechanical properties of heat resistant alloys  

International Nuclear Information System (INIS)

A brief review on the data about the influence of directional crystallization on such properties as elastic modulus, tensile and compressive properties, fatigue strength, long-term rupture strength is presented for a number of heat resistant nickel base alloys. The results of investigations carried out using cast specimens of alloys Rene-4, ZhS6U, ZhS6F with equiaxial, directionally solidified and monocrystalline structures testify to the fact that crystal orientation has a great effect on the mechanical properties. The alloys considered are commonly used materials for manufacturing turbine blades. 10 refs., 5 figs., 4 tabs

40

The effects of high-temperature exposure on the properties of heat-resistant alloys  

Energy Technology Data Exchange (ETDEWEB)

The exposure of heat-resistant alloys to high temperature can significantly change their mechanical properties. This paper presents and analyzes data on the effect of thermal exposure on the tensile and impact behavior of three cast materials -- the HK-40, HP-50, and 21Cr-32Ni-Fe alloys -- and of wrought material -- Alloy 800. The changes in tensile and impact properties caused by high-temperature exposure are reviewed. Reasons for these property changes and needs for considering them in the design, operation, and life assessment of high-temperature equipment are discussed.

Jaske, C.E. [CC Technologies, Inc., Columbus, OH (United States)

1994-12-31

 
 
 
 
41

Experiment planning during investigation of heat resistance of Fe-Cr-Ni-Mn-Si-Al-REM system alloys  

International Nuclear Information System (INIS)

Heat resistance of alloys of Fe-Cr-Ni-Mn-Si-Al-REM sytem is studied at temperatures of 800-900 deg C in the air medium. It is shown that in studied ranges the changes of alloys compositions, their heat resistance both at 900 and 800 deg C depends greatly on the content of silicon in alloys. In both cases the increase of silicon content up to 2% decreases the mass change sufficiently. The ratio between the quantities of chromium and silicon, and manganese and rare earth metals as well, has a notable effect on heat resistance at both temperatures of test

42

Structure of crater of sputtered electrode of heat resisting nickel alloy under granulation process  

International Nuclear Information System (INIS)

Analysis of the structure formed in the crater of centrifigally sputtered electrode of Ni-Al-Ti-Cr-Co-W-Mo-Nb-Hf-B system granulated heat-resistant nickel alloy is carried out. Essential difference in behaviour of boron and carbon in crater near-the-surface layer is determined. This difference results from the depth of homogeneous distribution of boron (up to 1 mm) in contrast to that of carbon (up to 0.1mm). Up to 10 mm depth crack formation is detected. That crack formation results from the effect of thermal gradient at electrode sputtering followed by formation of submelting pores due to boron intensive migration to crack and along it on the surface of crater. Compositions of boride and carbide phases are determined, mechanisms of crater formation of electrode crater of heat-resistant granulated nickel alloy are suggested

43

Surface microprofile production in electrochemical machining of heat-resistant nickel-chromium alloys  

International Nuclear Information System (INIS)

Surface microprofiling of some heat-resistant nickel-chromium alloys by electrochemical processing in chloride and ''passivating'' electrolytes is studied. It is shown that the existence of strengthening ?'-phase in the alloy, differing in its anode behaviour from nickel-chromium matrix, brings about different roughnesses, formed during processing in different electrolytes. Processing in chlorides is accompanied by etching of grain boundaries as far as in ''passivating'' electrolytes bumps are formed on the surface which is connected with difference in velocities of anode dissolving of different phases. In increasing the current density and using mixed chloride-nitrate electrolytes one can reduce the height of microroughnesses

44

Etude expérimentale du soudage par laser YAG de l'alliage base nickel Hastelloy X Experimental study of YAG laser welding of nickel base alloy Hastelloy X  

Directory of Open Access Journals (Sweden)

Full Text Available Le procédé de soudage laser YAG est envisagé pour remplacer le procédé de soudage TIG manuel pour la réalisation de pièces de turboréacteur en alliage nickel-chrome-molybdène Hastelloy X. Cette étude expérimentale a permis de définir un domaine de soudabilité de cet alliage répondant aux critères spécifiques du secteur aéronautique. The YAG laser welding process is contemplated to replace the manual TIG welding process for the production of parts of turbojet in Hastelloy X. This experimental study has identified the field of weldability of this alloy to meet the specific requirements of the aerospace industry.

Graneix Jérémie

2013-11-01

45

Effects of thermal neutron irradiation on ductility of austenitic heat resisting alloys for HTR application  

International Nuclear Information System (INIS)

Loss of high temperature ductility due to thermal neutron irradiation was examined by slow strain rate test in vaccum up to 10000C. The results on two heats of Hastelloy alloy X with different boron contents were analysed with respect to the influence of the temperatures of irradiation and tensile tests, neutron fluence and the associated helium production due to nuclear transmutation reaction. The loss of ductility was enhanced by increasing either temperature or neutron fluence. Simple extrapolations yielded the estimated threshold fluence and the end-of-life ductility values at 900 and 10000C in case where the materials were used in near-core regions of VHTR. The observed relationship between Ni content and the ductility loss has suggested a potential utilization of Fe-based alloys for seathing of the neutron absorber materials. Decreasing the impurity boron content is also suggested to be important in increasing the threshold fluence for embrittlement. (author)

46

Studies on the permeation of hydrogen and tritium through heat resistant alloys  

International Nuclear Information System (INIS)

At temperatures of 750 to 9500C the permeation of hydrogen through bare, heat resistant alloys was studied from 1 to 40 bar, the diffusion and permeation of tritium in the partial pressure range of 10-4 bar. Among the alloys studied were Incoloy 800, 800 H, 802, Inconel 617, 625, the Ni-based alloy Nimonic PE 13, and several non-commercial steels. At a given temperature, the permeation rate through samples with clean surfaces - substantially free of oxide films - was found to be proportional to the square root of the hydrogen pressure. The C and the Cr contents of the steels investigated proved to exert a strong influence on the activation energies of diffusion and permeation. In some alloys a reduction of the permeation rate was observed that can be attributed to the precipitation of intermetallic phases. In one case a decrease of the permeation rate occured during the measurements due to a phase transformation. (orig.)

47

Creep and tensile properties of alloy 800H-Hastelloy X weldments  

International Nuclear Information System (INIS)

Hastelloy X and alloy 800H were joined satisfactorily by the gas tungsten arc welding process with ERNiCr-3 filler and the shielded metal arc welding process with Inco Weld A filler. Test specimens were of two types: (1) made entirely of deposited Inco Weld A and (2) machined transverse across the weldments to include Hastelloy X, filler metal (ERNiCr-3 or Inco Weld A), and alloy 800H. They were aged 2000 and 10,000 h and subjected to short-term tensile and creep tests. Inco Weld A and ERNiCr-3 are both suitable filler metals and result in welds that are stronger than the alloy 800H base metal

48

Creep and tensile properties of alloy 800H-Hastelloy X weldments. [HTGR  

Energy Technology Data Exchange (ETDEWEB)

Hastelloy X and alloy 800H were joined satisfactorily by the gas tungsten arc welding process with ERNiCr-3 filler and the shielded metal arc welding process with Inco Weld A filler. Test specimens were of two types: (1) made entirely of deposited Inco Weld A and (2) machined transverse across the weldments to include Hastelloy X, filler metal (ERNiCr-3 or Inco Weld A), and alloy 800H. They were aged 2000 and 10,000 h and subjected to short-term tensile and creep tests. Inco Weld A and ERNiCr-3 are both suitable filler metals and result in welds that are stronger than the alloy 800H base metal.

McCoy, H. E.; King, J. F.

1983-08-01

49

Mastering of stampings of heat resistant nickel base alloys of improved quality  

International Nuclear Information System (INIS)

The process of manufacturing discs from heat resistant nickel base alloys (EI698-BD) is described. The technological scheme includes creation of ingots by a vacuum-arc melting, forging, surfacing, cutting, upsetting, ultrasound control, preliminary and finite stamping and thermal treatment. The levels of mechanical properties (strength limit, fluidity level, impact strength, relative change, relative constriction) after twofold quenching (at 1100 deg C, 8 hours, and 1000 deg C, 4 hours), cooling in the air and twofold aging (at 775 deg C, 16 hours and 750 deg C, 8 hours) meet the requirements of technical conditions

50

Design of model alloys for martensitic/ferritic super heat-resistant 650 C steels  

Energy Technology Data Exchange (ETDEWEB)

The key to high creep strength of steels, besides solid solution strengthening, are fine distributions of stable precipitates which block the movement of subgrain boundaries and dislocations and delay coarsening of microstructure. The aim of the present study is to design new super heat-resistant 12%Cr ferritic steels using basic principles and concepts of physical metallurgy, to test and optimise model alloys and to investigate and clarify their behaviour under long-term creep conditions with emphasis on microstructural stability. Taking into consideration recent world-wide developments of 9-12%Cr steels with screening of available data, a series of model alloys is designed, which is supported by theoretical calculations and simulations of the expected phase transformations and precipitation processes. The alloys are prepared and tested mechanically. The effects of different types of precipitates as well as alloying elements on mechanical long-term properties are investigated. In particular the Laves phase is studied, which precipitates during service and which is to strengthen the alloys when M{sub 23}C{sub 6} precipitate particles besides finely distributed other carbides and nitrides become less effective. The effects of various austenite-forming alloying elements are also studied. (orig.)

Knezevic, V.; Vilk, J.; Inden, G.; Sauthoff, G.; Agamennone, R.; Blum, W.

2001-07-01

51

Constitutive modeling of the visco-plastic response of Hastelloy-X and aluminum alloy 8009  

International Nuclear Information System (INIS)

The viscoplastic behavior of advanced, high temperature, metallic alloys is characterized using the Bodner Partom unified constitutive model. Material parameters for both Hastelloy-X and Aluminum alloy 8009 are obtained for this model. The Bodner-Partom constitutive model is summarized, and a detailed approach for determining the model parameters from experimental data is reviewed. Experimental methods for obtaining the mechanical test data are described. Bodner-Partom model parameters are determined from data obtained in uniaxial, isothermal, monotonic tension or compression tests and isothermal creep tests. Model predictions from the parameters determined are generated and compared to experimental data

52

Evaporation behavior of Hastelloy-X alloys in simulated very high temperature reactor environments  

International Nuclear Information System (INIS)

A sequential analysis was made on the material degradations during exposure of nickel-base corrosionresistant austenitic alloys to simulated very high temperature reactor environments. The materials tested were two modified versions of Hastelloy-X in terms of both increased manganese content for improved compatibility and decreased manganese content for possible adverse effects. Quantitative analysis of the specimens after exposure for 1000 h at several temperature steps from 850 to 10500C have revealed the temperature-dependent aspects of the processes including the depletion of chromium and manganese due to oxidation, evaporation, and carbon transfer into and/or from the materials. The material with enriched manganese, developed and specified as Hastelloy-XR, showed enhanced resistance to loss of chromium in terms of both oxidation and evaporation

53

Low-cyclic fatigue of heat resisting alloys under nonisothermal loading  

International Nuclear Information System (INIS)

On the example of two heat resisting EhP693VD and EhP220 alloys contrasting by short-term and long-term strength and ductility characteristics considered both specific features of the process of cyclic elastoplastic deformation under thermal-fatigue loading and conditions of maximum permissible damages formation are discussed. Tests have been performed at the temperatures from 20 to 1000 deg C. It is shown that the non-stationary character of the process of elastoplastic deformation with accumulation of unilateral strains and important quasistatic damages is characteristic of the thermal fatigue regime in the high temperature field. The deformation-kinetic dependence satisfactorily describing the limiting state on fracture under thermal-fatigue loading of steel samples is presented

54

Application of PSCPCSP program for optimization of series-produced compositions and development of new heat resistant nickel base alloys  

International Nuclear Information System (INIS)

The PSCPCSP computer program was applied for evaluation of changes in phase compositions, structure, mechanical and physical properties of 350 series-produced cast and deforming nickel base alloys with equiaxial, columnar and monocrystal structures by their alloying within standard compositions. Results of such calculations for a number of alloys (EI893L, ZhS6K, ZNKT, EP957, EP539LMU, ChS-104, etc.) by their alloying at the minimum, medium and maximum level within the limits of their brand compositions are presented. It is shown that the above program may be useful in developing new heat-resistant alloys. 11 refs., 8 tabs

55

Investigation of aging kinetics of heat resisting alloy-EhI698  

International Nuclear Information System (INIS)

The particularities of the aging kinetics have been studied for the EhI698 alloy conforming to the technological pattern used in the practice of stamped discs fabrication. The main part of the experiments was conducted with the melt of the following chemical composition (%): C 0.08; Cr 13.9; Ti 2.74; Al 1.68; Mo 2.95; Nb 2.11. A study was made of the hardness, the X-ray line widths, the solid solution lattice parameter, the amount of hardening phase and microstructure peculiarities under various aging conditions of the heat-resistant EhI698 alloy. The alloy structure study was made by means of transmission- and electron microscopy. The average size of the intermetallic ?'-phase (the main hardening phase in the alloy studied) corresponding to the structural formula (Ni, Cr)3(Al,Ti,Mo,Nb) was determined from the microphotographies. The estimation of the total amount of hardening phases (intermetallide and carbides) was made by electrolytic precipitation. It is found that the course of the kinetic curves during single and repeated aging is analogous. The main changes in the values studies occur during the first 10 hrs. of aging. The structure of the EhI698 alloy after the optimal heat treatment (quenching 1120 deg C for 8 hrs at 1000 deg C for 4 hrs, aging at 775 deg C for 16 hrs, at 700 deg C for 16 hrs) is characterized by the presence of dispersion hardening ?'-phase particles of 0.05 to 0.06 ?m size and a considerable amount of coagulated precipitations of about 0.2 ?m size

56

Cutting force regression modeling approach for turning Hastelloy X alloy by genetic algorithms  

Science.gov (United States)

According to tradition empirical formula form, the cutting force regression model for turning Hastelloy X alloy is assigned for the exponential form. Turning experiments were carried out based on the experimental plan designed on the principle of the quadratic rotary combination design technique. By identifying regression coefficient using genetic algorithm toolbox in MALAB7.1, cutting force regression models were established. The rule that the prediction models reveal is identical with both visual analyses result of experiment data and tradition basic cutting theory, in addition the residual error is smaller, so the regression models are fitted very well.

Yu, Chao; Guo, Jianye; Zhang, Yanli; Li, Jingkui

2012-01-01

57

SEM, EDS, EPMA-WDS and EBSD characterization of carbides in HP type heat resistant alloys  

International Nuclear Information System (INIS)

The microstructure of centrifugally cast heat resistant alloys of the HP-series (Fe-35Ni-25Cr-0.4C, wt.%) contains several minor phases, like carbides (M7C3, M23C6 and MC). Several alloys are characterized by means of scanning electron microscopy in back-scattered electron imaging and energy dispersive spectroscopy, of electron probe micro-analysis by X-ray wavelength dispersive spectroscopy, and of electron back-scattered diffraction. On the one hand, scanning electron microscopy imaging in the back-scattered mode, associated with energy dispersive spectroscopy analysis and electron back-scattered diffraction, can lead to the identification of all phases, but with a lack of accuracy in certain cases. On the other hand, electron probe micro-analysis by X-ray wavelength dispersive spectroscopy alone can always provide a strict identification of all phases, with additional precise information on phase composition, including for light elements, which is important in the case of carbides

58

APT characterization of a high strength corrosion-resistant Ni-Cr-Mo HastelloyR C-22HSTM alloy  

International Nuclear Information System (INIS)

Full text: The versatile C-type Ni-Cr-Mo alloys are well known for their corrosion resistance. These alloys have been used for many years in a wide variety of applications such as heat exchangers, scrubbers, reaction vessels, etc. as they exhibit significantly higher strength than most stainless steels. The strength of these alloys may be further increased by cold working. However, this mechanical processing approach limits the size and geometry of the final components. In addition, the high strength is lost in welds and associated heat affective zones. A new high strength corrosion-resistant alloy Ni-21% Cr-17% Mo, HASTELLOY C-22HS, has recently been developed to overcome these problems. This general purpose corrosion-resistant alloy may be used at temperatures of up to at least 600oC. Potential applications for this corrosion resistant high strength alloy include shafting, agitators, fan blades, hubs, springs, fasteners, valves, dies, rings and gaskets. The composition of the HASTELLOY C-22HS alloy used in this study was Ni, 20.6 wt. % Cr, 16.6% Mo, 1.1% Fe, 0.33% Al, 0.29% Mn, 0.11% Nb, 0.004% C and 0.004% B. The microstructure of the HASTELLOY C-22HS alloy was characterized in the age hardened condition - 16 h at 705oC, furnace cooled to 605oC, 32 h at 605oC and air cooled. The microstructure of this age hardened alloy was characterized with the Oak Ridge National Laboratory local electrode atom probe. The corrosion resil electrode atom probe. The corrosion resistance of this alloy in HCl at 52oC and H2SO4 at 79oC was found to be similar to N06022 alloy and better than N07725 alloy. The yield strength of this alloy and N06022 were similar in the mill annealed condition. After the age hardening treatment, the 0.2% yield strength of the HASTELLOY C-22HS alloy increased from 222 to 542 MPa. The tensile elongation and the reduction in area of the age hardened alloy were 40% and 50%, respectively at room temperature and 48% and 66%, respectively at 595oC. Atom probe tomography of the HASTELLOY C-22HS alloy revealed that the microstructure consisted of fine (?10-30 nm diameter) approximately spherical molybdenum-enriched Ni2(Cr, Mo) precipitates in an aluminum-, iron-, silicon-, and manganese-enriched matrix. The morphology of these precipitates was significantly finer than the lenticular Ni2(Cr, Mo) precipitates previously observed in a HAYNES 242 alloy. Ref. 1 (author)

59

Aging of a cast 35Cr–45Ni heat resistant alloy  

International Nuclear Information System (INIS)

Highlights: ? The as-cast microstructure is made of an austenitic matrix and primary carbides. ? The carbides are of two different types: Cr- and Nb-rich. ? The microstructure changes during aging. ? These microstructural changes result in the degradation of mechanical properties. - Abstract: The microstructural evolution during aging and its effect on the mechanical properties of a centrifugally cast 35Cr–45Ni heat resistant alloy was studied by means of optical and electron microscopy, and by mechanical testing in samples aged in air at 750 °C for a period of time of up to 1000 h. The as-cast microstructure consisted of an austenitic matrix and a network of two types of primary carbides that were identified as NbC and M7C3 by their light and dark tones when viewed in backscattered electron mode in a scanning electron microscope. Aging promoted the occurrence of different phenomena such as the transformation of primary M7C3 to M23C6 carbides, precipitation of secondary M23C6 carbides and the transformation of NbC to Nb3Ni2Si. It was found that aging promoted an increase in Vickers microhardness of more than 50%, the increment in tensile strength of around 20% and the reduction in ductility of close to 70%.

60

Development and investigation of industrial technique for hot rolling of small cross section rods of unyielding heat resisting alloys  

International Nuclear Information System (INIS)

A hot-rolling technology has been developed for rolling rods about 14 to 16 mm in diameter made of EI826, EI929VD, EI867VD heat-resistant nickel alloys, the rods being used for manufacturing the fastening parts and for die-forging blades. The blanks preheated up to a temperature of 1160 to 1190 deg C are rolled on ''300/450'' rolling mill in two processes according to two roll pass designs; namely, oval-round for rolling the rods 16 mm in diameter, and square-oval-round for the rods 14 mm in diameter. It is the installation of the technology of manufacturing rods of decreased diameters from the above heat-resistant alloys that yields a considerable economical effect, owing to the saving of up to 40% of an expensive metal and to the reducing of the amount of work as required for manufacturing the machine parts

 
 
 
 
61

Thermomechanical deformation behavior of a dynamic strain aging alloy, Hastelloy X  

Science.gov (United States)

An experimental study was performed to identify the effects of dynamic strain aging (solute drag) and metallurgical instabilities under thermomechanical loading conditions. The study involved a series of closely controlled thermomechanical deformation tests on the solid-solution-strenghened nickel-base superalloy, Hastelloy X. This alloy exhibits a strong isothermal strain aging peak at approximately 600 C, promoted by the effects of solute drag and precipitation hardening. Macroscopic thermomechanical hardening trends are correlated with microstructural characteristics through the use of transmission electron microscopy. These observations are compared and contrasted with isothermal conditions. Thermomechanical behavior unique to the isothermal database is identified and discussed. The microstructural characteristics were shown to be dominated by effects associated with the highest temperature of the thermomechanical cycle. Results indicate that the deformation behavior of Hastelloy X is thermomechanically path dependent. In addition, guidance is given pertaining to deformation modeling in the context of macroscopic unified theory. An internal state variable is formulated to qualitatively reflect the isotropic hardening trends identified in the TMD experiments.

Castelli, Michael G.; Miner, Robert V.; Robinson, David N.

1992-01-01

62

On correlation of fatigue resistance of heat-resisting nickel alloys during bending and tension-compression  

International Nuclear Information System (INIS)

Presented are the results of experimental studies of fatigue resistance of heat-resisting the EhI867, VZhL12U and ZhS6K nickel alloys under conditions of symmetric cycle at rotational bending and tension - compression in the temperature range of 20 to 1000 deg C. Valued is the influence of the stressed state type of test materials on fatigue resistance depending on temperature and test base

63

Relationship between carburization and zero-applied-stress creep dilation in Alloy 800H and Hastelloy X  

International Nuclear Information System (INIS)

Typical HTGR candidate alloys can carburize when exposed to simulated service environments. The carbon concentration gradients so formed give rise to internal stresses which could cause dilation. Studies performed with Hastelloy X and Alloy 800H showed that dilations of up to almost 1% can occur at 10000C when carbon pickup is high. Dilation was normally observed only when the carbon increase was >1000 ?g/cm2 and ceased when diffusing carbon reached the center of the specimen. (Auth.)

64

Heat treating of a lamellar eutectic alloy (gamma/gamma prime + delta). [heat resistant alloys  

Science.gov (United States)

Eutectic superalloys are being developed at several laboratories for application as aircraft gas turbine airfoils. One such alloy was subjected to several heat treatments to determine if its mechanical properties could be improved. It was found that by partially dissolving the alloy at 1210 C and then aging at 900 C the tensile strength can be increased about 12 percent at temperatures up to 900 C. At 1040 C no change in tensile strength was observed. Times to rupture were measured between 760 and 1040 C and were essentially the same or greater than for as-grown material. Tensile and rupture ductility of the alloy are reduced by heat treatment. Photographs of the microstructure are shown.

Tewari, S. N.; Dreshfield, R. L.

1976-01-01

65

Aging of a cast 35Cr-45Ni heat resistant alloy  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer The as-cast microstructure is made of an austenitic matrix and primary carbides. Black-Right-Pointing-Pointer The carbides are of two different types: Cr- and Nb-rich. Black-Right-Pointing-Pointer The microstructure changes during aging. Black-Right-Pointing-Pointer These microstructural changes result in the degradation of mechanical properties. - Abstract: The microstructural evolution during aging and its effect on the mechanical properties of a centrifugally cast 35Cr-45Ni heat resistant alloy was studied by means of optical and electron microscopy, and by mechanical testing in samples aged in air at 750 Degree-Sign C for a period of time of up to 1000 h. The as-cast microstructure consisted of an austenitic matrix and a network of two types of primary carbides that were identified as NbC and M{sub 7}C{sub 3} by their light and dark tones when viewed in backscattered electron mode in a scanning electron microscope. Aging promoted the occurrence of different phenomena such as the transformation of primary M{sub 7}C{sub 3} to M{sub 23}C{sub 6} carbides, precipitation of secondary M{sub 23}C{sub 6} carbides and the transformation of NbC to Nb{sub 3}Ni{sub 2}Si. It was found that aging promoted an increase in Vickers microhardness of more than 50%, the increment in tensile strength of around 20% and the reduction in ductility of close to 70%.

Sustaita-Torres, Ireri A., E-mail: ireri.sustaita@gmail.com [Unidad Academica de Ingenieria, Universidad Autonoma de Zacatecas, 98000 Zacatecas (Mexico); Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, 66450 San Nicolas de los Garza (Mexico); Haro-Rodriguez, Sergio, E-mail: haros907@hotmail.com [Unidad Academica de Ingenieria, Universidad Autonoma de Zacatecas, 98000 Zacatecas (Mexico); Guerrero-Mata, Martha P., E-mail: martha.guerreromt@uanl.edu.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, 66450 San Nicolas de los Garza (Mexico); Garza, Maribel de la, E-mail: maribeldelagarza@yahoo.com.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, 66450 San Nicolas de los Garza (Mexico); Valdes, Eduardo, E-mail: eduardo.valdes.57@gmail.com [Instituto Tecnologico de Saltillo, 25280 Saltillo (Mexico); Deschaux-Beaume, Frederic, E-mail: deschaux@iut-nimes.fr [Mechanical and Civil Engineering Laboratories, Universite de Montpellier 2, IUT Nimes, 30907 Nimes (France); and others

2012-04-16

66

High temperature, low-cycle fatigue strength of Hastelloy XR  

International Nuclear Information System (INIS)

The high temperature fatigue data on a heat resisting material, Hastelloy XR, are not sufficient at present, therefore, high temperature, low cycle fatigue test was carried out to collect the data, and its fatigue characteristics were clarified. Moreover, the comparison of its strength with that of Hastelloy X was carried out. Concerning the mutual effect of fatigue and creep, the case of applying the linear damage law that the ASME Code, Case N-47, has adopted to the temperature range of VHTRs was examined. Hastelloy XR is a heat-resisting alloy for the high temperature members of multi-purpose, high temperature gas-cooled reactors, of which the corrosion resistance in high temperature helium atmosphere was improved by decreasing Al and Ti for preventing local oxidation, increasing Mn for improving the protective film on metal surface, and decreasing Co due to the problem of induced radioactivity for the base of Hastelloy X. The experimental method and the results are reported. The temperature effect was conspicuous on the long side, and as temperature was higher, the fatigue strength was lower. The life was longer in helium atmosphere than in the air when strain was not maintained. The effect of strain rate on the fatigue strength was remarkable in the temperature range of VHTRs. (Kako, I.)

67

Experimental evaluation of the characteristics of super-heat-resisting Nb-based and Mo-based alloys  

International Nuclear Information System (INIS)

Both the Nb-based and Mo-based alloys have been designed and developed in order to establish the frontier technique for super-heat-resisting materials used in the liquid alkali metal environment at high temperatures. In this study, mechanical properties of the designed Nb-1Hf alloy were experimentally evaluated. In addition, the brittleness of Nb-based alloys observed at 1073K were discussed. Moreover, characteristics of both the designed Nb-based and the Mo-based alloys were summarized in a consistent way. The tensile strength of the designed Nb-1Hf alloy was slightly lower at room temperature than that of the commercial Nb-1Zr alloy. But, the designed alloy was superior in high temperature creep properties to any other solid solution hardened Nb-based alloys. In addition, the modulated structure was observed in the brittle specimen crept at 1073K, but not in the ductile specimen crept at 1273K. Therefore, it caused probably the brittleness of the Nb-1Zr alloy at 1073K. It was concluded that all the designed Nb-1Hf, Mo-15Re-0.1Zr and Mo-15Re-0.1Zr-0.1Ti alloys had an excellent total balance in the tensile and creep properties at high temperatures, corrosion resistance to liquid Li and cold-workability, compared to other experimental and commercial alloys. (J.P.N.)

68

Variation of microstructures and mechanical properties of hot heading process of super heat resisting alloy Inconel 718  

International Nuclear Information System (INIS)

Metal forming is the process changing shapes and mechanical properties of the workpiece without initial material reduction through plastic deformation. Above all, because of hot working carried out above recrystallization temperature can be generated large deformation with one blow, it can produce with forging complicated parts or heat resisting super alloy such as Inconel 718 has the worst forgeability. In this paper, we established optimal variation of hot heading process of the Inconel 718 used in heat resisting component and evaluated mechanical properties hot worked product. Die material is SKD61 and initial temperature is 300 .deg. C. Initial billet temperature and punch velocity changed, relatively. Friction coefficient is 0.3 as lubricated condition of hot working. CAE is carried out using DEFORM software before marking the tryout part, and it is manufactured 150 ton screw press with optimal condition. It is know that forming load was decreased according to decreasing punch velocity

69

Elastic plastic fracture toughness values for a hastelloy alloy sample submitted to a static load  

International Nuclear Information System (INIS)

In the High Temperature Reactor research programm of the french CEA, Hastelloy alloy plates contain mineral fibers used as insulating material and as such prevent the concrete core vessel from receiving excess heat. Due to the high pressure exerted on this insulating material, the Hastelloy plates are heavily stressed and, therefore, it is important to know their fracture strength. In the case of an elastic, brittle material, the fracture toughness is commonly defined through the well knownKsub(1c) parameter. But, for plastic materials, measuring Ksub(1c) requires very large samples and it was found more convenient to measure the fracture parameter Jsub(1c) instead of Ksub(1c). This parameter was determined according to the RICE or to the more sophisticated HERKLE and CORTEN formula. Two independent ways were followed to measure Jsub(1c): In the first one the shape of the crack after loading was made apparent by some fatigue cycles. After complete fracture of the sample, the amount of crack extension appears clearly and it becomes possible to generate a J resistance curve. As an alternative, we partially unloaded the specimen to get its compliance: the change in compliance was then supposed to coincide with the start of the crack extension. Finally a finite element code was used to compute the specimen state at the beginning of the crack extension. So we are able to obtain the shape of the Load-Displacement curve and to compare it with the experimental one. (orig.)e it with the experimental one. (orig.)

70

Effect of oxide film of heat resistant alloy on coke formation during naphtha pyrolysis  

International Nuclear Information System (INIS)

The coking of cracking furnace tubes has been an important subject of ethylene plants. The coke formations rate on the heat resistant alloys of 20Cr-4.5Al-0.5Y2O3 covered with Al2O3 oxide film and 25Cr-35Ni covered with Cr2O3 oxide film during the thermal cracking of naphtha was quantitatively evaluated at temperatures ranging from 810 to 930 .deg. C. The experimental results showed that the coke formation rate on 20Cr-4.5Al-0.5Y2O3 was lower than that on 25Cr-35Ni because of the difference of a catalytic activity to coke formation, especially in the case of a pre-carburized condition. Namely, the Al2O3 formed on 20Cr-4.5Al-0.5Y2O3 was stable even after carburization treatment and inert for catalytic coke formation, while coke formation on 25Cr-35Ni was under the control of catalytic coke formation, and carburization of 25Cr-35Ni accelerated catalytic coke formation. The stability of Al2O3 and Cr2O3 in a hydrocarbon with steam environment was thermodynamically calculated in 0.1mol of steam, 0.2mol of ethylene and 0.1mol of methane at 1,100 .deg. C. The simulation result shows that Al2O3 is exceedingly stable while Cr2O3 could be decomposed partially into chromium carbide. Therefore, it is concluded that Al2O3 on 20Cr-4.5Al-0.5YO3 on 20Cr-4.5Al-0.5Y2O3 is more stable than Cr2O3 on 25Cr-35Ni, and 20Cr-4.5Al-0.5Y2O3 is more resistant to coke formation and carburization than 25Cr-35Ni in a hydrocarbon with steam environment at high temperature

71

A study on the effect of helium environment and the grain size on the creep behaviour of Hastelloy X alloy  

International Nuclear Information System (INIS)

Creep tests have been carried out on Hastelloy X alloy at 9000C in air and in helium containing similar impurities to those in the coolant of the high temperature gas cooled reactor. (HTGR) The results indicate that creep lives and rates strongly depend on the grain size, that is, the creep rate increases linearly with (grain size)-1 and the time to 20% creep, T20 is proportional to (grain size)sup(0.86). The difference between the creep behaviour in air and in helium is discussed on the base of the creep property corrected with the grain size, and the metallurgical examination and analysis of carbon content are carried out on specimens tested in air and in helium. It is suggested that there is little deterioration in the creep property of Hastelloy X alloy under the simulated HTGR atmosphere at 9000C. (auth.)

72

Development testing of the two-watt RTG heat source and Hastelloy-S/T-111 alloy compatibility studies  

International Nuclear Information System (INIS)

The two-watt radioisotope thermoelectric generator heat source capsules were tested to determine their survivability under extreme environmental conditions: high external pressure, high impact, and high internal pressure. Test results showed that the capsules could withstand external pressures of 1,000 bars and impacts at velocities near 150 meters per second. However, the results of the internal pressure tests (stress-rupture) were not so favorable, possibly because of copper contamination, leading to a recommendation for additional testing. A material compatibility study examined the use of Hastelloy-S as a material to clad the tantalum strength member of the two-watt radioisotopic heat source. Test capsules were subjected to high temperatures for various lengths of time, then cross sectioned and examined with a scanning electron microscope. Results of the study indicate that Hastelloy-S would be compatible with the underlying alloy, not only at the normal operating temperatures of the heat source, but also when exposed to the much higher temperatures of a credible accident scenario

73

Corrosion products and formation mechanism of hastelloy C-276 alloy in supercritical water at 600?  

International Nuclear Information System (INIS)

The corrosion products of nickel-base alloy Hastelloy C-276 was investigated in supercritical water (SCW) at 600?/25 MPa through grazing incidence X-ray diffractometry, X-ray photoelectron spectroscopy and scanning electron microscopy, respectively. The results show that the uniform and complete oxide film was observed in SCW, which was identified to mainly consist of NiO, NiCr2O4, Cr2O3 and MoO2; The oxide films that had duplex structure were in poor in Ni and Mo, but the inner layer was rich in Cr. The loose outer layer lacked of protective, while the compact inner layer was favor of antioxidation. The formation mechanism of corrosion products on alloy C-276 in supercritical water seemed to be similar to that in high temperature water. The Ni(OH)2, NiO outer layer grew by dissolution and precipitation mechanism, while the Cr2O3 inner layer oxide was formed by oxygen diffusing inward and reacting with the retained Cr. (authors)

74

Development of heat resistant Pb-free joints by TLPS process of Ag and Sn-Bi-Ag alloy powders  

Directory of Open Access Journals (Sweden)

Full Text Available TLPS (Transient Liquid Phase Sintering process is a candidate method of heat-resistant bonding, which makes use of the reaction between low-melting temperature powder of Sn-Bi base alloys and reactive powder of Ag. During heat treatment above the melting temperature of a Sn-Bi base alloy, the molten Sn-Bi reacts rapidly with solid Ag particles, which results in the formation of heat-resistant intermetallic compound (IMC. In this study, the TLPS properties between Sn-17Bi-1Ag (at.% powder with its liquidus temperature of 200°C and pure Ag powder were investigated. During differential scanning calorimetry (DSC measurement, an exothermic reaction and an endothermic reaction occurred, which correspond to the formation of the e-Ag3Sn IMC phase and the melting of the Sn-17Bi-1Ag alloy, respectively. After the overall measurement, the obtained reactant consists of the Ag3Sn-IMC and Bi-rich phases, both of which start melting above 250°C, with a small amount of the residual Sn-Bi eutectic phase. These results suggest that the TLPS process can be applied for Pb-free heatresistant bonding.

Ohnuma I.

2012-01-01

75

High temperature corrosion of heat-resisting alloys by borosilicate melts containing simulated high level nuclear wastes  

International Nuclear Information System (INIS)

In connection with the development of vitrified solidification process of high level liquid wastes (HLLW) by metallic vessel, the high temperature corrosion of some heat-resisting alloys, such as stainless steel, Incoloy and Inconel, were investigated with the molten borosilicate glass containing simulated HLLW in the temperature range of 1,000--1,2000C for 3--50 days. The concentration distributions of various constituents in the vicinity of the interface between the glass and the various metals were determined by means of EPMA. In the case of stainless steel, the general corrosion of alloys was observed without a protective layer. But in the case of both of Incoloy and Inconel, a chromium oxide layer was consequently formed between the glass and the metal, giving a protective film against general corrosion of alloys. When a MgCr2O4 layer on the chromium oxide layer and the alumina in alloy were, furthermore, formed, the corrosion of alloys became extremely depressed. The growth rate of the layer was controlled by chromium diffusion in alloy. The values of the effective diffusion coefficients D tilde sub(Cr) were approximately 1x10-10cm2/s at 1,1050C. (author)

76

Total hemispherical emissivity of very high temperature reactor (VHTR) candidate materials: Hastelloy X, Haynes 230, and Alloy 617  

Science.gov (United States)

An experimental system was constructed in accordance with the standard ASTM C835-06 to measure the total hemispherical emissivity of structural materials of interest in Very High Temperature Reactor (VHTR) systems. The system was tested with304 stainless steel as well as for oxidized and un-oxidized nickel, and good reproducibility and agreement with the literature data was found. Emissivity of Hastelloy X was measured under different conditions that included: (i) "as received" (original sample) from the supplier; (ii) with increased surface roughness; (iii) oxidized, and; (iv) graphite coated. Measurements were made over a wide range of temperatures. Hastelloy X, as received from the supplier, was cleaned before additional roughening of the surface and coating with graphite. The emissivity of the original samples (cleaned after received) varied from around 0.18 to 0.28 in the temperature range of 473 K to 1498 K. The apparent emissivity increased only slightly as the roughness of the surface increased (without corrections for the increased surface area due to the increased surface roughness). When Hastelloy X was coated with graphite or oxidized however, its emissivity was observed to increase substantially. With a deposited graphite layer on the Hastelloy, emissivity increased from 0.2 to 0.53 at 473 K and from 0.25 to 0.6 at 1473 K; a finding that has strong favorable safety implications in terms of decay heat removal in post-accident VHTR environments. Although initial oxidation of Hastelloy X increased the emissivity prolonged oxidation did not significantly increase emissivity. However as there is some oxidation of Hastelloy X used in the construction of VHTRs, this represents an essentially neutral finding in terms of the safety implications in post-accident VHTR environments. The total hemispherical emissivity of Haynes 230 alloy, which is regarded as a leading candidate material for heat exchangers in VHTR systems, was measured under various surface conditions. The emissivity increased from 0.178 at 600 K to 0.235 at 1375 K for Haynes 230 as received sample. The emissivity increased significantly when its surface roughness was increased, or was oxidized in air, or coated with graphite dust, as compared to the as received material. The total hemispherical emissivity of Alloy 617 was measured as a function of temperature. The total emissivity increased from about 0.2 at 600 K to about 0.35 at 1275 K.

Maynard, Raymond K.

77

Study of connection between fine structure crystallographic orientations and microliquation and properties in directionally crystallized nickel heat resisting alloys  

International Nuclear Information System (INIS)

Studied has been the life of the VZhL-12UNK heat-resistant alloy samples, depending on the growth crystallographic orientations and the extent of liquation. The sample testing results at 1,100 deg C are given. It is pointed out, that the most strength-advantageous crystallographic orientations are positioned in the left side of the standard stereographic triangle in the direction. The samples fine structure after the fatigue test at high temperatures is similar to the fine structure, that conforms to the end of the settled accelerated creep stage. The tungsten liquation coefficient in the alloy varies in the 1.1.-1.8 range. The higher the liquation coefficient, the longer is the sample's pre-destruction time

78

The effects of controlled impurity helium on the mechanical behavior of Hastelloy Alloy X  

International Nuclear Information System (INIS)

The influence of a simulated advanced reactor helium environment, containing 50 Pa H2/5 Pa CH4/ 5 Pa CO/ about 0.1 Pa H2O, on the mechanical properties of two heats of Hastelloy alloy X is discussed. Simultaneous exposures in air and controlled impurity helium at temperatures in the range of 650 to 10000C for times of 3000 h or more were performed. A combination of tensile testing, Charpy V-notch impact toughness testing, and creep testing was used to study the effects of reactor helium/metal interactions on the mechanical behavior of this alloy. Carburization was identified as the primary corrosion phenomenon. Increasing exposure time and temperature were observed to increase the depth of carburization. The increase in carbon concentration in the carburized zone suppressed the additional formation of M C, which is observed in air-aged specimens, and resulted in the precipitation of M23C6 a chromium-rich carbide variant. The precipitation of M23C6 in the carburized zone occurred primarily along grain and twin boundaries; matrix precipitation, however, was also observed, the degree of which depended on exposure temperature. Strength and impact toughness properties were found to be controlled primarily by thermal aging reactions, with only a small effect related to the carburization. Although tensile and creep ductilities were decreased as a result of carburization, substantial ductiresult of carburization, substantial ductility remained. Variation was observed between the two heats, the finer grained heat appearing to be weaker in the high-temperature creep tests and also possibly more susceptible to a loss of creep strength as a result of carburization

79

Obtaining of plasma sprayed heat resistant coatings for niobium and its alloys  

International Nuclear Information System (INIS)

The paper is concerned with a possibility to obtain a hot-resistant molybdenum disilicide base coating by the plasma method. It is shown that preliminary boriding of sprayed molybdenum disilicide powders permits oxygen penetration to the substrate to be removed due to formation of fluid oxide SiO2-B2O3 film in oxidative media. It is determined that plasma-sprayed coatings produced from such powders are characterized by low temperature of vitrification (700-1000 deg C), porosity absence, strong cohesion of particles, high heat-resistance

80

Comparison of creep behavior under varying load/temperature conditions between Hastelloy XR alloys with different boron content levels  

International Nuclear Information System (INIS)

In the design of the high-temperature components, it is often required to predict the creep rupture life under the conditions in which the stress and/or temperature may vary by using the data obtained with the constant load and temperature creep rupture tests. Some conventional creep damage rules have been proposed to meet the above-mentioned requirement. Currently only limited data are available on the behavior of Hastelloy XR, which is a developed alloy as the structural material for high-temperature components of the High-Temperature Engineering Test Reactor (HTTR), under varying stress and/or temperature creep conditions. Hence a series of constant load and temperature creep rupture tests as well as varying load and temperature creep rupture tests was carried out on two kinds of Hastelloy XR alloys whose boron content levels are different, i.e., below 10 and 60 mass ppm. The life fraction rule completely fails in the prediction of the creep rupture life of Hastelloy XR with 60 mass ppm boron under varying load and temperature conditions though the rule shows good applicability for Hastelloy XR with below 10 mass ppm boron. The change of boron content level of the material during the tests is the most probable source of impairing the applicability of the life fraction rule to Hastelloy XR whose boron content level is 60 mass ppm. The modified life fraction rule has been proposed based on the dependence of the creep rupture strength on the boron content level of the alloy. The modified rule successfully predicts the creep rupture life under the two stage creep test conditions from 1000 to 900degC. The trend observed in the two stage creep tests from 900 to 1000degC can be qualitatively explained by the mechanism that the oxide film which is formed during the prior exposure to 900degC plays the role of the protective barrier against the boron dissipation into the environment. (J.P.N.)

 
 
 
 
81

Crevice Corrosion of Hastelloy C-276 and Inconel-625 Alloys in Chloride Environments, Determination of The Critical Crevice Solution  

International Nuclear Information System (INIS)

The crevice corrosion of hastelloy C-276 and Inconel-625 alloys is investigated. The effect of temperature on both passive current and the critical pH (at which the passive film breaks down) is studied in detail. potentiodynamic studies have been used to determine the critical crevice solution (CCS) in terms of pH and chloride iron concentration, and passive current. The criteria of both Crolet and Old field and Sutton are used for the determination of the critical pH for crevice corrosion. The results show that the critical pH for crevice corrosion of Inconel-625 alloy as defined by Old field and Sutton seems to be a function of both temperature and chloride ion concentration, whereas the same relationship does not appear to hold between these variables and the critical pH when the Crolet criterion is applied. The critical pH of crevice solution for Inconel-625 may vary between 1.7 and 0.0 depending on environmental condition and criteria applied. However, for the case of hastelloy C-276 alloy the critical pH for crevice corrosion could not be detected when applying both criteria. The results indicate that hastelloy C-276 alloy is more resistant to crevice corrosion than Inconel-625 under the same experimental conditions. The experimental results passive current (Ipass) and de passivation pH (dpH) of this investigation could be utilized as inputs to a mathematical model employed for the prediction of incubation period required to reach the critical crevice solution cd to reach the critical crevice solution composition, which leads to permanent breakdown of passive film. 10 figs., 5 tabs

82

Investigation of the thermal stability of a commercial Ni--Cr--Fe--Mo alloy (Hastelloy Alloy X)  

International Nuclear Information System (INIS)

The changes in hardness and room temperature impact toughness of Hastelloy Alloy X after aging at 1000, 1200, 1400 and 16000F (538, 649, 760 and 8710C) for times up to 10,000 hr were investigated. The alloy exhibts age-hardening at 1200 and 14000F (649 and 7600C). A slight hardness increase was observed at 16000F (8710C) followed by overaging after 4000 h. No age-hardening was observed at 10000F (5380C) up to 10,000 h. Aging at all temperatures resulted in a substantial drop in room temperature impact toughness. The microstructure after aging was characterized by optical metallography and x-ray diffraction, while fracture mode was characterized by scanning electron microscopy. The results suggest that the toughness degradation is primarily associated with carbide precipitation. M6C' type carbides are believed to be the major phase precipitated during aging at all temperatures, although sigma and ? phases were also detected after 10,000 h at 1400 and 16000F (760 and 8710C), respectively

83

Crevice Corrosion of hastelloy C-276 and Inconel-625 Alloys in Chloride Environment, Effect of Bulk Solution Environment  

International Nuclear Information System (INIS)

Electrochemical techniques have been applied to study the crevice corrosion resistance of two nickel-based alloys *namely, hastelloy C-276 and Inconel-625 in acidified sodium chloride aerated solution (pH=3), in the temperature range 25-100 degree C. Cyclic polarization (where the potential is reversed at 1.0 V(SCE) was performed on the two alloys at 25,50 and 100 degree C in the same pH chloride solution. Both alloys were resistant to this type of attack at 25 degree C, and both alloys were severely attacked at 100 degree C. This was clearly reflected in the value of ?I in the hysteresis loop and also in the values of both Ecorr. and Eb. The electrochemical results were substantiated by SEM investigation. The findings were interpreted in terms of the effect of chromium and molybdenum contents on the passive film characteristics and the influence of pH during polarization. 7 figs

84

9%Cr heat resistant steels: Alloy design, microstructure evolution and creep response at 650 deg. C  

Energy Technology Data Exchange (ETDEWEB)

Highlights: {yields} 9Cr alloys with varying Ti and C contents were designed, produced and crept at 650 deg. C. {yields} Sub-grain and precipitate distribution and evolution investigated by STEM-HAADF. {yields} Correlations between microstructure evolution and mechanical properties were studied. {yields} Coarsening of sub-grain size was larger for Ti-containing 9Cr alloys. {yields} 9Cr alloy with low C and no Ti showed the highest creep strength of all studied alloys. - Abstract: In this work 9%Cr alloys were designed supported by computational thermodynamic methods. Two sets of alloys were produced: 9%Cr alloys with 0.1%C and 0.05%C and 9%Cr alloys containing {approx}0.03% Ti with 0.1%C and 0.05%C (always wt%). Microstructure investigations showed good agreement with the predicted phases of the thermodynamic modeling. The volume fraction of precipitated M{sub 23}C{sub 6} carbides is directly related to the carbon content of the alloys. For Ti-containing alloys the precipitation of nano-sized Ti-rich MX carbonitrides was observed. The microstructure evolution (sub-grain and particle size) during creep at 650 deg. C/100 MPa was investigated by STEM-HAADF. The sub-grain size evolution and the coarsening of precipitates (MX carbonitrides, M{sub 23}C{sub 6} and Laves phase) were more pronounced for Ti-containing alloys. 9Cr alloys without Ti and with low carbon content presented the highest creep strength of all investigated alloys.

Rojas, D. [Universidad de Concepcion, Departamento de Ingenieria de Materiales, Edmundo Larenas 270, Concepcion (Chile); Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Garcia, J., E-mail: jose.garcia@helmholtz-berlin.de [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Prat, O. [Universidad de Concepcion, Departamento de Ingenieria de Materiales, Edmundo Larenas 270, Concepcion (Chile); Max-Planck-Institut fuer Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Duesseldorf (Germany); Sauthoff, G. [Max-Planck-Institut fuer Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Duesseldorf (Germany); Kaysser-Pyzalla, A.R. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)

2011-06-15

85

Effects of product form and boron addition on the creep damage in the modified Hastelloy X alloys in a simulated HTGR helium gas environment  

International Nuclear Information System (INIS)

The present paper investigates early-stage-creep damage of Hastelloy XR and XR-II alloys, modified versions of Hastelloy X alloy, which have been developed in Japan as most promising candidate structural alloys for Japanese high-temperature gas-cooled reactors (HTGRs). Creep tests were made on Hastelloy XR forging, tube and XR-II tube at 1,123 to 1,273 K in a simulated HTGR helium gas environment. The tests were interrupted at different strain levels of up to 5 % in order to evaluate creep damage via intergranular voids. The void sizes along grain boundaries and the A-parameter, the ratio of the number of damaged grain boundaries, on which one or more voids are found, to that of the total grain boundaries observed are used in order to evaluate creep damage. Statistical analysis of the A-parameter as well as the void sizes reveals that the values of the parameter show wide variations and follow the Weibull distribution, reflecting spatial randomness of the voids. The void sizes along grain boundaries, on the other hand, follow the log-normal distribution. The maximum void size dmax and the mean value of the A-parameter Am are calculated and plotted against interruption creep strain ?int. The resultant dmax vs. ?int and Am vs. ?int diagrams show that Hastelloy XR forging had suffered more damage than Hastelloy XR tube; nevertheless, the forging has longer interruption life, or the time to reach a given interruption creep strain. The result indicates that grains may have been deformed more easily in Hastelloy XR in the form of tube than in the form of forging. The diagrams also imply that the addition of boron has suppressed the nucleation as well as the growth of voids and thus has brought about longer interruption life of Hastelloy XR-II. (author)

86

Production of titanium alloys with uniform distribution of heat resisting metals  

International Nuclear Information System (INIS)

Consideration is given to the process of the formation of a titanium sponge alloyed with niobium or tantalum, in the joint metallic reduction of titanium, niobium and tantanum chlorides. A percentage composition of the phases observed and the structure of the alloyed sponge have been studied. It is shown that after one remelting operation of the alloyed sponge the alloys of titanium with niobium and tantalum have a uniform component distribution. At the stage of chloride reduction there appear solid solutions based on titanium and an alloying component. The stage of vacuum separation of the reaction mass is associated with a mutual dissolution of the primary phases and the formation of the solid solutions of the alloyed titanium sponge, which, by their composition, are close to the desired alloy composition. The principal features of the formation of a titanium sponge alloyed with niobium and tantalum are in a perfect agreemet with those typical of Ti-Mo and Ti-W sponges, therefore it can be assumed that these features will be also common to the other cases of the metallic reduction of titanium and refractory metals chlorides

87

Mechanical Properties Anisotropy of Cold-Rolled and Solution-Annealed Ni-Based Hastelloy C-276 Alloy  

Science.gov (United States)

This work describes a correlation among texture, in-plane anisotropy in tensile properties, and yield locus in Ni-based Hastelloy C-276 alloy. The alloy exhibits moderate values of in-plane anisotropy and anisotropy index, which has been attributed to the presence of moderate overall intensity of texture. The alloy displays two slopes in true plastic stress-strain curve and follows a Ludwigson relation. At low plastic strains, the sample displays the presence of annealing twins and less strain localization at grain boundaries, while the formation of deformation twins and high strain localization within the deformation twins and at the grain boundaries are observed in a high-strained region. The 45-deg and 67.5-deg orientation samples show relatively low ductility and low work-hardening exponent. This has been explained based on dislocation storage capacity and dynamic recovery coefficient using Kock-Mecking-Estrin analysis.

Mehta, K. K.; Mukhopadhyay, Prantik; Mandal, R. K.; Singh, A. K.

2014-07-01

88

The mechanism of elevated temperature intergranular cracking in heat-resistant alloys  

International Nuclear Information System (INIS)

e alloy containing a lower bulk content of phosphorus. The elevated temperature intergranular cracking under tensile stress occurs finally due to the carbide-free grain boundary cracking following the decohesion of the grain boundary carbide interfaces.

89

Martensitic/ferritic super heat-resistant 650 C steels - design of model alloys  

Energy Technology Data Exchange (ETDEWEB)

Tempered martensitic/ferritic 9-12%Cr steels are now recognized to be the most potential materials for 650 C ultra super critical (USC) Power Plants. The degradation of long-term creep strength, as a result of microstructural changes during long-term exposure at the elevated temperature, is the main problem for this group of steels. Therefore, to achieve sufficient creep resistance during the entire service life it is necessary to stabilize the microstructure by alloying with elements which provide enough solid solution and precipitation strengthening and slow down diffusion. The aim of the present study is to investigate the effect of different types of precipitates as well as alloying elements on mechanical long-term properties of new ferritic 12%Cr steels. Fine distributions of stable precipitates which block the movement of subgrain boundaries (M{sub 23}C{sub 6} carbides, Laves phase) and dislocations (MX carbonitrides) and delay coarsening of microstructure is the key to high creep strength of such steels. Furthermore, additional Laves phase, which precipitates during service, is to strengthen the alloys when M{sub 23}C{sub 6} particles become less effective. Addition of Co is to achieve an initially 100% martensitic microstructure and moreover to slow down diffusion processes and consequently coarsening of particles. The partial substitution of Co by Cu and Mn is also investigated to reduce costs. The first results of mechanical tests of the studied model alloys have shown positive effects of the addition of W as Laves phase forming element, as well as of the MX forming elements Ta and Ti. Alloying with Co has also shown beneficial effects on the creep strength of model alloys. Further optimisation of composition and microstructure is in progress. (orig.)

Knezevic, V.; Sauthoff, G. [Max-Planck-Inst. fuer Eisenforschung GmbH, Duesseldorf (Germany)

2002-07-01

90

Recovering heat treatment of turbine blades of heat resistant nickel alloys  

International Nuclear Information System (INIS)

The degree of structural degradation in gas turbine engine blades of cast ZhS6U nickel alloy was estimated using microscopical examination prior to and after turbine engine running for 1600 h. Quantitative structural criterion for estimating blades operational capability is the width of grain-boundary zone of coarse ?'-phase which on further operation can result in pores and cracks. It is proposed to use recovering heat treatment at 1225 deg C for 4h with air cooling to restore initial microstructure. The above-mentioned heat treatment allows to increase the durability of nickel ZhS6U alloy by 30-40%. 4 refs., 2 tabs

91

Influence of loading frequency and cycle shape on crack resistance in heat resisting nickel alloy  

International Nuclear Information System (INIS)

A study is made into the influence of loading frequency and cycle shape on fracture properties of granular nickel alloy EhP741NP at 650 deg C. It is shown that a loading frequency increase from 0.1 to 10 Hz results in a growth of crack resistance factor and in a decrease of crack growth rate and a coefficient of cycle asymmetry. The loading cyclicity is found to be a predominant factor of damageing which defines the time to fracture in the alloy EhP741NP. 5 refs.; 3 figs

92

Creep-rupture behavior of 2-1/4 Cr-1 Mo steel, Alloy 800H and Hastelloy Alloy X in a simulated HTGR helium environment  

International Nuclear Information System (INIS)

Creep-rupture testing was conducted on 1 1/4 Cr-1 Mo steel, Alloy 800H and Hastelloy Alloy X in flowing helium containing nominal concentration of following gases: 1500 ?atm H2, 450 ?atm CO, 50 ?atm CH4, 50 ?atm H2O and 5 ?atm CO2. This environment is believed to represent maximum permissible levels of impurities in the primary coolant for the steam-cycle system of a high-temperature gas-cooled reactor (HTGR) when it is operating continuously with a water and/or steam leak at technical specification limits. Two or three heats of material for each alloy were investigated. Tests were conducted at 4820C and 7600C (12000F and 14000F) for Alloy 800H, and at 7600C and 8710C (14000F and 16000F) for Hastelloy Alloy X for times up to 10,000 h. Selected tests were performed on same heat of material in both air and helium environments to make a direct comparison of creep-rupture behaviors between two environments. Metallurgical evaluation was performed on selected post test specimens with respect to gas-metal interactions which included oxidation, carburization and/or decarburization. Correlation between gaseous corrosion and creep-rupture behavior was attempted. Limited tests were also performed to investigate the specimen size effects on creep-rupture behavior in the helium environment

93

Variation of compositional content in subsurface layers of hastelloy N type alloys as caused by melt of fluorides ZrF4 - NaF and electron irradiation  

International Nuclear Information System (INIS)

The secondary-ion mass-spectrometry technique was applied to study the compositional content variation in subsurface layers of alloys of Hastelloy type that had been irradiated with electron beam with the average energy 9.6 MeV in the melt of sodium and zirconium fluoride salts at the temperature 650 degree C for 700 h

94

Alloying effect on the structure and properties of austenitic heat-resistant steels  

International Nuclear Information System (INIS)

Investigated have been mechanical properties at test temperatures of 20-95O deg C, wear resistance, softening at thermomechanical cycling and microstructure of cast austenitic chromium-nickel steels (13%Cr + 35%Ni), produced by electroslag remelting with variations in Ti, Mo, Nb and W contents. Regression equations for relationship of the investigated characteristics to alloying element content have been obtained. Titanium, molybdenum and niobium increasing hardness and strength limit at room and high temperatures promote a decrease in ductility. Tungsten increases strength properties, wear resistance and thermal stability of the steels without negative effect on the impact strength. The impact strength decrease with an increase in alloying is due to brittle precipitations along the boundaries of as-cast grains, containing Ti, Mo, Nb and Si

95

Influence of quenching temperature on the structure of cast heat resisting nickel base alloy  

International Nuclear Information System (INIS)

The influence of thermal treatment regime on structure and properties of a complex foundry alloy with a nickel base of the KhN77TYuR type was studied. The temperature dependence of internal friction was investigated after various thermal treatment regimes. It was found that quenching must be carried out from 12000C to obtain a significant reduction of the degree of liquation and hence a better distribution of the hardening ?'-phase. (L.M.)

96

Effect of various factors on recovery and recrystallization of a nickel base heat resisting alloy  

International Nuclear Information System (INIS)

The study of the KhN65VMTYu (EhI893) alloy shows that the first stage of recovery connected with the change of point defect concentration, takes place in the range of 100-250 deg C. Polygonization processes develop noticeably at 750-900 deg C. The improvement of intragranular structure is also continued in secondary recrystallization, up to the temperatures of 1160-1180 deg C. Primary recrystallization starts at 900-950 deg C and is finished at 980-1020 deg C, depending on the degree of preliminary cold working. An intensive development of secondary recrystallization starts at 1100 deg C, i.e. the temperature of dissolution of dispersed carbide and boride phases. The presence of segregation interlayers results in ineven grains. Holding at 1180 deg C during 2-3 h for an open arc melted alloy and at 1160 deg C during 2-3 h for an open induction melted alloy are found to be the optimum conditions of recrystallization annealing

97

Creep-Rupture Properties and Corrosion Behaviour of 21/4 Cr-1 Mo Steel and Hastelloy X-Alloys in Simulated HTGR Environment : Interim Report  

DEFF Research Database (Denmark)

Hastelloy X and 2/sup 1///sub 4/ Cr-1 Mo steel are being considered as structural alloys for components of a High-Temperature Gas-Cooled Reactor (HTGR) system. Among other mechanical properties, the creep behavior of these materials in HTGR primary coolant helium must be established to form part of the design criteria. This report describes the simulated HTGR-helium environmental creep facilities, summarizes preliminary creep properties of 2/sup 1///sub 4/ Cr-1 Mo steel and Hastelloy X generated in HTGR helium and compares these with data obtained by testing in air. Some corrosion characteristics of the two materials are also discussed.

Lystrup, Aage

1977-01-01

98

Some considerations on electron beam welding of heat-resistant superalloys for nuclear plants  

International Nuclear Information System (INIS)

For the establishment of the safety peculiar to nuclear equipments, there are the strict limit of dimensional accuracy and the requirement of high temperature strength structurally, and many problems exist concerning the welding of heat-resistant superalloys, such as Hastelloy, Inconel and Incoloy. Electron beam welding is suitable to the welding of the heat-resistant alloys for nuclear reactors, because the energy density is extremely high, and deep penetration can be obtained with small heat input. Also when the welding is carried out in high vacuum, the welded part of high accuracy and high quality can be obtained. However, the local, instant melting of parent metal with high density energy is apt to induce defects in welded parts, such as porosity and cracking. In this study, the penetration mode and the defects on the bead cross section, especially microcracks, of respective heat-resistant alloys were investigated by changing the welding conditions, and the range of the optimal welding conditions was determined. The characteristics of electron beam welding as heat source, and the microcracks generated in the electron beam welded parts of heat-resistant alloys are explained. At present, new knowledge was obtained on the correlation between the heat input at the limit of preventing cracking and the result of cracking test heretofore, and the mechanism of generating microcracks was clarified metallurgically. These will be reported later. (Kako, I.)

99

Influence of granule metallurgy stages on boron distribution in heat resisting nickel granular alloy  

International Nuclear Information System (INIS)

Methods of autoradiography, metallography and X-ray spectrum microanalysis were applied to study boron distribution throughout the structural constituents of granular nickel base alloy (Ni-9%Cr-16%Co-5%Al-7%W-2%Ti-Nb-Hf-C-B) at various stages of granule technology. The regularities of boron distribution are determined for compacts produced from granules of centrifugal and gas jet spraying. The mechanism of formation of granules with anomalously high boron concentration is proposed. A consideration is given to the phenomenon of boron migration to grain boundaries at heat treatment. 10 refs.; 4 figs

100

Behaviour of selected heat resistant nickel-base alloys for steam turbine bolting  

International Nuclear Information System (INIS)

The objective of the project was to optimize nickel-base turbine bolting by different heat treatments. The aim was to obtain the best comprise of the relevant bolting properties such as creep and relaxation strength, notch-rupture insensitivity, contraction and stress corrosion cracking-intensitivity. The investigations were carried out on the three creep-resistant nickel-base alloys NiCr 20Fe 25 TiAl (similar to Nimonic 70), NiCr 20 TiAl (corresponding to Nimonic 80A) and NiCr 15 TiAl (corresponding to Inconel X-750). (orig./MM) With 63 figs., 15 tabs

 
 
 
 
101

Resistance of heat resisting steels and alloys to thermal and mechanical low-cycle fatigue  

International Nuclear Information System (INIS)

Carried out is a comparative evalUation of resistance of different materials to thermocyclic deformation and fracture on the base of the experimental data on thermal and mechanical low-cycle fatigUe. Considered are peculiarities of thermal fatigue resistance depending on strength and ductility of the material. It is shown, that in the range of the cycle small numbers before the fracture preference is given to the high-ductility cyclically strengthening austenitic steels of 18Cr-10Ni type with slight relation of yield strength to the ?sub(0.2)/?sub(B) tensile strength Highly alloyed strength chromium-nickel steels, as well as cyclically destrengthening perlitic and ferritic steels with stronger ?sub(0.2)/?sub(B) relation as compared with simple austenitic steels turn to be more long-lived in the range of the cycle great numbers berore fracture. Perlitic steels are stated to have the lowest parameter values of the K crack growth intensity under the similar limiting conditions of the experiment, while steels and alloys with austenite structure-higher values of the K parameter

102

?????-?????????? ?????????? ???????????? ???????? ?? ???????? ??????? ??? ?? ??????????? ????????? ??????? Ion-plasma technology of deposition heat-resistant coatings for GTE turbine blades from resistant nickel alloys  

Directory of Open Access Journals (Sweden)

Full Text Available ??????????????? ??????????? ????????? ??????????? ??????????? ???????? ? ?????????????? ??????????, ?????????? ?? ???????????????????? ?????-??????????????? ? ?????-?????????? ??????? ???????-??????????? ????????? ? ????????? ????????. ?????????? ?????????? ???????????? ????????????? ? ??????? ???????????? ??????? ?? ????????? ??????????? ???????.The possibility of obtaining heat-resistant coatings using “nano-technology” based on high-energy ion-implantation and ion-plasma methods, protective and strengthening treatment and coating. The results of the study the heat resistance and fatigue strength of parts made of nickel-base superalloys.

?. ?. ???????

2012-10-01

103

Effects of composite scale on high temperature oxidation resistance of Fe-Cr-Ni heat resistant alloy  

Directory of Open Access Journals (Sweden)

Full Text Available Fe-Cr-Ni heat resistant alloys with aluminum and silicon addition, alone and in combination, were melted using an intermediate frequency induction furnace with a non-oxidation method. By the oxidation weight gain method, the oxidation resistances of the test alloys were determined at 1,200 ìC for 500 hours. According to the oxidation weight gains, the oxidation kinetic curves were plotted and the functions were regressed by the least squares method. The results show that the oxidation kinetic curves follow the power function of y = axb (a>0, 0

Wang Haitao

2009-05-01

104

High temperature diffusion induced liquid phase joining of a heat resistant alloy  

Energy Technology Data Exchange (ETDEWEB)

Transient liquid phase bonding (TLP) of a nickel base superalloy, Waspaloy, was performed to study the influence of holding time and temperature on the joint microstructure. Insufficient holding time for complete isothermal solidification of liquated insert caused formation of eutectic-type microconstituent along the joint centerline region in the alloy. In agreement with prediction by conventional TLP diffusion models, an increase in bonding temperature for a constant gap size, resulted in decrease in the time, t{sub f,} required to form a eutectic-free joint by complete isothermal solidification. However, a significant deviation from these models was observed in specimens bonded at and above 1175 deg. C. A reduction in isothermal solidification rate with increased temperature was observed in these specimens, such that a eutectic-free joint could not be achieved by holding for a time period that produced complete isothermal solidification at lower temperatures. Boron-rich particles were observed within the eutectic that formed in the joints prepared at the higher temperatures. An overriding effect of decrease in boron solubility relative to increase in its diffusivity with increase in temperature, is a plausible important factor responsible for the reduction in isothermal solidification rate at the higher bonding temperatures.

Wikstrom, N.P.; Egbewande, A.T. [Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, Manitoba, R3T 5V6 (Canada); Ojo, O.A. [Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, Manitoba, R3T 5V6 (Canada)], E-mail: ojo@cc.umanitoba.ca

2008-07-28

105

High temperature diffusion induced liquid phase joining of a heat resistant alloy  

International Nuclear Information System (INIS)

Transient liquid phase bonding (TLP) of a nickel base superalloy, Waspaloy, was performed to study the influence of holding time and temperature on the joint microstructure. Insufficient holding time for complete isothermal solidification of liquated insert caused formation of eutectic-type microconstituent along the joint centerline region in the alloy. In agreement with prediction by conventional TLP diffusion models, an increase in bonding temperature for a constant gap size, resulted in decrease in the time, tf, required to form a eutectic-free joint by complete isothermal solidification. However, a significant deviation from these models was observed in specimens bonded at and above 1175 deg. C. A reduction in isothermal solidification rate with increased temperature was observed in these specimens, such that a eutectic-free joint could not be achieved by holding for a time period that produced complete isothermal solidification at lower temperatures. Boron-rich particles were observed within the eutectic that formed in the joints prepared at the higher temperatures. An overriding effect of decrease in boron solubility relative to increase in its diffusivity with increase in temperature, is a plausible important factor responsible for the reduction in isothermal solidification rate at the higher bonding temperatures

106

Evaluation on materials performance of hastelloy alloy XR for HTTR uses. 4. Tensile properties of base metals and welded joints  

International Nuclear Information System (INIS)

Tensile properties due to thermal aging on Hastelloy Alloy XR base metals and welded joints were investigated as a series of evaluation test on the base metals and filler metals for the High Temperature Engineering Test Reactor (HTTR) components. Tensile test in air was performed at R.T. and then same temperatures as the thermal aging temperatures after the specimens were aged at 800, 900 and 1000degC for 1000hrs. In comparison with the previous data, the present results had no significant difference on the strength characteristics, and were in the previous data band on the ductility. Therefore, it is concluded that these base metals and filler metals for the HTTR components have excellent tensile properties. (author)

107

Heat Treatment Development for a Rapidly Solidified Heat Resistant Cast Al-Si Alloy  

Science.gov (United States)

Existing heat treatment standards do not properly define tempers for thin-walled castings that solidified with high solidification rates. Recently emerged casting processes such as vacuum high pressure die casting should not require long solution treatment times due to the fine microstructures arising from rapid solidification rates. The heat treatment studies involving rapidly solidified samples with secondary dendrite arm spacing between 10 and 35 ?m were conducted for solution times between 30 min and 9 h and temperatures of 510 and 525 °C and for various aging parameters. The metallurgical analysis revealed that an increase in microstructure refinement could enable a reduction of solution time up to 88%. Solution treatment resulted in the dissolution of Al2Cu and Al5Mg8Si6Cu2, while Fe- and TiZrV-based phases remained partially in the microstructure. The highest strength of approximately 351 ± 9.7 and 309 ± 3.4 MPa for the UTS and YS, respectively, was achieved for a 2-step solution treatment at 510 and 525 °C in the T6 peak aging conditions, i.e., 150 °C for 100 h. The T6 temper did not yield dimensionally stable microstructure since exceeding 250 °C during in-service operation could result in phase transformation corresponding to the over-aging reaction. The microstructure refinement had a statistically stronger effect on the alloy strength than the increase in solutionizing time. Additionally, thermal analysis and dilatometer results were presented to assess the dissolution of phases during solution treatment, aging kinetics as well as dimensional stability.

Kasprzak, W.; Chen, D. L.; Shaha, S. K.

2013-07-01

108

Hardening mechanisms in a dynamic strain aging alloy, Hastelloy X, during isothermal and thermomechanical cyclic deformation  

Science.gov (United States)

The relative contributions of the hardening mechanisms in Hastelloy X during cyclic deformation were investigated by conducting isothermal cyclic deformation tests within a total strain range of +/-0.3 pct and at several temperatures and strain rates, and thermomechanical tests within several different temperature limits. The results of the TEM examinations and special constant structure tests showed that the precipitation on dislocations of Cr23C6 contributed to hardening, but only after sufficient time above 500 C. Solute drag alone produced very considerable cyclic hardening. Heat dislocation densities, peaking around 10 exp 11 per sq cm, were found to develop at temperatures producing the greatest cyclic hardening.

Miner, R. V.; Castelli, M. G.

1992-01-01

109

Electrochemical investigation of the effect of different laser surface treatments on Hastelloy G alloy  

International Nuclear Information System (INIS)

In the present study, the corrosion resistance behavior of untreated and laser treated Hastelloy was examined. The electrochemical tests including potentiodynamic polarization, Tafel analysis, and linear polarization resistance were carried out in deaerated 0.5% NaCl aqueous solution at room temperature. Surface roughness was measured to correlate it with corrosion resistance properties of the materials. Surface morphology of the samples after corrosion tests was examined using scanning electron microscopy and energy dispersive X-ray spectroscopy. Results showed that laser treated surface exhibited better corrosion resistance properties as compared to untreated surface. (orig.)

110

Electrochemical investigation of the effect of different laser surface treatments on Hastelloy G alloy  

Energy Technology Data Exchange (ETDEWEB)

In the present study, the corrosion resistance behavior of untreated and laser treated Hastelloy was examined. The electrochemical tests including potentiodynamic polarization, Tafel analysis, and linear polarization resistance were carried out in deaerated 0.5% NaCl aqueous solution at room temperature. Surface roughness was measured to correlate it with corrosion resistance properties of the materials. Surface morphology of the samples after corrosion tests was examined using scanning electron microscopy and energy dispersive X-ray spectroscopy. Results showed that laser treated surface exhibited better corrosion resistance properties as compared to untreated surface. (orig.)

Toor, Ihsan H.; Yilbas, Bekir S.; Hussein, Mohammed A.; Zafar, Mohammed N. [King Fahd Univ. of Petroleum and Minerals (KFUPM), Dhahran (Saudi Arabia). Dept. of Mechanical Engineering; Karatas, Cihan [Hacettepe Univ., Ankara (Turkey). Engineering Faculty

2013-10-15

111

Evaluation on materials performance of Hastelloy Alloy XR for HTTR uses-5 (Creep properties of base metal and weldment in air)  

International Nuclear Information System (INIS)

Creep properties of weldment made from Hastelloy Alloy XR base metals and filler metals for the High Temperature Engineering Test Reactor (HTTR) components were examined by means of creep and creep rupture tests at 900 and 950degC in air. The results obtained are as follows: creep rupture strength was nearly equal or higher than that of Hastelloy Alloy XR master curve and was much higher than design creep rupture strength [SR]. Furthermore, creep rupture strength and ductility of the present filler metal was in the data band in comparison with those of the previous filler metals. It is concluded from these reasons that this filler metal has fully favorable properties for HTTR uses. (author)

112

High-temperature low-cycle fatigue and tensile properties of Hastelloy X and alloy 617 in air and HTGR-helium  

International Nuclear Information System (INIS)

Results of strain controlled fatigue and tensile tests are presented for two nickel base solution hardened alloys which are reference structural alloys for use in several high temperature gas cooled reactor concepts. These alloys, Hastelloy X Inconel 617, were tested at temperatures ranging from room temperature to 8710C in air and impure helium. Materials were tested in the solution annealed as well as in the pre-aged condition where aging consisted of isothermal exposure at one of several temperatures for periods of up to 20,000 h. Comparisons are also given between the strain controlled fatigue lives of these alloys and several other commonly used alloys all tested at 5380C

113

High temperature low-cycle fatigue and tensile properties of Hastelloy X and alloy 617 in air and HTGR-helium  

International Nuclear Information System (INIS)

Results of strain controlled fatigue and tensile tests are presented for two nickel base solution hardened alloys which are reference structural alloys for use in several high temperature gas cooled reactor concepts. These alloys, Hastelloy X and Inconel 617, were tested at temperatures ranging from room temperature to 8170C in air and impure helium. Materials were tested in the solution annealed as well as in the pre-aged condition where aging consisted of isothermal exposure at one of several temperatures for periods of up to 20,000 h. Comparisons are also given between the strain controlled fatigue lives of these alloys and several other commonly used alloys all tested at 5380C. (Auth.)

114

Modulation Effects of K2ZrF6 Additive on Microstructure and Heat Resistance of Micro-arc Oxide Coatings Fabricated on LY12 Aluminum Alloy  

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Full Text Available Zr(OH4 particle can be formed and negatively charged in alkaline solution with K2ZrF6 addition. Based on this mechanism, Zr-containing ceramic coatings were fabricated on LY12 aluminum alloy by microarc oxidation (MAO using K2ZrF6 as a special additive in Na2SiO3-KOH base electrolyte. The modulation effects of K2ZrF6 addition on micro-microstructure, element distribution and phase composition were analyzed by SEM, EDS and XRD, respectively. Heat resistance of MAO coatings formed on LY12 aluminum alloy in different electrolyte was investigated. The results show that the K2ZrF6 addition can increase the micro-arc oxidation rate and significantly alter the structure of MAO coatings. Both the top surface and inner surface of MAO coatings fabricated in Zr-containing electrolyte become relatively smooth. Compared with the coating formed in Zr-free electrolyte, a large amount of Zr element is found in the coating formed in electrolyte with K2ZrF6 addition. Two main phases, ?-Al2O3 and ?-Al2O3, are contained in Zr-free coating. In contrast, more amorphous phase is found in Zr-containing coating with reduced amount of crystalline alumina. Experimental results also demonstrate that Zr-containing coating exhibits higher heat resistance.

ZHANG Xin-Meng, CHEN Dong-Fang, GONG Chun-Zhi , YANG Shi-Qin, TIAN Xiu-Bo

2010-07-01

115

Selection of canister materials: electrochemical corrosion tests of HASTELLOY C4 and other Ni-Cr(-Mo) alloys in chloride containing solutions  

International Nuclear Information System (INIS)

Several Ni-Cr(-Mo) alloys (HASTELLOY C4, INCONEL 625, SANICRO 28, INCOLOY 825, INCONEL 690) were tested by electrochemical methods to characterize their corrosion behaviour in chloride containing solutions at various temperatures and pH-values in respect to their application as canister materials for final radioactive waste storage. Especially, HASTELLOY C4 which proved to have the highest corrosion resistance of all tested alloys was tested by the following electrochemical methods: (1) Poteniodynamic measurements to determine the characteristic potentials, passive current densities and critical pitting potentials. (2) Potentiostatic measurements in order to evaluate the duration of the incubation period at various potentials. (3) Galvanostatic measurements in order to characterize critical pitting potentials. As electrolyte 1 m H2SO4 was used, as parameters temperature, chloride content and pH-value were varied. Variation of temperature gives the following results: an increase in temperature leads to an increase of the critical passivation current density, the passive potential bandwidth decreases slightly and the passive current density increases with rising temperature. The addition of different chloride contents to the H2SO4 solution shows the following effects: the critical passivation current density and the passive current density increase with increasing chloride concentration and both, the critical pitting potentialn and both, the critical pitting potentials and the pitting nucleation potentials, shift towards negative values. As third parameter the pH-value was varied. As expected, an increase of the pH-value extends the passive region to more negative values, the passive current density decreases. The variation of the pH-value does not affect the critical pitting potential. All tested alloys showed a clearly limited resistance against pitting corrosion phenomena. However, the best corrosion behaviour is shown by HASTELLOY C4, which has of all tested alloys the lowest passivation current density and the largest potential region with protection against local corrosion phenomena. (author)

116

Laser cladding of stainless steel with hastelloy  

Energy Technology Data Exchange (ETDEWEB)

Hastelloy alloys combine good mechanical properties with excellent resistance to corrosion. One of their potential applications is in deep gas wells where there is a high concentration of H{sub 2}S. In such conditions, mechanical resistance to very high pressures in combination with chemical resistance to the acidic environment is required. However, use of Hastelloy is limited by the cost. Therefore, it appeared interesting to study the feasibility of covering a less expensive base material with a coating of Hastelloy of appropriate thickness, recognizing that the corrosion resistance is essentially a surface property. An economic evaluation indicates that a cost reduction of 50-60% is expected if using tubes coated with Hastelloy instead of tubes fully made of Hastelloy. (orig.)

Haemers, T.A.M.; Rickerby, D.G.; Lanza, F.; Geiger, F. [Commission of the European Communities, Ispra (Italy). Joint Research Centre; Technische Univ. Delft (Netherlands). Lab. of Materials Science; Mittemeijer, E.J. [Max-Planck-Institut fuer Metallforschung, Stuttgart (Germany)

2001-04-01

117

Influence of ?-phase on properties of heat resistant wrought nickel alloy type KhN60KVYuMB  

International Nuclear Information System (INIS)

Investigation into the structure and mechanical properties (impact strength, long-term strength, fatigue and plastic limits) of extruded bars of KhN60KVYuMB alloy designed for operation at high temperatures (700-800 deg C) is conducted. Microstructural investigations have shown that ?-phase, precipitating under isothermal ageing, does not spoil the alloy properties. 6 refs.; 5 figs.; 6 tabs

118

Analysis of the in-reactor creep and rupture life behavior of stabilized austenitic stainless steels and the nickel-base alloy Hastelloy-X  

International Nuclear Information System (INIS)

An overall evaluation of several in-reactor creep and creep-rupture experiments in BR2 and FFTF on pressurized tubes of the stabilized austenitic stainless steels 1.4970, 1.4981, and 1.4988 and the Ni-base alloy Hastelloy-X is given in this report. Even at temperatures around and above 0.5 T/sub m/ the analysis of the data implies that for low stress levels the stress-induced preferred absorption (SIPA) creep process is the predominant deformation mechanism. The results show that the in-reactor rupture lives of the austenitic steels as well as the Ni-base alloy Hastelloy-X are reduced compared with the rupture lives of the corresponding material in the unirradiated and post-irradiation tested conditions, so that an additional damage mechanism via helium has to be assumed to account for the reduction in rupture life. Analytical models have been developed, which accounts for the critical variables stress, temperature, and dpa rate and which describes in a more general way the in-reactor creep and creep-rupture life behavior of the materials mentioned above. The analysis of the results indicates clearly that the use of the unirradiated and post-irradiation data for predicting in reactor creep and failures is invalid for these materials

119

Influence of a simulated HTGR environment on the mechanical properties of a commercial Ni-Cr-Mo-Fe alloy (Hastelloy Alloy X)  

International Nuclear Information System (INIS)

The influence of a simulated advanced-reactor helium environment, containing 500 ?atm H2/50 ?atm CH4/50 ?atm CO/approx. 1 ?atm H2O, on the mechanical properties of two heats of Hastelloy Alloy X is discussed. Simultaneous exposures in air and controlled-impurity helium at temperatures in the range of 6500 to 10000C for times of 3000 h or more were performed. A combination of tensile testing, Charpy V-notch impact toughness testing, and creep testing was used to study the effects of reactor helium/metal interactions on the mechanical behavior of this alloy. Carburization was identified as the primary corrosion phenomenon. Increasing exposure time and temperature were observed to increase the depth of carburization. The increase in carbon concentration in the carburized zone suppressed the additional formation of M6C, which is observed in air-aged specimens, and resulted in the precipitation of M23C6, a chromium-rich carbide variant. The precipitation of M23C6 in the carburized zone occurred primarily along grain and twin boundaries; however, matrix precipitation was also observed, the degree of which depended on exposure temperature. Strength and impact toughness properties were found to be controlled primarily by thermal aging reactions, with only a small effect related to the carburization. Although tensile and creep ductilities were decreased as a resultductilities were decreased as a result of carburization, substantial ductility remained. Variation was observed between the two heats, the finer-grained heat appearing to be weaker in the high-temperature creep tests and also possibly more susceptible to a loss of creep strength as a result of carburization

120

Main ways of heat resistant steels design  

International Nuclear Information System (INIS)

Main directions of development of heat resistant steels including including new approaches and methods both in part of structural investigations and in the field of applying more perfect technological processes of their production and treatment are considered. The necessity of preparing materials for nuclear and thermonuclear engineering with a special complex of mechanical properties is underlined. Austenitic steels and ferritic steels with the Curie point close to room temperature are considered as promising materials for first wall of TNR. A possibility of using high-alloyed nickel alloys is considered for high temperature heat exchangers. Primary attention is paid to heat resistant pearlitic steels and methods of their substructural hardening for an essential increase of creep resistance and long-term rupture strength. Perspectiveness of applying powder metallurgy methods, thermomechanical treatment, microalloying and nitrogen substitution in steels for carbon is revealed. The necessity of reinforcing coordination of research works in the field of heat resistant alloys is noted

 
 
 
 
121

Hafnium-silicon precipitate structure determination in a new heat-resistant ferritic alloy by precession electron diffraction techniques.  

Science.gov (United States)

The structure determination of an HfSi4 precipitate has been carried out by a combination of two precession electron diffraction techniques: high precession angle, 2.2°, single pattern collection at eight different zone axes and low precession angle, 0.5°, serial collection of patterns obtained by increasing tilts of 1°. A three-dimensional reconstruction of the associated reciprocal space shows an orthorhombic unit cell with parameters a = 11.4 Å, b = 11.8 Å, c = 14.6 Å, and an extinction condition of (hkl) h + k odd. The merged intensities from the high angle precession patterns have been symmetry tested for possible space groups (SG) fulfilling this condition and a best symmetrization residual found at 18% for SG 65 Cmmm. Use of the SIR2011 direct methods program allowed solving the structure with a structure residual of 18%. The precipitate objects of this study were reproducibly found in a newly implemented alloy, designed according to molecular orbital theory. PMID:24172206

Viladot, Désirée; Portillo, Joaquim; Gemí, Mauro; Nicolopoulos, Stavros; Llorca-Isern, Núria

2014-02-01

122

Effects of stress aging on changes in mechanical properties and microstructures of Hastelloy-X and Hastelloy-XR  

International Nuclear Information System (INIS)

Mechanical property and Microstructural changes of Ni-base super alloys after aging with and without tensile stress were observed in the temperature range of 500-10000C for durations to 305 hr. The materials tested are Hastelloy-X and its modified heat (Hastelloy-XR). Changes of the mechanical properties are appreciably enhanced by the application of stress during the aging. The changes are interpreted in connection with microstructural changes due to the enhanced carbide precipitation caused by the stress aging. Commercial grade Hastelloy-X is found to be more influenced by the stress than Hastelloy-XR. (auth.)

123

Heat-resisting steels  

International Nuclear Information System (INIS)

The main part of this work is high temperature corrosion by hot gases or molten sats. In order to have a better understanding of alloying techniques, the kinetic and thermodynamic interrelations of high temperature corrosion are explained. (IHOE)

124

Flow behaviour and microstructure of the heat-resistant steels X20CrMoV12.1 and X5NiCrTiAl32.20 (alloy 800)  

International Nuclear Information System (INIS)

Flow-curve characteristics of the heat-resistant steels X 20 CrMoV 12.1 and alloy 800 (X5NiCrTiAl32.20) were measured by tensile and compression tests at temperatures between room temperature and 800 C and strain rates ??10 s-1 in connection with microstructure investigations (dislocation content, carbide precipitation) by TEM and X-ray diffraction analysis (XDA). Modelling the deformation behaviour of the steels in terms of the microstructure development indicates that it cannot be explained in a simple manner. The flow curves ?=?(?, ?, T) lie, in general, between those predicted by the Kocks-Mecking-Estrin model and a modified (i.e. two-parameter) Roberts model. Because of the less complicated nature of the deformation process the correspondence of experiment and modelling is more satisfying in the case of the material X 20 CrMoV 12.1. (orig.)

125

Corrosion of nickel alloys in nuclear fuel reprocessing  

International Nuclear Information System (INIS)

Corrosion studies were made of high Ni alloys in process solutions which will be encountered during reprocessing of fuel from Shippingport PWR Core 2, seeds 1 and 2. The alloys were Hastelloy C-276 and C-4, Inconel 625, Incoloy 825, Hastelloy S, Hastelloy G, and Inconel 671. Effects of process variables were studied. Welded Hastelloy C-276 vessels were constructed and tested. (DLC)

126

Microstructures and creep behavior of as-cast and annealed heat-resistant Mg–4Al–2Sr–1Ca alloy  

International Nuclear Information System (INIS)

Highlights: ? Determining the intermetallics of the Mg–4Al–2Sr–1Ca alloy in as-cast and as-annealed state. ? Grain boundary phases play an important role during creep. ? The combination of dislocation motion and grain boundary sliding contributes to the creep deformation at high temperature. - Abstract: Microstructures, mechanical and creep properties of Mg–4Al–2Sr–1Ca alloy were investigated. As-cast microstructure of the experimental alloy consists of dendritic ?-Mg and grain boundary intermetallics, predominantly lamellar eutectic C14–Mg2Ca and bulky Mg–Al–Sr ternary phase. In addition, small amounts of C36–(Mg, Al)2Ca and Mg17Sr2 phases were also observed. Annealing at 400 °C leads to the transformation of Laves phases from C14 (or C14 + C36) to C15. Meanwhile, the lamellar eutectic tends to be spheroidised and the continuous intermetallic network is broken up with prolongation of annealing time. The as-cast alloy shows a very high creep resistance at the temperatures between 150 and 200 °C and applied stresses between 50 and 80 MPa. Annealing at 400 °C results in a remarkable decrease of creep properties due to the morphological modification of the grain boundary intermetallics. It is proposed that both dislocation motion and grain boundary sliding contribute to the creep deformation of the present alloy.

127

Effects of oxidation on the impact energy of Hastelloy S and Hastelloy C-4 Charpy V-notch specimens heated in air at 6000 to 8000C  

International Nuclear Information System (INIS)

The 90SrF2 heat source being developed at PNL utilizes a Hastelloy S or Hastelloy C-4 outer capsule having a 0.5-in.-thick wall to contain the Hastelloy C-276 inner capsule. The primary objective of the study was to demonstrate that the air oxidation of the outer capsule that could occur during heat-source service would not degrade the ductility and Charpy impact strength of the capsule below the licensing requirements given in Section 1.1. The 90SrF2 heat source under development is intended for general-purpose use. Compatibility considerations limit the interface temperature between the 90SrF2 and Hastelloy C-276 inner capsule to a maximum of 8000C. The outer capsule surface temperature will be somewhat less than 8000C, and depending on the service, may be substantially lower. The oxidation tests were therefore carried out at 6000 to 8000C for exposures up to 10,000h to cover the range of temperature the outer capsule might expect to encounter in service. The results showed that the oxidation of Hastelloy S and Hastelloy C-4 in air at 6000 to 8000C is very slow, and both alloys form adherent oxide layers that serve to protect the underlying metal. Subsurface attack of Hastelloy S and Hastelloy C-4 due to oxidation was greater than expected, considering the slow oxidation rates of the two alloys at 6000 to 8000C. Estimates of subsurface attack, determined from micrographs of the oxidized specimens, showed erratic results and it was impossible to assign any type of rate equation to the subsurface attack. A conservative estimate of long-term effects can be made using a linear extrapolation of the test results. There were no significant differences between the room-temperature Charpy impact energy of Hastelloy S and Hastelloy C-4 specimens oxidized in air at 6000 to 8000C and control specimens heated in vacuum

128

Kinetics of evaporation from the surface of refractory nickel and titanium alloys with heat resistant coatings during their irradiation by high-power pulsed ion beams  

International Nuclear Information System (INIS)

The effect of the irradiating conditions by high-power pulsed ion beams (HPPIB) on the ablation rate was studied. The conditions of irradiation (ions of carbon and protons, ion energy E=300-600 keV, the ion current density in a pulse j=60-500 A·cm-2, pulse duration ?=50-100 ns) were realized in 'Temp' and 'Vera' accelerators. The study of the evaporation kinetics was carried out using targets manufactured from GS26NK nickel super-alloy with NiCrAlY coating and from Vt9 and VT18U titanium alloys with Zr N and TiSiB coatings. It is shown that values of the ablation rate achieve 0.04 ?m (TiSiB), 0.4 ?m (NiCrAlY), and 1 ?m (Zr N) during a pulse under the optimal conditions of HPPIB irradiation

129

HEAT RESISTANCE OF GRAPHITIZED STEEL  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose. The investigation of temperature dependences of steels' mechanical properties and heat resistance under conditions of thermal cyclic loads. It's necessary to determine the mechanical properties and heat resistance indices of graphitized steels and cast iron VCh400 within the temperature range of 20…800°?. Methodology. Graphitized steels of the following chemical composition (mass %: 0.61…1.04C; 1.19…1.59%Si; 0.32…0.37%Mn; 0.12…0.17%Al; 0.008…0.014%S and 0.016…0.025%? have been heat-treated according to the mode: heating up to 810°? – holding for 2 hours; cooling down to 680°? – holding for 2 hours with further cooling using the furnace in order to provide the ferrite-pearlite metallic base with graphite inclusions. In order to determine heat resistance indices (heat stresses index K and the material's resistance criterion at thermal cyclic load C the indices of graphitized steels' and cast irons' mechanical properties in the temperature range of 20…800°? have been investigated. Findings. It has been established that as a result of lower carbon content and smaller quantity of graphite inclusions, graphitized steel exceeds such indices of nodular cast iron VCh400 as: tensile strength and plasticity at room and high temperatures, and also heat resistance criteria K and C. This steel can be used to manufacture articles operating under conditions of thermal cyclic loads. Originality. Tensile strength and percent elongation of graphitized steels within the temperature range of 20…800°? have been determined. Calculations of heat resistance criteria to the heat stresses index K and the material's resistance criterion at thermal cyclic loads C within the temperature range 20…800°? in comparison with nodular cast iron of VCh400 grade have been carried out. Practical value. The expediency of using graphitized steel for manufacturing of articles operating under conditions of thermal cyclic loads has been shown.

V. O. Savchenko

2014-06-01

130

The flow behavior modeling of as-extruded 3Cr20Ni10W2 austenitic heat-resistant alloy at elevated temperatures considering the effect of strain  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english In order to investigate the compressive deformation behavior of 3Cr20Ni10W2 alloy, a series of isothermal upsetting experiments were carried out in the temperature range of 1203-1403 K and strain rate range of 0.01-10 s-1 on a Gleeble-1500 thermo-mechanical simulator. The results indicate that the f [...] low stress initially increases to a peak value and then decreases gradually to a steady state. The characteristics of the curves are determined by the interaction of work hardening (WH), dynamic recovery (DRV) and dynamic recrystallization (DRX). The flow stress decreases with increasing temperature and decreasing strain rate. The relationship between microstructure and processing parameters is discussed to give an insight into the hot deformation behavior of 3Cr20Ni10W2 alloy. Then, by regression analysis for constitutive equation, material constants (n, ?, ?, A and Q) were calculated for the peak stress. Further, the constitutive equation along the flow curve was developed by utilizing an eighth order polynomial of strain for variable coefficients (including n, ?, A and Q). The validity of the developed constitutive equation incorporating the influence of strain was verified through comparing the experimental and predicted data by using standard statistical parameters such as correlation coefficient (R) and average absolute relative error (AARE) that are 0.995 and 4.08% respectively.

Guo-Zheng, Quan; Yuan-Ping, Mao; Chun-Tang, Yu; Wen-Quan, Lv; Jie, Zhou.

2014-04-01

131

Long-term corrosion behaviors of Hastelloy-N and Hastelloy-B3 in moisture-containing molten FLiNaK salt environments  

International Nuclear Information System (INIS)

Highlights: •Corrosion behaviors of Hastelloy-N and -B3 in molten FLiNaK salt at 700 °C. •The alleviated corrosion rate of alloys was observed after long-hour immersion. •Long-term corrosion rate was limited by diffusion from matrix to alloy surface. •Corrosion pattern transferred from intergranular corrosion into general corrosion. •Presence of minor H2O did not greatly influence the long-term corrosion behavior. -- Abstract: This study investigated long-term corrosion behaviors of Ni-based Hastelloy-N and Hastelloy-B3 under moisture-containing molten alkali fluoride salt (LiF–NaF–KF: 46.5–11.5–42%) environment at an ambient temperature of 700 °C. The Hastelloy-N and Hastelloy-B3 experienced similar weight losses for tested duration of 100–1000 h, which was caused by aggregate dissolution of Cr and Mo into FLiNaK salts. The corrosion rate of both alloys was high initially, but then reduced during the course of the test. The alleviated corrosion rate was due to the depletion of Cr and Mo near surface of the alloys and thus the long-term corrosion rate was controlled by diffusion of Cr and Mo outward to the alloy surface. The results of microstructural characterization revealed that the corrosion pattern for both alloys tended to be intergranular corrosion at early stage of corrosion test, and then transferred to general corrosion for longer immersion hours

132

The suitability of selected austenitic stainless steels and Hastelloy C276 alloys as substrates for thin film deposition using spray pyrolysis  

Energy Technology Data Exchange (ETDEWEB)

To detect the suitability of the American Iron and Steel Institute grade 304, 309, 310, 316L steels and Hastelloy C276 substrates for thin film deposition using spray pyrolysis, the substrates were pre-heated between 400-700 C and soaked for one hour. American Society for Testing and Materials standards A262-A, E and G28-A were then applied. The substrates of 304 heated at 400, 600-700 C, the 310 heated between 450-700 C and the as-received 310 were not found suitable. However it was found that the 304, 309, and 310 substrates were suitable up to 550 C, the 316L up to 700 C and the C276 up to 550 C. (orig.)

Al Khateeb, Shadi [Al-Balqa' Applied Univ., Al-Salt, Jordan (Jordan). Materials Engineering Dept.

2013-03-15

133

Nitrogen effect on heat resistance and structure of subscale layer of chromium-manganese steel  

International Nuclear Information System (INIS)

The possibility of achieving high heat resistance with conservation of austenite structure under the scale was investigated. For this purpose chrome-manganese steel was alloyed by nitrogen-strong #betta#-stabilizer. Nitrogen effect on component distribution in subscale layer and depth of this layer, as well as heat resistance of alloys with preliminarily prepared surface ?-layer and without it were studied. It was established that at 0.55-0.60% nitrogen content high heat resistance is achieved and austenite structure is conserved under the scale; it must promote the increase of contant strength

134

Heat-resistant materials 2. Conference proceedings of the 2. international conference on heat-resistant materials  

International Nuclear Information System (INIS)

The Second International Conference on Heat-Resistant Materials was held in Gatlinburg, Tennessee, September 11--14, 1995 and focused on materials performance in cross-cutting technologies where heat resistant materials play a large and sometimes life-and performance-limiting roles in process schemes. The scope of materials for heat-resistant applications included structural iron- and nickel-base alloys, intermetallics, and ceramics. The conference focused on materials development, performance of materials in simulated laboratory and actual service environments on mechanical and structural integrity of components, and state-of-the-art techniques for processing and evaluating materials performance. The three keynote talks described the history of heat-resistant materials, relationship between microstructure and mechanical behavior, and applications of these materials in process schemes. The technical sessions included alloy metallurgy and properties, environmental effects and properties, deformation behavior and properties, relation between corrosion and mechanical properties, coatings, intermetallics, ceramics, and materials for waste incineration. Seventy one papers have been processed separately for inclusion on the data base

135

High temperature low-cycle fatigue strength of Hastelloy-XR  

International Nuclear Information System (INIS)

This paper describes the low-cycle fatigue and creep-fatigue interaction properties of Hastelloy-XR in air and helium containing a small quantity of impurity gas. All tests at temperatures of 700, 800, 900 and 1000 deg. C are carried out at the strain rate of 0.1 and 0.01%/sec under the control of axial strain. Wave forms are triangular for continuous cycling tests and trapezoidal for tension hold time tests. The test results are compared with the fatigue property of Hastelloy-X which is the original alloy of Hastelloy-XR. The applicability of linear damage rule in ASME Code Case N-47 is discussed about creep-fatigue interaction property of Hastelloy-XR in High Temperature Gas-Cooled Reactor's temperature region. (author). 6 refs, 7 figs, 2 tabs

136

Fundamental studies on electron beam welding on heat-resistant superalloys for nuclear plants, 7  

International Nuclear Information System (INIS)

In this paper, the environmental effect of weld zone of heat-resistant superalloys by aging in high temperature helium was examined. Obtained conclusions are summarized as follows: 1) Hastelloy X showed the most smallest weight gain among the materials used, and no difference was discovered among the base metal, the electron beam weld joints and TIG weld joints for the respective materials. 2) Regarding the internal oxidation resistance, the electron beam weld metal was equivalent to or superior to the base metal, while the TIG weld metal was generally inferior to it. Among the materials used, Hastelloy X showed the most excellent internal oxidation resistance. 3) The oxide film of Hastelloy X showed the most excellent adherence property among the materials used. 4) Concerning the precipitation process of carbides, it followed the precipitation and cohesion with a rise in aging temperature and a lapse of aging time, and a change in hardness corresponded to it. However, notable difference in precipitation process was not noted among the base metal, electron beam weld metal and TIG weld metal. (author)

137

Larson-Miller Constant of Heat-Resistant Steel  

Science.gov (United States)

Long-term rupture data for 79 types of heat-resistant steels including carbon steel, low-alloy steel, high-alloy steel, austenitic stainless steel, and superalloy were analyzed, and a constant for the Larson-Miller (LM) parameter was obtained in the current study for each material. The calculated LM constant, C, is approximately 20 for heat-resistant steels and alloys except for high-alloy martensitic steels with high creep resistance, for which C ? 30 . The apparent activation energy was also calculated, and the LM constant was found to be proportional to the apparent activation energy with a high correlation coefficient, which suggests that the LM constant is a material constant possessing intrinsic physical meaning. The contribution of the entropy change to the LM constant is not small, especially for several martensitic steels with large values of C. Deformation of such martensitic steels should accompany a large entropy change of 10 times the gas constant at least, besides the entropy change due to self-diffusion.

Tamura, Manabu; Abe, Fujio; Shiba, Kiyoyuki; Sakasegawa, Hideo; Tanigawa, Hiroyasu

2013-06-01

138

High-temperature stress rupture performance of Hastelloy C-276  

International Nuclear Information System (INIS)

Hastelloy C-276 is one of the candidate cladding materials in supercritical water cooling reactor (SWCR). In this study, the SEM and TEM were used to investigate the microstructure of C-276 alloy before and after ruptured at 650 ? under different tensile stresses. Based on the experimental results, it can be concluded that the C-276 alloy has a good high-temperature stress rupture performance which is speculated to be the co-effects of solid solution-strengthening, precipitation-strengthening and deformation twin-strengthening. (author)

139

Effect of alloying with TiC, NbC and TiN on heat-resistance of NiAl alloy produced by high-temperature synthesis compacting  

International Nuclear Information System (INIS)

By self-propagating high-temperature synthesis (SHS)-compacting the composition materials based on intermetallic compound NiAl alloyed by fine particles of TiC, NbC, and TiN (up to 20 wt.%) were obtained. The thermal stability of these materials at 1000 deg C for 350 h was investigated. The alloying of NiAl by TiC and NbC particles decreases the thermal stability, and TiN sharply increases it. The thermal stability increasing is explained by TiNO particles formation in Al2O3 scale. Particles of TiNO refine the grains of Al2O3 and increase its adhesion by anchor-type mechanism

140

Long-term corrosion behaviors of Hastelloy-N and Hastelloy-B3 in moisture-containing molten FLiNaK salt environments  

Science.gov (United States)

This study investigated long-term corrosion behaviors of Ni-based Hastelloy-N and Hastelloy-B3 under moisture-containing molten alkali fluoride salt (LiF-NaF-KF: 46.5-11.5-42%) environment at an ambient temperature of 700 °C. The Hastelloy-N and Hastelloy-B3 experienced similar weight losses for tested duration of 100-1000 h, which was caused by aggregate dissolution of Cr and Mo into FLiNaK salts. The corrosion rate of both alloys was high initially, but then reduced during the course of the test. The alleviated corrosion rate was due to the depletion of Cr and Mo near surface of the alloys and thus the long-term corrosion rate was controlled by diffusion of Cr and Mo outward to the alloy surface. The results of microstructural characterization revealed that the corrosion pattern for both alloys tended to be intergranular corrosion at early stage of corrosion test, and then transferred to general corrosion for longer immersion hours.

Ouyang, Fan-Yi; Chang, Chi-Hung; Kai, Ji-Jung

2014-03-01

 
 
 
 
141

Evaluation of Heat Checking and Washout of Heat Resistant Superalloys and Coatings for Die inserts  

Energy Technology Data Exchange (ETDEWEB)

This project had two main objectives: (1) To design, fabricate and run a full size test for evaluating soldering and washout in die insert materials. This test utilizes the unique capabilities of the 350 Ton Squeeze Casting machine available in the Case Meal Casting Laboratory. Apply the test to evaluate resistance of die materials and coating, including heat resistant alloys to soldering and washout damage. (2) To evaluate materials and coatings, including heat resistant superalloys, for use as inserts in die casting of aluminum alloys.

David Schwam; John F. Wallace; Yulong Zhu; Edward Courtright; Harold Adkins

2005-01-30

142

Application of Hastelloy X in Gas-Cooled Reactor Systems  

DEFF Research Database (Denmark)

Hastelloy X, an Ni--Cr--Fe--Mo alloy, may be an important structural alloy for components of gas-cooled reactor systems. Expected applications of this alloy in the High-Temperature Gas-Cooled Reactor (HTGR) are discussed, and the development of interim mechanical properties and supporting data are reported. Properties of concern include tensile, creep, creep-rupture, fatigue, creep-fatigue interaction, subcritical crack growth, thermal stability, and the influence of helium environments with controlled amounts of impurities on these properties. In order to develop these properties in helium environments that are expected to be prototypic of HTGR operating conditions, it was necessary to construct special environmental test systems. Details of construction and operating parameters are described. Interim results from tests designed to determine the above properties are presented. To date a fairly extensive amount of information has been generated on this material at Oak Ridge National Laboratory and elsewhere concerning behavior in air, which is reviewed. However, only limited data are available from tests conducted in helium. Comparisons of the fatigue and subcritical growth behavior in air between Hastelloy X and a number of other structural alloys are given.

Lystrup, Aage

1976-01-01

143

A Study on the High Temperature Oxidation Behavior of Hastelloy X and Inconel 713C  

Energy Technology Data Exchange (ETDEWEB)

In order to preserve surface stability and mechanical properties of the substrate materials, coatings are applied to the alloy surfaces for the high temperature applications. Even with the application of coating, the substrate materials must also have its own resistance to the high temperature oxidation because the substrate may be catastrophically degraded when coatings are failed. In this research, Ni-base superalloys, IN 713C and Hastelloy X for the substrate materials of coatings, were examined by the isothermal and cyclic oxidation experiments. In the isothermal oxidation experiments, the dominant protective oxide scale of Hastelloy X was Cr{sub 2}O{sub 3} and that of IN 713C was the Al-rich oxide scale. Both alloys formed protective oxide scales, and showed good isothermal oxidation resistance but IN 713C showed better oxidation resistance than Hastelloy X owing to the formation of Al-rich oxide scales. Also for cyclic oxidation experiments, due to the favorable adhesion between the substrate and oxide scales, IN 713C having thin Al-rich oxide scales showed better oxidation resistance than Hastelloy X throughout the temperature ranges tested. Comparing these two alloys IN 713C had better oxidation resistance but both alloys showed good oxidation resistance up to 1000 .deg. C.

Kim, J. C.; Park, Y. K. [KEPRI, Daejoen (Korea, Republic of); Shin, E. K.; Kim, G. M. [Chungnam National University, Daejeon (Korea, Republic of); Choi, S. K. [KAIST, Daejeon (Korea, Republic of)

1997-08-15

144

A Study on the High Temperature Oxidation Behavior of Hastelloy X and Inconel 713C  

International Nuclear Information System (INIS)

In order to preserve surface stability and mechanical properties of the substrate materials, coatings are applied to the alloy surfaces for the high temperature applications. Even with the application of coating, the substrate materials must also have its own resistance to the high temperature oxidation because the substrate may be catastrophically degraded when coatings are failed. In this research, Ni-base superalloys, IN 713C and Hastelloy X for the substrate materials of coatings, were examined by the isothermal and cyclic oxidation experiments. In the isothermal oxidation experiments, the dominant protective oxide scale of Hastelloy X was Cr2O3 and that of IN 713C was the Al-rich oxide scale. Both alloys formed protective oxide scales, and showed good isothermal oxidation resistance but IN 713C showed better oxidation resistance than Hastelloy X owing to the formation of Al-rich oxide scales. Also for cyclic oxidation experiments, due to the favorable adhesion between the substrate and oxide scales, IN 713C having thin Al-rich oxide scales showed better oxidation resistance than Hastelloy X throughout the temperature ranges tested. Comparing these two alloys IN 713C had better oxidation resistance but both alloys showed good oxidation resistance up to 1000 .deg. C

145

Crack propagation in Hastelloy X  

International Nuclear Information System (INIS)

The fatigue and creep crack growth rates of Hastelloy X were examined both in air and impure helium. Creep crack growth rate is higher in air and impure helium at 6500C. Initial creep crack growth from the original sharp fatigue crack is by an intergranular mode of fracture. As the cracking accelerates at higher stress intensities, growth is by a mixed mode of both intergranular and transgranular fracture. Fatigue crack growth rate increases with increasing temperature and decreasing frequency for the range of stress intensities reported in the literature and is lower in impure helium than in air

146

Isolation, Identification of Heat Resistant Moulds in Margarine and Determination of Their Heat Resistance  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, moulds that cause problems in a margarine production plant which is located in Trakyaregion have been isolated and identified. In addition to, their heat resistance and lipolytic activity werestudied. For this purpose, margarine samples from various production lots and process water samples fromproduction plant were taken aseptically, transported immediately to the laboratory and analyzed. In thisresearch, two different heat resistant mould strains have been isolated from margarines and process water.After identification of this moulds, their heat resistances at different temperatures have been investigated.Mould isolates were identified as heat resistant Aspergillus fumigatus, Paecilomyces variotii based onmacroscopic and microscopic features. To this analyses results about thermal resistance, Aspergillusfumigatus and Paecilomyces variotii were ability to survive heat treatment at 95oC 10 minutes and 90oC 10minutes, respectively.

A. S. Demirci

2006-09-01

147

Application of newly developed heat resistant materials for USC boilers  

International Nuclear Information System (INIS)

This paper describes the research on the development and improvement of new high strength heat resistant steels such as SUPER304H (18Cr-9Ni-3Cu-Nb-N), NF709 (20Cr-25Ni-1.5Mo-Nb-Ti-N) and HR3C (25Cr-20Ni-Nb-N) as boiler tube, and NF616 (9Cr-0.5Mo-1.8W-Nb-V) and HCM12A (11Cr-0.4Mo-2W-Nb-V-Cu) as thick section pipe. The latest manufacturing techniques applied for these steels are introduced. In addition the high temperature strength of Alloy617 (52Ni-22Cr-13Co-9Mo-Ti-Al) that is one of the candidate materials for the next generation 700 ? USC boilers is described. (orig.)

148

Application of newly developed heat resistant materials for USC boilers  

Energy Technology Data Exchange (ETDEWEB)

This paper describes the research on the development and improvement of new high strength heat resistant steels such as SUPER304H (18Cr-9Ni-3Cu-Nb-N), NF709 (20Cr-25Ni-1.5Mo-Nb-Ti-N) and HR3C (25Cr-20Ni-Nb-N) as boiler tube, and NF616 (9Cr-0.5Mo-1.8W-Nb-V) and HCM12A (11Cr-0.4Mo-2W-Nb-V-Cu) as thick section pipe. The latest manufacturing techniques applied for these steels are introduced. In addition the high temperature strength of Alloy617 (52Ni-22Cr-13Co-9Mo-Ti-Al) that is one of the candidate materials for the next generation 700 {open_square} USC boilers is described. (orig.)

Sato, T.; Tamura, K.; Fukuda, Y. [Kure Research Lab., Babcock-Hitachi K.K., Hiroshima (Japan); Matsuda, J. [Kure Div., Babcock-Hitachi K.K., Hiroshima (Japan)

2004-07-01

149

Phase precipitation and time-temperature-transformation diagram of Hastelloy  

International Nuclear Information System (INIS)

Transmission electron microscopy (TEM) was employed to study the phase precipitation in Hastelloy X heat-treated at 750, 850, and 900 C for 26 and 100 h. Phase identification was made by electron micro-diffraction and energy dispersion spectroscopy (EDS) X-ray micro-chemical analysis. In addition to the fcc matrix, four different precipitation phases were observed: M6C, M23C6, ?, and ?. The current observations were combined with literature results to build a time-temperature-transformation (TTT) diagram for this alloy. This TTT diagram depicted time-temperature regimes where various phases were formed; thus, it provided information about the general precipitation kinetics for the alloy. (orig.)

150

Heat resistance of juice spoilage microorganisms.  

Science.gov (United States)

The heat resistance of various yeasts (Saccharomyces cerevisiae, Rhodotorula mucilaginosa, Torulaspora delbrueckii, and Zygosaccharomyces rouxii), molds (Penicillium citrinum, Penicillium roquefortii, and Aspergillus niger), and lactic acid bacteria (Lactobacillus fermentum and Lactobacillus plantarum) obtained from spoiled acid or acidified food products was determined in 0.1 M citrate buffer at pH values of 3.0, 3.5, and 4.0. S. cerevisiae was the most heat resistant of the microorganisms in citrate buffer, and its heat resistance was further evaluated in apple, grapefruit, calcium-fortified apple, and tomato juices as well as in a juice base with high fructose corn syrup. Decimal reduction times (D-values) and changes in temperature required to change the D-value (z-values) for S. cerevisiae were higher in the juices than in citrate buffer at all pH values tested. The D57 degrees C(135 degrees F)-values varied from 9.4 min in the juice product with pH 2.8 to 32 min in a calcium-added apple juice with pH 3.9. The S. cerevisiae strain used in this study can be used in thermal-death-time experiments in acidic products to calculate process conditions and in challenge tests to validate the calculated temperatures and hold times during processing. PMID:12182479

Shearer, Adrienne E H; Mazzotta, Alejandro S; Chuyate, Rolenda; Gombas, David E

2002-08-01

151

Martensitic/ferritic super heat-resistant 650 C steels  

Energy Technology Data Exchange (ETDEWEB)

World-wide demand for higher steam parameters of ultra super critical (USC) Power Plants has led to developments of new materials with improved high-temperature properties. A new project aims at new ferritic creep-resistant steels for application at 650 C and 300 bar. The critical issues are improvement of long-term creep strength as well as oxidation and corrosion resistance. The aim of the present research is to design new super heat-resistant martensitic/ferritic 9-12%Cr steels using basic principles and concepts of physical metallurgy, to test and optimise model alloys and to investigate and clarify their behaviour under long-term creep conditions with emphasis on microstructural stability and corrosion resistance. Model alloys have been designed, produced and tested with respect to deformation and corrosion. The design of model alloys has been supported by theoretical simulations and transmission electron microscopy investigations. First results for various modified 12%Cr model steels are reported, which indicate a high potential for reaching sufficient creep and corrosion resistance at 650 C. The work with further optimisation of composition and microstructure is in progress. (orig.)

Agamennone, R.; Blum, W. [IWW-LS1, Univ. Erlangen-Nuernberg, Erlangen (Germany); Berger, C.; Granacher, J.; Scholz, A.; Wang, Y. [IfW, TU Darmstadt, Darmstadt (Germany); Ehlers, J.; Ennis, P.J.; Quadakkers, J.W.; Singheiser, L. [IWV2, Forschungszentrum Juelich GmbH, Juelich (Germany); Inden, G.; Knezevic, V.; Sauthoff, G.; Vilk, J. [Max-Planck-Inst. fuer Eisenforschung GmbH, Duesseldorf (Germany)

2002-07-01

152

Flexible heat resistant neutron shielding resin  

Energy Technology Data Exchange (ETDEWEB)

A flexible heat resistant neutron shielding material has been developed, which consists of polymer resin with 1 wt% boron. The neutron shielding performance of the developed resin, examined by the {sup 252}Cf neutron source, is almost the same as that of the polyethylene. The outgas of H{sub 2}, H{sub 2}O, CO and CO{sub 2} from the resin have been measured at {approx}250 deg. C environment. The resin will be applied around the port of the vacuum vessel as an additional shielding material and reduce the neutron streaming from a superconducting tokamak device such as JT-60SA.

Sukegawa, Atsuhiko M., E-mail: morioka.atsuhiko@jaea.go.jp [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka-machi, Ibaraki 311-0193 (Japan); Anayama, Yoshimasa [Neo-Tech R and D, 6-6-1, Ginza, Chuo-ku, Tokyo 104-0061 (Japan); Okuno, Koichi, E-mail: okunok@hazama.co.jp [Hazama Technical Research Institute, 515-1 Karima, Tsukuba-shi, Ibaraki 305-0822 (Japan); Sakurai, Shinji, E-mail: sakurai.shinji@jaea.go.jp [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka-machi, Ibaraki 311-0193 (Japan); Kaminaga, Atsushi, E-mail: kaminaga.atsushi@jaea.go.jp [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka-machi, Ibaraki 311-0193 (Japan)

2011-10-01

153

Flexible heat resistant neutron shielding resin  

International Nuclear Information System (INIS)

A flexible heat resistant neutron shielding material has been developed, which consists of polymer resin with 1 wt% boron. The neutron shielding performance of the developed resin, examined by the 252Cf neutron source, is almost the same as that of the polyethylene. The outgas of H2, H2O, CO and CO2 from the resin have been measured at ?250 deg. C environment. The resin will be applied around the port of the vacuum vessel as an additional shielding material and reduce the neutron streaming from a superconducting tokamak device such as JT-60SA.

154

Radiation testing of heat resisting thermocouple wires  

International Nuclear Information System (INIS)

Samples of thermocouple wires from chromel-alumel cable conductor with alumoborosilicate glass winding were tested in the WWER-440 fuel assembly measuring channel. Isolated cable conductors were fastened by the same glass winding impregnated by heat resisting organosilicate composition and insulated by silicon-organic lac. Test temperature in the channel at thermal neutron flux density of 1.2x1018 s-1xm-2 did not exceed 950 K. The conclusion on satisfactory radiation resistance of thermocouple wire was made according to the test results

155

Effects of high temperature brazing and thermal cycling on mechanical properties of Hastelloy X.  

Science.gov (United States)

Data are presented on the effects of brazing alloy, brazing operation, thermal cycling, and combinations of these on the yield strength, elongation, ultimate tensile strength, and fatigue life of thin gage Hastelloy X. These data show that brazing with a Ni-Pd-Au alloy at 1461 K resulted in reductions of 35 percent in yield strength and elongation, 6 percent in ultimate tensile strength, and 18 percent in fatigue limit of Hastelloy X, as compared with as-received material. Subsequent exposure to 200 thermal cycles between 533 K and 1144 K after brazing caused further losses of 4 percent in yield strength, 8 percent in ultimate tensile strength, and 6 percent in fatigue limit.

Dicus, D. L.; Buckley, J. D.

1973-01-01

156

Effect of temperature on corrosion of hastelloy XR exposed to simulated VHTR environments  

International Nuclear Information System (INIS)

Corrosion behavior of Hastelloy XR, i.e. a version of Hastelloy X with modified oxidation resistance specification, was made with special emphasis placed on the effect of test temperature. Tests were conducted at temperatures ranged from 8000C to 10500C for 1000hr. Attention was focussed on the role of Mn-Cr spinel oxide layer formation in keeping the protective function of the surface film and its influence on the evaporation of Cr and Mn. As a side effect of the exposure, carburization was also examined. The results were compared with those of Mn-free Hastelloy X. The protective layer formation of Mn-Cr spinel oxide was seen to be valid nearly up to 10500C, while the evaporation of Mn reached significant levels above 9500C although the loss of Cr from the alloy was minimized by the sacrifice of Mn evaporation. Carbon analysis of Hastelloy XR after each exposure showed a trend of slightly enhanced carburization at lower temperatures. The trend changed to decarburization as temperature was increased in the same test environments. (author)

157

Heat resistant fast neutron shielding material  

International Nuclear Information System (INIS)

A heat resistant binder comprising a metal hydride powder and calcium silicate is dispersed finely, to provide a structure having a porosity of less than 45%. It contains to 50 to 800 parts by weight of metal hydride based on 100 parts by weight of calcium silicate, in which the calcium silicate has a CaO/SiO2 molar ratio of silicic acid and lime materials within a range of 0.5 to 2.0. The metal hydride comprises one of metals of Ti, Zr, Y and Gd having hydrogen/metal atom ratio within a range of greater than 0.7. Oxide coating layers are formed on the surface of the fine powder of the metal hydride, thereby enabling to suppress the release of hydrogen gases caused by dissociation. Since the heat resistant binder is stable up to a high temperature of about 700degC, and excellent in moldability, it has mechanical strength and thermal stability such as dimensional stability for the molding products. (T.M.)

158

Resistance to isothermal and non-isothermal low cycle loading in heat resisting materials  

International Nuclear Information System (INIS)

An equation for preliminary estimation of the material durability at thermal fatigue taking into account a decrease of strength and ductility with time under loading is suggested. The calculated curves are compared with the experimental ones for a number of heat resisting nickel alloys (EhI437B, ZhS6K and others). A good correspondence of the results for the cases of loading without holding at the maximum temperature is obtained

159

Hydrogen permeation through heat transfer pipes made of Hastelloy XR during the initial 950 deg. C operation of the HTTR  

International Nuclear Information System (INIS)

The permeation of hydrogen isotopes through the Hastelloy XR high-temperature alloy adopted for the heat transfer pipes of the intermediate heat exchanger in the HTTR, is one of the concerns in the hydrogen production system, which will be connected to the HTTR in the near future. The hydrogen permeation between the primary and secondary coolants through the Hastelloy XR was evaluated using the actual hydrogen concentrations observed during the initial 950 deg. C operation of the HTTR. The hydrogen permeability of the Hastelloy XR was estimated conservatively high as follows. The activation energy E 0 and pre-exponential factor F 0 of the permeability of hydrogen were E 0 = 65.8 kJ/mol and F 0 = 7.8 x 10-9 m3(STP)/(m s Pa0.5), respectively, in the temperature range from 707 to 900 K

160

Effects of gaseous environments in gas-cooled reactors and solar thermal heat exchangers on the creep and creep-rupture properties of heat-resisting metals and alloys. Final report  

International Nuclear Information System (INIS)

Energy conversion systems employing heat exchangers use closed cycle gas turbines with helium as the working fluid. An important design criterion for heat exchanger and turbine systems is the creep strength of the tubing, blading, and vane materials. The design data for these materials generally has been obtained in air. However, there have been reports of adverse environmental effects of helium on the creep strength and ductility of these materials. Much of the environmental data has been obtained using relatively impure helium from high temperature helium-cooled reactor systems (HTGR's). However, power conversion systems using coal or solar energy as the heat source would use commercially pure helium, not subject to the carbonaceous gases that are picked up when helium is used as the coolant for the HTGR's. Stanford University was asked to summarize the environmental effects of helium on the creep properties of heat exchanger alloys. Also, they were asked to conduct critical experiments under what ought to probably be the worst conditions, based on the literature, to determine the maximum extent of the environmental effect. It was found that the environmental effects reported in the literature are relatively small, not more than a factor of two in rupture time or creep rate, which is within the usual experimental scatter and in heat-to-heat variations. The experimental work reported on a HA188 confirmed this conclusion

 
 
 
 
161

Thermal adhesion of heat-resistant materials in high temperature gas-cooled reactors and methods to prevent it  

International Nuclear Information System (INIS)

High temperature gas-cooled reactors (HTGRs) have many high-temperature sliding or contacting parts. Generally these can be divided into contact between metal parts in each other and contact between metal and graphite. The authors set out to clarify adhesion behavior between metal and metal, and to acquire techniques that effectively prevent adherence of various heat-resistant materials in high temperature helium gas environments. Hastelloy X, Incoloy 800, Inconel 625 and Inconel 601 were investigated in the experiments. The obtained result shows that the ZrO2 coating using a plasma spray process is the most effective method to prevent adhesion of these materials at working temperatures in excess of 8000C (1,4700F). Subsequently the experimental results were actually applied in the design and fabrication of the Oarai Gas Loop 1 (OGL-1) and the High Temperature Gas Loop (HTGL) in the Japan Atomic Energy Research Institute. (author)

162

Study on the nickel-free high manganese austenitic heat resisting steel  

International Nuclear Information System (INIS)

This investigation is to develop the nickel-free high manganese austenitic heat resisting steel. The effect of alloying elements on the forgeability, microstructure, creep repture life, oxidation resistance, PbO corrosion resistance and sulfidation resistance was investigated. It was found that the 12M41 alloy whose composition was 12% Mn, 17% Cr, 4.5% W, 0.9% Mo, 0.3% Nb, 0.3% C, 0.6% N, 0.01% B exhibited good hot workability, creep rupture life and corrosion resistance. (author)

163

Heat resistance of Fe-Al intermetallics in the context of selected heat-resistant and hihg-temperature creep resistant steels  

Directory of Open Access Journals (Sweden)

Full Text Available Results are hereby presented of heat-resistance tests of two Fe3Al and FeAl intermetallic phase-based alloys in the context of St41k-typeboiler steel and 50H21G9N4 high-temperature creep resistant steel. It has been ascertained that heat resistance of the 50H21G9N4 steeland of the Fe3Al and FeAl intermetallic phase-based alloys significantly exceeds that of the boiler steel tested in the air atmosphere and the atmosphere of a flue gas with CO, CO2, SiO2 content alike. Improvement of these properties depends of exposure conditions. The largest differences have been observed when the tests were carried out in temperature 1023 K and in the flue gas atmosphere. The differences have been more and more noticeable as the exposition duration extended. A tendency has been also recorded of smaller mass decrements of the Fe3Al and FeAl intermetallic phase-based alloys as compared to the 50H21G9N4 steel.

P. Baranowski

2009-04-01

164

Efficiency of out-of-furnace modification of heat resistant chromium-nickel steel with titanium and boron  

International Nuclear Information System (INIS)

The investigation results on out-of-furnace modifying a heat resisting steel with Al, Ti, B, Ce and Ca are presented. the influence of above-mentioned alloying elements on room and high temperature mechanical properties is shown. A modifying complex of titanium and boron has been selected, and the needed quantity of these elements ensuring an increase of mechanical and service properties of heat resistant articles has been determined. Based on the results obtained the chemical composition of steel 35Kh22N10STRL has been corrected. The technology has been put into practice

165

Development of Heat-resistant XLPE Cable and Accessories  

Science.gov (United States)

We have developed heat-resistant XLPE cable and accessories that can be operated at 105°C as the maximum permissible conductor temperature in normal operation. Through this cable system, greater transmission capacity can be achieved using existing cable ducts and without increasing the conductor size of the cable. We have developed heat-resistant XLPE insulation material which has a higher melting point than that of conventional XLPE. The breakdown strength of heat-resistant XLPE cable at 105°C is almost the same as that of conventional XLPE cable at 90°C. The heat deformation of the new cable at 105°C is almost the same as that of conventional XLPE cable at 90°C. Conventional self-pressurized rubber joints can be applied to heat-resistant cable lines with the new waterproof joint compound with low heat resistivity.

Yamada, Hiroyuki; Nakagawa, Shinichi; Murata, Yoshinao; Kishi, Kouji; Katakai, Shoshi

166

Air oxidation and seawater corrosion of Hastelloy S and Hastelloy C-4  

International Nuclear Information System (INIS)

A program is currently under way at the Pacific Northwest Laboratory (PNL) to develop the data and technology needed to permit the licensing of 90SrF2 as a radioisotope heat source fuel for terrestrial applications. The WESF 90SrF2 storage capsule consists of a Hastelloy C-276 inner capsule (2 in. I.D. x 19 in. long) and a 316L stainless steel outer capsule (2-3/8 in. I.D. x 20 in. long). Preliminary experimental tests and theoretical calculations show that the WESF storage capsule is incapable of meeting current licensing requirements for heat sources that are to be used for terrestrial applications. Therefore, the DOE decision was to develop a new heat source design that would retain the existing WESF Hastelloy C-276 inner capsule and replace the current WESF outer capsule with a new outer capsule capable of meeting current licensing requirements. Based on a number of factors, Hastelloy S was selected as the outer capsule material. Hastelloy C-4 was selected as a backup material in case the Hastelloy S had to be rejected for any reason. This report summarizes the results of studies carried out to determine the effects of both air oxidation at heat source operating temperatures and seawater corrosion on the tensile properties of the outer capsule materials

167

A new ferritic heat resisting steel  

International Nuclear Information System (INIS)

A new ferritic heat resisting steel, 9Cr-2Mo-Nb-V steel (NSCR9), with almost the same strength as that of austenitic stainless steel 304 at temperatures of about 6000C has been developed in response to strong demands by boiler fabricators. Advantages of this new type steel compared with conventional 9Cr-1Mo steel are: 1) less carbon content which improves weldability and formability; 2) higher creep rupture strength which is caused by precipitation of fine carbides and carbonitrides. The fine precipitates are obtained by addition of a small amount of Nb and V corresponding to the carbon content. This new steel exhibits at least twice as much strength in the temperature range of 5500C to 6000C as compared with 2 1/4Cr-1Mo steel and with conventional 9Cr-1Mo steel, and is superior to HT-9 by approximately 30%. Its allowable stress is the same as that of TP304H at 5850C. This steel also shows higher resistance to embrittlement during service. The necessary welding electrodes with similar composition have been developed for gas tungsten arc and for submerged manual arc welding. Welded joint characteristics are satisfactory. As ferritic steels in general have higher resistance to swelling by neutron irradiation, this new type steel can also be useful for nuclear service in FBR and fusion reactor

168

Fundamental studies on electron beam welding of heat-resistant superalloy for nuclear plants, (2)  

International Nuclear Information System (INIS)

In the previous report, it was described that the defects occurred in electron beam welds were porosity and microcracks which ran approximately perpendicular to the fusion lines and were found much in the nailhead area. In this report, the consideration and investigation have been carried out on the mechanism of weld crack generation. As the metallurgical studies, observation of the structure of heat-affected zones adjacent to the fusion lines of electron beam welds with a scanning electron microscope, composition analysis of the precipitates with an X-ray microanalyzer and identification of the precipitates by X-ray diffraction have been carried out, using Hastelloy-group, Inconel-group and Incoloy-group heat-resistant superalloys for nuclear plants, and austenitic stainless steel for comparison. Further, the temperature, stress and strain distribution in heat-affected zone adjacent to the fusion line of a model has been analyzed, which has been provided to simulate the conditions in the processes of electron beam welding. As a result, it has been clarified that such microcracks were mainly caused by both melting of precipitates in the heat-affected zone adjacent to the fusion line, and the behaviors of temperature, stress and strain distributions in the nailhead area peculiar to electron beam welding. (Wakatsuki, Y.)

169

Long-term behaviour of heat-resistant steels and high-temperature materials  

International Nuclear Information System (INIS)

This book contains 10 lectures with the following subjects: On the effect of thermal pretreatment on the structure and creep behaviour of the alloy 800 H (V. Guttmann, J. Timm); Material properties of heat resistant ferritic and austenitic steels after cold forming (W. Bendick, H. Weber); Investigations for judging the working behaviour of components made of alloy 800 and alloy 617 under creep stress (H.J. Penkalla, F. Schubert); Creep behaviour of gas turbine materials in hot gas (K.H. Kloos et al.); Effect of small cold forming on the creep beahviour of gas turbine blades made of Nimonic 90 (K.H. Keienburg et al.); Investigations on creep fatigue alternating load strength of nickel alloys (G. Raule); Change of structure, creep fatigue behaviour and life of X20 Cr Mo V 12 1 (by G. Eggeler et al.); Investigations on thermal fatigue behaviour (K.H. Mayer et al.); Creep behaviour of similar welds of the steels 13 Cr Mo 4 4, 14 MoV 6 3, 10 Cr Mo 910 and GS-17 Cr Mo V 5 11 (K. Niel et al.); Determining the creep crack behaviour of heat resistant steels with samples of different geometry (K. Maile, R. Tscheuschner). (orig.,/MM)

170

Performance of heat resistant steel castings as pallet sidewalls in an iron ore pellet induration plant  

International Nuclear Information System (INIS)

Pallet sidewall castings in five different heat resistant alloys were field tested in Iron Ore Company of Canada's iron ore pellet induration plant. Performance of four new alloys, HL, HP, HU, and Haynes Alloy A230, were compared with the traditional HH alloy after a period of 24 months in service. First, the alloys were ranked visually from best to worst. The 'new' alloys were considerably better than the HH alloy. Alloys having high chromium (HL, HP), with the exception of HH, seemed to perform the best. Surprisingly, alloys high in nickel content (HU, A230) did not fair as well. Later, metallographic examination revealed extensive micro-void formation in the interior of the heat affected areas of HH, HL and HP. The tendency for micro-void formation decreased with increasing nickel content in HU and A230. The progression of internal unsoundness in HL and HP could lead to their catastrophic failure during service. In summary, chromium imparted resistance to surface degradation, while nickel imparted resistance to internal micro-void formation. (author)

171

Oxidation of carburized Hastelloy X  

International Nuclear Information System (INIS)

In a high temperature gas-cooled reactor (HTGR), small quantities of impurities such as H2, H2O, CO, CO2, and CH4 are present in the helium coolant. Prolonged exposure to these impurities at high temperature can result in undesirable mechanical properties due to corrosion. Extensive research has been performed on many candidate alloys to study their properties in HTGR helium, and in addition to oxidation, it has been found that carburization is also a possible problem in HTGR. Carbon in the graphite core, carried out by carbon-containing impurities such as CO and CH4, can deposit on and diffuse into metallic components and cause carburization. The purpose of this research was to study the effects of carburization on an accelerated test

172

Design and characterization of microstructure evolution during creep of 12% Cr heat resistant steels  

International Nuclear Information System (INIS)

12% Cr heat resistant steels with a fine dispersion of nano precipitates were designed supported by thermodynamic modeling. A detailed characterization of the microstructure evolution at different creep times (100 MPa/650 deg. C/8000 h) was carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis are correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M23C6) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M23C6 precipitates show best creep properties.

173

TEM characterization of microstructure evolution of 12%Cr heat resistant steels  

Energy Technology Data Exchange (ETDEWEB)

A detailed characterization of the microstructure evolution of 12%Cr heat resistant steels at different creep times (100 MPa / 650 C / 8000 h) were carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis are correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M{sub 23}C{sub 6}) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M{sub 23}C{sub 6} precipitates show best creep properties. (orig.)

Rojas, D.; Prat, O.; Sauthoff, G. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany); Garcia, J. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Kaysser-Pyzalla, A.R. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Bochum Univ. (Germany)

2010-07-01

174

Design and characterization of microstructure evolution during creep of 12% Cr heat resistant steels  

Energy Technology Data Exchange (ETDEWEB)

12% Cr heat resistant steels with a fine dispersion of nano precipitates were designed supported by thermodynamic modeling. A detailed characterization of the microstructure evolution at different creep times (100 MPa/650 deg. C/8000 h) was carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis are correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M{sub 23}C{sub 6}) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M{sub 23}C{sub 6} precipitates show best creep properties.

Rojas, D. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Str. 1, 40237 Duesseldorf (Germany); Garcia, J., E-mail: jose.garcia@helmholtz-berlin.de [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Prat, O. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Str. 1, 40237 Duesseldorf (Germany); Carrasco, C. [Universidad de Concepcion, Departamento de Ingenieria de Materiales, Edmundo Larenas 270, Concepcion (Chile); Sauthoff, G. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Str. 1, 40237 Duesseldorf (Germany); Kaysser-Pyzalla, A.R. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Ruhr Universitaet Bochum, Universitaetstr. 150 IA2, 44780 Bochum (Germany)

2010-06-25

175

Dense heat-resistant ceramics on yttrium oxide base  

International Nuclear Information System (INIS)

Heat-resistant ceramics on the yttrium oxide base reinforced with thread-like fibres of oxygen-free compound has been produced. The behaviour of introduced fibres during the mixture preparation and sample production has been studied. It has been established that it is possible to distribute uniformly fibres over the powder volume and to fabricate dense ceramics with considerably higher heat-resistance as compared to pure yttrium oxide using the method of hot pressing

176

Development of super heat-resistant turbocharger  

Energy Technology Data Exchange (ETDEWEB)

In recent years, the exhaust gas temperature has increased due to high power of motorvehicles, causing such problems as breakage of turbine blades resulting from the shortage of high temperature creep strength, and as for turbine casings, as thermal deformation, cracks and generation of oxide films resulting from the shortages of high temperature creep strength and acid resistance. For these problems, it was tried to adopt Ni-base super-alloy, MAR-M247 for turbine blades and Co-base super-alloy FSX414 for turbine casings. During the above process, the knowledge which is stated hereunder was obtained. Breakage life of turbine blade is related closely to the high temperature stability of ..cap alpha..' phase of the super-alloy concerned. As for the mechanism of breakage, it starts from the elongation of turbine blade, followed by the creation of creepvoid inside which develops to cracks on the outer surface before reaching the breakage stage. Fracturing starts from the inside cristal grains. Stronger blades are made as the unidirectional solidified organization without lateral cristal grains is formed as perfectly as possible. Consequently, it is necessary to control positively the organization formation in order to achieve this unidirectional solidified organization. (16 figs, 3 tabs, 7 refs)

Yoritaka, Masashi; Yamamoto, Yukio; Hasegawa, Yasuaki; Hokari, Tomio

1987-09-01

177

The effects of high-temperature brazing and thermal cycling on the mechanical properties of Hastelloy X  

Science.gov (United States)

Data are presented on the effects of brazing alloy, brazing operation, thermal cycling, and combinations of these on the yield strength, elongation, tensile strength, and fatigue life of thin gage Hastelloy X. These data show that brazing at 1461 K (2170 F) with a Ni-Pd-Au alloy and subsequent exposure to 200 service thermal cycles between 533 and 1144 K (500 and 1600 F) result in reduction of as much as 39 percent in yield strength, 33 percent in elongation, 14 percent in tensile strength, and 26 percent in fatigue limit of Hastelloy X, as compared to as-received materials. These property losses are primarily caused by the brazing operation rather than the subsequent service thermal cycles.

Dicus, D. L.; Buckley, J. D.

1972-01-01

178

Hydrogen permeation through nickel and Hastelloy X  

International Nuclear Information System (INIS)

efore measurements P = (3.14 +- 1.07) x 10-4 exp(-(75.3 +- 2.4)kJ.mol-1/RT)cm3(NTP).cm-1.s-1.Pasup(-1/2); for a sample heated at 1023 K for 100 h before measurements P = (3.27 +- 0.28) x 10-4 exp(-(71.6 +- 0.6)kJ.mol-1/RT)cm3(NTP).cm-1.s-1.Pasup(-1/2). (5) Activation energy of hydrogen permeation in Hastelloy X was increased by the heat treatments, and this was qualitatively explained connecting with some precipitates. (auth.)

179

Electrochemical impedance spectrometry using 316L steel, hastelloy, maraging, Inconel 600, Elgiloy, carbon steel, TiN and NiCr. Simulation in tritiated water. 2 volumes  

International Nuclear Information System (INIS)

Polarization and electrochemical impedance spectrometry curves are presented and discussed. These curves make it possible to ascertain the corrosion domains and to compare the slow and fast kinetics (voltammetry) of different stainless steel alloys. These corrosion kinetics, the actual or simulated tritiated water redox potentials, and the corrosion potentials provide a classification of the steels studied here: 316L, Hastelloy, Maraging, Inconel 600, Elgiloy, carbon steel and TiN and NiCr deposits. From the results it can be concluded that Hastelloy and Elgiloy have the best corrosion resistance. (author). 49 refs., 695 figs., tabs

180

Effect of Mn on oxidation resistance of hastelloy X in simulated VHTR helium environment  

International Nuclear Information System (INIS)

Oxidation behavior of several heats of Ni-base alloy Hastelloy X with different Mn contents was studied. The exposure tests were made with impure helium at 10000C simulating a Very High Temperature Reactor (VHTR) coolant. Characterized by the selective oxidation of some limited number of chemically active minor elements in the alloy in the low potential oxidizing environment, the oxidation resistance was found to be controlled by factors unique to this system. Manganese in particular was shown to be a special element that formed a spinel oxide with Cr in the environment; its effect on kinetics of the surface reactions was studied. The addition of Mn up to 1.3% improve oxidation resistance of Hastelloy X, possibly due to the formation of the outer MnCr2O4 spinel oxide layer outside the inner Cr2O3 oxide layer. Based on the observed increase in the MnCr2O4/Cr2O3 thickness ratio with Mn content, a proposal was made in protecting the alloy by the optimum Mn addition. (author)

 
 
 
 
181

An Experimental Study on Heat Resistance by Split Dose Hyperthermia  

International Nuclear Information System (INIS)

The study was undertaken to evaluate the heat resistance by split dose hyperthermia in various time interval and temperature. For the experiments, 96 mice were divided into 2 groups: the first, 36 mice were used to evaluate the skin reaction of mouse tail to single dose hyperathermia, the second, 60 mice were used to evaluate heat resistance by split dose hyperthermia in various time intervals. The results obtained are summarized as follows: 1. The ND'5'0 was 101 minutes at 43 .deg. C and 24 minutes at 45 .deg. C. 2. For a 1 .deg. C increase in temperature, a half in time was required to same degree of skin reaction. 3. Heat resistance was significantly developed in split dose hyperthermia at 43 .deg. C and 45 .deg. C 4. Development, maximum and decay of heat resistance were constant regardless of change in temperature. In summary, heat resistance in split dose hyperthermia is important in study and clinical application of heat therapy in malignant disease.

182

Thermal response of heat-resistant layer with pyrolysis  

Directory of Open Access Journals (Sweden)

Full Text Available A model is developed for analyzing the thermal response of the heat-resistant layer composed of high silica fiber reinforced phenolic matrix composites(SiO2/P and aluminum, in which pyrolysis and phase transitions are exsited, such as melt, vaporization and sublimation. Based on this model, the thermal response of the heat-resistant layer with different SiO2/P thickness is calculated under a heat flux by using FORTRAN codes. As indicated in the results, the slope of temperature gets a sudden decline at the pyrolysis interface, which is due to the latent heat of pyrolysis; the thickness of heat-resistant layer has little influence on the heating-surface temperature, however, the back temperature may increase with the decreasing thickness; and the thermal conductivity of carbonized layer is very important to thermal response.

Huang Haiming

2012-01-01

183

Study on the heat-resistant EB curing composites  

International Nuclear Information System (INIS)

There are many advantages in the EB-curing process of composites. Heat-resistant EB-curing composites could substitute for polyimide composites used in aeronautical engine. The effects of catalyst and dose on the cured resin were investigated. The heat-resistance of the resin cured by EB was evaluated by dynamic mechanical thermal analysis (DMTA). The experiment result shows that the mechanical property of the composites cured by EB could meet the needs of the aeronautical engine in 250degC. (author)

184

Compatibility of aluminide-coated Hastelloy X and Inconel 617 in a simulated gas-cooled reactor environment  

International Nuclear Information System (INIS)

Commercially prepared aluminide coatings on Hastelloy X and Inconel 617 substrates were exposed to controlled-impurity helium at 850 and 9500C for 3000 h. Optical microscopy, scanning electron microscopy (SEM), electron microprobe profiles and SEM X-ray mapping were used to evaluate and compare exposed and unexposed control samples. Four coatings were evaluated: aluminide, aluminide with platinum, aluminide with chromium, and aluminide with rhodium. With extended time at elevated temperature, nickel diffused into the aluminide coatings to form epsilon phase (Ni3Al). This diffusion was the primary cause of porosity formation at the aluminide-alloy interface. Aluminide coatings with chromium (HI-15) showed the lowest coating-substrate interface porosity and intermetallic phase growth. The presence of excess chromium in the HI-15-aluminide-coated Hastelloy X sample is believed to have compensated partially for the nickel loss by its diffusion into the nickel-depleted coating-substrate transition zone. None of the other coating additions had an obvious effect on the overall behavior of aluminide-coated Hastelloy X or Inconel 617 in the impure helium environment. The exterior of the aluminide coatings was not visually affected by the impure helium. Carbide precipitation below the coating-substrate interface, resulting from carbon ingress from the helium environment, was observed in uncoated control samples. Carburization of aluminide-coated substratesrburization of aluminide-coated substrates was less extensive than that of uncoated materials and was related to the degree of porosity at the coating-alloy interface. (Auth.)

185

TEM investigation on the microstructural evolution of Hastelloy N induced by Ar? ion irradiation.  

Science.gov (United States)

Hastelloy N alloy has been selected as the primary structure material for molten salt reactor. In this article, Hastelloy N alloy samples were irradiated to different doses at room temperature using 300 keV Ar(+) ions. The microstructural evolution was investigated by transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS). Black dot defects emerged in sample irradiated at low dose (0.4 displacement per atom (dpa)), and they grew up with irradiation doses (0.4-2 dpa). A high density of small dislocation loops (nano meters in size) were observed in the sample irradiated to 4 dpa. When the ion dose increased to 12 dpa, complicated structures with defects (including dislocation lines, larger loops and smaller black dots) were observed. Dislocation networks were detected from high-angle annular dark field (HAADF) images. Larger dislocation loops (size: 30-80 nm) were visible in the sample irradiated to 40 dpa. Irradiation with dose of 120 dpa led to the formation of face-centered cubic nanocrystallites with preferred orientations. PMID:24285574

Liu, Min; Lu, Yanling; Liu, Renduo; Zhou, Xingtai

2014-02-01

186

Effect of temperature and strain rate on serrated flow behaviour of Hastelloy X  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer Tensile serrated flow behaviour of Hastelloy X was examined. Black-Right-Pointing-Pointer A, A + B, B and C types of serrated flow behaviour have been observed. Black-Right-Pointing-Pointer Molybdenum solute has been found to be responsible for serrated flow behaviour. Black-Right-Pointing-Pointer M{sub 6}C, M{sub 23}C{sub 6} and {sigma}-phase were observed at higher temperatures. - Abstract: Serrated flow behaviour of Hastelloy X has been examined over a wide range of temperature (300-1023 K) and strain rate (3 Multiplication-Sign 10{sup -3}s{sup -1} to 3 Multiplication-Sign 10{sup -5}s{sup -1}). The alloy exhibited different types of tensile serrated flow in the intermediate temperature range of 473-923 K. Normal portevin-Le Chatelier effect (PLE) exhibiting type A and B serrations were observed at temperatures less than 823 K and inverse PLE exhibiting type C serrations was noticed at temperatures above 823 K. The average activation energy value of 106 kJ mol{sup -1} for the A and B types of serrated flow has been evaluated. The evaluated activation energy value revealed that the migration of molybdenum in the nickel matrix has been found to be responsible for the occurrence of serrated flow in the alloy.

Sakthivel, T., E-mail: tsakthivel@igcar.gov.in [Mechanical Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpakkam - 603 102 (India); Laha, K.; Nandagopal, M.; Chandravathi, K.S.; Parameswaran, P.; Panneer Selvi, S.; Mathew, M.D. [Mechanical Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpakkam - 603 102 (India); Mannan, Sarwan K. [Special Metals Corporation, Huntington, WV 25705 (United States)

2012-02-01

187

Effect of temperature and strain rate on serrated flow behaviour of Hastelloy X  

International Nuclear Information System (INIS)

Highlights: ? Tensile serrated flow behaviour of Hastelloy X was examined. ? A, A + B, B and C types of serrated flow behaviour have been observed. ? Molybdenum solute has been found to be responsible for serrated flow behaviour. ? M6C, M23C6 and ?-phase were observed at higher temperatures. - Abstract: Serrated flow behaviour of Hastelloy X has been examined over a wide range of temperature (300–1023 K) and strain rate (3 × 10?3s?1 to 3 × 10?5s?1). The alloy exhibited different types of tensile serrated flow in the intermediate temperature range of 473–923 K. Normal portevin-Le Chatelier effect (PLE) exhibiting type A and B serrations were observed at temperatures less than 823 K and inverse PLE exhibiting type C serrations was noticed at temperatures above 823 K. The average activation energy value of 106 kJ mol?1 for the A and B types of serrated flow has been evaluated. The evaluated activation energy value revealed that the migration of molybdenum in the nickel matrix has been found to be responsible for the occurrence of serrated flow in the alloy.

188

Optimization in Si content of hastelloy XR for oxidation resistance and oxide film adherence during oxidation in VHTR helium  

International Nuclear Information System (INIS)

Oxidation behavior of several heats of modified Hastelloy alloy X, named Hastelloy XR, with different Si contents was examined in isothermal, thermal cycling exposure tests. The test environment was flowing helium at 10000C containing controlled amounts of impurities simulating the Very High Temperature gas-cooled Reactor (VHTR) coolant. Tests were made to determine an optimization rang of Si content for obtaining higher resistance to the oxidation and less oxide spallation in the service environment. Up to 1% content, increase of the Si caused decrease of the oxidation rate, while the oxide spallation in thermal cycling was a minimum in the range of about 0.2 to 0.4% Si. These two could be explained in formation and morphology of the SiO2 phase in the oxide and metal interface by metallographic observation and analysis. (author)

189

Microstructure and hardness studies of the electron beam welded zone of Hastelloy C-276  

International Nuclear Information System (INIS)

Electron beam welding (EBW) technique is becoming popular in nuclear, chemical and aerospace industries due to its high penetration depth and fast cooling rate. Samples of Hastelloy C-276 have been welded by electron beam (EB). A scanning electron microscope (SEM) having the attachment of an energy dispersive system (EDS) has been employed to study the resulting microstructure and micro-eutectic phases. The microstructure of the molten zone (MZ) is found to be of fine lamellar type. The hardness of the MZ is found to be 35% higher compared to as-received alloy. The micro-eutectoids are rich in Mo and W. The X-ray diffraction patterns of the MZ show shifting of peaks towards higher angle compared to the diffraction pattern of the as-received alloy. Broadening of the peaks is also observed in the diffraction pattern of the MZ. Formation of the ?-phase was observed in the MZ after a tempering treatment at 950 deg. C

190

Heat resistant steel having excellent toughness for use in thermonuclear reactor, and manufacturing method therefor  

International Nuclear Information System (INIS)

Mo and Nb which have been used so far for improvement of creep strength of a heat resistant steel are replaced with W and Ta for lowering radio-activation, and the content thereof and amount of other alloy elements are optimized to attain both of high temperature creep strength and reduction of radio-activity. Among factors giving influences on the stability of the performance or on embrittlement of the steel containing W and Ta during long time use, trace amount of B, Nb and Mo at a level of impurities causes the largest aging degradation of toughness and, next to them, P, Cu, Sn, Sb and As have significant undesired effects. Since the embrittlement during use can be prevented by strictly controlling the impurity elements, chemical ingredients are restricted to manufacture a heat resistant steel having excellent toughness for use in a thermonuclear reactor. Since high temperature strength, especially, high temperature strength at creep rupture is greatly improved, and excellent performance, especially, stability in the toughness for a long period of time is attained, it is extremely useful as a material for a first wall of a thermonuclear reactor. (N.H.)

191

Developmentof plaster compositions that have improved heat resistance ?????????? ??????????? ???????? ?????????? ??????????????  

Directory of Open Access Journals (Sweden)

Full Text Available Protection of structures and materials from the adverse effects of the environment is a relevant challenge to be tacked both by the teams of researchers and workers on site. A universal method of protection contemplates the use of cladding and paints. There are classes of finishing materials that have special protective properties.Flame-resistant finishes obstruct the burning of structures, and in some cases they can even prevent inflammation. A universal method of protection is the plastering of the surface of a structure. Plastering is applicable to concrete, masonry, metal as well as timber. Development of heat resistant plaster is relevant due to numerous fires in Russia.This article represents an overview of the research into the influence of composite binders and fillers onto the physical and mechanical properties of the heat resistant plaster.Portland cement M 500 was used as a composite binder. Liquid sodium water glass with the density of 1,300 – 1,500 kg/m3 and the silicate modulus value of 2.4 – 2.8 was also applied. Glass sand with the fineness of 0.315 – 1.25, mineral wool fibers that were4 - 6 mm long (with the density of 50 kg/m3 were applied as fillers.Sugar is known as an excellent inhibitor of Portland cement. Liquid glass binders are very effective if added to heat resistant concretes and mortars. This fact was mentioned in the works of K.D. Nekrasov, A.P. Tarasov, G.P. Gorlov, B.D. Toturbiev and others, and it has been proven in practice. It is noteworthy that liquid glass demonstrates high adhesive strength in terms of all materials. Its adhesive strength is 3...5 times higher than that of the cement, and this fact can serve as the basis for the development of highquality heat-resistant solutions.The resulting composition is an excellent heat resistant plaster; its physical-mechanical and thermal properties are not inferior to heat resistant mortars based on imported additives.??????????? ???????? ?????????? ?????????????? ???????? ?????????? ????????? ?????? ???????????? ??????????? ?? ??????????? ?????????? ??????????. ????????? ???????????? ??????? ???????? ? ????????????, ????????? ????????????? ??????????? ????????????? ? ??????? ???????? ?????????? ???????????? ??? ???? ??????????. ???????? ??????????? ????????, ?????????????? ??????? ? ???? ????, ??? ? ???????? ????????.

Akulova Mariya Vladimirovna

2013-02-01

192

Determination of Heat Resistance of Exponential Phase Enterococcal Cells  

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Full Text Available The heat resistance of exponential phase cells of environmental barley isolates Enterococcus faecium BAR 1 and a hospital isolate Enterococcus faecalis MI 2 grown at 37 or 45 was determined at 55, 60 and 62.5 ° C for 30 min. From the survival curves, the decimal reduction times (D-values were determined. Cells grown at 45° C showed higher D-values. It was determined that the exponential phase cells grown at 45 were more resistant to heat than the heat resistance of cells grown at 37° C. The cells of both isolates were found resistant to heat treatment at 55, 60 and 62.5 as compared with the control in which cells were grown at 37° C and treated at 62.5° C.

Mushtaq Ahmad

2003-01-01

193

'Heat resistant silicone carbide fiber': radiation processing for ceramics  

International Nuclear Information System (INIS)

New technology developed by JAERI produced a ultra heat resistant silicone carbide fiber. Polycarbosilane (PCS) fiber is changed to ceramics by the infusible process, the thermal oxidation in the ordinary method and the electron beam radiation in new technology. The physical properties of new PCS fiber showed 1700degC heat resistant (higher 500degC) and kept 1GPa strength at 2000degC. the electric resistance decreased to 1.4 Ohm-cm (103-104 Ohm-cm ordinary PCS) but Young's modulus and the thermal conductivity increased to 270 GPa and 10.1 W/m K, respectively. The crystal type of new PCS fiber is constructed by amorphous particle and a few nm fine crystals shown by X-ray analysis and an electron microscope. New carbon silicone fibers will be used as a part of rocket engine, gas turbine and materials for nuclear fusion reactor and space planes. (S.Y.)

194

Determination of Heat Resistance of Exponential Phase Enterococcal Cells  

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The heat resistance of exponential phase cells of environmental barley isolates Enterococcus faecium BAR 1 and a hospital isolate Enterococcus faecalis MI 2 grown at 37 or 45 was determined at 55, 60 and 62.5 ° C for 30 min. From the survival curves, the decimal reduction times (D-values) were determined. Cells grown at 45° C showed higher D-values. It was determined that the exponential phase cells grown at 45 were more resistant to heat...

Mushtaq Ahmad; Smith, David G.; Mahboob, S.

2003-01-01

195

Epitaxial growth of YBCO on Hastelloy with YSZ buffer layer by laser ablation  

International Nuclear Information System (INIS)

Good quality superconducting YBa2Cu3O7-?(YBCO) thin films were grown on Hastelloy (Ni-Cr-Mo alloys) with yttria-stabilized zirconia (YSZ) buffer layers by in situ pulsed laser deposition in a multi-target processing chamber. Generally, Hastelloy exhibits excellent resistance to corrosion, fatigue, thermal shock, impact, and erosion. However, it is difficult to make films on flexible metallic substrates due to interdiffusion problems between metallic substrates and superconducting overlayers. To overcome this difficulty, it is necessary to use YSZ buffer layer since it will not only limit the interdiffusion process but also minimize the surface microcrack formation due to smaller mismatch between the film and the substrate. In order to enhance the crystallinity of YBCO films on metallic substrates, YSZ buffer layers were grown at various temperatures different from the deposition temperature of YBCO films. On YSZ buffer layer grown at higher temperature than that for depositing YBCO film, the YBCO thin film was found to be textured with c-axis orientation by X-ray diffraction and had a zero-resistance critical temperature of about 83 K. (orig.)

196

Mo-Type Superlattices in Hastelloy C-2000 Superalloy with Low Mo/Cr Ratio  

Science.gov (United States)

This paper focuses on the precipitation behavior of superlattices phases in new Hastelloy C-2000 alloy with low Mo/Cr ratio owing to their detrimental effects on both mechanical and corrosion-resistance properties of the alloys. The precipitation behavior of superlattices phases in the C-2000 alloy was investigated at 600 °C in the aging time range of 100-500 h. The results revealed that Pt2Mo-type superlattices phases have been precipitated after aging at 600 °C for 100 h. Typically, the Pt2Mo-type precipitated phases meet to a stoichiometric ratio of Ni2(Cr, Mo) in this alloy. As increasing aging time from 100 to 500 h, size of the phase increases from around 13 to 55 nm. Besides, morphology of the Ni2(Cr, Mo) precipitated phases changes from a lean to a fat ellipse with increasing aging time due to the effect of the Mo/Cr atomic ratio and alloying elements on transformation paths from disorder to order. In addition, solution temperature of the Pt2Mo-type superlattices is around 725 °C determined by differential scanning calorimetry method, which was significantly dependent on the heating rate.

Yuan, Liang; Hu, Rui; Zhang, Tiebang; Han, Yinben; Xue, Xiangyi; Li, Jinshan

2014-09-01

197

16. lecture meeting of the Association for Heat-Resistant Steels and the Association for High-Temperature Materials, on 'Long-term performance of heat-resistant steels and high-temperature materials'. Thermal stress of materials. Proceedings  

International Nuclear Information System (INIS)

The proceedings contain 17 contributions on the following subjects (selection): 1) Development of the microstructure of the martensitic tempered steel X22CrMoV12-1 in fatigue tests up to 80000 h. 2) Influences on creep-induced pore formation and their detection in heat-resistant, low-alloyed steels CrMoV. 3) Endurance properties of highly creep-resistant bolt and blade steel X19CrMoVNbN11-1 in fatigue tests up to 600 C. 4) Creep behaviour of a welded 'P91' pressure vessel. 5) State of the development of improved 9 to 10%-CrMoVNb steels for turbines having steam parameters of 600 C. 6) Fracture-mechanical comparison of the mixed compound X20CrMoV12-1 and G17CrMoV5-11 for determining critical defect variables. 7) Creep-to-crack behaviour of powerplant steels. 8) Behaviour of defects in forgings or castings under creep or creep-fatigue stress. 9) Behaviour of heat-resistant steels under multistage fatigue stress. 10) Connection between failure and multiaxial stress in creep loaded pipe elbows. 11) Contribution to the characterization of long-term heat resistance of steels 12CrMo9-10 and their welds. 12) Contribution to the estimation of long-term heat resistance of the higher-resistant unalloyed steel type G20Mn5, well suitable for welding. 13) Creep equations for highly creep resistant materials. (orig./MM)

198

Design of martensitic/ferritic heat-resistant steels for application at 650 deg. C with supporting thermodynamic modelling  

International Nuclear Information System (INIS)

In view of developing novel heat-resisting steels for applications in conventional power plants with service temperatures of 650 deg. C, a series of martensitic/ferritic model steels with 12 wt.%Cr were studied to achieve an increased creep resistance through additional alloying with various elements for controlled precipitation of M23C6 carbides, MX carbonitrides and intermetallic Laves phase. The alloy design relied on thermodynamic simulation calculations using Thermo-Calc and DICTRA. The mechanical testing concentrated on creep at 650 deg. C for up to 8000 h. The alloy optimization resulted in creep rupture strengths above those of the martensitic/ferritic P92 steel. The work was part of a cooperative project within the German MARCKO program

199

Design of martensitic/ferritic heat-resistant steels for application at 650 deg. C with supporting thermodynamic modelling  

Energy Technology Data Exchange (ETDEWEB)

In view of developing novel heat-resisting steels for applications in conventional power plants with service temperatures of 650 deg. C, a series of martensitic/ferritic model steels with 12 wt.%Cr were studied to achieve an increased creep resistance through additional alloying with various elements for controlled precipitation of M{sub 23}C{sub 6} carbides, MX carbonitrides and intermetallic Laves phase. The alloy design relied on thermodynamic simulation calculations using Thermo-Calc and DICTRA. The mechanical testing concentrated on creep at 650 deg. C for up to 8000 h. The alloy optimization resulted in creep rupture strengths above those of the martensitic/ferritic P92 steel. The work was part of a cooperative project within the German MARCKO program.

Knezevic, V.; Balun, J. [Max-Planck-Institut fuer Eisenforschung GmbH, 40074 Duesseldorf (Germany); Sauthoff, G. [Max-Planck-Institut fuer Eisenforschung GmbH, 40074 Duesseldorf (Germany)], E-mail: g.sauthoff@mpie.de; Inden, G.; Schneider, A. [Max-Planck-Institut fuer Eisenforschung GmbH, 40074 Duesseldorf (Germany)

2008-03-25

200

Microstructural aspects of low-pressure plasma-sprayed CoNiCrAlY coating on Hastelloy X  

International Nuclear Information System (INIS)

A Co-32Ni-21Cr-8Al-0.5Y alloy coating plasma sprayed on Hastelloy X. The microstructure of the coating layer consist of ? phase solid solution, ?' phase, and Y-rich intermetallic phase. This coating exhibits excellent oxidation and sulfidation resistance after exposure in air and in sodium sulfate at 1,0000C for 60 h, due to the formation of ?-Al/sub 2/O/sub 3/ oxide scale. However, the presence of chloride in the sodium sulfate leads to rupture of the aluminium oxide scale, and this results in the precipitation of chlorides and sulfides within the coating layer

 
 
 
 
201

Compatibility of aluminide-coated Hastelloy x and Inconel 617 in a simulated gas-cooled reactor environment  

International Nuclear Information System (INIS)

Commercially prepared aluminide coatings on Hastelloy X and Inconel 617 substrates were exposed to controlled-impurity helium at 8500 and 9500C for 3000 h. Optical and scanning electron (SEM) microscopy, electron microprobe profiles, and SEM X-ray mapping were used to evaluate and compare exposed and unexposed control samples. Four coatings were evaluated: aluminide, aluminide with platinum, aluminide with chromium, and aluminide with rhodium. With extended time at elevated temperature, nickel diffused into the aluminide coatings to form epsilon-phase (Ni3Al). This diffusion was the primary cause of porosity formation at the aluminide/alloy interface

202

Metallurgical and environmental factors influencing creep behaviour of hastelloy-X  

International Nuclear Information System (INIS)

Creep and rupture behaviours of Hastelloy-X and its modified version were examined with special reference to the effect of different test environments; i.e. air, high vacuum and the simulated HTR helium coolant. The respective environments showed different effects. The vacuum environment of about 10-8 torr. gave best reproducible behaviour with essentially no surface-to-volume ratio effect. Such size effect was significant in the other two environments. The simulated HTR environment was characterized in its potentiality of both oxidizing selected alloy constituents and carburization. The observed behaviour was attributed to the depletion of strengthning solute elements caused by the surface reactions and the associated solid state reactions. (author)

203

Corrosion of Thermal Spray Hastelloy C-22 Coatings in Dilute HCI  

Energy Technology Data Exchange (ETDEWEB)

The microstructure and corrosion behavior of Hastelloy C-22 coatings produced using the high velocity oxygen fuel (HVOF) method have been determined and related to in-flight measurements of the particle velocity and temperature. Average particle temperatures ranged from 1280-1450 °C and velocities ranged from 565-640 ms-1. All of the coatings were greater than 98% of theoretical density and exhibited passivating behavior in 0.1 M HCl during cyclic potentiodynamic polarization testing. The passive current density was somewhat higher compared with wrought C-22 alloy and an active-passive peak attributed to the formation of a Cr-rich surface layer was observed. Resistance to corrosion and deposition efficiency improved as the particle temperature decreased. There was little effect of particle velocity on the corrosion behavior over the range of deposition conditions examined. Our results suggest that feedback control based on measurement of the particle temperature can be used to process coatings with optimum properties.

Lister, Tedd Edward; Wright, Richard Neil; Pinhero, Patrick Joseph; Swank, William David

2002-12-01

204

Hafnium as alloy component  

International Nuclear Information System (INIS)

Characteristics are given of heat resistant alloys containing hafnium. It is indicated that the alloying element capable of stabilizing the high-temperature modification of hafnium oxide is tantalum. The presence in the alloy of such components as niobium and zirconium enhances the ultimate strength of alloys by almost twice as compared to commercial pure hafnium. Hafnium is widely used for strengthening alloying of alloys based on tantalum, tungsten, nickel. Hafnium carbide may be successfully used instead of tantalum carbide in the manufacture of hard alloys

205

Hemispherical total emissivity of Hastelloy N with different surface conditions  

International Nuclear Information System (INIS)

The hemispherical total emissivity of Hastelloy N (a candidate structural material for Next Generation Nuclear Plants (NGNPs), particularly for the molten fluoride cooled reactors) was measured using an experimental set-up that was constructed in accordance with the standard ASTM C835-06. The material surface conditions included: (i) ‘as received’ (original) sample from the supplier; (ii) samples with increased surface roughness through sand blasting; (iii) oxidized surface, and (iv) samples coated with graphite powder. The emissivity of the as received samples varied from around 0.22 to 0.28 in the temperature range of 473 K to 1498 K. The emissivity increased when the roughness of the surface increased compared to an as received sample. When Hastelloy N was oxidized in air at 1153 K or coated with graphite powder, its emissivity increased substantially. The sample sand blasted with 60 grit beads and sprinkled with graphite powder showed an increase of emissivity from 0.2 to 0.60 at 473 K and from 0.25 to 0.67 at 1473 K. The oxidized surface showed a similar behavior: an increase in emissivity compared to an unoxidized sample. This increase in emissivity has strong favorable safety implications in terms of decay heat removal in post-accident environments. The data were compared with another Hastelloy family member, Hastelloy X.

206

Self-healing of creep damage in heat resisting steels  

Science.gov (United States)

In heat resisting steels, micro holes, called creep cavities, are formed at grain boundaries by long term use at high temperatures. These creep cavities grow along grain boundaries, form grain boundary cracks by linking up each other anc cause low ductility and premature fracture as shown in Fig. 1. Therefore long term creep rupture strength and ductilities chiefly depend upon the behavior of nucleation and growth of creep cavities. If the growth of creep cavities could be suppressed, creep rupture strength and ductilities should be improved remarkably. Present work is intended to propose a self-healing process for the cavitation, and improve the creep rupture properties by the self-healing. It is thought that chemical compound of BN precipitates at inside surface of creep cavity by addition of B and N to heat resisting steels. As the BN is very stable at high temperatures, the precipitation of BN at creep cavity surface is expected to suppress the creep cavity growth and bring about the healing effect on the cavitation.

Shinya, Norio; Kyono, Junro

2002-07-01

207

Permeation of hydrogen and tritium through heat resistant steels up to 9500C  

International Nuclear Information System (INIS)

For permeation and diffusion measurements of hydrogen isotopes through heat resistant alloys with bare or oxide coated surface two new methods have been developed. The first works with high-frequency heating of a tabular sample (HF-method), and is used for steady-state hydrogen permeation in the range 700 to 9500C and H2 pressures up to 40 bar. The second method uses two gas loops (TL-method) and a disc-shaped sample in between, and is applicable also for non-steady state (time-lag) measurements. It has been used for tritium permeation between 650 and 9500C at T2 pressures of 10 to 100 ?bar. The HF-method turned out suitable for quick tests of materials behaviour, especially with respect to the overall dependence of permeation on pressure and temperature. The TL-method yields besides permeability also data on diffusivity and solubility. It proved appropriate particularly for investigating the influence of different alloy components, for instance C and Cr content in austenitic steels. With regard to the effect of oxide coatings it seems certain now that restraints of hydrogen dissociation and recombination processes are of stronger importance for the impediment of permeation than presumed so far. (orig.)

208

Effect of strain rate on high-temperature low-cycle fatigue behavior of hastelloy X and hastelloy XR  

International Nuclear Information System (INIS)

A series of strain controlled low-cycle fatigue tests at 900 deg C in the simulated HTGR helium environment were conducted on Hastelloy X and its modified version, Hastelloy XR, and the effect of strain rate on high-temperature low-cycle fatigue behavior was investigated. The results of this study provide the following conclusions; (1) Decreasing the strain rate led to notable reductions in the fatigue life. (2) Trends of strain softening and cyclic softening were observed at lower strain rates of 1 x 10-4 s-1 and 2 x 10-5 s-1. (3) Both fracture modes of the transgranular and the intergranular were recognized on the fracture surfaces, with the former mode being predominant at a comparatively high strain rate of 1 x 10-3 s-1. The intergranular fracture mode, however, became predominant at lower strain rates, 1 x 10-4 s-1 and 2 x 10-5 s-1. (4) The cumulative damage rule predicted an excessively coservative value for creep damage. (5) The data obtained lay on the straight line plots when the frequency modified fatigue life method was applied. No significant difference in fatigue behavior was resolved between Hastelloy X and Hastelloy XR under the test conditions employed. (author)

209

Study of Rigid Cross-Linked PVC Foams with Heat Resistance  

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Full Text Available Three heat resistant cross-linked PVC foam plastics were prepared and their performances were compared with universal cross-linked PVC structural foam. The results show that these three heat resistant foams have higher glass transition temperatures (close to 100 °C than universal structural foam (83.2 °C. Compared with the universal structural foam, the three heat resistant foams show much higher decomposition temperature and better chemical stability due to the crosslinking of PVC macromolecular chains. The heat distortion temperature (HDT values of the three heat resistant foam plastics are just a little higher than that of universal structural foam. The three heat resistant foam plastics have good dimensional stability at 140 °C, and when used as core material can closely adhere to the face plates in medium temperature curing processes. Compared with universal structural foam, the three heat resistant foam plastics have slightly better mechanical properties.

Chenhui Zhao

2012-12-01

210

Effects of strain rate on high temperature mechanical properties of irradiated Incoloy 800 and Hastelloy X  

International Nuclear Information System (INIS)

Austenitic steels with about 15% chromium content and about 10% nickel content, respectively, have been mainly used as cladding and core structural materials in the first generation of fast breeder reactors. Previous results on the irradiation behavior of these materials indicate that they probably will not allow attainment of very high burnups. This is due above all to the fact that void formation and irradiation induced creep will result in considerable deformations of the core components and thus set a limit to their service lives in the reactor. For this reason, intensive investigations have been carried on to improve core materials for commercial fast breeder reactors. A promising way seems to be the use of steels having higher nickel contents and of nickel base alloys, respectively. However, the helium production rates of these alloys are higher in the neutron spectrum of fast breeder reactors and thus the problem of high temperature embrittlement might become even more accentuated. Experience on the mechanical behavior under and after irradiation is relatively scarce for these materials. So, in order to get more details about high temperature embrittlement and the irradiation behavior of alloys having high nickel contents, the Incoloy 800 and Hastelloy X materials were irradiated up to high helium concentrations and the dependence of the mechanical properties on the strain rate was studied

211

Analyzing the effect of cutting parameters on surface roughness and tool wear when machining nickel based hastelloy - 276  

International Nuclear Information System (INIS)

Machining parameters has an important factor on tool wear and surface finish, for that the manufacturers need to obtain optimal operating parameters with a minimum set of experiments as well as minimizing the simulations in order to reduce machining set up costs. The cutting speed is one of the most important cutting parameter to evaluate, it clearly most influences on one hand, tool life, tool stability, and cutting process quality, and on the other hand controls production flow. Due to more demanding manufacturing systems, the requirements for reliable technological information have increased. For a reliable analysis in cutting, the cutting zone (tip insert-workpiece-chip system) as the mechanics of cutting in this area are very complicated, the chip is formed in the shear plane (entrance the shear zone) and is shape in the sliding plane. The temperature contributed in the primary shear, chamfer and sticking, sliding zones are expressed as a function of unknown shear angle on the rake face and temperature modified flow stress in each zone. The experiments were carried out on a CNC lathe and surface finish and tool tip wear are measured in process. Machining experiments are conducted. Reasonable agreement is observed under turning with high depth of cut. Results of this research help to guide the design of new cutting tool materials and the studies on evaluation of machining parameters to further advance the productivity of nickel based alloy Hastelloy - 276 machininickel based alloy Hastelloy - 276 machining.

212

Precipitation behavior of Ni-Cr-22 Fe-18 Mo (Hastelloy-X) and Ni-Cr-22 Co-12 Mo (Inconel-617) after isothermal aging  

International Nuclear Information System (INIS)

The precipitation behavior of the nickel-base alloys Ni-Cr-22Fe-18Mo (Hastelloy-X) and Ni-Cr-22Co12Mo (Inconel-617) has been investigated as a function of aging temperature. Hastelloy-X shows that M6C and TiN are primary precipitates and M12C, A3B2 (approx. = Fe3Mo2), and M23C6 are secondary precipitates, while Inconel-617 also has M6C and TiN as primary precipitates and M23C6, M12C, and Ni3AlTi as secondary precipitates. The characterization has been carried out by metallographic and transmission electron microscopy investigations and by x-ray examinations of electrochemical isolated precipitates

213

Creep properties of Hastelloy X in a carburizing helium environment  

International Nuclear Information System (INIS)

In this work, we investigate the environmental effect on the creep behavior of Hastelloy X at 9000C in helium and air. Since helium coolant in HTGR is expected to be carburizing and very weakly oxidizing for most metals, testings were focused on the effect of carburizing and slight oxidation. Carburization decreases secondary creep strain rate and delays tertiary creep initiation. On the other hand, the crack growth rate on the specimen surface is enhanced due to very weak oxidation in helium, therefore the tertiary creep strain rate becomes larger than that in air. The rupture time of Hastelloy X was shorter in helium when compared with in air. Stress versus rupture time curves for both environments do not deviate with each other during up to 5000 hours test, and a ratio of rupture stress in helium to that in air was about 0.9

214

Corrosion resistance of ?-solid solution and hardening ?'-phase of nickel alloys in sodium sulfate and chloride melts  

International Nuclear Information System (INIS)

Corrosion testings of model alloys, corresponding by chemical composition to simple and complex-alloyed ?- and ?'-phases of nickel heat-resistant alloys are conducted in sodium sulfate and chloride melts. It is ascertained that heat resistant nickel alloys containing over 50 % of hardening ?'-phase, are subject to disastrous sulfide corrosion (SC). Resistance against SC alloys containing below 50 % of ?'-phase is determined by the resistance of ?-solid solution. 10 refs., 3 figs., 2 tabs

215

Features of abrasive machining of high alloy and high-alloy steels  

International Nuclear Information System (INIS)

Machinability of steels and alloys of different types by the method of abrasive polishing is considered. Analysis of microstructures, suitable for abrasive polishing was conducted. Recommendations on preparation of a series of steels and alloys for abrasive polishing with the use of corresponding heat treatment are given. The following heat treatment are given. The following materials are among considered ones: stainless steels, corrosion resistant nickel base alloys with molybdenum, heat resistant nickel alloys, magnetically soft alloys, amorphous ferromagnetic alloys, manganese steels and others

216

15. lecture meeting of the Association for heat-resistant steels and the Association for high-temperature materials, on ''Long-term performance of heat-resistant steels and high-temperature materials''. Thermal stress of materials  

International Nuclear Information System (INIS)

The proceedings contain 15 contributions with the following titles: 1. Documentation of fatigue data and preparation for the evaluation with the ZSF program system; 2. Evaluation of strain limit-spread bands with the DESA program; 3. Evaluation of fatigue data with the MCM program; 4. Calculated evaluation of fatigue tests with the example of steel 13 CrMo 4 4; 5. How to improve the creep properties of modified chromium steels; 6. Development work at Nb-stabilized martensitic 9 to 12% chromium steels for applications in energy technology; 7. Microstructure and deformation of the steel X 20 CrMoV 12 1 at high temperature; 8. Influence of multiaxial stress on the long-term creep processes in steels; 9. Determination of the lifetime of an austenitic big-sized plate under creep-fatigue stress - comparative evaluations of design calculation and experiment; 10. Experimental and calculated examination of the fatigue performance of notched specimens; 11. Structure-property relations at heat resistant pipe steel 15 CrMoV 5 10; 12. Results of the quantitative structural analysis of long-term stressed 15 CrMoV 5 10 and 14 MoV 6 3; 13. Behaviour of protective coatings on high temeprature materials under cyclical stress; 14. Mechanical endurance of nickel-base alloys in the high temperature range; 15. Influence of scaling on the fatigue performance of heat resistant steels. (orig./MM)

217

Oxidation resistance of nickel alloys at high temperature  

International Nuclear Information System (INIS)

The heat resistance properties of nickel alloys Ni-Cr-Si, Ni-Si-Al, Ni-Si-Mn and Ni-Al-Mn have been studied by the weight method during oxidation in air at 1000 deg and 1200 deg C. It is demonstrated that manganese reduces the heat resistance properties of Ni-Si and Ni-Al alloys, whilst the addition of over 3% aluminium enhances the heat resistance properties of Ni-Si (over 1.5%) alloys. The maximum heat resistance properties are shown by Ni-Si-Al and Ni-Cr-Si alloys with over 2% Si. These alloys offer 3 to 4 times better oxidation resistance as compared with pure nickel at 1000 deg C and 10 times at 1200 deg C

218

Change of heat resistance on spore forming bacteria after irradiation  

International Nuclear Information System (INIS)

The effect of heat resistance of endospores after gamma-irradiation were investigated for application to decontaminate microorganisms in spices or other dried food materials. D10 values of endospores dried on glass fiber filter with additives of 2% peptone + 1% glycerin were obtained to be 1.8 kGy for Bacillus pumilus, 1.1 kGy for B. cereus, 2.2 kGy for Clostridium botulinum Type A and 2.4 kGy for Cl. botulinum Type E, respectively. Non-irradiated endospores of B. pumilus and B. cereus were inactivated with 40 min of heat treatment at 100degC in water. When endospores were irradiated with 5 kGy, these bacteria were inactivated below 20 min of heating at 100degC in water. In the case of Cl. botulinum Type A and Type E, non-irradiated endospores were inactivated with 30 min of heat treatment at 100degC in water, and irradiated endospores at 5 kGy were inactivated below 15 min of heating. However, all of these bacteria could not inactivate endospores even after heating more than 2 hours at 100degC in dry condition or 80degC in water, and decreased a little of necessary times for inactivation of heat treatment after irradiation at 5 kGy. (author)

219

Studies Concerning Heat-Resisting Additives for Bitumens  

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Full Text Available The improvement of causeway’s bitumen adhesiveness is becoming a current practice in our country, especially when is used acid (siliceous aggregate. One of the most important properties of bitumen is its adhesiveness to aggregate, and this property determine the using of bitumen in causeways area. Usually the adhesiveness is defined as the capacity of a binder to cover an aggregate without dispersing itself when touching the water or the traffic aggressions. Therefore, the adhesiveness additives are products that improve the adhesiveness of the bitumen to a certain aggregate. The used additives – ADETEN type (A01 and A03 have a high stocking stability, a low toxicity degree toward the amine, diamine, polyamine-based additives and are liquid products perfectly compatible with all bitumens and easy to use, in comparison to the paste or solid additives, which must be made liquid to be used. But a very important condition, which must be fulfilled by these promoters is the heat-resisting condition.

Livia Groll

2008-01-01

220

Determination of J-integral R-curves for Hastelloy X and Inconel 617 up to 1223 K using the potential drop technique  

International Nuclear Information System (INIS)

ror Hastelloy X (T = 308 K and T = 1223 K) and for Inconel 617 (T = 308 K, 473 K, 673 K, 873 K, 973 K, 998 K, 1023 K, 1048 K, 1073 K, 1173 K, and 1223 K) the J-integral R-curves have been determined. For Hastelloy X at 308 K the multispecimen technique has been compared with the single specimen method using the potential drop technique. At 1223 K Hastelloy X delivered a low J0-integral value. Inconel 617 showed a smooth increase in J0 with increasing temperature, up to 998 K; above this temperature ven for large loadline displacements only blunting behaviour has been observed. The same tendency has been found for the evaluation of the tearing modulus. With increasing temperature the tearing modulus increases. In the temperature range from 998 to 1223 K the tearing modulus increases by about one order of magnitude. For both alloys the onset of stable crack growth in most cases is earlier than the load maximum is reached in the load versus load-line displacement curves. (orig.)

 
 
 
 
221

Genome-wide deficiency screen for the genomic regions responsible for heat resistance in Drosophila melanogaster  

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Full Text Available Abstract Background Temperature adaptation is one of the most important determinants of distribution and population size of organisms in nature. Recently, quantitative trait loci (QTL mapping and gene expression profiling approaches have been used for detecting candidate genes for heat resistance. However, the resolution of QTL mapping is not high enough to examine the individual effects of various genes in each QTL. Heat stress-responsive genes, characterized by gene expression profiling studies, are not necessarily responsible for heat resistance. Some of these genes may be regulated in association with the heat stress response of other genes. Results To evaluate which heat-responsive genes are potential candidates for heat resistance with higher resolution than previous QTL mapping studies, we performed genome-wide deficiency screen for QTL for heat resistance. We screened 439 isogenic deficiency strains from the DrosDel project, covering 65.6% of the Drosophila melanogaster genome in order to map QTL for thermal resistance. As a result, we found 19 QTL for heat resistance, including 3 novel QTL outside the QTL found in previous studies. Conclusion The QTL found in this study encompassed 19 heat-responsive genes found in the previous gene expression profiling studies, suggesting that they were strong candidates for heat resistance. This result provides new insights into the genetic architecture of heat resistance. It also emphasizes the advantages of genome-wide deficiency screen using isogenic deficiency libraries.

Teramura Kouhei

2011-06-01

222

Fatigue crack propagation in Hastelloy X weld metal  

International Nuclear Information System (INIS)

The fatigue crack growth rate of Hastelloy X weld metal increased with stress intensity, temperature, and inverse frequency. The results were correlated with the equation da/dN = (?K)/sup n/, for constant frequency or constant temperature. The values of A and n were computed with a linear regression algorithm. With decreasing frequency at constant ?K and constant temperature (5380C) fatigue crack growth rates approach an upper limit. Fatigue crack growth rate of the weld metal was lower than that reported for base metal at 5380C and lower at 6490C for a frequency of 1 Hz

223

Mechanical properties of rapidly solidified Al-Ti-Fe, Al-Cu-Fe and Al-Fe-Cu-Ti based alloys extruded from their atomized powders  

Energy Technology Data Exchange (ETDEWEB)

Mechanical properties and heat-resistant properties of rapidly solidified Al-Ti-Fe, Al-Cu-Fe and Al-Fe-Cu-Ti based alloys extruded from their atomized powders are investigated. These alloys have tensile strength in the range of 700-880 MPa, good elongation and large Young`s modulus at room temperature. At high temperature they show excellent heat-resistant properties. Some of them have the heat-resistant tensile strength as high as 350 MPa at 573 K. The phase structures of these alloys are analyzed and the origin of heat-resistance is discussed. (orig.)

Guo, J.Q. [Sendai Inst. of Mater, Sci. and Technol., Miyagi (Japan). YKK Corp.; Kazama, N.S. [Sendai Inst. of Mater, Sci. and Technol., Miyagi (Japan). YKK Corp.

1997-07-31

224

Oxidation characteristics of oxide dispersion strengthened (ODS) alloy  

International Nuclear Information System (INIS)

For the feasibility study of an oxide dispersion strengthened (ODS) alloy to apply to a high temperature structural material in advanced High Temperature Gas-cooled Reactors (HTGRs) and heat utilization systems of HTGR, the oxidation tests of Fe-Cr-Al-Y2O3-based ODS alloy in the simulated HTGR helium environment and the air were carried out together with two kinds of high temperature alloys, i.e., Hastelloy XR and Ni-Cr-W alloys. It was clarified that the ODS alloy had excellent oxidation characteristics in both the environments due to the formation of protective Al-based oxide scale with dispersed Y2O3 on the alloy surface. Furthermore, the comparison between Hastelloy XR and Ni-Cr-W alloys on the oxidation behavior was also discussed. (author)

225

Changes in the mechanical properties of Hastelloy X when exposed to a typical gas-cooled reactor environment  

International Nuclear Information System (INIS)

The helium used in a gas-cooled reactor will contain small amounts of H2, CO, CH4, H2O, and N2 which can lead to oxidation and carburization/decarburization of structural materials. Long-term creep tests were run on Hastelloy X to 30,000 h at 649 to 8710C. It was found that extensive carburization occurred, the minimum creep rate and time to rupture were equal in air and impure helium environments, and the fracture strain was less in helium than in air. Thermal exposure in the temperature range of 538 to 8710C resulted in the reduction of ductility in impact and tensile tests at ambient temperature, and this reduction was greater when the exposure was in impure helium rather than in air. A modified alloy with lower chromium and 2% titanium resisted carburization

226

Evaluation of Hastelloy X for gas-cooled-reactor applications  

International Nuclear Information System (INIS)

Hastelloy X is a potential structural material for use in gas-cooled reactor systems. In this application data are necessary on the mechanical properties of base metals and weldments under realistic service conditions. The test environment studied was helium that contained small amounts of H2, CH4, and CO. It is shown that this environment is carburizing with the kinetics of this process, becoming rapid above 8000C. Suitable weldments of Hastelloy X were prepared by several processes; those weldments generally had properties similar to the base metal except for lower fracture strains under some conditions. Some samples were aged up to 20,000 h in the test gas and tested, and some creep tests on as-received material exceeded 40,000 h. The predominant effect of aging was the significant reduction of the fracture strains at ambient temperature; the strains were lower when the samples were aged in HTGR helium than when aged in inert gas. Under some conditions aging also increased the yield and ultimate tensile strength. Limited impact testing showed that the impact energy at 250C was reduced drastically by aging at 871 and 7040C

227

Cold Shock Response in Sporulating Bacillus subtilis and Its Effect on Spore Heat Resistance  

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Cold shock and ethanol and puromycin stress responses in sporulating Bacillus subtilis cells have been investigated. We show that a total of 13 proteins are strongly induced after a short cold shock treatment of sporulating cells. The cold shock pretreatment affected the heat resistance of the spores formed subsequently, with spores heat killed at 85 or 90°C being more heat resistant than the control spores while they were more heat sensitive than controls that were heat treated at 95 or 100...

Movahedi, Sara; Waites, William

2002-01-01

228

Technique for thermal stability determination of heat resisting coatings on graphite  

International Nuclear Information System (INIS)

It is shown possible to produce certain heat-resisting coatings on graphite by plasma spraying. A diagram of the device for a qualitative estimation of the coating for thermal stability using a plasmatron for spraying is given. The procedure developed may be recommended as a proximate method for estimating thermal stability of heat-resisting coatings applied to graphite and other structural materials according to the plasma spraying technique

229

Weldability of the superalloys Haynes 188 and Hastelloy X by Nd:YAG  

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Full Text Available The requirements for welded aircraft parts have become increasingly severe, especially in terms of the reproducibility of the geometry and metallurgical grade of the weld bead. Laser welding is a viable method of assembly to meet these new demands, because of automation, to replace the manual TIG welding process. The purpose of this study is to determine the weldability of Hastelloy X and Haynes 188 alloys by the butt welding process with a Nd:YAG laser. To identify the influential parameters of the welding process (laser power, feed rate, focal diameter and flow of gas while streamlining testing, an experimental design was established with the CORICO software using the graphic correlation method. The position of the focal point was fixed at 1/3 of the thickness of the sheet. The gas flow rate and the power of the beam have a major effect on the mechanical properties and geometry of the weld. The strength of the weld is comparable to that of the base metal. However, there is a significant decrease in the elongation at break of approximately 30%. The first observations of the cross section of the weld by scanning electron microscopy coupled with EBSD analysis show a molten zone presenting dendritic large grains compared to the equiaxed grains of the base metals without a heat affected zone.

Graneix Jérémie

2014-01-01

230

The strain-controlled fatigue behavior and modeling of Haynes HASTELLOY C-2000 superalloy  

International Nuclear Information System (INIS)

Research highlights: ? Low-cycle fatigue tests were conducted at temperatures of 24 deg. C, 204 deg. C, and 427 deg. C. ? Metallographic and fractographic characterization was performed. ? Coffin-Manson and Holloman curves were generated. ? A strain energy theoretical life prediction model was introduced. - Abstract: The strain-controlled fatigue behavior of the new nickel-chromium-molybdenum superalloy, HASTELLOY C-2000 was investigated. Low-cycle fatigue specimens were tested in strain-controlled fatigue conditions under axial strain range control at 24 deg. C, 204 deg. C and 427 deg. C. The results indicated that at total strain ranges below 0.8%, temperature does not significantly influence fatigue life, whereas at high total strain ranges, there is a significant drop in fatigue life at 427 deg. C. At room temperature and 204 deg. C, the cyclic stress response was cyclic hardening, followed by cyclic stability, cyclic hardening, or cyclic softening, depending on the total strain range. At 427 deg. C, only cyclic hardening was observed. Fractographic and metallographic analyses were also conducted. The strain-life and Holloman relation parameters are calculated. A theoretical model that predicts the life of this alloy under the tested conditions using the plastic strain energy method is also presented. The results of the theoretical model are in good agreement with the experimental results.

231

FY 1998 annual report on the study on solidification process of hot, heat-resistant metal melts; 1998 nendo tainetsu kinzoku koon yueki no gyoko katei no kenkyu chosa hokokusho  

Energy Technology Data Exchange (ETDEWEB)

Described herein are results of the studies on basic aspects of solidification process of hot, heat-resistant metal melts under a microgravity atmosphere, its applicability to industrial purposes, production of new metallic structures by precision casting and supercooling solidification of the heat-resistant, metal alloy parts, and evaluation techniques therefor. In the supercooling solidification of Al, its purity greatly determines the crystal morphology. The single crystal can be produced under a microgravity when it is 99.9% pure. The supercooling solidification under a microgravity can give an Al-Pb alloy structure of uniform dendrite structure both on the surface and inside, free of gravity-caused segregation of Pb. The welding problems caused by Al{sub 2}O{sub 3} present in the Al are solved. The study also clarifies the effects of the microgravity atmosphere in the spot welding by a pulsed YAG laser on, e.g., melting characteristics, welding phenomena and formation of welding defects. The basic knowledge obtained is expected to contribute to, e.g., precision casting and welding of heat-resistant alloys, and creation of new alloys. (NEDO)

NONE

1999-03-01

232

Microstructure evolution during service exposure of two cast, heat-resisting stainless steels - HP-Nb modified and 20-32Nb  

International Nuclear Information System (INIS)

The repair weldability of two types of heat-resistant austenitic stainless steel castings, HP-Nb modified alloys and 20-32Nb alloys, has been evaluated after extended service exposure of these materials at temperatures on the order of 815 deg. C (1500 deg. F). The initial part of this investigation has focused on characterization of the microstructure of these alloys after service exposure times of up to 12 years. Microstructure evolution from the as-cast condition to the service-exposed condition is described. In the as-cast condition, both eutectic NbC and Cr-rich M7C3 carbides were observed in the HP-Nb alloys. In contrast, only eutectic NbC carbides were present in the as-cast 20-32Nb alloys due to a significantly higher atomic ratio of Nb/C as compared to the HP-Nb alloys. In the service-exposed condition, an Ni-Nb silicide and Cr-rich M23C6 were identified in both alloys. The HP-Nb alloys exhibited a much higher total volume fraction of microconstituents than the 20-32Nb alloys and the M23C6 phase was more prevalent than Ni-Nb silicide. In contrast, the Ni-Nb silicide was dominant in the service-exposed 20-32Nb alloys. This difference resulted in a significant increase in the repair welding liquation cracking susceptibility of the 20-32Nb service-exposed alloy

233

Electron emission from nickel-alloy surfaces in cesium vapor  

Science.gov (United States)

The cesiated electron emission was measured for three candidate electrodes for use as collectors in thermionic converters. Nickel, Inconel 600 and Hastelloy were tested with a 412 K cesium reservoir. Peak emission from the alloys was found to be comparable to that from pure nickel. Both the Inconel and the Hastelloy samples had work functions of 1.64 eV at peak emission. The minimum work functions were estimated to be 1.37 eV at a probe temperature of 750 K for Inconel and 1.40 eV for Hastelloy at 665 K. The bare work function for both alloys is estimated to be approximately the same as for pure nickel, 4.8 eV.

Manda, M.; Jacobson, D.

1978-01-01

234

Study on the creep constitutive equation of Hastelloy X, (1)  

International Nuclear Information System (INIS)

A creep constitutive equation of Hastelloy X was obtained from available experimental data. A sensitivity analysis of this creep constitutive equation was carried out. As the result, the following were revealed: (i) Variations in creep behavior with creep constitutive equation are not small. (ii) In a simpler stress change pattern, variations in creep behavior are similar to those in the corresponding fundamental creep characteristics (creep strain curve, stress relaxation curve, etc.). (iii) Cumulative creep damage estimated in accordance with ASME Boiler and Pressure Vessel Code Case N-47 from a stress history predicted by ''the standard creep constitutive equation'' which predicts the average behavior of creep strain curve data is not thought to be on the safe side on account of uncertainties in creep damage caused by variations in creep strain curve. (author)

235

Koch–Haaf reaction of adamantanols in an acid-tolerant hastelloy-made microreactor  

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The Koch–Haaf reaction of adamantanols was successfully carried out in a microflow system at room temperature. By combining an acid-tolerant hastelloy-made micromixer, a PTFE tube, and a hastelloy-made microextraction unit, a packaged reaction-to-workup system was developed. By means of the present system, the multigram scale synthesis of 1-adamantanecarboxylic acid was achieved in ca. one hour operation.

Fukuyama, Takahide; Mukai, Yu; Ryu, Ilhyong

2011-01-01

236

Koch-Haaf reaction of adamantanols in an acid-tolerant hastelloy-made microreactor.  

Science.gov (United States)

The Koch-Haaf reaction of adamantanols was successfully carried out in a microflow system at room temperature. By combining an acid-tolerant hastelloy-made micromixer, a PTFE tube, and a hastelloy-made microextraction unit, a packaged reaction-to-workup system was developed. By means of the present system, the multigram scale synthesis of 1-adamantanecarboxylic acid was achieved in ca. one hour operation. PMID:21977213

Fukuyama, Takahide; Mukai, Yu; Ryu, Ilhyong

2011-01-01

237

Koch–Haaf reaction of adamantanols in an acid-tolerant hastelloy-made microreactor  

Directory of Open Access Journals (Sweden)

Full Text Available The Koch–Haaf reaction of adamantanols was successfully carried out in a microflow system at room temperature. By combining an acid-tolerant hastelloy-made micromixer, a PTFE tube, and a hastelloy-made microextraction unit, a packaged reaction-to-workup system was developed. By means of the present system, the multigram scale synthesis of 1-adamantanecarboxylic acid was achieved in ca. one hour operation.

Takahide Fukuyama

2011-09-01

238

Evaluation of long-term creep properties of hastelloy XR in simulated high-temperature gas-cooled reactor helium  

International Nuclear Information System (INIS)

Creep properties are among the important basic items of material performance for design of high temperature components of high-temperature gas-cooled reactors (HTGRs). In order to evaluate creep properties of Hastelloy XR (a modified version of the conventional Hastelloy X) developed for the High-Temperature Engineering Test Reactor (HTTR), long-term creep tests were carried out in simulated HTGR helium at 800, 900 and 1000degC. The test results up to about 50,000h showed no significant degradation in creep properties. The creep-rupture strength obtained through the long-term tests was above the level corresponding to the design allowable creep-rupture stress of the HTTR. Rupture lives could be estimated with sufficient accuracy using Larson-Miller parameter. The values of the stress exponent were 4.5 to 5.7 when the stress dependence of the steady-state creep rate was expressed in terms of the Norton equation. It was judged that dominant creep process was dislocation creep. The relationship between the steady-state creep rate and the rupture life was expressed in terms of the Monkman-Grant equation. Carburization during creep in simulated HTGR helium did not degrade creep properties of this alloy. Internally formed cavities and cracks were initiated at sites of precipitates at grain boundaries, growing nearly perpendicular to the stress axis. Creep fracture was caused by the nucleation, growth and link-up of grain boundary cavities in long-term tests. Two phases, Cr-rich carbide and Mo-rich carbide, co-existed in specimens after long-term creep tests. (author)

239

Fundamental studies on electron beam welding of heat resistant superalloys for nuclear plants, (4)  

International Nuclear Information System (INIS)

In this paper, corrosion behavior and change of structure of base metal, its electron beam and TIG weld zone of superalloys for nuclear plants in the environment of high temperature helium were made clear and compared with each other. As results, it has been clarified that the corrosion resistance of Hastelloy X is superior to the other superalloys and the corrosion resistance of electron beam weld zone is superior to TIG weld zone and nearly comparable to base metal. (author)

240

Implementation of heat resistant fiber bragg grating sensors for seismic safety in nuclear power plant facilities  

International Nuclear Information System (INIS)

A Fiber Bragg Grating (FBG) sensor with heat resistance was produced via a point microfabrication technique using a femtosecond pulse laser. FBG is the periodic refractive-index structure in an optical fiber core, where the light of a specific wavelength is reflected. It can be used as temperature or a distorted sensor by measuring change of the reflective wavelength of FBG. We processed FBG using a Chirped Pulse Amplification Erbium-doped Fiber laser. Heating test under operational temperature of Fast Breeder Reactors is now planed. The heat-resistant FBG sensor developed using ultra-short pulse laser processing will contribute to the surveillance of power plants for seismic safety. (author)

 
 
 
 
241

Structure optimization and damage behaviour of heat-resistant CrMoV-steels  

International Nuclear Information System (INIS)

The object of the investigations was to optimize the heat treatment conditions of steel 12 CrMoV 4 3 (around 0,12% C; 1% Cr; 0,3% Mo; 0,25% V) on the basis of known structure-property relations of heat resistant steel-CrMoV in such way that the performance of this steel relating to its long-term heat resistance is completely utilized. Further, the influence of heat treatment or of the initial structure was analyzed as well as of further factors on the evolution of damages by formation of pores due to creep. (orig.)

242

Alloy  

Science.gov (United States)

The Mg98.5Gd1Zn0.5 alloy produced by a powder metallurgy route was studied and compared with the same alloy produced by extrusion of ingots. Atomized powders were cold compacted and extruded at 623 K and 673 K (350 °C and 400 °C). The microstructure of extruded materials was characterized by ?-Mg grains, and Mg3Gd and 14H-LPSO particles located at grain boundaries. Grain size decreased from 6.8 ?m in the extruded ingot, down to 1.6 ?m for powders extruded at 623 K (350 °C). Grain refinement resulted in an increase in mechanical properties at room and high temperatures. Moreover, at high temperatures the PM alloy showed superplasticity at high strain rates, with elongations to failure up to 700 pct.

Cabeza, Sandra; Garcés, Gerardo; Pérez, Pablo; Adeva, Paloma

2014-07-01

243

Cast, heat-resistant austenitic stainless steels having reduced alloying element content  

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A cast, austenitic steel composed essentially of, expressed in weight percent of the total composition, about 0.4 to about 0.7 C, about 20 to about 30 Cr, about 20 to about 30 Ni, about 0.5 to about 1 Mn, about 0.6 to about 2 Si, about 0.05 to about 1 Nb, about 0.05 to about 1 W, about 0.05 to about 1.0 Mo, balance Fe, the steel being essentially free of Ti and Co, the steel characterized by at least one microstructural component selected from the group consisting of MC, M.sub.23C.sub.6, and M(C, N).

Muralidharan, Govindarajan [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN; Pankiw, Roman I [Greensburg, PA

2011-08-23

244

The one-parameter-model - a constitutive equation applied to a heat resistant alloy  

International Nuclear Information System (INIS)

In the present work a constitutive model earlier developed and used to predict experimental results of hot tests and fatigue tests from creep experiments of metallic materials were modified to comply with the properties of a high temperature resistant material. The improved model accounts for the properties of a material developing a density and a structure of dislocation lines which are capable of interactions with particles (carbides) from a second phase. The time and temperature dependent evolution of the carbide structure has been described by an equation which explains the formation of seeds as well as their growths (Ostwald ripening). The extended model was applied to Incoloy 800H which is known to develop a carbide structure. Therefore hot tensile and fatigue tests, creep and relaxation experiments using the heats ADU and BAK (KFA specifications) at temperature between 800deg C and 900deg C were performed including both solution treated specimens and specimens heat treated for 10, 100 and 1000 hours. As compared with the results from tensile tests where the carbide structures play a subordinated role, alternately, these structures have a decisive influence on the creep properties of specimens during the primary creep phase, i.e. low stresses and high temperatures. (orig.)

245

Study on internal pressure creep strength of Hastelloy X cylindrical specimen containing an axial surface notch  

International Nuclear Information System (INIS)

Creep tests of Hastelloy X alloy have been performed at 900 deg C under internal pressure, using cylindrical specimens with an artificial defect. The purpose of this research is to investigate the effect of defect size on the creep strength. Two kinds of cylindrical specimens were used. One was 62 mm in outer diameter, 3.0 mm in thickness and 240 mm in length. Another was 66 mm in outer diameter, 6.0 mm in thickness and 240 mm in length. Axial notches were machined on the outer surface of these specimens by a milling cutting. Diametral deformation of the specimen was measured during the test by dial gauges mounted on quartz rods. Creep crack growth depth was measured using the electrical potential method. The numerical analysis using a finite element program ADINA has been performed to investigate the creep deformation around the artificial defect. Analytical model represents one-half of the cylindrical specimen which is 56.0 mm in inner diameter and 3.0 mm in thickness, and has the axial notch of 1.0 mm in depth with infinite length. Elastic-plastic and creep analysis of this model was carried out by incremental method of the time step of 0.01 hours. The following results are concluded from these tests and analyses. [1] The creep rupture time decreases with increasing notch length. [2] The electric potential method is very useful for measuring the creep crack growth depth. [3] The initial creep deformation around the notch is obtained from the finite element analysis obtained from the finite element analysis. (author)

246

Microstructural stability of 9-12%Cr ferrite/martensite heat-resistant steels  

Science.gov (United States)

The microstructural evolutions of advanced 9-12%Cr ferrite/martensite heat-resistant steels used for power generation plants are reviewed in this article. Despite of the small differences in chemical compositions, the steels share the same microstructure of the as-tempered martensite. It is the thermal stability of the initial microstructure that matters the creep behavior of these heat-resistant steels. The microstructural evolutions involved in 9-12%Cr ferrite heat-resistant steels are elaborated, including (1) martensitic lath widening, (2) disappearance of prior austenite grain boundary, (32) emergence of subgrains, (4) coarsening of precipitates, and (5) formation of new precipitates, such as Laves-phase and Z-phase. The former three microstructural evolutions could be retarded by properly disposing the latter two. Namely improving the stability of precipitates and optimizing their size distribution can effectively exert the beneficial influence of precipitates on microstructures. In this sense, the microstructural stability of the tempered martensite is in fact the stability of precipitates during the creep. Many attempts have been carried out to improve the microstructural stability of 9-12%Cr steels and several promising heat-resistant steels have been developed.

Yan, Wei; Wang, Wei; Shan, Yi-Yin; Yang, Ke

2013-03-01

247

Frictional and heat resistance characteristics of coconut husk particle filled automotive brake pad  

Science.gov (United States)

The objective of this study was to determine the friction and heat resistance characteristics of automotive brake pad composed with different sizes and percentages of coconut husk particle. The materials used were phenolic resin (phenol formaldehyde) as binder, copper, graphite and brass as friction producer/modifiers, magnesium oxide as abrasive material, steel and barium sulfate as reinforcement while coconut husk particle as filler. To obtain particle, the coconut husk was ground and dried to 3% moisture content. Then the coconut husk particle was screened using 80 mesh (to obtain coarse dust) and 100 mesh (to obtain fine dust). Different percentages of particle, such as 10 and 30% were used in the mixture of brake pad materials. Then the mixture was hot-pressed to produce brake pad. Chase machine was used to determine the friction coefficient in friction resistance testing, while thermogravimetric analyzer (TGA) machine was used to determine the heat decomposition values in heat resistance testing. Results showed that brake pad with 100 mesh and 10% composition of coconut husk particle showed the highest friction coefficient. For heat resistance, brake pad with 100 mesh and 30% composition of coconut husk dust showed the highest decomposition temperature, due to the high percentage of coconut husk particle in the composition, thus increased the thermal stability. As a comparison, brake pad composed with coconut husk particle showed better heat resistance results than commercial brake pad.

Bahari, Shahril Anuar; Chik, Mohd Syahrizul; Kassim, Masitah Abu; Som Said, Che Mohamad; Misnon, Mohd Iqbal; Mohamed, Zulkifli; Othman, Eliasidi Abu

2012-06-01

248

Type sichromal steel with high heat resistance under operation conditions of refractory-faced water wall screens of steam boilers  

International Nuclear Information System (INIS)

Investigation results of aluminium (1...3%) influence on the heat resistance of the O3Kh8S steel under conditions, close to operation conditions of refractory-faced water wall sereens (in the contact with carborundum packing), are presented. Reasons for decrease of the 03Kh8SYu steel heat resistance under conditions of carborundum packing influence are analysed

249

Preselection of Ni-Cr(-Mo) alloys as potential canister materials for vitrified high active nuclear waste by electrochemical testing  

International Nuclear Information System (INIS)

Several Ni-Cr(-Mo) alloys (Hastelloy C4, Inconel 625, Sanicro 28, Incoloy 825, Inconel 690) were tested by electrochemical methods to characterize their corrosion behavior in chloride containing solutions at various temperatures and pH-values in respect to their application as canister materials for final radioactive waste storage. Especially, Hastelloy C4 was tested by potentiodynamic, potentiostatic and galvanostic measurements. As electrolytes H2SO4 solutions were used, as parameters temperature, chloride content and pH-value were varied. All tested alloys showed a clearly limited resistance against pitting corrosion phenomena; under severe conditions even crevice corrosion phenomena were observed. The best corrosion behavior, however, is shown by Hastelloy C4, which has the lowest passivation current density of all tested alloys and the largest potential region with protection against local corrosion phenomena. (orig.)

250

Electrochemical Impedance Spectroscopy Of Metal Alloys  

Science.gov (United States)

Report describes use of electrochemical impedance spectroscopy (EIS) to investigate resistances of 19 alloys to corrosion under conditions similar to those of corrosive, chloride-laden seaside environment of Space Transportation System launch site. Alloys investigated: Hastelloy C-4, C-22, C-276, and B-2; Inconel(R) 600, 625, and 825; Inco(R) G-3; Monel 400; Zirconium 702; Stainless Steel 304L, 304LN, 316L, 317L, and 904L; 20Cb-3; 7Mo+N; ES2205; and Ferralium 255. Results suggest electrochemical impedance spectroscopy used to predict corrosion performances of metal alloys.

Macdowell, L. G.; Calle, L. M.

1993-01-01

251

Surface modification of Hastelloy C-276 by SiC addition and electron beam melting  

Science.gov (United States)

Electron beam surface melting of Hastelloy C-276 with the SiC addition is carried out to improve the surface properties. The resulted microstructure and non-equilibrium phases are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive system (EDS). The Hastelloy C-276 is successfully surface-hardened by electron beam melting, the surface hardening effect can be attributed to both microstructure refinement and eutectic phases produced by EB. During EB melting the SiC broke into small pieces and spread in the microstructure increasing the surface hardness by thirteen times.

Ahmad, M.; Akhter, J. I.; Iqbal, M.; Akhtar, M.; Ahmed, E.; Shaikh, M. A.; Saeed, K.

2005-01-01

252

FINITE ELEMENT ANALYSIS OF HASTELLOY C-22HS IN END MILLING  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a finite element analysis of the stress distribution in the end milling operation of nickel-based superalloy HASTELLOY C-2000. Commercially available finite element software was used to develop the model and analyze the distribution of stress components in the machined surface of HASTELLOY C-22HS following end milling with coated carbide tools. The friction interaction along the tool-chip interface was modeled using the Coulomb friction law. It was found that the stress had lower values under the cut surface and that it increased gradually near the cutting edge.

K. Kadirgama

2011-12-01

253

Surface modification of Hastelloy C-276 by SiC addition and electron beam melting  

International Nuclear Information System (INIS)

Electron beam surface melting of Hastelloy C-276 with the SiC addition is carried out to improve the surface properties. The resulted microstructure and non-equilibrium phases are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive system (EDS). The Hastelloy C-276 is successfully surface-hardened by electron beam melting, the surface hardening effect can be attributed to both microstructure refinement and eutectic phases produced by EB. During EB melting the SiC broke into small pieces and spread in the microstructure increasing the surface hardness by thirteen times

254

A life evaluation under creep-fatigue-environment interaction of Ni-base wrought alloys  

International Nuclear Information System (INIS)

In order to determine a failure criteria under cyclic loading and affective environment for HTGR systems, a series of strain controlled low-cycle fatigue tests were carried out at HTGR maximum gas temperatures in air, in vacuum and in HTGR helium environments on two nickel-base wrought alloys, namely Inconel 617 and Hastelloy XR. This paper first describes the creep-fatigue-environment properties of these alloys followed by a proposal of an evaluation method of creep-fatigue-environment interaction based on the experimental data to define the more reasonable design criteria, which is a modification of the linear damage summation rule. Second, the creep-fatigue properties of Hastelloy XR at 900 deg C and the result evaluated by this proposed method are shown. This criterion is successfully applied to the life prediction at 900 deg C. In addition, the creep-fatigue properties of Hastelloy XR-II are discussed. (author)

255

On accelerated crack growth in reactor vessel heat resistant steels under the action of hydrogenating environment  

International Nuclear Information System (INIS)

Precritical growing of cracks and character of destruction of reactor vessel heat resistant steels 15Kh2MFA and 15Kh2NMFA in the air, in aqueous medium of boron regulation at the temperature of 80 deg C, taking into account the frequency of deformation and asymmetry of loading cycle, have been studied. It is established that aqueous medium of boron regulation accelerates fatigue crack development in reactor vessel heat resistant steels 15Kh2MFA and 15Kh1NMFA, which is explained by hydrogen embrittlement of material in the crack vertex. The increase of material strength category by means of heat treatment, decrease of cyclic loading frequency, increase of loading cycle asymmetry coefficient activate considerably the propagation of fatigue crack in steets. The steet 15Kh2MFA is more crack resistant both during static and cyclic loadings in aqueous medium of boron regulation

256

Accelerated crack growth in reactor vessel heat resistant steels under the action of hydrogenating environment  

Energy Technology Data Exchange (ETDEWEB)

Precritical growing of cracks and character of destruction of reactor vessel heat resistant steels 15Kh2MFA and 15Kh2NMFA in the air, in aqueous medium of boron regulation at the temperature of 80 deg C, taking into account the frequency of deformation and asymmetry of loading cycle, have been studied. It is established that aqueous medium of boron regulation accelerates fatigue crack development in reactor vessel heat resistant steels 15Kh2MFA and 15Kh1NMFA, which is explained by hydrogen embrittlement of material in the crack vertex. The increase of material strength category by means of heat treatment, decrease of cyclic loading frequency, increase of loading cycle asymmetry coefficient activate considerably the propagation of fatigue crack in steels. The steel 15Kh2MFA is more crack resistant both during static and cyclic loadings in aqueous medium of boron regulation.

Pokhmurskij, V.I.; Bilyj, L.M.; Timofeev, B.T.; Fedorova, V.A.; Shved, M.M. (AN Ukrainskoj SSR, Lvov. Fiziko-Mekhanicheskij Inst.)

257

Basic study of electron beam welding of heat-resistant superalloys for nuclear plants, (5)  

International Nuclear Information System (INIS)

This is the fifth in a series of report on ongoing investigations into the properties and performance of electron beam (EB) welded joints of various superalloys, such as Hastelloy, Inconel and Incoloy, used in nuclear plants. The corrosion behavior, structural changes and creep properties of both the base metals and their welded joints were studied and compared. As a result of these investigations, it was clarified that the corrosion resistance of Hastelloy X is superior to that of the other superalloys studied, and that in terms of corrosion resistance of the weld zone the EB weld is superior to TIG, and nearly equal to that of the base metal. It was also clarified that the creep rupture strength of the EB and TIG welded joints are nearly comparable to that of the base metal, and that the creep rupture ductility of EB welded joints is comparable or even superior to that of TIG welded joints, though inferior to that of the base metal. (author)

258

Experimental determination of contact heat resistance between uranium dioxide and cladding  

International Nuclear Information System (INIS)

The objective of this work was studying thermal contact resistance between fuel and cladding under different conditions similar to reactor operating conditions in order to avoid overheating that could cause damage. According to experimental data, variation of contact heat resistance was analyzed dependent on the neutron flux. Using calculated values of fuel pellets radial expansion, dependence of heat contact resistance is given as a function of gap dimensions at constant temperature

259

Phase-tunable colossal magneto-heat resistance in ferromagnetic Josephson thermal valves  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We propose a heat valve based on the interplay between thermal transport and proximity-induced exchange splitting in Josephson tunnel junctions. We demonstrate that the junction heat conductance strongly depends on the relative alignment of the exchange fields induced in the superconductors. Colossal magneto-heat resistance ratios as large as 10^7% are predicted to occur under proper temperature and phase conditions, as well as suitable ferromagnet-superconductor combination...

Giazotto, F.; Bergeret, F. S.

2012-01-01

260

Significant effect of Ca2+ on improving the heat resistance of lactic acid bacteria.  

Science.gov (United States)

The heat resistance of lactic acid bacteria (LAB) has been extensively investigated due to its highly practical significance. Reconstituted skim milk (RSM) has been found to be one of the most effective protectant wall materials for microencapsulating microorganisms during convective drying, such as spray drying. In addition to proteins and carbohydrate, RSM is rich in calcium. It is not clear which component is critical in the RSM protection mechanism. This study investigated the independent effect of calcium. Ca(2+) was added to lactose solution to examine its influence on the heat resistance of Lactobacillus rhamnosus ZY, Lactobacillus casei Zhang, Lactobacillus plantarum P8 and Streptococcus thermophilus ND03. The results showed that certain Ca(2+) concentrations enhanced the heat resistance of the LAB strains to different extents, that is produced higher survival and shorter regrowth lag times of the bacterial cells. In some cases, the improvements were dramatic. More scientifically insightful and more intensive instrumental study of the Ca(2+) behavior around and in the cells should be carried out in the near future. In the meantime, this work may lead to the development of more cost-effective wall materials with Ca(2+) added as a prime factor. PMID:23617813

Huang, Song; Chen, Xiao Dong

2013-07-01

 
 
 
 
261

The use of aluminium-enriched layers on Hastelloy X against high temperature carburization in high temperature gas-cooled reactor helium  

International Nuclear Information System (INIS)

The possibility of protecting nickel-based alloys against carburization using Ni-Al layers is discussed. Ni-Al layers were produced using the chemical vapour deposition reaction: AlCl3+(3/2)H2+Ni-based alloy ? Ni-Al+3HCl. The kinetics of growth of an Ni-Al layer on nickel and the nickel-based alloys Hastelloy X, IN-738LC and IN-617 in the temperature range 1173-1373 K at total pressures ranging from 100 to 800 mbar are described. No carbon uptake occurs in the layer or in the bulk alloy, because of the formation of an ?-Al2O3 oxide layer in CH4-H2 gas mixtures with carbon activities from 0.2 to 0.8 and at temperatures of up to 1273 K. Al2O3 formation is caused by the presence of oxygen as an impurity in the CH4-H2 gas mixtures. (Auth.)

262

Oxidability of certain cast and sintered alloys on the base of TiAl, NiAl and Ni3Al intermetallides  

International Nuclear Information System (INIS)

TiAl, NiAl, Ni3Al produced by the methods of power metallurgy and casting are studied for heat-resistance and strength. It is stated that the heat-resistance and strength of TiAl produced by the powder metallurgy method is lower than those of the cast one. The heat-resistance of the powdered Ni3Al is similar to the heat-resistance of the cast one at 1000 deg C, but its strength is higher. Yttrium microalloying of TiAl as well as molybdenum alloying of Ni3Al appreciably decreases the oxidation rate of intermetallides mentioned above

263

Corrosion of high nickel alloys in combined fluoride solutions for nuclear fuel reprocessing  

International Nuclear Information System (INIS)

The chemical reprocessing of fuel from the Pressurized Water Reactor (PWR) Core 2, Seed 1 and 2, requires hydrofluoric acid, nitric acid, and sulfuric acid singly and in mixtures. High nickel alloys tested in scoping tests at the boiling point in PWR process solutions included Hastelloy C-276, Hastelloy C-4, Hastelloy S, Hastelloy G, Inconel 625, Inconel 690 and Incoloy 825. Evaluations of weld performance including some metallographic examinations are included. Different methods of welding and different heats of alloys were investigated. The effect of varying compositions and concentration of process solutions were examined in order to select conditions which would minimize corrosion. Corrosion results are also presented for two Hastelloy C276 corrosion test vessels fabricated from 3-inch welded pipe with welded nozzles. These vessels have been exposed to PWR process solution for several months. They have provided valuable information on the performance of welds, the attack at the vapor-liquid interface, and the mode of attack to be expected in process service. (U.S.)

264

Investigation on corrosion behavior of Ni-based alloys in molten fluoride salt using synchrotron radiation techniques  

Energy Technology Data Exchange (ETDEWEB)

Ni-based alloys have been selected as the structural materials in molten-salt reactors due to their high corrosion resistance and excellent mechanical properties. In this paper, the corrosion behavior of some Ni-based superalloys including Inconel 600, Hastelloy X and Hastelloy C-276 were investigated in molten fluoride salts at 750 °C. Morphology and microstructure of corroded samples were analyzed using scanning electron microscope (SEM), synchrotron radiation X-ray microbeam fluorescence (?-XRF) and synchrotron radiation X-ray diffraction (SR-XRD) techniques. Results from ?-XRF and SR-XRD show that the main depleted alloying element of Ni-based alloys in molten fluoride salt is Cr. In addition, the results indicate that Mo can enhance the corrosion resistance in molten FLiNaK salts. Among the above three Ni-based alloys, Hastelloy C-276 exhibits the best corrosion resistance in molten fluoride salts 750 °C. Higher-content Mo and lower-content Cr in Hastelloy C-276 alloy were responsible for the better anti-corrosive performance, compared to the other two alloys.

Liu, Min, E-mail: liumin@sinap.ac.cn; Zheng, Junyi; Lu, Yanling, E-mail: luyanling@sinap.ac.cn; Li, Zhijun; Zou, Yang; Yu, Xiaohan; Zhou, Xingtai, E-mail: zhouxingtai@sinap.ac.cn

2013-09-15

265

Investigation on corrosion behavior of Ni-based alloys in molten fluoride salt using synchrotron radiation techniques  

Science.gov (United States)

Ni-based alloys have been selected as the structural materials in molten-salt reactors due to their high corrosion resistance and excellent mechanical properties. In this paper, the corrosion behavior of some Ni-based superalloys including Inconel 600, Hastelloy X and Hastelloy C-276 were investigated in molten fluoride salts at 750 °C. Morphology and microstructure of corroded samples were analyzed using scanning electron microscope (SEM), synchrotron radiation X-ray microbeam fluorescence (?-XRF) and synchrotron radiation X-ray diffraction (SR-XRD) techniques. Results from ?-XRF and SR-XRD show that the main depleted alloying element of Ni-based alloys in molten fluoride salt is Cr. In addition, the results indicate that Mo can enhance the corrosion resistance in molten FLiNaK salts. Among the above three Ni-based alloys, Hastelloy C-276 exhibits the best corrosion resistance in molten fluoride salts 750 °C. Higher-content Mo and lower-content Cr in Hastelloy C-276 alloy were responsible for the better anti-corrosive performance, compared to the other two alloys.

Liu, Min; Zheng, Junyi; Lu, Yanling; Li, Zhijun; Zou, Yang; Yu, Xiaohan; Zhou, Xingtai

2013-09-01

266

Investigation on corrosion behavior of Ni-based alloys in molten fluoride salt using synchrotron radiation techniques  

International Nuclear Information System (INIS)

Ni-based alloys have been selected as the structural materials in molten-salt reactors due to their high corrosion resistance and excellent mechanical properties. In this paper, the corrosion behavior of some Ni-based superalloys including Inconel 600, Hastelloy X and Hastelloy C-276 were investigated in molten fluoride salts at 750 °C. Morphology and microstructure of corroded samples were analyzed using scanning electron microscope (SEM), synchrotron radiation X-ray microbeam fluorescence (?-XRF) and synchrotron radiation X-ray diffraction (SR-XRD) techniques. Results from ?-XRF and SR-XRD show that the main depleted alloying element of Ni-based alloys in molten fluoride salt is Cr. In addition, the results indicate that Mo can enhance the corrosion resistance in molten FLiNaK salts. Among the above three Ni-based alloys, Hastelloy C-276 exhibits the best corrosion resistance in molten fluoride salts 750 °C. Higher-content Mo and lower-content Cr in Hastelloy C-276 alloy were responsible for the better anti-corrosive performance, compared to the other two alloys

267

Analyzing the effect of cutting parameters on surface roughness and tool wear when machining nickel based hastelloy - 276  

Energy Technology Data Exchange (ETDEWEB)

Machining parameters has an important factor on tool wear and surface finish, for that the manufacturers need to obtain optimal operating parameters with a minimum set of experiments as well as minimizing the simulations in order to reduce machining set up costs. The cutting speed is one of the most important cutting parameter to evaluate, it clearly most influences on one hand, tool life, tool stability, and cutting process quality, and on the other hand controls production flow. Due to more demanding manufacturing systems, the requirements for reliable technological information have increased. For a reliable analysis in cutting, the cutting zone (tip insert-workpiece-chip system) as the mechanics of cutting in this area are very complicated, the chip is formed in the shear plane (entrance the shear zone) and is shape in the sliding plane. The temperature contributed in the primary shear, chamfer and sticking, sliding zones are expressed as a function of unknown shear angle on the rake face and temperature modified flow stress in each zone. The experiments were carried out on a CNC lathe and surface finish and tool tip wear are measured in process. Machining experiments are conducted. Reasonable agreement is observed under turning with high depth of cut. Results of this research help to guide the design of new cutting tool materials and the studies on evaluation of machining parameters to further advance the productivity of nickel based alloy Hastelloy - 276 machining.

Khidhir, Basim A; Mohamed, Bashir, E-mail: Basim@student.uniten.edu.my [Department of Mechanical Engineering, College of Engineering, University Tenaga Nasional, 43009 Kajang, Selangor (Malaysia)

2011-02-15

268

Radiation embrittlement and swelling of austenitic alloys in different structural state  

International Nuclear Information System (INIS)

Reviewed are the investigations of the heat-resistance and swelling of the chrome-nickel austenite steels and alloys. Pointed out is the importance of the early stages of decay in solid solutions and also the influence of the iniformity of the secondary phase precipitation in the grains on the heat-resistance criteria and opposition to the radiation swelling of alloys. It is shown that through alloying swelling may be suppressed and the influence of the neutron impact on the deformation ability of high-nickel austenite steels and alloys reduced considerably

269

Weld procedure produces quality welds for thick sections of Hastelloy-X  

Science.gov (United States)

Welding program produces premium quality, multipass welds in heavy tube sections of Hastelloy-X. It develops semiautomatic tungsten/inert gas procedures, weld wire procurement specifications material weld properties, welder-operator training, and nondestructive testing inspection techniques and procedures.

Flens, F. J.; Fletcher, C. W.; Glasier, L. F., Jr.

1967-01-01

270

Microstructures, mechanical properties and corrosion resistance of Hastelloy C22 coating produced by laser cladding  

International Nuclear Information System (INIS)

Highlights: ? Hastelloy C22 coatings were prepared by diode laser cladding technique. ? Higher laser speed resulted in smaller grain size. ? Size-effect played the key role in the hardness measurements by different ways. ? Coating with higher laser scanning speed displayed higher nano-scratch resistance. ? Small grain size was beneficial for improvement of coating corrosion resistance. -- Abstract: The Hastelloy C22 coatings H1 and H2 were prepared by laser cladding technique with laser scanning speeds of 6 and 12 mm/s, respectively. Their microstructures, mechanical properties and corrosion resistance were investigated. The microstructures and phase compositions were studied by metallurgical microscope, scanning electron microscope and X-ray diffraction analysis. The hardness and scratch resistance were measured by micro-hardness and nanoindentation tests. The polarization curves and electrochemical impedance spectroscopy were tested by electrochemical workstation. Planar, cellular and dendritic solidifications were observed in the coating cross-sections. The coatings metallurgically well-bonded with the substrate are mainly composed of primary phase ?-nickel with solution of Fe, W, Cr and grain boundary precipitate of Mo6Ni6C. The hardness and corrosion resistance of steel substrate are significantly improved by laser cladding Hastelloy C22 coating. Coating H2 shows higher micro-hardness than that of H1 by 34% and it also exhibits better corrosion resistance. The results indicate that the increase of laser scanning speed improves the microstuctures, mechanical properties and corrosion resistance of Hastelloy C22 coating

271

Microstructures, mechanical properties and corrosion resistance of Hastelloy C22 coating produced by laser cladding  

Energy Technology Data Exchange (ETDEWEB)

Highlights: ? Hastelloy C22 coatings were prepared by diode laser cladding technique. ? Higher laser speed resulted in smaller grain size. ? Size-effect played the key role in the hardness measurements by different ways. ? Coating with higher laser scanning speed displayed higher nano-scratch resistance. ? Small grain size was beneficial for improvement of coating corrosion resistance. -- Abstract: The Hastelloy C22 coatings H1 and H2 were prepared by laser cladding technique with laser scanning speeds of 6 and 12 mm/s, respectively. Their microstructures, mechanical properties and corrosion resistance were investigated. The microstructures and phase compositions were studied by metallurgical microscope, scanning electron microscope and X-ray diffraction analysis. The hardness and scratch resistance were measured by micro-hardness and nanoindentation tests. The polarization curves and electrochemical impedance spectroscopy were tested by electrochemical workstation. Planar, cellular and dendritic solidifications were observed in the coating cross-sections. The coatings metallurgically well-bonded with the substrate are mainly composed of primary phase ?-nickel with solution of Fe, W, Cr and grain boundary precipitate of Mo{sub 6}Ni{sub 6}C. The hardness and corrosion resistance of steel substrate are significantly improved by laser cladding Hastelloy C22 coating. Coating H2 shows higher micro-hardness than that of H1 by 34% and it also exhibits better corrosion resistance. The results indicate that the increase of laser scanning speed improves the microstuctures, mechanical properties and corrosion resistance of Hastelloy C22 coating.

Wang, Qin-Ying; Zhang, Yang-Fei [Department of Materials Science and Engineering, HEDPS, Center for Applied Physics and Technology, LTCS, College of Engineering, Peking University, Beijing 100871 (China); Bai, Shu-Lin, E-mail: slbai@pku.edu.cn [Department of Materials Science and Engineering, HEDPS, Center for Applied Physics and Technology, LTCS, College of Engineering, Peking University, Beijing 100871 (China); Liu, Zong-De [Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education, North China Electric Power University, Beijing 102206 (China)

2013-03-15

272

Properties of super alloys for high temperature gas cooled reactor  

International Nuclear Information System (INIS)

The existing data on the properties at high temperature in helium gas of iron base super alloys. Incoloy-800, -802 and -807, nickel base super alloys, Hastelloy-X, Inconel-600, -617 and -625, and a casting alloy HK-40 were collectively evaluated from the viewpoint of the selection of material for HTGRs. These properties include corrosion resistance, strength and toughness, weldability, tube making, formability, radioactivation, etc. Creep strength was specially studied, taking into consideration the data on the creep characteristics in the actual helium gas atmosphere. The necessity of further long run creep data is suggested. Hastelloy-X has completely stable corrosion resistance at high temperature in helium gas. Incoloy 800 and 807 and Inconel 617 are not preferable in view of corrosion resistance. The creep strength of Inconel 617 extraporated to 1,000 deg C for 100,000 hours in air was the greatest rupture strength of 0.6 kg/mm2 in all above alloys. However, its strength in helium gas began to fall during a relatively short time, so that its creep strength must be re-evaluated in the use for long time. The radioactivation and separation of oxide film in primary construction materials came into question, Inconel 617 and Incoloy 807 showed high induced radioactivity intensity. Generally speaking, in case of nickel base alloys such as Hastelloy-X, oxide film is difficult to break away. (Iwakiri, K.)

273

Changes of the permeability of hydrogen of heat resisting metallic materials caused by thin oxide barriers on the surface  

International Nuclear Information System (INIS)

The permeability of hydrogen and tritium through oxide surface layers of Incoloy 800, Incoloy 800H, Incoloy 802, Incoloy 807, IN 586, Inconel 617, Hastelloy X, HK 40, Manaurite 36X, IN 519, IN 638 and IN 643 was studied dependent on temperature (600-10000C) and hydrogen pressure (1-20 bar). (TWO)

274

Investigations into forming process of subsurface layers of the titanium VT-9 alloy after electropark alloying  

International Nuclear Information System (INIS)

Investigation result of the phase composition and structure of the surface layer of the VT-9 titanium alloy after electrospark alloying with Ni, Al, NiAl are presented. It is shown that the surface layer is formed at the expense of the anode material deposition, its interaction with the cathode material and interelectrode medium. At that, the thickness of the layer detected roentgenographically exceeds the thickness of the layer detected metallographically. The obtained data of phase composition as to the depth of the alloyed layer permit to approach selectively to the material of the alloying electrode to increase heat resistance of the VT-9 titanium alloy

275

Formation Mechanism of Type IV Failure in High Cr Ferritic Heat-Resistant Steel-Welded Joint  

Science.gov (United States)

The mechanism of type IV failure has been investigated by using a conventional 9Cr ferritic heat-resistant steel Gr.92. In order to clarify the main cause of type IV failure, different heat treatments were performed on the base metal in order to change the prior austenite grain (PAG) size and precipitate distribution after applying the heat-affected zone (HAZ) simulated thermal cycle at the peak temperature of around A c3 ( A c3 HAZ thermal cycle) and postweld heat treatment (PWHT). The microstructural evolution during the A c3 HAZ thermal cycle and PWHT was investigated by means of scanning electron microscope (SEM), electron backscatter diffraction (EBSD), electron probe microanalysis (EPMA), and transmission electron microscope (TEM). It was found that M23C6 carbides were scarcely precipitated at the newly formed fine PAG, block, and lath boundaries in A c3 HAZ-simulated Gr.92, because the carbide forming elements such as Cr and C were segregated at the former PAG and block boundaries of the base metal. On the other hand, if all the boundaries were covered by sufficient M23C6 carbides by homogenization of the alloying elements prior to applying the HAZ thermal cycle, the creep strength was much improved even if the fine PAG was formed. From these results, it is concluded that fine-grained microstructure cannot account for the occurrence of type IV failure, and it only has a small effect during long-term creep. The most important factor is the precipitate formation behavior at various boundaries. Without sufficient boundary strengthening by precipitates, the microstructure of A c3 HAZ undergoes severe changes even during PWHT and causes premature failure during creep.

Liu, Y.; Tsukamoto, S.; Shirane, T.; Abe, F.

2013-10-01

276

Fundamental studies on electron-beam welding of heat-resistant superalloys for nuclear plants, (4)  

International Nuclear Information System (INIS)

In this report, electron-beam (EB) welded joints and TIG welded joints of various superalloys to be used for nuclear plants, such as Hastelloy-type, Inconel-type and Incoloy-type, are systematically evaluated in terms of tensile properties, low-cycle fatigue properties at elevated temperatures, creep and creep-rupture properties. It was fully confirmed as conclusion that the EB welded joints are superior to the TIG welded ones in mechanical properties, especially at high temperatures. In the evaluation of creep properties, ductility is one of the most important criteria to represent the resistance against fracture due to creep deformation, and this criterion is very useful in evaluating the properties of welded joints. Therefore, the more comparable to the base metal the electron beam welded joint becomes in terms of ductility, the more resistant is it against fracture. From this point of view, the electron beam welded joint is considerably superior to the TIG welded joint. (author)

277

16. lecture meeting of the Association for Heat-Resistant Steels and the Association for High-Temperature Materials, on 'Long-term performance of heat-resistant steels and high-temperature materials'. Thermal stress of materials. Proceedings. 16. Vortragsveranstaltung der Arbeitsgemeinschaft fuer warmfeste Staehle und Arbeitsgemeinschaft fuer Hochtemperaturwerkstoffe 'Langzeitverhalten warmfester Staehle und Hochtemperaturwerkstoffe'. Thermische Werkstoffbeanspruchung. Vortraege  

Energy Technology Data Exchange (ETDEWEB)

The proceedings contain 17 contributions on the following subjects (selection): (1) Development of the microstructure of the martensitic tempered steel X22CrMoV12-1 in fatigue tests up to 80000 h. (2) Influences on creep-induced pore formation and their detection in heat-resistant, low-alloyed steels CrMoV. (3) Endurance properties of highly creep-resistant bolt and blade steel X19CrMoVNbN11-1 in fatigue tests up to 600 C. (4) Creep behaviour of a welded 'P91' pressure vessel. (5) State of the development of improved 9 to 10%-CrMoVNb steels for turbines having steam parameters of 600 C. (6) Fracture-mechanical comparison of the mixed compound X20CrMoV12-1 and G17CrMoV5-11 for determining critical defect variables. (7) Creep-to-crack behaviour of powerplant steels. (8) Behaviour of defects in forgings or castings under creep or creep-fatigue stress. (9) Behaviour of heat-resistant steels under multistage fatigue stress. (10) Connection between failure and multiaxial stress in creep loaded pipe elbows. (11) Contribution to the characterization of long-term heat resistance of steels 12CrMo9-10 and their welds. (12) Contribution to the estimation of long-term heat resistance of the higher-resistant unalloyed steel type G20Mn5, well suitable for welding. (13) Creep equations for highly creep resistant materials. (orig./MM)

1993-01-01

278

Preparation, characterization, and heat resistance studies of a holographic photopolymer based on SU-8 epoxy resin.  

Science.gov (United States)

A holographic photopolymer based on SU-8 epoxy resin as the binder and trimethylolpropane ethoxylate triacrylate as the monomer with an iodonium salt photoinitiator was studied. A diffraction efficiency of 93% and a refractive index modulation (Delta n) of 1.3 x 10(-2) were obtained from a 16 microm thick sample with write beam intensities of 50 mW/cm(2) at a wavelength of 514.5 nm, an exposure time of 60 s, and a postbaking at 65 degrees C for 1 h. The material exhibits good heat resistance in the range from 40 degrees C to 160 degrees C and long projected life. PMID:18157240

Takamatsu, Yasushi; Dunmeyer, David; Thomas, Edwin L; Warde, Cardinal

2008-01-01

279

Estimation of work capacity of welded mounting joints of pipelines of heat resisting steel  

International Nuclear Information System (INIS)

The analysis of a work capacity of circular welds made for the Dsub(y)850 pipeline connection with high pressure vessels of heat resisting steel of the 15Kh1NMFA type has been carried out on the base of test results with small samples and real units. Welds were performed using the manual electric arc welding without the following heat treatment. It has been shown that residual stresses in such welds do not produce an essential effect on the resistance of weld metal and heat affected zone on the formation and developments of cracks

280

REM effect on nonmetallic inclusion composition and heat resistance in an austenitic steel  

International Nuclear Information System (INIS)

Studies were made to elucidate the effect of rare earths (lanthanum, neodymium, praseodymium, cerium) on the composition of non-metallic inclusions and heat resistance of an austenitic chromium-nickel steel. Common sulfide and oxide inclusions are shown to be substituted by rare earth sulfide and oxide inclusions at RE metal content in the steel up to 0.1%. Further increase of RE metal content results in increasing non-metallic inclusions containing RE metals, phosphorus and non-ferrous impurities. Creep rate changes insignificantly at RE metal content up to 0.1%, and then it sharply grows with the quantity of non-metallic inclusions in the steel

 
 
 
 
281

Resistance to corrosion fatigue fracture in heat resistant steels and their welded joints  

International Nuclear Information System (INIS)

Experimental data on cyclic crack resistance of heat-resistant steels and their welded joints employed for production of the reactor bodies are for the first time generalized and systematized. The formula is suggested accounting for surface and inner defects to calculate the fatigue crack growth in the process of operation. This formula for surface defects regards also the effect of the corrosion factor. Mechanisms of the reactor water effect on the fatigue crack growth rate are considered as well as a combined effect of radiation and corrosive medium on this characteristic

282

Welding consumables for mechanized welding of heat-resistant steel pipelines  

International Nuclear Information System (INIS)

A study was made on properties of welding joints of 15Kh1M1F steel produced under the flux AN-43 in combination with Sv-08KhGSMFA and Sv-08KhMFA wires, as well as under the flux ANK-47 in combination with Sv-08KhMFA wire. It was established that AN-43 flux with Sv-08KhGSMFA wire provided for higher level of mechanical properties and long-term strength and could be recommended for automatic welding of heat resisting steels of 15Kh1M1F type

283

Microstructural evolution during creep deformation of an 11CrMoVNb ferritic heat resistant steel  

Energy Technology Data Exchange (ETDEWEB)

The effect of creep deformation on the microstructural development of an 11CrMoVNb ferritic heat resistant steel during high temperature creep test is investigated. Coarsening behavior of the precipitates, M{sub 23}C{sub 6} and MX, and growth behavior of martensite laths of crept specimens are carefully observed from both gage and grip parts of the specimens in order to discuss the effect of deformation. Particle coarsening and martensite lath widening are pronounced in the gage part due to the creep deformation. (orig.)

Lee, Kyu-Ho; Park, Dae-Bum [Korea Institute of Science and Technology, Seoul (Korea, Republic of). Materials and Devices Div.; Korea Univ., Seoul (Korea, Republic of). Dept. of Materials Science; Kwun, S.I. [Korea Univ., Seoul (Korea, Republic of). Dept. of Materials Science; Suh, Jin-Yoo; Jung, Woo-Sang [Korea Institute of Science and Technology, Seoul (Korea, Republic of). Materials and Devices Div.

2010-07-01

284

High-temperature low-cycle-fatigue and crack-growth behaviors of three superalloys: HASTELLOY X, HAYNES 230, and HAYNES 188  

Science.gov (United States)

Low cycle fatigue (LCF) and fatigue crack growth (FCG) experiments on three superalloys HASTELLOY X, HAYNES 230, and HAYNES 188 have been conducted at temperatures from 649 to 982°C. Hold times were imposed at the maximum strain or load to investigate the hold-time effect. In general, the fatigue life decreased as the temperature or hold time increased. However, for the HAYNES 230 alloy at total strain ranges higher than 1.0% and without a hold time, the LCF life was longer at 927°C than at 816°C. This "abnormal" behavior was found to result from the smaller plastic strain amplitude at half-life at 927°C than that at 816°C. An increase in the temperature and/or the introduction of a hold time decreased the hardening rate and increased the softening rate for all the three alloys. The introduction of a hold time and/or the increase of the test temperature progressively changed the fracture mode from the transgranular to mixed trans/inter-granular, then to intergranular feature. Within the two phases of the fatigue process, crack initiation was more severely influenced by the change of the hold time and/or temperature. The FCG data of HASTELLOY X and HAYNES 230 alloys were analyzed with an emphasis on hold-time and temperature effects. The crack grew faster at a higher temperature and a longer hold time. Fracture-mechanics parameters, C*, Ct, and (Ct)avg, were applied to correlate the crack-growth rates. The fatigue-cracking path was mainly transgranular at 816 and 927°C. The cracking path became dominantly intergranular if the hold time increased to 2 min, indicating that the time-dependent damage mechanisms were in control. The Ct and (Ct)avg parameters were capable of consolidating time dependent crack growth rate from different temperatures and alloys. The tests were conducted in air. Therefore, the fracture surfaces were frequently covered with a dark layer of oxides, making fracture feature difficult to identify under scanning-electron-microscopy. To overcome this problem, an oxide-stripping technique has been developed. The sample is first boiled in a potassium permanganate solution for 1 h, and then electrolytically cleaned in an alkaline solution for 5 min.

Lu, Yulin

285

Prediction of long-term precipitate evolution in austenitic heat-resistant steels  

Energy Technology Data Exchange (ETDEWEB)

Numerical prediction of the long-term precipitate evolution in five different austenitic heat-resistant stainless steels, NF709, Super304H, Sanicro25, CF8C-PLUS and HTUPS has been carried out. MX and M{sub 23}C{sub 6} are predicted to remain as major precipitates during long-term aging in these steels. The addition of 3 wt% Cu produces very fine Cu-rich precipitates during aging in Super304H and Sanicro25. It is found that the amount of Z phase start to increase remarkably between 1,000 and 10,000 hours of aging at the expense of MX precipitates in the steels containing a high nitrogen content. However, the growth rate of Z phase is relatively slow and its average size reaches at most a few tens of nanometers after 100,000 hours of aging at 700 C, compared with 9-12% Cr ferritic/martensitic heat-resistant steels. The predicted precipitation sequence and precipitate size during aging are in general agreement with experimental observations. (orig.)

Shim, Jae-Hyeok; Jung, Woo-Sang; Cho, Young Whan [Korea Institute of Science and Technology, Seoul (Korea, Republic of). Materials/Devices Div.; Kozeschnik, Ernst [Vienna Univ. of Technology (Austria). Inst. of Materials Science and Technology

2010-07-01

286

The heat resistance of a polyurethane coating filled with modified nano-CaCO3  

Science.gov (United States)

The modification of polyurethane coating by adding surface-modified CaCO3 nanoparticles (nano-CaCO3) was investigated in this paper. To improve interfacial interaction between the nano-CaCO3 and the polyurethane (PU) matrix, a silane coupling agent (KH560) was used to modify the nano-CaCO3. The grafting of KH560 on the nano-CaCO3 surfaces was characterized by the TEM, FTIR and TGA techniques. The modification of the nano-CaCO3 surfaces with KH560 was demonstrated to improve the dispersity of nano-CaCO3. FTIR, SEM and AFM were used to characterize the polyurethane coating. The FTIR spectrum indicated that the modification of nano-CaCO3 does not influence the chemical structure of the PU matrix. The roughness and gloss of the nanocomposite coatings containing various amount of nano-CaCO3 were evaluated using a roughness tester and a brightness meter. The heat resistance of the polyurethane coating containing various amounts of nano-CaCO3 was evaluated using the TGA technique. The results revealed that nano-CaCO3 treatment with KH560 improves the nanoparticle dispersion and heat-resistance of polyurethane coating.

Li, Bin; Li, Song-Mei; Liu, Jian-Hua; Yu, Mei

2014-10-01

287

Evolution of the Laves Phase in Ferritic Heat-Resistant Steels During Long-term Annealing and its Influence on the High-Temperature Strength  

Science.gov (United States)

Heat-resistant ferritic steels containing Laves phase precipitates were designed supported by thermodynamic modeling. High-temperature compression tests at 1173.15 K (900 °C) and a detailed characterization of the microstructural evolution during annealing at 1173.15 K (900 °C) were carried out to investigate the effect of Laves phase formation on the high-temperature strength. Due to the addition of W/Mo and/or Nb, the high-temperature strength of the newly designed alloys is significantly higher than that of the reference steels. However, the high-temperature strength of all investigated steels decreases slightly as the annealing time is increased up to 1440 hours. To determine the influence of Laves phase formation and coarsening on the high-temperature strength during long-term annealing, the precipitates were extracted from the ferritic matrix in different annealing states. The phases in the powder residue were determined by XRD, and the chemical composition of the Laves phase in dependence of the annealing time was analyzed by EDS measurements. During annealing, steel Fe18CrMoW forms Nb(C,N), Ti(C,N), Laves phase (Fe2Nb) and Fe3Nb3C, whereas alloy Fe19CrWAl forms Nb(C,N), Ti(C,N), and Laves phase (Fe2Nb). The Laves phase within the alloys Fe18CrMoW and Fe19CrWAl differs in its morphology as well as its chemical composition. The Laves phase in steel Fe18CrMoW attains its chemical equilibrium after 192 hours, whereas alloy Fe19CrWAl required 24 hours. Overall, the formation of the Laves phase prevents significant grain growth during high-temperature annealing, thus preserving the high-temperature strength over a long time period.

Nabiran, Nilofar; Klein, Simon; Weber, Sebastian; Theisen, Werner

2014-10-01

288

Influencia de los parámetros de soldeo fuerte en la microestructura y propiedades mecánicas de la unión de la aleación base níquel Hastelloy B2  

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Full Text Available A study of the high vacuum brazing process of solid solution strengthened Hastelloy B2 nickel alloy has been done. A first stage of research has focused on the selection of the most appropriate brazing filler metal to the base material and vacuum furnace brazing process. The influence of welding parameters on joint microstructure constituents, relating the microstructure of the joint to its mechanical properties, has been evaluated. Two gaps of 50 and 200 micrometers, and two dwell times at brazing temperature of 10 and 90 minutes were studied. The braze joint mainly consists of the nickel rich matrix, nickel silicide and ternary compounds. Finally, the results of this study have shown the high bond strength for small gaps and increased dwell times of 90 minutes.Se realizó un estudio pormenorizado del proceso de soldeo fuerte en horno de alto vacío de la aleación base níquel Hastelloy B2 fortalecida por solución sólida. En una primera fase del trabajo se seleccionó el material de aporte acorde al material objeto de unión y a la fuente de calentamiento seleccionada. Posteriormente, se evaluó la influencia del gap (50 y 200 micrómetros y tiempo de permanencia a temperatura de soldeo (10 y 90 minutos sobre los microconstituyentes de la unión, relacionando la microestructura con las propiedades mecánicas de la junta. Los análisis metalográficos mostraron una unión constituida por una matriz rica en níquel, siliciuros de níquel y compuestos ternarios. Finalmente, los resultados de los ensayos mecánicos a esfuerzos cortantes mostraron una elevada resistencia para gaps de 50 micrómetros y tiempos de permanencia de 90 minutos.

Sotelo, José Carlos

2014-09-01

289

Effect of moisture on corrosion of Ni-based alloys in molten alkali fluoride FLiNaK salt environments  

Science.gov (United States)

We investigated the corrosion characteristics on several selected alloys at 600 and 700 °C in FLiNaK molten salts with different moisture contents. Hastelloys-N and Hastelloys-B3 exhibited better corrosion resistances, while Haynes 263 showed the poorest corrosion resistance. The mass loss of the tested alloys is primarily determined by the purity of FLiNaK salts; however, the effect of temperature becomes more important on the mass loss of the tested alloys in the non-purified FLiNaK salts. When the residual moisture is present in the FLiNaK salts, the mass losses of the tested alloys varied linearly with original Cr content plus one-third of Mo content. The results of structural characterization revealed that the tested alloys in the FLiNaK salts with higher moisture content would aggravate intergranular corrosion and pitting.

Ouyang, Fan-Yi; Chang, Chi-Hung; You, Bo-Chien; Yeh, Tsung-Kuang; Kai, Ji-Jung

2013-06-01

290

The microstructure and its impact on the high-temperature properties of the heat-resistant cast steel G-X 40 NiCr 35 25  

International Nuclear Information System (INIS)

The report explains the influence of the elements Mo, W, Nb and Ti on the microstructure and thus on the high-temperature properties of the heat-resistant cast steel G-X 40 NiCr 35 25. The creep-rupture tests carried out at temperatures between 900deg C and 1100deg C for 2000 hours suggest that the interdendritic carbide skeleton as a non-creeping fiber reinforcement has a strong effect on the minimum creep rate. Especially the elements Nb and Ti have been found to reduce the minimum creep rate. Oxidation experiments have shown that the alloys with the lowest concentrations of the four elements varied in the alloying composition exhibit the least mass increases within the duration of the experiments. But enhanced concentrations of the dissolved elements Nb and Ti in the matrix have been found to reduce the solubility of the matrix with regard to carbon, and thus protect the material from carburization. (orig.) With 66 figs., 16 tabs

291

The height and temperature effects on the Leidenfrost phenomenon with hastelloy  

Science.gov (United States)

The interaction phenomena of one drop impinging on a hot surface around Leidenfrost temperature have been experimentally investigated. In this experiment especially droplet interaction behavior with respect to the different droplet height was analyzed with high speed camera at 5000 frame per second. A large influence on the Leidenfrost phenomena of hastelloy and several materials was determined. In addition to the hastelloy, SUS 304, SUS 316, Aluminum, Titanium and Zircalloy were used as specimens. It has been observed that with increasing the droplet falling height, evaporation time of the droplet was decreased. At a certain droplet falling height and surface temperature, a droplet jet extraction phenomenon has been observed. Because of the vaporization at the first impact of the droplet bottom, the vaporization pressure attack top of the droplet, then the jet has been extracted from top of the droplet. At higher droplet falling distance and temperature, the jet extraction phenomenon does not occur, since the droplet has higher impact moment.

Yoshida, Satoshi; Uddin, Mezbah; Someya, Satoshi; Okamoto, Koji

2007-11-01

292

Long term creep behavior of Incoloy 800H and Hastelloy X in simulated HTGR environments  

International Nuclear Information System (INIS)

Creep rupture tests on Incoloy 800H and Hastelloy X had been carried out in simulated steam-cycle HTGR helium environments for two levels of moisture. The wet helium studies have been completed for a maximum test time of 16,000 hours; the dry helium tests are still in progress with a maximum test time of 18,000 hours. Standard air tests have been running for over 35,000 hours. The creep rupture behavior of Incoloy 800H in the wet helium is not significantly different from that in air but the dry helium increases the rupture life. Hastelloy X shows a slightly lower rupture life in the wet helium while the dry helium improves the creep properties in comparison with standard air tests. Oxidation is the major gas-metal interaction in both helium environments

293

Galvanic corrosion resistance of welded dissimilar nickel-base alloys  

International Nuclear Information System (INIS)

A program for evaluating the corrosion resistance of various dissimilar welded nickel-base alloy combinations is outlined. Alloy combinations included ALLCORR, Hastelloy C-276, Inconel 72 and Inconel 690. The GTAW welding process involved both high and minimum heat in-put conditions. Samples were evaluated in the as-welded condition, as well as after having been aged at various condtions of time and temperature. These were judged to be most representative of process upset conditions which might be expected. Corrosion testing evaluated resistance to an oxidizing acid and a severe service environment in which the alloy combinations might be used. Mechanical properties are also discussed

294

Process of brazing using low temperature braze alloy of gold-indium tin  

International Nuclear Information System (INIS)

A heat resistant brazing alloy of a major amount of gold, a lesser amount of indium and a minor amount of tin. The alloy is particularly suited for use in bonding electrical components to chip carrying substrates which are to be reworked

295

Morphology of extremely heat-resistant spores from Bacillus sp. ATCC 27380 by scanning and transmission electron microscopy  

Science.gov (United States)

A structural analysis of the internal and external mature spore morphology of an extremely heat resistant Bacillus spore was obtained by both scanning and transmission electron microscopy and is described. With dry heat, 139 hr at 125 C or 13-17 hr at 138 C is required to kill 90% of Bacillus sp. ATCC 27380 spores. A morel-like structure characterized by irregular but distinct polygonal ridges suggestive of extreme dehydration was observed in spore specimens. Some spores also possess a brioche-shaped appendage which is perhaps unique to this species. The explanation of the extreme heat resistance remains unknown, but it is suggested that heat resistance would result if dehydration converts the spore contents into a solid state, either amorphous or quasi-crystalline. The organism was isolated from a surface soil sample.

Youvan, D.; Watanabe, M.; Holmquist, R.

1977-01-01

296

Study of heat resistance of chromium-nickel-manganese ferritic-austenitic steels  

International Nuclear Information System (INIS)

Effect of chemical composition of austenitic-ferritic steels on their scale resistance at 800, 900 and 1000 deg C was studied. Investigation was conducted for steel of 16 casts, differing with respect to nickel, manganese, as well as chromium contents. Certain steel casts had molybdenum additions. Considerable decrease of heat resistance of chromium-nickel ferritic-austenitic steels with 18-23% Cr and variable nickel contents from 0.2 up to 6.03% in the air in 800-1000 deg C temperature range was noted when manganese content was increased. Positive chromium effect on scale resistance with increase of its concentration in steel from 18 up to 23% is manifested only at certain manganese contents

297

Structure and mechanical properties of low-activated heat-resistant reactor steel  

International Nuclear Information System (INIS)

A low-activated high-strength heat-resistant steel type 15Kh2V2FA-A is designed and intended to be used for reactor vessels of increased safety and service life. The steel provides an induced radioactivity level approximately hundred times lower compared to commonly used molybdenum-bearing steels for a 40- year period after reactor shutdown. Comprehensive kinetic studies of phase and structural transformations in austenite of commercial steel are carried out and optimum heat treatment conditions are determined. For the first time a 52-t ingot of ultrahigh purity steel is cast and two reactor vessel shells 170 and 375 mm thick are manufactured by forging. It is shown that the resistance to brittle fracture and the level of tensile properties of the steel proposed meet the requirements to reactor steels

298

Evaluating the effectiveness of heat-resistant cast steel filtration from the results of structure examinations  

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Full Text Available Filtration guarantees castings characterised by high quality and free from any non-metallic inclusions, which are formed at the stage of melting and pouring of liquid metal. This article discusses the problem of the effectiveness of filtration process taking as an example heat-resistant cast steel poured into ceramic moulds. In investigations, foamed zircon filters made by FerroTerm Sp. z o.o. The effectiveness of filtration was described and examined using the results of metallographic examinations, including macro- and micro-structure examinations of metal and of cast metal/ceramic filter interface, and measurements of the content of non-metallic inclusions. The methods of investigations were presented, the obtained results were described, and relevant conclusions were drawn, all of them unmistakably indicating a very beneficial effect that filtration has on molten metal quality. ?ód?, Poland, were used.

As?anowicz M.

2007-01-01

299

Structure and heat-resisting properties of slurry-diffusion coating on niobium  

International Nuclear Information System (INIS)

The Fe-Ti-Si coatings of niobium obtained by slurry-diffusion method are studied for their phase composition and heat- resistance in the air up to 1300 deg C. A multilayer structure of the coating consists of a zone of niobium silicides Nb5Si3 and NbSi2; separated by a layer of binary silicide Nb7Fe3Si6, as well as of the zone of titanium and iron silicides. It is established that the coatings are high-resistant due to a specific structure of films formed under their oxidation. The films consist of the SiO2 matrix and fillers, simple and binary Ti, Nb and Fe oxides. The loss of protecting properties by coatings is connected with the consumption of the titanium and iron silicides external layer

300

Preparation of heat-resistant silicon carbide fiber from polycarbosilane fiber cured by electron beam irradiation  

International Nuclear Information System (INIS)

Heat-resistant silicon carbide (SiC) fiber was synthesized by the heat treatment of polycarbosilane (PCS) fiber with electron beam irradiation curing. PCS fiber was irradiated up to 10 - 15 MGy by 2 MeV electron beam under He gas atmosphere, then the fiber was well cured. The SiC fiber obtained from the radiation cured PCS fiber contained lesser oxygen comparing with the Si-C-O fiber 'Nicalon', which was synthesized by thermal oxidation curing of PCS fiber and contained oxygen of about 10 wt%. The thermal decomposition temperature of Si-C-O fiber increased by decrease of oxygen content in the fiber. For the very low oxygen content (0.35 wt%) fiber, the tensile strength and the Young's modulus was 2.5 GPa and 250 GPa, respectively, after heat treatment at 1,973 K. Applying this radiation curing technique, long size of SiC fiber (several 100g) was synthesized. (author)

 
 
 
 
301

Method of improving the heat resistance of parts working under conditions of discontinuous lubrication  

International Nuclear Information System (INIS)

In the present work the possibilities are studied for using thermochemical treatment methods to improve heat resistance of parts working under conditions of discontinuous lubricant supply. The main aim of the study is to produce rubbing surfaces, the microstructure of which would possess high antifriction as well as antigalling properties. Diffusion impregnation of steel with boron and silicon followed by sulfur impregnation produced two types of coatings. Coatings of the first type are formed at 10000C when silicon forces iron boride off the surface, while coatings of the second type are formed at 9000C when silicon to some degree hinders boron diffusion to the surface. Sulfur diffusion does not affect the surface microstructure. The wear-resistance and galling-resistance of parts subjected to diffusion impregnation with boron, silicon, and sulfur are 1.6-2.1 times higher than for parts subjected to boron impregnation alone

302

Investigation of the spallation of oxides grown on thermally cycled heat resistant cast steels  

Energy Technology Data Exchange (ETDEWEB)

Heat resistant cast stainless steels used as tooling for titanium sheet superplastic forming (SPF) are oxidised in near service thermal conditions. Those materials mainly develop chromium and mixed chromium manganese oxide scales which are partially adherent to the metal substrate and show significant spallation depending on the exposure time and thermal cycling. The oxidation and spallation kinetics of an austenitic and a ferritic materials are monitored using thermogravimetry. Acoustic emission technique is used to detect critical temperatures corresponding to spallation and geometric parameters of the spall residues are determined using image analysis of scanning electron micrographs. Thermoelastic and strain energy models are employed to address the preferential mode of spallation of the oxides depending on the exposure time and the conditions of thermal cycling. An attempt is made to estimate the fracture energy of the oxide / metal interface using microstructural consideration such as the interface degradation during the oxidation process. (orig.)

Baleix, S.; Bernhart, G.; Lours, P. [Ecole des Mines d' Albi-Carmaux (France). Centre Materiaux

2001-07-01

303

Estimating the Condition of the Heat Resistant Lining in an Electrical Reduction Furnace  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a system for estimating the condition of the heat resistant lining in an electrical reduction furnace for ferrosilicon. The system uses temperature measured with thermocouples placed on the outside of the furnace-pot. These measurements are used together with a mathematical model of the temperature distribution in the lining in a recursive least squares algorithm to estimate the position of 'the transformation front'. The system is part of a monitoring system which is being developed in the AIP-project: 'Condition monitoring of strongly exposed process equipment in thc ferroalloy industry'. The estimator runs on-line, and results arc presented in colour-graphics on a display unit. The goal is to locate the transformation front with an accuracy of +- 5cm.

Jan G. Waalmann

1988-01-01

304

Creep curve modeling of hastelloy-X alloy by using the theta projection method  

International Nuclear Information System (INIS)

, the plot of the log stress versus log the time to a 1% strain was predicted, and the creep rate curves with time and a cutoff strain at 950 C degrees were constructed numerically for a wide rang of stresses by using the Theta projection method. (authors)

305

Data on post irradiation experiments of heat resistant ceramic composite materials. PIE for 97M-13A  

Energy Technology Data Exchange (ETDEWEB)

The research on the radiation damage mechanism of heat resistant ceramic composite materials is one of the research subjects of the innovative basic research in the field of high temperature engineering, using the High Temperature engineering Test Reactor (HTTR). Three series of irradiation tests on the heat resistant ceramic composite materials, first to third irradiation test program, were carried out using the Japan Material Testing Reactor (JMTR). This is a summary report on the first irradiation test program; irradiation induced dimensional change, thermal expansion coefficient, X-ray diffraction and {gamma}-ray spectrum are reported. (author)

Baba, Shin-ichi; Ishihara, Masahiro; Souzawa, Shizuo [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Sekino, Hajime [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2003-03-01

306

CHANGES IN STREPTOMYCES HYGROSCOPICUS 155 ENDOPEPTIDASE AND AMINOPEPTIDASE ACTIVITY AND HEAT RESISTANCE UNDER STARVATION AND INCREASED TEMPERATURE  

Directory of Open Access Journals (Sweden)

Full Text Available The influence of temperature stress and starvation for amino acids, glucose and phosphates, on the heat resistance of mycelium and endo- and aminopeptidase activity of Streptomyces hygroscopicus 155, was studied. The strongest growth inhibition was determined at temperature elevation from 30° to 39°C and at starvation for amino acids. Also these stress treatments mostly induce the heat resistance of the mycelium. A correlation between the intracellular endo- and aminopeptidase activity and decrease in biomass yield was registered. The process of catabolization of proteins, during the adaptation to stress treatments, depends on energy and is stimulated by the presence of Mg2+ ions.

Zdravka Sholeva and Iskra Ivanova

1995-01-01

307

[Changes in heat resistance of the muscle and glycerinated muscle fibers of green toad (Bufo viridis complex)].  

Science.gov (United States)

Heat resistance of muscles and actomyosin proteins was determined at damaging temperatures of 41, 42, and 43 degrees C in three green toad (Bufo viridis complex) populations from different climatic zones of Uzbekistan. The highest muscle and model resistance to these temperatures was revealed in toads living in the warmest plain regions of the country, while the lowest resistance was specific for animals from the piedmont and mountain regions. The variability of heat resistance of the muscle and models was also the highest in toads of the first group. Divergence going in this animal species is proposed. PMID:16004272

Pashkova, I M; Korotneva, N V; Pasynkova, R A

2005-01-01

308

The fabrication of a process heat exchanger for a SO3 decomposer using surface-modified hastelloy X materials  

International Nuclear Information System (INIS)

This study investigates the surface modification of a Hastelloy X plate and diffusion bonding in the assembly of surface modified plates. These types of plates are involved in the key processes in the fabrication of a Process Heat Exchanger (PHE) for a SO3 decomposer. Strong adhesion of a SiC film deposited onto Hastelloy X can be achieved by a thin SiC film deposition and a subsequent N ion beam bombardment followed by an additional deposition of a thicker film that prevents the Hastelloy X surface from becoming exposed to a corrosive environment through the pores. This process not only produces higher corrosion resistance as proved by electrolytic etching but also exhibits higher endurance against thermal stress above 900 .deg. C. A process for a good bonding between Hastelloy X sheets, which is essential for a good heat exchanger, was developed by diffusion bonding. The diffusion bonding was done by mechanically clamping the sheets under a heat treatment at 900 .deg. C. When the clamping jig consisted of materials with a thermal expansion coefficient that was equal to or less than that of the Hastelloy X, sound bonding was achieved

309

Physiological quality and gene expression related to heat-resistant proteins at different stages of development of maize seeds.  

Science.gov (United States)

We quantified and characterized the expression of heat-resistant proteins during seed development of maize lines with distinct levels of tolerance to high drying temperature. A corn field was planted for multiplication of seeds of different lines, two tolerant and two non-tolerant to high drying temperatures. Harvest of the seeds was carried out at various stages of development and they were then subjected to tests of moisture content, germination, first count of germination, accelerated aging, and cold test. The seeds were stored in a freezer for later analysis of expression of heat-resistant proteins by means of real-time PCR, electrophoresis, and spectrophotometry. We observed that heat-resistant proteins are expressed in a differential manner in seeds from different lines and at different stages of development. The expression of heat-resistant proteins was earlier in lines tolerant to high drying temperatures. Greater germination and vigor values was found for seeds collected at the last stage of development. PMID:24085427

Andrade, T; Von Pinho, E V R; Von Pinho, R G; Oliveira, G E; Andrade, V; Fernandes, J S

2013-01-01

310

Fundamental studies on electron beam welding on heat resistant superalloys for nuclear plants, 6  

International Nuclear Information System (INIS)

In this report, base metal of superalloys for nuclear plants, its electron beam and TIG weld joints were compared with each other in the mechanical properties. Obtained conclusions are summarized as follows: 1) TIG weld joint is superior to electron beam weld joint and base metal in 0.2% proof stress irrespective of the material, and electron beam weld joint is also superior to base metal. There is an appreciable difference in tensile stress between base metal and weld joint regardless of the materials. Meanwhile, electron beam weld joint is superior to TIG weld joint in both elongation and reduction of area. 2) Electron beam weld joint has considerably higher low-cycle fatigue properties at elevated temperatures than TIG weld joint, and it is usually as high as base metal. 3) In the secondary creep rate, base metal of Hastelloy X (HAEM) has higher one than its weld joints. However, electron beam weld joint is nearly comparable to the base metal. 4) There is hardly any appreciable difference between base metal and weld joint in the creep rupture strength without distinction of the material. In the ductility, base metal is much superior and is followed by electron beam weld joint and TIG weld joint in the order of high ductility. However, electron beam weld joint is rather comparable to base metal. 5) In consideration of welded pipe with a circumferential joint, the weld joint should be evaluated in terms of secondary creep rate, elongation and rupture strength. As the weld joint of high creep rupture strength approaches the base metal in the secondary creep rate and the elongation, it seems to be more resistant against the fracture due to creep deformation. In this point of view, electron beam weld joint is far superior to TIG weld joint and nearly comparable to the base metal. (author)

311

Materials for Advanced Turbine Engines (MATE): Project 3: Design, fabrication and evaluation of an oxide dispersion strengthened sheet alloy combustor liner, volume 1  

Science.gov (United States)

The suitability of wrought oxide dispersion strengthened (ODS) superalloy sheet for gas turbine engine combustor applications was evaluated. Incoloy MA 956 (FeCrAl base) and Haynes Developmental Alloy (HDA) 8077 (NiCrAl base) were evaluated. Preliminary tests showed both alloys to be potentially viable combustor materials, with neither alloy exhibiting a significant advantage over the other. Both alloys demonstrated a +167C (300 F) advantage of creep and oxidation resistance with no improvement in thermal fatigue capability compared to a current generation combustor alloy (Hastelloy X). MA956 alloy was selected for further demonstration because it exhibited better manufacturing reproducibility than HDA8077. Additional property tests were conducted on MA956. To accommodate the limited thermal fatigue capability of ODS alloys, two segmented, mechanically attached, low strain ODS combustor design concepts having predicted fatigue lives or = 10,000 engine cycles were identified. One of these was a relatively conventional louvered geometry, while the other involved a transpiration cooled configuration. A series of 10,000 cycle combustor rig tests on subscale MA956 and Hastelloy X combustor components showed no cracking, thereby confirming the beneficial effect of the segmented design on thermal fatigue capability. These tests also confirmed the superior oxidation and thermal distortion resistance of the ODS alloy. A hybrid PW2037 inner burner liner containing MA956 and Hastelloy X components was designed and constructed.

Henricks, R. J.; Sheffler, K. D.

1984-01-01

312

Metal microcrystal pollutants: the heat resistant, transmissible nucleating agents that initiate the pathogenesis of TSEs?  

Science.gov (United States)

This paper exposes the flaws in the conventional consensus on the origins of transmissible spongiform encephalopathies (TSEs) which decrees that the protein-only misfolded 'prion' represents the primary aetiological transmissible agent, and then reviews/presents the emerging data which indicates that environmental exposure to metal microcrystal pollutants (sourced from munitions, etc.) represents the heat resistant, transmissible nucleating agents which seed the metal-prion protein (PrP)-ferritin fibril crystals that cause TSE. Fresh analytical data is presented on the levels of metals in ecosystems which support populations affected by clusters of variant Creutzfeldt-Jacob disease (vCJD), sporadic/familial CJD, and the scrapie types of TSE that have emerged in the UK, Sicily, Sardinia, Calabria and Japan. This data further substantiates the abnormal geochemical template (e.g., elevated strontium (Sr), barium (Ba) and silver (Ag)) which was observed as a common hallmark of the TSE cluster ecosystems across North America, thereby supporting the hypothesis that these microcrystals serve as the piezoelectrion nucleators which seed the growth/multireplication of the aberrant metal-PrP-ferritin fibril features which characterise the neuropathology of the TSE diseased brain. A secondary pathogenic mechanism entails the inactivation of the sulphated proteoglycans which normally regulate the mineralisation process. This can be induced by a rogue metal mediated chelation of free sulphur, or by contamination with organo-sulphur pollutants that substitute at natural sulphur bonds, or via a mutation to the S-proteoglycan cell line; thereby enabling the aberrant overgrowth of rogue fibril crystal formations that possess a piezoelectric capacity which compromises the ability of the contaminated individual to process incoming acoustic/tactile pressure waves in the normal way. The crystals transduce incoming sonic energy into electrical energy, which, in turn, generates magnetic fields on the crystal surfaces that initiate chain reactions of free radical mediated spongiform neurodegeneration. Metal microcrystal nucleating agents provide a group of plausible aetiological candidates that explain the unique properties of the TSE causal agent - such as heat resistance, transmissibility, etc. - which the protein-only prion model fails to fulfill. This paper also discusses the possible nutritional measures that could best be adopted by populations living in high risk TSE ecosystems; as a means of preventing the successful implantation of these rogue microcrystals and their consequent hypermineralisation of the soft tissues within the CNS. PMID:15908137

Purdey, Mark

2005-01-01

313

Furnace alloys update  

Energy Technology Data Exchange (ETDEWEB)

The principal share of the cast heat resistant alloy market has long been held by HK-40, a 25Cr/20Ni steel with an average carbon content of 0.40 percent. HK-40 alloy has done a commendable job, especially after its limitations in the various processes were better understood, by designers and operators alike. Presently, and in the future, the materials performance demands of new reformers, ethylene pyrolysis, coal gasification, iron ore reduction and other thermally intensive processes will require alloy capabilities frequently beyond those of HK-40. This article presents an update of the capabilities and limitations of HK-40 and describes a group of higher nickel 25Cr/35Ni alloys of the HP-base, mostly modified by various additions such as columbian, tungsten, titanium, zirconium, cobalt, chromium, molybdenum, silicon and/or aluminum. A number of these alloys are proprietary. Data on the 24Cr/24Ni and 30Cr/30Ni alloys are presented as they have proven, reliable performance at an economical price.

Vervalin, C.H.

1984-12-01

314

Hot hardness measurements on heat-resistant cast steels by the UCI process. [UCI = Ultrasonic Contact Impedance]. Warmhaertemessungen an hitzebestaendigen Gussstaehlen nach dem UCI-Verfahren  

Energy Technology Data Exchange (ETDEWEB)

Heat-restistant cast materials are used in industry in furnace construction. These materials are exposed to temperatures above 1000deg C. At these temperatures they must also be restistant to high mechanical stresses. As the knowledge of material behaviour and the properties at high ambient temperatures is essential, test processes and equipment must be developed, which permit test at such a temperature. A MICRODUR 2 hardness testing equipment from the firm of Krautkraemer working on the UCI process was used for hardness measurements. Samples of heat-resistant cast steels with the material numbers 1.4837 and 1.4848 and of alloy No. 2.4879 were examined at temperatures between room temperature 1000deg C. The material behaviour at high temperatures could be characterized from the UCI hardness values determined. In order to examine the behaviour of the material after a certain period and temperature of operation, some samples were stored at T=600deg C and for periods of 10 to 100 hours. The hardness/temperature curves were then determined. (orig./MM).

Halim, A.; Schiller, J. (Krautkraemer GmbH und Co., Huerth (Germany)); Schmitz, H.P.; Deilmann, M.; Dahl, W. (RWTH Aachen (Germany). Inst. fuer Eisenhuettenkunde)

1991-01-01

315

Corrosion tests of 316L and Hastelloy C-22 in simulated tank waste solutions  

International Nuclear Information System (INIS)

Both the 316L stainless steel and Hastelloy C-22 gave satisfactory corrosion performance in the simulated test environments. They were subjected to 100 day weight loss corrosion tests and electrochemical potentiodynamic evaluation. This activity supports confirmation of the design basis for the materials of construction of process vessels and equipment used to handle the feed to the LAW-melter evaporator. BNFL process and mechanical engineering will use the information derived from this task to select material of construction for process vessels and equipment

316

Corrosion tests of 316L and Hastelloy C-22 in simulated tank waste solutions  

Energy Technology Data Exchange (ETDEWEB)

Both the 316L stainless steel and Hastelloy{reg_sign} C-22 gave satisfactory corrosion performance in the simulated test environments. They were subjected to 100 day weight loss corrosion tests and electrochemical potentiodynamic evaluation. This activity supports confirmation of the design basis for the materials of construction of process vessels and equipment used to handle the feed to the LAW-melter evaporator. BNFL process and mechanical engineering will use the information derived from this task to select material of construction for process vessels and equipment.

MJ Danielson; SG Pitman

2000-02-23

317

Deformation effect on structure and properties of cast nickel alloys  

International Nuclear Information System (INIS)

The effect of deformation at 1000-2200 deg C on the properties of precipitation hardening cast KhN62MKYuTB (with tantalum) and KhN64KYuVMT alloys, are investigated. It is shown that the deformation of cast nickel alloys with a high content of hardening ?-phase brings about a sharp decrease of heat resistance. Low creep resistance of deformed material is conditioned by a more developed intergrain surface and rough heterophase intragrain metal structure

318

Tungsten and tungsten carbide base alloys  

International Nuclear Information System (INIS)

Considered is the composition, physico-mechanical properties and structure of heat-resistant tungsten base alloys (alloys of tungsten with molybdenum, rhenium, niobium, tantalum, dispersion-hardened alloys, where ThO2 and ZrO2, HfO2 oxides, TaC and NbC carbides and ZrN and HfN nitrides are hardening phases), composition pseudoalloys (W-Cu and W-Ag), ternary alloys of high density such as W-Ni-Cu and W-Ni-Fe. Presented are also composition, physico-mechanical properties and structure of tungsten carbides and hard alloys on the tungsten carbide base. The production technology of cast carbides and tungsten-cobalt alloys is described

319

The technology for automated development of economically doped heat-resistant nickel superalloys  

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents the usage of computational technology, aimed at automated search for optimum compositions of nickel superalloys, being minimally doped by expensive rhenium and having no ruthenium. Resulting doping compositions ensure ultimate long-term high-temperature strength. The technology is based on computer model of alloy and numerical optimization routine. The model computes relation between an alloy composition and its performance characteristics. Multiobjective optimization procedure provides for an automated search for alloy composition to ensure the set of pre-defined properties of a new material. Two new nickel-based single-crystal superalloys are presented, which were created using this technology. SLGS-3 features high-temperature strength (100 hours at 1,000 degrees Centigrade at approximately 345?MPa. Its composition does not contain ruthenium. SLGS-1 alloy provided for 265?MPa and contained neither rhenium nor ruthenium in its composition.

Shmotin Yuriy

2014-01-01

320

The effect of creep on magnetic domain structure of heat resistant steels  

Science.gov (United States)

The magnetic domain and magnetic properties of heat resistant steels including 10CrMo910, P91 and 23CrMoNiWV88 are investigated in the present work. The magnetic properties characterized by magnetic hysteresis loop of the three materials under 500-600°C are measured by vibrating sample magnetometer (VSM). The magnetic domain structure of as-received and crept specimens is observed by magnetic force microscope (MFM). The magnetic domain of ferrite phase change from initial stripe pattern to maze pattern during creep. The black and white fringes and stripe-like pattern have also been found in the P91 and 23CrMoNiWV88 specimens, respectively. The experimental results reveal that the magnetic domain structure is strongly influenced by microstructures with different distributions of the carbides. It is shown that the coercivity and remanence of each material although has a remarkable decrease at 500-600°C especially for P91 almost 64% decrease, it's still the same magnitude as the one at room temperature. All the short-term crept specimens with different creep damage have a linear increase in coercivity and remanence comparing to the as-received 10CrMo910 specimens. These results indicate that it should be possible to develop an in-situ monitoring technology for creep damage based on magnetism measurement.

Zhang, S. Z.; Tu, S. T.

2013-04-01

 
 
 
 
321

Effect of temperature on the physical properties of ilmenite-serpentine heat resistant concrete radiation shields  

International Nuclear Information System (INIS)

A series of experimental studies has been carried out to determine the change in unit weight, compressive strength, water content and neutron macroscopic cross section of a new type of concrete shields made from egyptian limonite and serpentine ores when heated for long period at temperatures up to 600 degree C. Results show that the unit weight of the cure concrete has a value 2.98 Ton/M3 and decreases with increasing temperature, while the compressive strength reaches a maximum value of 19 Ton/M2 at 100 degree C. The differential thermal analysis (D.T.A.)of this concrete shows three endothermic peaks at 100 degree C, 480 degree C. Also, the thermogravimetry analysis (T.G.A.) shows that the cure concrete retains about 11% water content of the total sample weight and still retains 4.5% of its initial value when heated for long period at 600 degree C. Results also show that the neutron macroscopic cross section (for neutrons of energies <1 MeV) of the limonite-serpentine heat resistant concrete decreases to 18.6% of its initial value after heating 600 degree C

322

Microstructural Evolution and Magnetic Property of Creep-Fatigued Ferritic 9Cr Heat-Resisting Steel  

International Nuclear Information System (INIS)

The ferritic 9Cr-1Mo-V-Nb heat-resisting steel was experimentally studied in order to characterize its microstructural evolution during creep-fatigue by coercivity measurement. The creep-fatigue test was conducted at 550 .deg. C with the tensile holding time of 60s and 600s, respectively. The coercivity decreased until the failure and the hardness monotonously decreased for the whole fatigue life. As the life fraction of creep-fatigue increased, the M23C6 carbide coarsened following the Ostwald ripening mechanism. However, the MX carbonitrides did not grow during creep-fatigue due to so stable at 550 .deg. C. The width of martensite lath increased because of the dislocation recovery at the lath boundaries. The magnetic coercivity has an influence on the microstructural properties such as dislocation, precipitates and martensite lath boundaries, which interpreted in relation to microstructural changes. Consequently, this study proposes a magnetic coercivity to quantify the level of damage and microstructural change during the creep-fatigue of ferritic 9Cr-1Mo-V-Nb steel

323

Fabrication process of heat-resisting electrically conductive bodies made of borides and boron nitride  

International Nuclear Information System (INIS)

The object of the present invention is the fabrication of bodies containing less than 0.5 wt.% oxygen in a single, easily accomplished process step. According to the invention, 50-70 wt.% of an electrically conducting, heat resisting boride, e.g. zirconium boride, titanium boride and 30-50 wt.% boron nitride containing boroxide, are mixed to a uniform dispersion and then pressed at 1700-20000C under a pressure of 35 to 140 kp/cm2. The hot-pressed piece is immersed in a suitable solvent to reduce the boroxide content which either dissolves the boroxide or forms soluable conversion products with it. This treatment is carried out until the weight remains constant. The solutions used according to the invention contain water (preferably with addition of small quantities of strong acid), low primary, secondary and tertiary alcohols (aliphatic as well as aromatic). Following the solvent treatment, the compact is dried by heating and sintered without pressure in a innert atmosphere preferably at 1800-21000C. The sintered bodies are characterized by high density, good thermal resistance, small heat expansion coefficients, a low irreversible thermal expansion nonsensitiveness to moisture and excellent resistance to thermal shocks. Due to the latter property, the material in recommended for the manufacture of crucibles, particularly suitable for fast evaporation of metals (can be used to temperatures > 22000C). 4 manufacturing examples. (IHOE) 891 IHOE

324

Polyphasic taxonomy of the heat resistant ascomycete genus Byssochlamys and its Paecilomyces anamorphs.  

Science.gov (United States)

Byssochlamys and related Paecilomyces strains are often heat resistant and may produce mycotoxins in contaminated pasteurised foodstuffs. A comparative study of all Byssochlamys species was carried out using a polyphasic approach to find characters that differentiate species and to establish accurate data on potential mycotoxin production by each species. Phylogenetic analysis of the ITS region, parts of the beta-tubulin and calmodulin genes, macro- and micromorphological examinations and analysis of extrolite profiles were applied. Phylogenetic analyses revealed that the genus Byssochlamys includes nine species, five of which form a teleomorph, i.e. B. fulva, B. lagunculariae, B. nivea, B. spectabilis and B. zollerniae, while four are asexual, namely P. brunneolus, P. divaricatus, P. formosus and P. saturatus. Among these, B. nivea produces the mycotoxins patulin and byssochlamic acid and the immunosuppressant mycophenolic acid. Byssochlamys lagunculariae produces byssochlamic acid and mycophenolic acid and thus chemically resembles B. nivea. Some strains of P. saturatus produce patulin and brefeldin A, while B. spectabilis (anamorph P. variotii s.s.) produces viriditoxin. Some micro- and macromorphological characters are valuable for identification purposes, including the shape and size of conidia and ascospores, presence and ornamentation of chlamydospores, growth rates on MEA and CYA and acid production on CREA. A dichotomous key is provided for species identification based on phenotypical characters. PMID:20198134

Samson, R A; Houbraken, J; Varga, J; Frisvad, J C

2009-06-01

325

Molybdenum-boron-silicon coating on VN-3 niobium alloy  

International Nuclear Information System (INIS)

Heat resistance of the complex molybdenum-boron-silicon coating on VN-3 niobium alloy is studied. The coating phase composition in the initial state and after heating in air at 1200 deg C during 100-1300 h is determined using X-ray diffraction, electron diffraction and X-ray spectrum analyses. It is shown that high heat resistance of the coating is ensured due to formation of an external film of silicon oxide and a boride sublayer between the metal and coating

326

Single crystal rhenium-containing nickel alloys for turbine engine blades  

International Nuclear Information System (INIS)

The fundamental potentials for designing single crystal nickel-base carbon-free alloys doped with rhenium up to 9-10% and exhibiting a high castability are established. It is shown that a 9%-Re alloy surpasses the III generation alloys in the properties. In so doing, the attained level of heat resistance is high enough to warrant using high rhenium content. The phase stability of high-rhenium alloys is provided by the limitation of IV group elements (Cr, Mo, W) in alloy composition to prevent TCP-phase formation. A high content of refractory elements provides an alloy stability to bulk recrystallization on high-temperature homogenizing annealing

327

Autoradiographic investigations of segregation of boron in cast steel and cast nickel alloys  

International Nuclear Information System (INIS)

Boron segregation has been investigated in low alloy cast steels containing very small amounts of boron, and in nickel base heat resisting alloys with higher concentrations of boron using neutron induced autoradiography, emulsion autoradiography, X-ray microanalysis, and X-ray phase analysis. The effects of heat treatment of the castings on the segregation of boron and alloy elements were found to be little. The boron containing phases could be identified

328

Material design data of 2.25Cr-1Mo steel and hastelloy-x for the experimental multi-purpose very-high temperature gas-cooled reactor  

International Nuclear Information System (INIS)

The preliminary structural design guidelines for the experimental multi-purpose very-high temperature gas-cooled reactor have recently been prepared. The components of the primary system operating at temperatures of creep dominant range are grouped in those of pressure and temperature boundaries respectively. In the material selection, 2 1/4Cr-1Mo steel is chosen for the former and Hastelloy-X for the latter taking into account of material properties at operating temperature. Deriving from the literature in the field, material design data of the alloys are established in design forms such as Sy, So, Sm, St, 100% of minimum stress to rupture, design fatigue curves, isochronous stress-strain curves, creep-fatigue interaction damage factor and so on, which are defined in ASME Code Section III, Code Case 1592. (auth.)

329

Seizure and wear characteristics of Hastelloy XR and titanium nitride coating in high temperature condition  

International Nuclear Information System (INIS)

A concentric hot gas duct between the reactor core of the High Temperature engineering Test Reactor (HTTR) and primary heat exchangers consists of a pressure tube, inner tube, liner and so on. Axial and radial thermal expansion difference between the liner and inner tube caused by the different temperature is absorbed by liner slide joints and by liner supports and spacers respectively. We have proposed to coat Titanium Nitride (TiN) on the surface of the liner slide joints, supports and spacers using the thermal CVD (Chemical Vapor Deposition) method in order to prevent their seizure and excessive wear at service temperature of 950degC. Seizure and wear characteristics of Hastelloy XR and TiN coating in high temperature condition of 950degC were studied experimentally. As a result, it has been confirmed that TiN coating film of 3?m on the surface of Hastelloy XR is sufficient to prevent seizure and excessive wear of the liner slide joints, supports and spacers during the life time of the HTTR. TiN coating by their thermal CVD method was adopted as the coating method for the liner slide joints, supports and spacers of the HTTR. (author)

330

Heat treatment of incoloy 800 and Hastelloy X for boiler tubes  

International Nuclear Information System (INIS)

A recent tendency in steam generated by boilers for industrial use is that temperature and pressure values are getting higher than ever, and so the research and development of valves for such use are now in progress. We lately succeeded in getting an order from a customer for the manufacture of a boiler to be used for the above-mentioned research and development, which produces for the purpose 350 kg/cm2 and 6500C steam at the outlet of the final superheater. In manufacturing the above boiler, Incoloy 800 and Hastelloy X tubes, which had not been used for boilers before, were adopted for the first time for the high temperature and pressure part of the boiler (the final superheater). Although there were no processing standards officially approved and regulated concerning the materials, the solution heat treatment after welding and bending performance were considered necessary, and the microstructure and hardness tests were conducted to select the optimum heat treatment condition. As a result of our study, we have found that when Incoloy 800 and Hastelloy X are solution heat treated at 1,1250C for 2 minutes per 1 mm thickness of steel pipe wall, satisfactory results can be attained. (author)

331

High-temperature gas-cooled reactor helium compatibility studies: results of 10,000-hour exposure of selected alloys in simulated reactor helium  

Energy Technology Data Exchange (ETDEWEB)

Work on the HTGR Helium Compatibility Task accomplished during the period March 31, 1977 through September 30, 1979, is documented in this report. Emphasis is on the results and analyses of creep data to 10,000 h and the detailed metallurgical evaluations performed on candidate alloy specimens tested for up to 10,000 h. Long-term creep and unstressed aging data in controlled-impurity helium and in air at 800, 900, and 1000/sup 0/C are reported for alloys included in the program in FY-76, including the wrought solid-solution-strengthened alloys, Hastelloy X, Hastelloy S, RA 333, and HD 556, and the centrifugally cast austenitic alloys, HK 40, Supertherm, Manaurite 36X, Manaurite 36XS, and Manaurite 900.

Lechtenberg, T.A.; Stevenson, R.D.; Johnson, W.R.

1980-05-01

332

Segregation in welded nickel-base alloys  

International Nuclear Information System (INIS)

Segregation effects have been investigated in nickel-base alloys monel 400, inconel 625, hastelloy C-276 and incoloy 825, test welded under controlled conditions. Deviations from the normal composition have been observed to varying extents in the welded zone of these alloys. Least effect of this type occurred in Monel 400 where the content of Cu increased in some of the areas. Enhancement of Al and Ti has been found over large areas in the other alloys which has been attributed to the formation of low melting slag. Another common feature is the segregation of Cr, Fe or Ti, most likely in the form of carbides. Enrichment of Al, Ti, Nb, Mb, Mo, etc., to different amounts in some of the areas of these materials is in- terpretted in terms of the formation of gamma prime precipitates or of Laves phases. (author)

333

Study of heat resistance of casted turbine vessel elements of chromium-molybdenum steel after long service  

International Nuclear Information System (INIS)

To predict residual durability of power equipment structural elements on the basis of test results for specimens of metal damaged during operation, investigation into heat resistance properties of chromium-molybdenum steel specimens cut out of the steam turbine vessel after 180 thousand hours operation at 9 MPa steam pressure has been carried out on. Creep test and long-term rupture strength test were conducted at 743, 783 and 823 K which corresponds to different temperature zones of the structural elements under investigation. Data of microstructural analysis and mechanical tests testify to microstructure stability and satisfactory values of heat resistance and long-term ductility which permits to recommend increase of life-time of casted turbine vessel components up to 250-280 thousand hours

334

Cr - Ni system alloys composition impact on durability value  

Directory of Open Access Journals (Sweden)

Full Text Available There are considered the alloys of the Cr – Ni system with addition of iron, molybdenum and other alloying elements. In the alloys there varied chrome content from 35 to 55 %. The alloys were subjected to various types of heat treatment. There were measured mechanical properties at the room temperature, then the alloys were studied for the durability limit. There was additionally studied the impact of chrome content in the alloy and operation temperatures on the value of rupture stress. All the indicators studied were compared with similar parameters of the ??77??? alloy.It was established that in terms of heat resistance with the present combination of alloying elements the most optimal chrome content is 40…45 %.

A. Z. Issagulov

2014-10-01

335

Wear resistant steels and casting alloys containing niobium carbide  

Energy Technology Data Exchange (ETDEWEB)

Niobium, like titanium and vanadium, forms superhard MC carbides that remain relatively pure in technical alloys on account of their low solubility for other metallic alloying elements. However, because they have a greater hardness than the precipitated chromium carbides commonly used in wear-resistant alloys, they are suitable as alternative hard phases. This contribution deals with new wear-resistant steels and casting alloys containing niobium carbide. These include a secondary hardening hardfacing alloy, a composite casting alloy for wear applications at elevated temperatures, a white cast iron as well as two variants of a corrosion-resistant cold-work tool steel produced by melt metallurgy and by powder metallurgy. A heat-resistant casting alloy is also discussed. Based on equilibrium calculations the microstructures developing during production of the alloys are analysed, and the results are discussed with respect to important properties such as abrasive wear and corrosion resistance. (orig.)

Theisen, W.; Siebert, S.; Huth, S. [Lehrstuhl Werkstofftechnik, Ruhr-Univ. Bochum (Germany)

2007-12-15

336

Study on functional heat-resistant ceramics SiC using small angle neutron scattering  

International Nuclear Information System (INIS)

The mechanical properties of functional heat-resistant silicon carbide SiC ceramics are significantly influenced by the concentration and dimensions of pores. 3 SiC samples with different densities were sintered with different kind and amount of additives (such as Al2O3, B4C and C) using different sintering conditions of the Department of Material Science and Engineering at the University of Science and Technology in Beijing. Small angle neutron scattering measurements for 3 SiC samples were carried out at C1-2 SANS instrument of the University of Tokyo in Japan Atomic Energy Research Institute. The neutron data with 8 and 16 in of secondary flight path and 10 and 7 A of neutron wave length respectively have been obtained. After deduction of background measurement and transmission correction, both neutron data were linked up with each other. The cubic patterns of 3 neutron data with Q range from 0.0028 - 0.05 A-1 are almost with axial symmetry. It shows that the shape of pores, whose dimensions are relative to the Q range, is almost spherical. For spherical particles (or pores) we can obtain an expression of size distribution directly, using Mellin Transform (J. Appl. Phys. 45, 1974, 46.). According to our calculating program for the expression, the size distribution of pores for 3 samples were obtained. The average size (? 190 A) of pores for hot-pressed SiC sample with more density is smaller than others (? 210 A). It seems to be the reason why the density of hot-pressed SiC sample is higher than no-hot-pressed sample. (author)

337

Attachment and Heat Resistance of Campylobacter jejuni on Enterococcus faecium Biofilm  

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Full Text Available Attachment and heat resistance of Campylobacter jejuni in Enterococcus faecium biofilm were studied. E. faecium biofilm were incubated with 107 cfu mL-1 C. jejuni for 4.5 h at 23 ° C under atmospheric conditions or 12 h at 42 ° C under microaerophilic conditions. The coupons were heat treated at 56 and 63 ° C for 30, 60 and 120 sec. In addition, C. jejuni in E. faecium biofilm was incubated for up to 4 days at 23 ° C under atmospheric conditions in 50% trypticase soy broth for survival study. Hydrophobicity of C. jejuni planktonic cells, E. faecium planktonic and biofilm cells, as determined by salt aggregation test and microbial adhesion to hydrocarbon test using hexadecane were determined. D-value of C. jejuni planktonic cells at 56 and 63 ° C were 46 and 12 sec, respectively. D-value of E. faecium planktonic cells at 56 and 63 ° C were 117 and 80 sec, respectively. The presence of E. faecium biofilm reduced the lethal effect of heat on C. jejuni cells when heated at 56 and 63 ° C. C. jejuni formed biofilm on stainless steel when grown at 42 ° C under microaerophilic conditions for 12 h but the biofilm did not survive the heat treatments nor did C. jejuni cells in E. faecium biofilm. C. jejuni in biofilm persisted under atmospheric condition at 23 ° C for up to 2 days while C. jejuni attached on stainless steel without biofilm could not be recovered after two days of incubation. After forming E. faecium biofilm, became more hydrophobic than its planktonic cells. This may attract C. jejuni cells to attach on the biofilm as C. jejuni was found to be more hydrophobic than E. faecium planktonic cells.

N. Trachoo

2005-01-01

338

Assessment of Heat Resistance of Bacterial Spores from Food Product Isolates by Fluorescence Monitoring of Dipicolinic Acid Release  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study is aimed at the development and application of a convenient and rapid optical assay to monitor the wet-heat resistance of bacterial endospores occurring in food samples. We tested the feasibility of measuring the release of the abundant spore component dipicolinic acid (DPA) as a probe for heat inactivation. Spores were isolated from the laboratory type strain Bacillus subtilis 168 and from two food product isolates, Bacillus subtilis A163 and Bacillus sporothermodurans IC4. Spores...

Kort, Remco; O Brien, Andrea C.; Stokkum, Ivo H. M.; Oomes, Suus J. C. M.; Crielaard, Wim; Hellingwerf, Klaas J.; Brul, Stanley

2005-01-01

339

Effects of deformation, oxidation, and temperature on the long-term cyclic strain fatigue behaviour of heat-resisting steels  

International Nuclear Information System (INIS)

This report is a parameter study of the creep and fatigue strength of heat-resisting steels, with the main points of interest being the following. Creep-fatigue interaction, initiation, propagation and accumulation of defects, effects of pre-operational defects, detection and evaluation of materials damage owing to creep-induced fatigue, as well as assessment of the creep and fatigue behaviour of welds. (orig.)

340

Heat-resistant DNA tile arrays constructed by template-directed photoligation through 5-carboxyvinyl-2?-deoxyuridine  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Template-directed DNA photoligation has been applied to a method to construct heat-resistant two-dimensional (2D) DNA arrays that can work as scaffolds in bottom-up assembly of functional biomolecules and nano-electronic components. DNA double-crossover AB-staggered (DXAB) tiles were covalently connected by enzyme-free template-directed photoligation, which enables a specific ligation reaction in an extremely tight space and under buffer conditions where no enzymes work efficiently. DNA nanos...

Tagawa, Miho; Shohda, Koh-ichiroh; Fujimoto, Kenzo; Sugawara, Tadashi; Suyama, Akira

2007-01-01

 
 
 
 
341

Cobalt base alloys as structural materials  

International Nuclear Information System (INIS)

Cobalt and its alloys have been used in technique for tens years. They make up the group of materials with special chemical properties as well as chemical - mechanical properties. They are used mainly as a heat-resistant materials and heat-strength materials on elements of engines, turbines etc., as well as in medicine as corrosion-resistant materials. Moreover they are used as matrix of sintered tool and as magnet materials. The chemical composition of majority of cobalt alloys is based on system Co-Cr-Ni, moreover practical alloys are type Co-Cr-Mo, Co-Cr-W. Under structural regard they are the most often single-phase solution strengthened alloys or containing second phase (intermetallic), dispersion strengthened alloys. They are produced as cast, wrought, the macrocrystalline, and in case of tool materials they are then the sinters of type of cermets. In article are described some of Co-base materials, interesting with regard on use in construction of machines, in peculiarity on elements for power engineering as well as on factorials the loaded elements of gas turbine engines. Moreover introduced the preliminary results of investigations of experimental alloys Co-Cr-Ni from point of view of their heat resistance. (author)

342

Induction of Heat Resistance in Wheat Coleoptiles by 4-Hydroxybenzoic Acid: Connection with the Generation of Reactive Oxygen Species  

Directory of Open Access Journals (Sweden)

Full Text Available The effect of 4-hydroxybenzoic acid (4-HBA on resistance of coleoptiles of 4-day-old etiolated seedlings of wheat (Triticum aestivum L., cv. Elegiya to damaging heating (10 min at 43°C and possible dependence of this effect on changes in the activities of enzymes producing and scavenging reactive oxygen species (ROS were investigated. Treatment of coleoptiles with 10 ?M 4-HBA resulted in enhancing of superoxide anion-radical generation and maintaining of hydrogen peroxide content there in. Increasing of the rate of ROS production was significantly suppressed by inhibitors of NADPH oxidase (?-naphthol and peroxidase (salicylhydroxamic acid. Under the influence of 4-HBA the activities of superoxide dismutase and apoplastic forms of peroxidase were increased. The activity of oxalate oxidase and catalase has not changed. Exogenous 4-HBA improved coleoptiles heat resistance and its effects were comparable with the influence of salicylic acid. Antioxidant agent BHT (butylhydroxytoluene, inhibitors of NADPH oxidase and peroxidase significantly reduced the increasing of wheat coleoptiles heat resistance, caused by 4-HBA action. It was concluded that 4-HBA influence on coleoptiles heat resistance is realized with the ROS mediation.

Yastreb T.O.

2012-08-01

343

Effects of minerals on sporulation and heat resistance of Clostridium sporogenes.  

Science.gov (United States)

In this study, various mineral supplements, such as chloride salts (CaCl2, MgCl2, MnCl2, FeCl2 and KCl) supplying cations and calcium salts (CaCl2, CaCO3, CaSO4, Ca(OH)2 and CaHPO4) supplying anions, were tested if they could stimulate the sporulation of Clostridium sporogenes, a surrogate microorganism for C. botulinum. Of the cations tested, the addition of CaCl2 showed a slightly, but not significantly, greater increase in spore levels within 3 weeks of incubation, compared to that of the other cations. The optimum concentration of CaCl2 was 0.5%, which yielded nearly 10(4) CFU/ml of spores. Of the anions tested, CaCO3 promoted sporulation within one week, which was the most effective compound for promoting rapid sporulation among the minerals tested. CaSO4 produced a pattern of sporulation similar to that of CaCl2. While CaHPO4 resulted in the maximum production of spores after 4 weeks, Ca(OH)2 failed to induce sporulation. With an optimized concentration of 0.5% CaCO3, the spore yield was approximately 10(5) CFU/ml. The spores prepared in sporulation medium with CaCO3 (pH 5.0) had slightly, but not significantly, higher D values than those produced with CaCl2 (pH 5.0) at temperatures ranging from 113 to 121 degrees C. However, no significant differences were observed in Z values (both 10.76 degrees C). In a large scale spore production, D(121 degrees C) values of the spore crops prepared with CaCl2 and CaCO3 and resuspended in phosphate buffer (pH 7.0) were found to be both 0.92 min. In conclusion, our data suggest that CaCO3 is highly effective in reducing sporulation time as well as enhancing heat resistance. PMID:18986726

Mah, Jae-Hyung; Kang, Dong-Hyun; Tang, Juming

2008-12-10

344

Wettability and interface considerations in advanced heat-resistant Ni-base composites  

International Nuclear Information System (INIS)

Oxide fiber-reinforced Ni-base composites have long been considered as attractive heat-resistant materials. After several decades of active research, however, interest in these materials began to decline around mid-1990's due chiefly to 1) a lack of manufacturing technology to grow inexpensive single-crystal oxide fibers to be used in structural composites, and 2) fiber strength loss during processing due to chemical interactions with reactive solutes in the matrix. The cost disadvantage has been mitigated to a large extent by the development of innovative fiber fabrication processes such as the Internal Crystallization Method (ICM) that produces monocrystalline oxide fibers in a cost-effective manner. Fiber strength loss has been an equally restrictive issue but recent work has shown that it may be possible to design creep-resistant composites even when fiber surface reconstruction from chemical interactions has degraded the strength of extracted fibers tested outside the matrix. The key issue is the optimization of the composite- and interface structure. Reaction-formed defects may be healed by the matrix (or a suitable coating material) so that the fiber residing in the matrix may exhibit diminished sensitivity to flaws as compared to fibers extracted from the matrix and tested in isolation of the matrix. Generally, the Ni-base/Al2O3 composites exhibit acceptable levels of wettability and interface strength (further improved with the aid of reactive solutes), which are required for elevated-temperature creep-resistance. In order to harness the full potential of these composites, the quality of the interface as manifested in the fiber/matrix wettability, interface composition, interphase morphology, and interface strength must be designed. We identify key issues related to the measurement of contact angle, interface strength, and chemical and structural properties at the fiber/matrix interface in the Ni/alumina composites, and present the current state-of the-art in understanding and designing the Ni/alumina interface. There should be no doubt that optimization of the interface- and composite microstructure through judicious control of the fabrication process and surface modification shall yield technologically promising Ni-base/oxide fiber composites. (authors)

345

On the metallurgical and environmental factors affecting creep behaviour of hastelloy-x  

International Nuclear Information System (INIS)

Deformation and rupture processes of Hastelloy-X and its modified version in different environment including air, the simulated HTR helium and high vacuum were compared. All the environments showed the effects different from each other. The high vacuum condition caused best reproducible creep and rupture behaviour, and essentially no size effect was involved. While the others caused considerable surface-to-volume ratio effect, and the simulated HTR helium environment showed characteristic effects. The latters were interpleted as the results of the depletion of chromium and molybdenum due respectively to the selective oxidation of the active elements and carburization to enhance the formation of M6C to eventually cause recrystallization of the austenite matrix. (author)

346

Effect of grain size and cold working on high temperature strength of Hastelloy X  

International Nuclear Information System (INIS)

Effect of grain size and cold working on creep, creep rupture, low cycle fatigue and tensile strengths of Hastelloy X were studied at temperatures ranging from 800 to 10000C. In order to apply these data to design, the allowable design stresses were estimated by expanding the criteria of ASME Code Case 1592 to such a high temperature range. The allowable design stress increased, on the other hand, the low cycle fatigue life decreased with increasing grain size. Cold working up to a ratio of 5 per cent may not be a serious problem in design, because the allowable design stress and the fatigue life were little affected. The cause of these variations in strength was discussed by examining the initiation and growth of cracks, and the microstructures. (author)

347

Kinetics of chromium evaporation from heat-resisting steel under reduced pressure  

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This paper describes a kinetic analysis of the process of chromium evaporation from ferrous alloys smelted under reduced pressure. The study discussed comprised determination of the liquid phase mass transfer coefficient as well as the value of the constant evaporation rate. By applying these values as well as the values of the overall mass transfer coefficient estimated based on the relevant experimental data, the fractions of resistance of the individual process stages were established.

Kolmasiak, C.

2012-01-01

348

Kinetics of chromium evaporation from heat-resisting steel under reduced pressure  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes a kinetic analysis of the process of chromium evaporation from ferrous alloys smelted under reduced pressure. The study discussed comprised determination of the liquid phase mass transfer coefficient as well as the value of the constant evaporation rate. By applying these values as well as the values of the overall mass transfer coefficient estimated based on the relevant experimental data, the fractions of resistance of the individual process stages were established.

C. Kolmasiak

2012-07-01

349

Study on the structural strength and corrosion resistance of nickel-base alloys under normal industrial welding conditions by the example of the materials type NiMo 28 and NiMo 16Cr16Ti  

International Nuclear Information System (INIS)

The sensitivity of the nickel-base alloys NiMo28 (Hastelloy B-2) and NiMo16Cr16Ti (Hastelloy C-4) to intercrystalline corrosion in the heat-affected zone of welded joints was studied. The temperature curves associated with different welding processes were simulated by temperature cycles (peak temperature 1,3000C). To determine the temperature-time curves, a temperature-measuring device (with Ni-Cr/Ni thermoelements) was constructed and tested. The corrosion resistance was assessed by metallographic, hardness, and corrosion testing of the simulation samples. The influence of the welding technique employed was determined. (GSC)

350

Investigation of several commercial aluminide coatings for carburization protection of a nickel-base alloy  

International Nuclear Information System (INIS)

Four commercial aluminide coatings applied to Hastelloy Alloy X were investigated with respect to their carburization resistance in a carburizing impure helium environment. The test gas was helium with 500 ?atm H2, 50 ?atm CO, 50 ?atm CH4, and 2O. The uncoated specimens exposed to this test environment at 9000C (16500F) for 1000 and 2000 h exhibited significant carburization. All four coatings provided good protection against carburization of the substrate Hastelloy Alloy X, presumably due to the formation of an Al2O3 oxide scale on the coating surface during the high-temperature corrosion exposure. The Al2O3 oxide is believed to be an effective barrier to carbon transport. Aluminide coatings applied to Hastelloy Alloy X exhibited a tendency for forming Kirkendall diffusion voids (or pores) in the diffusion zone during long-term high-temperature exposures [e.g., 9000C (16500F) for 1000 h]. Chromium addition during aluminizing, which resulted in a high chromium content in the coating, appears to be effective in preventing the pore formation during subsequent long-term high-temperature exposures

351

Ocorrência de fungos filamentosos termo-resistentes em polpa de tomate envasada assepticamente Occurrence of heat resistant molds in tomato pulp packed aseptically  

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Full Text Available Este trabalho teve como objetivo principal determinar a ocorrência de fungos filamentosos termo-resistentes durante o processamento asséptico de polpa de tomate (8° BRIX. Durante o período de safra de tomate foram feitas amostragens em 9 lotes (3 no início, 3 no pico e 3 em fim de safra e no período de entresafra em 5 lotes. Foi feita a enumeração de fungos termo-resistentes nas amostras coletadas durante as diferentes etapas do processo asséptico de cada lote. Foram obtidas contagens médias relativamente baixas, variando entre This work aimed at determining the occurrence of heat resistant molds during the aseptic processing of tomato pulp (8° BRIX. During tomato harvest, 9 lots were sampled (3 at the beginning, 3 at the apex and 3 at the end of harvest and other 5 lots were sampled between harvest. For each lot, the enumeration of heat resistant molds was carried out in samples collected during the aseptic process. The mean count of heat resistant molds was relatively low, ranging from <1 to 8CFU/100mL of sample. The higher counts were observed in the raw material and the pre-wash and transportation water. Fifty strains of heat resistant molds detected in the enumeration procedure were isolated, codified and stocked. One-month-old spores of each isolate were submitted to different heat shocks to select the most heat resistant mold. The most heat resistant isolated strain (survived 100° C/25 minutes was identified as Neosartorya fischeri.

Flávio BAGLIONI

1999-05-01

352

In situ investigation of structure and stability of niobium carbonitrides in an austenitic heat-resistant steel  

International Nuclear Information System (INIS)

The structure and stability of Nb(C,N) precipitates were direct observed during reheating of an austenitic heat-resistant steel using in situ hybrid observations. The coarsened ?-Nb(C,N) and finer ?-Nb(C,N) were present in as-received steel. During the coarsening process, the d-spacing of cubic ?-Nb(C,N) exhibits a sharp decrease with increasing temperature, while that of hexagonal ?-Nb(C,N) maintains a steady increase. Compared to ?-Nb(C,N), the ?-Nb(C,N) was quickly dissolved into the austenite during heating, and it would no longer reprecipitate in the subsequent cooling.

353

Effects of gamma irradiation on two heat resistant moulds: Aspergillus fumigatus and Paecilomyces variotii isolated from margarine  

Science.gov (United States)

The present study was undertaken to evaluate the effect of gamma irradiation on two heat-resistant moulds, namely Aspergillus fumigatus and Paecilomyces variotii isolated from margarine samples. The irradiation process of these moulds was carried out in a 60Co gamma ( ?) irradiator at average absorbed doses of 1, 3, 5 and 7 kGy for exposure times of 52, 156, 260 and 364 min, respectively. The average D10 value for A. fumigatus was 1.08±0.08 kGy while it was 0.59±0.10 kGy for P. variotii. Consequently, the sensitivity of P. variotii against ? irradiation was more than A. fumigatus.

Gumus, Tuncay; Gecgel, Umit; Demirci, A. Sukru; Arici, Muhammet

2008-05-01

354

Effects of gamma irradiation on two heat resistant moulds: Aspergillus fumigatus and Paecilomyces variotii isolated from margarine  

International Nuclear Information System (INIS)

The present study was undertaken to evaluate the effect of gamma irradiation on two heat-resistant moulds, namely Aspergillus fumigatus and Paecilomyces variotii isolated from margarine samples. The irradiation process of these moulds was carried out in a 60Co gamma (?) irradiator at average absorbed doses of 1, 3, 5 and 7 kGy for exposure times of 52, 156, 260 and 364 min, respectively. The average D10 value for A. fumigatus was 1.08±0.08 kGy while it was 0.59±0.10 kGy for P. variotii. Consequently, the sensitivity of P. variotii against ? irradiation was more than A. fumigatus

355

Wrought stainless steel compositions having engineered microstructures for improved heat resistance  

Science.gov (United States)

A wrought stainless steel alloy composition includes 12% to 25% Cr, 8% to 25% Ni, 0.05% to 1% Nb, 0.05% to 10% Mn, 0.02% to 0.15% C, 0.02% to 0.5% N, with the balance iron, the composition having the capability of developing an engineered microstructure at a temperature above 550.degree. C. The engineered microstructure includes an austenite matrix having therein a dispersion of intragranular NbC precipitates in a concentration in the range of 10.sup.10 to 10.sup.17 precipitates per cm.sup.3.

Maziasz, Philip J [Oak Ridge, TN; Swindeman, Robert W [Oak Ridge, TN; Pint, Bruce A [Knoxville, TN; Santella, Michael L [Knoxville, TN; More, Karren L [Knoxville, TN

2007-08-21

356

Fiber reinforced superalloys, ceramics, and refractory metals, and directionally solidified eutectics (heat-resistant composites)  

International Nuclear Information System (INIS)

High-temperature composites have been shown to have excellent elevated-temperature tensile and stress-rupture strengths and specific strengths. Tungsten alloy fiber reinforced superalloys have been demonstrated to have stress rupture strengths at 20000F superior to superalloys and sufficient impact resistance for gas turbines. Recently developed tungsten alloy fibers should permit production of composites with use-temperatures (gas turbine blades, vanes) as high as 24000F. Their main problem is associated with the direction and perfection of growth of strong whiskers or lamina in irregularly shaped components. Artificially made whisker composites are believed to warrant serious consideration. Use-temperatures of refractory metal matrix composites can be as much as 25000F for Nb matrix composites and over 30000F for W matrix composites. Ceramic matrix composites with use-temperatures ranging from 18000F to over 30000F are possibilities. Stationary, large, turbines for power generation may make use of refractory fiber/superalloy matrix, ceramic matrix, and coated refractory matrix composites. Such an application may capitalize on the high-temperature strength and high use-temperatures of the composites, which, in turn, will enhance engine performance. (127 references, 62 fig, 22 tables) (U.S.)

357

Magnesium Cermets and Magnesium-Beryllium Alloys  

International Nuclear Information System (INIS)

The paper describes some results of work on the development of magnesium-magnesium oxide cermets and of super heat-resistant magnesiumberyllium alloys produced by powder metallurgical methods. The introduction of even a minute quantity of finely dispersed magnesium oxide into magnesium results in a strengthening of the material, the degree of which increases with increased magnesium oxide concentration, although variation of this concentration within the limits of 0.3 to 5 wt.% has a comparatively slight effect on the corresponding variation in the short-term strength over the whole range of temperatures investigated. At 20oC, in the case of the cermets, ?? = 28 to 31 kg/mm2 and ? = 3 .5 to 4.5%; at 500oC ?? = 2.6 to 3.2 kg/mm2 and ? =30 to 40%. The positive effect of the finely dispersed oxide phase is particularly evident in protracted tests. For magnesium cermets, ? (300)/100 = 2.2 kg/mm2. Characteristic of the mixtures is the high thermal stability of the strength properties, linked chiefly with the thermodynamic stability of the strength-giving oxide phase in the metal matrix. The use of powder metallurgical methods has yielded super heat-resistant magnesium-beryllium alloys containing heightened concentrations of beryllium (PMB alloys). In their strength characteristics PMB alloys are close to Mg-MgO cermets, but the magnesium-beryllium alloys have a degree and duration of resistave a degree and duration of resistance to high temperature oxidation which exceeds the corresponding qualities of the magnesium alloys at present known. Thus, in air of 580oC, PMB alloys with 2 to 5% beryllium maintain a high resistance to oxidation for a period of over 12000 to 14000 h. This long-term heat resistance is chiefly a result of the amount of beryllium in the alloy, and increases with increasing beryllium content. PMB alloys are also marked by high resistance to short bursts of overheating. Magnesium cermets and magnesium-beryllium alloys, with their enhanced high-temperature stability, are capable of finding extensive application in various branches of technology. (author)

358

Long-term creep properties of hastelloy XR in simulated high-temperature gas-cooled reactor helium  

International Nuclear Information System (INIS)

Creep tests of Hastelloy XR (a modified version of the conventional Hastelloy X) were carried out in simulated high-temperature gas-cooled reactor (HTGR) helium at 800, 900 and 1,000degC. The test results up to about 50,000 h showed no significant degradation in creep properties. The creep-rupture strength obtained through long-term tests was above the level corresponding to the design allowable creep-rupture stress of the High-Temperature Engineering Test Reactor. The values of the stress exponent were 4.5 to 5.7 when the stress dependence of the steady-state creep rate was expressed in terms of the Norton equation. It is judged that dominant creep process is dislocation creep. Rupture lives could be estimated with sufficient accuracy using Larson-Miller parameter. Carburization during creep in simulated HTGR helium did not degrade creep properties of Hastelloy XR. Internally formed cracks were initiated at sites of precipitates at grain boundaries, growing nearly perpendicular to the stress axis. Two phases, Cr-rich carbide and Mo-rich carbide, co-existed in specimens after long-term creep tests. (author)

359

Corrosion behavior of Hastelloy C4 in a MgCl2 rich brine under gamma irradiation  

International Nuclear Information System (INIS)

Corrosion studies performed until now on a number of materials in salt brines have shown that besides the unalloyed steels and Ti 99.8-Pd, also Hastelloy C4 is a promising material for HLW packagings serving as a barrier in a rock salt repository. In order to characterize the corrosion behavior of Hastelloy C4 in more detail, additional corrosion studies under gamma-irradiation were performed. The corrosion medium was a salt brine (Q-brine) rich in MgCl2 which is relevant for accident scenarios in a repository. The test temperature was 90 degree C, the applied dose rates 1 Gy/h, 10 Gy/h and 100 Gy/h and the testing time 1 year at the maximum. The corrosion studies revealed that Hastelloy C4 is susceptible to local corrosion at gamma-dose rates higher than 1 Gy/h. This means that if this material is used for HLW packagings an adequate gamma-shielding will be required

360

Effect of moisture on corrosion of Ni-based alloys in molten alkali fluoride FLiNaK salt environments  

International Nuclear Information System (INIS)

Highlights: ? High-temperature corrosion behaviors of Ni-based alloys in molten FLiNaK salts. ? Effect of different residual moistures of FLiNaK salts on corrosion behaviors. ? Mass loss of tested alloys is primarily determined by the purity of FLiNaK salts. ? Original Mo content of alloys affects mass losses in moisture-containing salts. ? Higher moisture content in salts aggravates intergranular corrosion and pitting. -- Abstract: We investigated the corrosion characteristics on several selected alloys at 600 and 700 °C in FLiNaK molten salts with different moisture contents. Hastelloys-N and Hastelloys-B3 exhibited better corrosion resistances, while Haynes 263 showed the poorest corrosion resistance. The mass loss of the tested alloys is primarily determined by the purity of FLiNaK salts; however, the effect of temperature becomes more important on the mass loss of the tested alloys in the non-purified FLiNaK salts. When the residual moisture is present in the FLiNaK salts, the mass losses of the tested alloys varied linearly with original Cr content plus one-third of Mo content. The results of structural characterization revealed that the tested alloys in the FLiNaK salts with higher moisture content would aggravate intergranular corrosion and pitting

 
 
 
 
361

Dependence of Precipitation Behavior and Creep Strength on Cr Content in High Cr Ferritic Heat Resistant Steels  

Science.gov (United States)

It is known that high temperature tensile strength increases with increasing Cr content in Cr containing heat resistant steels. Recently, however, it was found that long-term creep strength decreased with increasing Cr content in the heat resistant steels containing 8.5-12%Cr. In this study, precipitation behavior of M23C6 carbide and the Z phase after creep tests was investigated using two kinds of high Cr ferritic steels (9Cr and 10.5Cr). As a result, 10.5Cr steel exhibited larger average particle size of M23C6 than 9Cr steel irrespective of creep stress levels, but the amount of M23C6 carbide was almost the same in both steels. On the other hand, the amount of the Z phase became large in 10.5Cr steel compared with 9Cr steel. These experimental results indicate that high level of Cr content accelerates precipitation and coalescence rate of both M23C6 carbide and the Z phase, resulting in degradation of long term creep strength in 10.5 Cr steel compared to 9Cr steel.

Murata, Yoshinori; Yamashita, Koji; Morinaga, Masahiko; Hara, Toru; Miki, Kazuhiro; Azuma, Tsukasa; Ishiguro, Toru; Hashizume, Ryokichi

362

Heat Resistance in Liquids of Enterococcus spp., Listeria spp., Escherichia coli, Yersinia enterocolitica, Salmonella spp. and Campylobacter spp  

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Full Text Available The aim of the work was to collect, evaluate, summarize and compare heat resistance data reported for Campylobacter, Enterococcus, Escherichia, Listeria, Salmonella and Yersinia spp. The work was limited to resistance in liquids with pH values 6–8. Results obtained under similar experimental conditions were sought. Thermal destruction lines for the various bacterial groups studied were constructed using log10 D values and treatment temperatures. There was a good linear relationship between log10 D and temperature with Escherichia coli, listerias and salmonellas. For campylobacters, enterococci and yersinias the relationships were weaker but, nevertheless, present. Using the slopes of the lines and their 95% confidence limits, z values and their 95% confidence limits were calculated. z values were compared with z values obtained from reports. The equations for the lines were also used for calculation of predicted means of D values at various treatment temperatures. 95% confidence limits on predicted means of D values and on predicted individual D values were also calculated. Lines and values are shown in figures and tables. Differences in heat resistance noted between and within the bacterial groups studied are discussed.

Sörqvist S

2003-03-01

363

Microstructural analysis as the indicator for suitability of weld repairing of the heat resistant Cr - Ni steel  

International Nuclear Information System (INIS)

Metallurgical evaluation was performed on a fractured column tube of the reformer furnace in an ammonia plant. The tubes were manufactured from centrifugally cast heat resistant steel HK 40. Optical and scanning electron microscope (SEM) were used for microstructural and fracture analysis. For composition determination of the micro constituents energy dispersive X ray spectroscopy (EDS) was used. To evaluate mechanical properties, hardness and microhardness measurements were performed. Investigations based on the microstructural features with the idea to indicate suitability of weld repair of the column were performed in this study. It was observed that the crack initiation, caused by oxidation/corrosion and thermal stresses induced by temperature gradient, appeared in the inner side of the tube wall and propagation occurred along grain boundaries. The results clearly showed the presence of an irregular microstructure which contributed to crack propagation through the tube wall. An occurrence of precipitated needle-shaped carbides/carbonitrides and brittle s phase was also identified in the microstructure. Results of the microstructural and fracture analysis clearly indicate that reformer furnace columns made of heat resistant steel HK 40 were unsuitable for weld repair. (Author)

364

Lanthanum, yttrium, titanium, zirconium and boron effect on high-tem erature properties of chromium-nicel alloys in different media  

International Nuclear Information System (INIS)

To further improve the properties of chromium-nickel steels with a high chromium content the effect of small additions of yttrium, lanthanum, titanium and zirconium (up to 1%) and boron (up to 0.01%) on oxidation kinetics, composition and structure of oxide films formed on 40Ni-60Cr alloy during oxidation in the air and during interaction with products of natural gas burning and products of mazut burning, containing approximately 3% S, has been studied. It is shown that alloying the 40Ni-60Cr alloy with low additions of boron, lanthanum, yttrium, titanium and zirconium decreases considerably the rate of its oxidation in the air, especially at high temperatures. Alloying with rare earths is the most efficient one. Heat resistance of chromium-nickel alloys in products of natural gas burning is higher than in the air. Corrosion resistance of chromium-nickel alloys with high chromium content in products of high-sulphur mazut burning is higher than that of industrial heat resisting alloys. Alloying the 40Ni-60Cr alloy with small additions of lanthanum or titanium increases its corrosion resistance 5-15%. Low additions of boron, lanthanum, yttrium, titanium and zirconium increase significantly plasticity of the 40Ni-60Cr alloy without considerable decrease of its heat resistance

365

Electrochemical impedance spectroscopy of metal alloys in the space transportation system launch environment  

International Nuclear Information System (INIS)

AC impedance measurements were performed to investigate the corrosion resistance of 18 alloys under conditions similar to the Space Transportation System (STS) launch environment. The alloys were: (1) zirconium 702; (2) Hastelloy C-22, C-276, C-4, and B-2; (3) Inconel 600 and 825; (4) Ferralium 255; (5) Inco Alloy G-3; (6) 20Cb-3; (7) SS 904L, 304LN, 316L, 317L, and 304L; (8) ES 2205; and (9) Monel 400. AC impedance data were gathered for each alloy at various immersion times in 3.55 percent NaCl-0.1N HCl. Polarization resistance values were obtained for the Nyguist plots at each immersion time using the EQUIVALENT CIRCUIT software package available with the 388 electrochemical impedance software. Hastelloy C-22 showed the highest overall values for polarization resistance while Monel 400 and Inconel 600 had the lowest overall values. There was good general correlation between the corrosion performance of the alloys at the beach corrosion testing site, and the expected rate of corrosion as predicted based on the polarization resistance values obtained. The data indicate that electrochemical impedance spectroscopy can be used to predict the corrosion performance of metal alloys

366

Production and testing of the rolled ring with the regulated structure from the foreign nickel alloys  

International Nuclear Information System (INIS)

With the aim of meeting the required combination of mechanical properties for rolled rings of nickel base alloys Waspaloy, Haynes-188 and Hastelloy-X, newly developed regimes of hot working and heat treatments are proposed. Both seamless and welded ring-like rolling billets are used to study the influence of conditions of alloy deformation on grain structure uniformity. It is established that hot working of the billet at a temperature below 1000 deg C allows one to meet rigid requirements to microstructure, to assure stable high mechanical properties and to prevent crack propagation

367

Rough turning of nickel base alloys with plasma heating  

International Nuclear Information System (INIS)

To raise the productivity of machining parts of heat-resistant nickel base alloys the process of rough turning for these materials with plasma heating has been investigated. Air and nitrogen have been used as plasma-forming gases to ensure optimum heating temperature of 830-900 deg C. Due to a better workability of heated metal the productivity raises 4-6 times as much

368

Corrosion behavior of nickel-containing alloys in artificial sweat.  

Science.gov (United States)

The corrosion resistance of various nickel-containing alloys was measured in artificial sweat (perspiration) using the Tafel extrapolation method. It was found that Ni, CuNi 25 (coin alloy), NiAl (colored intermetallic compounds), WC + Ni (hard metal), white gold (jewelry alloy), FN42 and Nilo Alby K (controlled expansion alloys), and NiP (electroless nickel coating) are in an active state and dissolve readily in oxygenated artificial sweat. By contrast, austenitic stainless steels, TiC + Mo2C + Ni (hard metal), NiTi (shape-memory alloy), Hastelloy X (superalloy), Phydur (precipitation hardening alloy), PdNi and SnNi (nickel-containing coatings) are in a passive state but may pit under certain conditions. Cobalt, Cr, Ti, and some of their alloys were also investigated for the purpose of comparison. Cobalt and its alloys have poor corrosion resistance except for Stellite 20. Chromium and high-chromium ferritic stainless steels have a high pitting potential but the latter are susceptible to crevice corrosion. Ti has a pitting potential greater than 3 V. Comparison between the in vitro measurements of the corrosion rate of nickel-based alloys and the clinical observation of the occurrence of contact dermatitis is discussed. PMID:3403567

Randin, J P

1988-07-01

369

Biaxially aligned YSZ and CeO2 buffer layers on hastelloy prepared by magnetron IBAD  

International Nuclear Information System (INIS)

Full text: The development of high-current, flexible superconducting YBCO tapes is based on a metal substrates overcoated with a biaxially aligned oxide buffer layer to serve as a template for the epitaxial growth of c-axis oriented Yba2Cu3O7 thin films. A secondary function of the buffer is to act as a diffusion barrier to metal species to prevent them from poisoning the superconducting film. Widely studied oxide buffer layers include yttria-stabilised zirconia (YSZ) and cerium oxide (CeO2) produced by ion-beam-assisted deposition (IBAD). We have combined IBAD with magnetron sputtering to deposit biaxially aligned YSZ and CeO2 on Hastelloy C276 substrates held at room temperature. The ion beam is directed at 55deg to the normal of the film plane. In addition, we achieved room temperature epitaxial growth of CeO2 films on IBAD YSZ films by bias sputtering to form biaxially aligned CeO2/YSZ bilayers. The crystalline quality and inplane orientation of the films (200 nm thick) were investigated by x-ray diffraction techniques including ? and ? scans and pole figures. The IBAD YSZ and CeO2 films have a (111) pole in the ion beam direction with a full width at half maximum, FWHM = 24 - 30 deg; the CeO2/YSZ bilayer is similarly aligned with FWHM = 32 deg

370

Transport properties of MgB2 films grown on Hastelloy tape: Substrate temperature effect  

Science.gov (United States)

We report on the transport properties of MgB2 films that were directly grown on Hastelloy tapes by using a hybrid physical chemical deposition method. The substrate temperatures was varied from 480 °C to 540 °C in 20 °C increment while the deposition time and the gas mixing ratio were kept constant at 10 min and H2:B2H6 = 70:30, respectively. Within this window of substrate temperature, all the samples except the one grown at 480 °C exhibited critical current densities, J c , much higher than those observed in MgB2 wires and tapes that were made by using the powder method. For instance, the film grown at 500 °C exhibited a value of J c exceeding 3 × 105 A/cm2 at 4 T and 5 K measured in magnetic fields applied perpendicular to the substrate. In the samples grown at temperatures above 500 °C, a resistance dip was observed in the same field orientation, which can be regarded as evidence for strong flux pinning.

Kim, Dong-Ho; Park, Young-Soon; Hwang, Tae-Jong; Ranot, Mahipal; Kang, Won-Nam; Chung, Kook-Chae

2013-01-01

371

Study on high temperature design methodology of heat-resistant materials for GEN-IV systems  

International Nuclear Information System (INIS)

Analysis of the existing high temperature design and assessment codes such as US(ASME-NH,Draft Code Case for Alloy 617), France(RCC-MR), UK(R5), Japan(BDS/DDS/FDS) for Gen IV reactor structure has been carried out. In addition the scope and fields for research and development is needed in the future have been defined. For assessing the high temperature creep cracks, time dependent fracture mechanics (TDFM) parameters of the C and Ct were analyzed. The creep propagation data were obtained from the creep crack growth tests for type 316LN stainless steels, and creep crack growth testing machine for Gen-IV system up to 950 .deg. C was set up. Damage mechanism and causes for creep-fatigue were investigated. The difference between prediction creep-fatigue life and experimental life were investigated. Material properties for analysis creep-fatigue damage were recommended. The assessment procedure (Draft) on creep-fatigue crack initiation has been developed based on the technical appendix A16 of French RCC-MR code. Ultrasonic wave signal against creep ruptured specimens of type 316LN stainless steel was obtained. It was identified that creep damage can be evaluated by ultrasonic method. The NDT techniques evaluated include Barkhausen noise, magnetic hysteresis parameters, positron annihilation, X-ray diffraction and small angle neutron scattering. Experimental procedure and evaluation method of material integrity were developed through the fracture toughness test of Cr-Mo steel

372

Development of a cheep creep resistant Mg-Al-Zn-Si-base alloy  

Energy Technology Data Exchange (ETDEWEB)

Magnesium alloys containing Mg{sub 2}Si particles, as a promising cheap heat-resistant magnesium alloy for automobile engine applications, are attracting more and more attention of both material scientists and design engineers. Refinement of the Chinese script Mg{sub 2}Si particle is a key for using this kind of alloy in sand casting or permanent mould casting. In the present work, a new type of heat-resistant magnesium alloy with low cost based on Mg-Al-Zn-Si is developed. The effect of Sb addition and mischmetal (MM, a mixture of rare-earth, RE elements) microaddition on the microstructure, solidification process, mechanical properties and corrosion resistance of Mg-Al-Zn-Si alloy is investigated systematically. The result shows that Sb promotes the formation of fine polygonal-type Mg{sub 2}Si particles by providing the nucleation sites. Meanwhile, the grain sizes of Sb modified Mg-Al-Zn-Si alloy are much finer than that of the base alloy. Such improved microstructure of the modified alloy results in significant improvement in tensile properties, toughness and creep resistance at elevated temperatures up to 200 C, which exceed or are comparable to AE42 alloy. Moreover, the corrosion resistance of the new alloy is improved greatly by MM microaddition. (orig.)

Guangyin Yuan [Light Alloy Net Forming National Engineering Research Center, Shanghai Jiaotong Univ., Shanghai, SH (China); Inst. for Materials Research, Tohoku Univ., Sendai (Japan); Manping Liu; Wenjiang Ding [Light Alloy Net Forming National Engineering Research Center, Shanghai Jiaotong Univ., Shanghai, SH (China); Inoue, A. [Inst. for Materials Research, Tohoku Univ., Sendai (Japan)

2003-07-01

373

The effect of alloying on the ordering processes in near-alpha titanium alloys  

International Nuclear Information System (INIS)

The substructure of near-alpha Ti–Al–Sn–Zr–Mo–Si alloys containing up to 12.5 at% aluminum was studied by transmission electron microscopy (TEM). It was shown that long-range order sections are formed at aging temperatures up to 500 °C in alloys, high in aluminum, and the ordered phase is formed by the nucleation and growth mechanism at 700 °C aging temperatures. Causes of changing the phase transformation mechanism have been discussed, and the relationship between the structure and properties of alloys, depending on modes of heat treatment has been analyzed. Also the influence of aluminides and silicides precipitation on the mechanical alloy properties after aging was examined. It was shown that the aluminide formation led to a slight hardening and a significant viscosity decrease. The silicide particles formation reduced the heat resistance properties, due to the depletion of the solid solution by silicon

374

Microbiological aspects of heat sterilization of drugs. III. Heat resistance of spore-forming bacteria, isolated from large-volume parenterals.  

Science.gov (United States)

In order to calculate the minimum sterilization process conditions to obtain the generally accepted sterility level (less than 1.10(-6) probability of microbial survival), we determined the bioburden and its heat resistance of 500 ml large-volume parenteral bottles over a period of 5 years. For the bioburden determination 1,832 bottles were examined by the membrane filtration method. Mean bioburden was 9.36 colony-forming units/bottle. Of the colony-forming units isolated 118 were heat resistant (0.69%). These were spore-forming Bacillus species. Of the isolated Bacillus species heat resistance was determined in 5% glucose, 0.9% sodium chloride and 8% amino acids solution. D values greater than 1 min at 105 degrees C were found for 2, 5 and 4 different Bacillus species in glucose 5%, sodium chloride 0.9% and amino acids 8%, respectively. 2 Bacillus species showed a D value over 2 min at 105 degrees C in all three media. D values at 110 degrees C in sodium chloride 0.9% for these 2 Bacillus species were 1.8 and 2.6 min and in amino acids 8% 0.9 and 1.7 min, respectively. The minimum sterilization process time at 110 degrees C, calculated with the experimentally determined bioburden and D values is less than 25 min. When introducing reduced exposure times/temperatures, each individual manufacturer should assess the bioburden. The time-consuming determination of the heat resistance of bioburden isolates is not always necessary. By dividing the isolated colony-forming units in a 'heat-resistant' group and a 'not-heat-resistant' group, changing from standard overkill sterilization procedures to processes with lower F0 values is possible. PMID:1923703

Boom, F A; Van der Heijden Van Beek, M A; Paalman, A C; Stout-Zonneveld, A

1991-06-21

375

Microstructural Evolution and Mechanical Properties of Short-Term Thermally Exposed 9/12Cr Heat-Resistant Steels  

Science.gov (United States)

The microstructural evolution during short-term (up to 3000 hours) thermal exposure of three 9/12Cr heat-resistant steels was studied, as well as the mechanical properties after exposure. The tempered martensitic lath structure, as well as the precipitation of carbide and MX type carbonitrides in the steel matrix, was stable after 3000 hours of exposure at 873 K (600 °C). A microstructure observation showed that during the short-term thermal exposure process, the change of mechanical properties was caused mainly by the formation and growth of Laves-phase precipitates in the steels. On thermal exposure, with an increase of cobalt and tungsten contents, cobalt could promote the segregation of tungsten along the martensite lath to form Laves phase, and a large size and high density of Laves-phase precipitates along the grain boundaries could lead to the brittle intergranular fracture of the steels.

Wang, Wei; Yan, Wei; Sha, Wei; Shan, Yiyin; Yang, Ke

2012-11-01

376

Effects of gamma irradiation on two heat resistant moulds: Aspergillus fumigatus and Paecilomyces variotii isolated from margarine  

Energy Technology Data Exchange (ETDEWEB)

The present study was undertaken to evaluate the effect of gamma irradiation on two heat-resistant moulds, namely Aspergillus fumigatus and Paecilomyces variotii isolated from margarine samples. The irradiation process of these moulds was carried out in a {sup 60}Co gamma ({gamma}) irradiator at average absorbed doses of 1, 3, 5 and 7 kGy for exposure times of 52, 156, 260 and 364 min, respectively. The average D{sub 10} value for A. fumigatus was 1.08{+-}0.08 kGy while it was 0.59{+-}0.10 kGy for P. variotii. Consequently, the sensitivity of P. variotii against {gamma} irradiation was more than A. fumigatus.

Gumus, Tuncay [Agricultural Faculty, Department of Food Engineering, 59030, Namik Kemal University, Tekirdag (Turkey)], E-mail: tuncaygumus@tu.tzf.edu.tr; Gecgel, Umit; Demirci, A. Sukru; Arici, Muhammet [Agricultural Faculty, Department of Food Engineering, 59030, Namik Kemal University, Tekirdag (Turkey)

2008-05-15

377

Multi-Phase High Temperature Alloys: Exploration of Alumina-Forming, Creep-Resistant Austenitic Stainless Steels.  

Science.gov (United States)

Work in 2007 focused on the development of a new class of heat-resistant austenitic stainless steel alloys which achieved a unique combination of high-temperature creep strength and excellent oxidation resistance via protective Al(sub 2)O(sub 3) scale for...

M. P. Brady, P. J. Lu P. J. Maziasz, Y. Yamamoto, Z. P. Lu

2008-01-01

378

Fundamental studies on electron beam welding on heat-resistant superalloys for nuclear plants, (5)  

International Nuclear Information System (INIS)

To investigate the preventive measure of microcracks observed in the electron beam welds of the superalloys, modified Inconel 617, to which Nb was systematically added to a proper degree, was experimentally produced. Thereafter, metallurgical studies were carried out on the electron beam welds of the modified Inconel 617. Obtained conclusions may be summarized as follows: 1) The main precipitates of these superalloys are respectively M6C for standard Inconel 617, M6C and NbC for modified Inconel 617 with Nb of approximately 1%+ and NbC for modified ones with Nb of approximately 2% and 4%. 2) These precipitates in the heat affected zone adjacent to the fusion line are accompanied with the liquation in any case except for the modified Inconel 617 with Nb of approximately 4%. No liquation is observed in Inconel 617 with 4% Nb just because the temperature of eutectic reaction between NbC and ? is higher than the temperature of melting start of matrix T sub(s). 3) Modified Inconel 617 becomes less susceptible to microcracking with the increase in Nb content. The effect of Nb addition is increasingly distinguished in the Nb content of approximately 2% or more. As a result, no microcracks occur at the Nb content of approximately 4%. 4) It is generally considered to be effective as one of the preventive measures of microcracks to add a certain alloying element so that both the melting temperature of precipitate and the temperature of eutecticecipitate and the temperature of eutectic reaction between precipitate and ? become higher than the temperature of melting start of matrix T sub(s). (author)

379

Contemporary tendency of alloyed steel development  

International Nuclear Information System (INIS)

Perspectives of developing alloyed steels based on structure improvement and increase of technologic and service properties are considered. It is shown that for economy of the alloying elements it is necessary: to amplify works on steel microalloying; to develop the processes of obtaining steel pure by impurities in mass quantities (powder metallurgy, remelting processes, out-of-furnace refining); to arrange wide production of heat treated steel; to expand theoretical works and arsenal of industrial technical means providing use of strain hardening as a method for increasing mechanical properties of wide purpose steel; to develop methods of effective use of production wastes of alloyed steels fabrication and ferroalloyed production; to essentially expand application of corrosion-resistant heat-resistant and wear- resistant coatings

380

New structural high strength rationally alloyed steels  

International Nuclear Information System (INIS)

New developments in high strength structural steels are reported. Properties and perspective fields of application are described for the following materials: austenitic chromium steels with ultra equilibrium nitrogen content, steels with nitrogen martensite structure, microalloyed ferritic-pearlitic steels with decreased concentrations of Mn and Ni, high ductility heat resisting steels, nonmagnetic chromium free Mn-Ni-Cu-V-C steels and iron powder alloys with superhard carbon phases. Steel 02Kh12G14N4YuM is recommended to be used for parts and assemblies of nuclear power plants

 
 
 
 
381

Microstructure and texture evolution of CeO2 buffer layers prepared via dip-coating sol-gel method on IBAD-YSZ/Hastelloy substrates  

International Nuclear Information System (INIS)

We have fabricated CeO2 buffer layers on IBAD-YSZ/Hastelloy substrates via dip-coating sol-gel method using inorganic salts as starting materials. X-ray diffraction (XRD), scanning electron microscopy (SEM) and scanning probe microscope (SPM) were applied to investigate the influential factors in film formation and texture evolution. Flat, crack-free CeO2 films with sharp (0 0 2) c-axis orientation and good texture were obtained by carefully controlling the precursor solution quality, dip-coating and heating process. Compared with IBAD-YSZ/Hastelloy substrates, textures of CeO2 films were effectively improved

382

Fatigue strength of high-temperature alloys with coatings  

Energy Technology Data Exchange (ETDEWEB)

A study is made of the effect of various heat-resistant coatings (e.g., aluminide, silicide, and Co- and Ni-based condensation coatings) on the room-temperature and high-temperature fatigue strength of high-temperature alloys (SEL15, IN-738, IN-939, ZhS6F, and EI893, EI 826, and EI929). It is shown, in particular, that the Locati method is unsuitable for determining the fatigue strength of materials with low-ductility coatings. The effect of condensation coatings on the fatigue life of high-temperature alloys at room temperature is characterized. 10 refs.

Getsov, L.B.; Rybnikov, A.I.; Malashenko, I.S.; Iakovchuk, K.IU.; Belolipetskii, IU.P. (Tsentral' nyi Nauchno-Issledovatel' skii Kotloturbinnyi Institut, Leningrad (USSR) Tsentral' nyi Nauchno-Issledovatel' skii Institut Tiazhelogo Mashinostroeniia, Moscow (USSR) Institut Elektrosvarki, Kiev (Ukrainian SSR))

1990-05-01

383

Microstructural analysis as the indicator for suitability of weld repairing of the heat resistant Cr - Ni steel  

Directory of Open Access Journals (Sweden)

Full Text Available Metallurgical evaluation was performed on a fractured column tube of the reformer furnace in an ammonia plant. The tubes were manufactured from centrifugally cast heat resistant steel HK 40. Optical and scanning electron microscope (SEM were used for microstructural and fracture analysis. For composition determination of the microconstituents energy dispersive X ray spectroscopy (EDS was used. To evaluate mechanical properties, hardness and microhardness measurements were performed. Investigations based on the microstructural features with the idea to indicate suitability of weld repair of the column were performed in this study. It was observed that the crack initiation, caused by oxidation/corrosion and thermal stresses induced by temperature gradient, appeared in the inner side of the tube wall and propagation occurred along grain boundaries. The results clearly showed the presence of an irregular microstructure which contributed to crack propagation through the tube wall. An occurrence of precipitated needle-shaped carbides/carbonitrides and brittle ? phase was also identified in the microstructure. Results of the microstructural and fracture analysis clearly indicate that reformer furnace columns made of heat resistant steel HK 40 were unsuitable for weld repair.

La evaluación metalúrgica se realizó en un tubo de columna con fracturas, que es parte del horno reformador en una planta de amoníaco. Estos tubos son fundidos centrífugamente y fabricados en acero resistente al calor, de tipo HK- 40. Para el análisis microestructural de la fractura se ha utilizado microscopía óptica y electrónica de barrido (SEM. La composición de los micro-constituyentes se determinó por espectrometría de rayos X de energía dispersiva (EDS. Las propiedades mecánicas se evaluaron mediante mediciones de microdureza Vickers. Las investigaciones en este estudio se han llevado a cabo con el fin de demostrar la idoneidad de reparación por soldadura de columnas en base a sus características micro-estructurales. Se ha observado que el inicio de la rotura, causada por el efecto de la oxidación/corrosión y el choque térmico ocasionado por el gradiente de temperatura, aparece en la pared interna del tubo y se propaga a lo largo de los bordes de grano. Los resultados demuestran la presencia de una microestructura irregular que contribuyó a la propagación de la rotura a lo largo de la pared del tubo. En la microestructura también se ha registrado la formación da la precipitación de fases de carburo/carbón nitrito que aparecen en forma de agujas y fase ? frágil. Con base en los resultados obtenidos, se puede concluir que la microestructura investigada no es idónea para aplicar la reparación por soldadura.

Odanovi?, Z.

2010-08-01

384

Modification Approach of Fuzzy Logic Model for Predicting of Cutting Force When Machining Nickel Based Hastelloy C-276  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: Most Nickel based Hastelloy C-276 is a difficult-to-machine material because of its low thermal diffusive property and high strength at high temperature. Machinability consideration of nickel based Hastelloy C-276 in turning operations has been carried out using ceramic inserts under dry conditions. Approach: This study described a modification approach applied to a fuzzy logic based model for predicting cutting force where the machining parameters for cutting speed ranges, feed rate, depth of cut and approach angle are not overlapping. For this study, data were selected depending on the design of experiments. Response surface methodology was applied to predict the cutting force and to examine the fuzzy logic based model. Results: The modification approach fuzzy logic based model produced the cutting force data providing good correlation with response surface data. In this situation the cutting force data were superimposed and results were adjusted according to their own ranges. Conclusion: A review of literatures on optimization techniques revealed that there were, in particular, successful industrial applications of design of experiment-based approaches for optimal settings of process variables.

Basim A. Khidhir

2010-01-01

385

Sustainable, heat-resistant and flame-retardant cellulose-based composite separator for high-performance lithium ion battery  

Science.gov (United States)

A sustainable, heat-resistant and flame-retardant cellulose-based composite nonwoven has been successfully fabricated and explored its potential application for promising separator of high-performance lithium ion battery. It was demonstrated that this flame-retardant cellulose-based composite separator possessed good flame retardancy, superior heat tolerance and proper mechanical strength. As compared to the commercialized polypropylene (PP) separator, such composite separator presented improved electrolyte uptake, better interface stability and enhanced ionic conductivity. In addition, the lithium cobalt oxide (LiCoO2)/graphite cell using this composite separator exhibited better rate capability and cycling retention than that for PP separator owing to its facile ion transport and excellent interfacial compatibility. Furthermore, the lithium iron phosphate (LiFePO4)/lithium cell with such composite separator delivered stable cycling performance and thermal dimensional stability even at an elevated temperature of 120°C. All these fascinating characteristics would boost the application of this composite separator for high-performance lithium ion battery. PMID:24488228

Zhang, Jianjun; Yue, Liping; Kong, Qingshan; Liu, Zhihong; Zhou, Xinhong; Zhang, Chuanjian; Xu, Quan; Zhang, Bo; Ding, Guoliang; Qin, Bingsheng; Duan, Yulong; Wang, Qingfu; Yao, Jianhua; Cui, Guanglei; Chen, Liquan

2014-01-01

386

Influence of salicylic and succinic acids on antioxidant enzymes activity, heat resistance and productivity of Panicum miliaceum L.  

Directory of Open Access Journals (Sweden)

Full Text Available The influence of treatment of millet (Panicum miliaceum L. seeds with the solutions of salicylic and succinic acids on the heat resistance of plantlets and activity of antioxidant enzymes – superoxide dismutase (SOD, catalase and peroxidase – in them have been investigated. In the micro-field experiment the influence of these acids on the millet yield was estimated. The action of salicylic (10 ?M and succinic (1 mM acids caused the increase of plantlets resistance to the damaging heating that expressed in the rise of relative quantity of survived plantlets in 5 days after heating at the temperature of 47°? and in the reduced content of lipid peroxidation product malonic dialdehyde during the poststress period. The increase of activity of SOD, catalase and peroxidase took place in millet plantlets under the influence of salicylic and succinic acids. The increase of productivity of millet grain under the action of salicylic and succinic acids on 13,3-52,0 and 6,4-38,8% respectively depending on weather conditions in the field experiments was noted.

Miroshnichenko N.N.

2011-05-01

387

Sustainable, heat-resistant and flame-retardant cellulose-based composite separator for high-performance lithium ion battery  

Science.gov (United States)

A sustainable, heat-resistant and flame-retardant cellulose-based composite nonwoven has been successfully fabricated and explored its potential application for promising separator of high-performance lithium ion battery. It was demonstrated that this flame-retardant cellulose-based composite separator possessed good flame retardancy, superior heat tolerance and proper mechanical strength. As compared to the commercialized polypropylene (PP) separator, such composite separator presented improved electrolyte uptake, better interface stability and enhanced ionic conductivity. In addition, the lithium cobalt oxide (LiCoO2)/graphite cell using this composite separator exhibited better rate capability and cycling retention than that for PP separator owing to its facile ion transport and excellent interfacial compatibility. Furthermore, the lithium iron phosphate (LiFePO4)/lithium cell with such composite separator delivered stable cycling performance and thermal dimensional stability even at an elevated temperature of 120°C. All these fascinating characteristics would boost the application of this composite separator for high-performance lithium ion battery.

Zhang, Jianjun; Yue, Liping; Kong, Qingshan; Liu, Zhihong; Zhou, Xinhong; Zhang, Chuanjian; Xu, Quan; Zhang, Bo; Ding, Guoliang; Qin, Bingsheng; Duan, Yulong; Wang, Qingfu; Yao, Jianhua; Cui, Guanglei; Chen, Liquan

2014-02-01

388

Sustainable, heat-resistant and flame-retardant cellulose-based composite separator for high-performance lithium ion battery.  

Science.gov (United States)

A sustainable, heat-resistant and flame-retardant cellulose-based composite nonwoven has been successfully fabricated and explored its potential application for promising separator of high-performance lithium ion battery. It was demonstrated that this flame-retardant cellulose-based composite separator possessed good flame retardancy, superior heat tolerance and proper mechanical strength. As compared to the commercialized polypropylene (PP) separator, such composite separator presented improved electrolyte uptake, better interface stability and enhanced ionic conductivity. In addition, the lithium cobalt oxide (LiCoO2)/graphite cell using this composite separator exhibited better rate capability and cycling retention than that for PP separator owing to its facile ion transport and excellent interfacial compatibility. Furthermore, the lithium iron phosphate (LiFePO4)/lithium cell with such composite separator delivered stable cycling performance and thermal dimensional stability even at an elevated temperature of 120°C. All these fascinating characteristics would boost the application of this composite separator for high-performance lithium ion battery. PMID:24488228

Zhang, Jianjun; Yue, Liping; Kong, Qingshan; Liu, Zhihong; Zhou, Xinhong; Zhang, Chuanjian; Xu, Quan; Zhang, Bo; Ding, Guoliang; Qin, Bingsheng; Duan, Yulong; Wang, Qingfu; Yao, Jianhua; Cui, Guanglei; Chen, Liquan

2014-01-01

389

Precipitation behavior and martensite lath coarsening during tempering of T/P92 ferritic heat-resistant steel  

Science.gov (United States)

Tempering is an important process for T/P92 ferritic heat-resistant steel from the viewpoint of microstructure control, as it facilitates the formation of final tempered martensite under serving conditions. In this study, we have gained deeper insights on the mechanism underlying the microstructural evolution during tempering treatment, including the precipitation of carbides and the coarsening of martensite laths, as systematically analyzed by optical microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The chemical composition of the precipitates was analyzed using energy dispersive X-ray spectroscopy. Results indicate the formation of M3C (cementite) precipitates under normalized conditions. However, they tend to dissolve within a short time of tempering, owing to their low thermal stability. This phenomenon was substantiated by X-ray diffraction analysis. Besides, we could observe the precipitation of fine carbonitrides (MX) along the dislocations. The mechanism of carbon diffusion controlled growth of M23C6 can be expressed by the Zener's equation. The movement of Y-junctions was determined to be the fundamental mechanism underlying the martensite lath coarsening process. Vickers hardness was estimated to determine their mechanical properties. Based on the comprehensive analysis of both the micro-structural evolution and hardness variation, the process of tempering can be separated into three steps.

Xu, Lin-qing; Zhang, Dan-tian; Liu, Yong-chang; Ning, Bao-qun; Qiao, Zhi-xia; Yan, Ze-sheng; Li, Hui-jun

2014-05-01

390

Effect of creep deformation on the microstructural evolution of 11CrMoVNb heat resistant steel  

International Nuclear Information System (INIS)

Highlights: ? The coarsening rate of the precipitates was accelerated by applied stress. ? The coalescence of martensite laths was accelerated by applied stress. ? The Laves phase and Z-phase were not observed after creep. ? The predicted size of MX precipitates by MatCalc agreed well with measured size. - Abstract: The effect of creep deformation on the microstructural evolution of an 11CrMoVNb ferritic heat resistant steel during high temperature creep tests was investigated. The creep test was performed within a temperatures range from 593 to 621 °C under different stress levels. For the detailed understanding of precipitate coarsening behavior, transmission electron microscopy (TEM) was used to analyze thin foils and replica films obtained from the crept specimens. The major precipitates were found to be M23C6, MX and Cr2N phases and there was no change in precipitation sequence during creep. Coarsening behavior of the precipitates and growth behavior of martensite laths of the crept specimens were carefully examined in both regions of the grip and gage parts of the specimens in order to identify the effect of creep deformation. On the whole, precipitate size increased with increasing creep rupture time. On the other hand, precipitate coarsening and martensite lath widening were pronounced in the gage part compared to those in the grip part. This suggests that the creep deformation accelerates the rates of precipitate coarsening and martensite lath widening.

391

Creep Rupture Strength and Microstructure of Low C-10Cr-2Mo Heat-Resisting Steels with V and Nb  

Science.gov (United States)

The new ferritic heat-resisting steels of 0.05C-10Cr-2Mo-0.10V-0.05Nb (Cb) composition with high creep rupture strength and good ductility have already been reported. The optimum amounts of V and Nb that can be added to the 0.05C-10Cr-2Mo steels and their effects on the creep rupture strength and microstructure of the steels have been studied in this experiment. The optimum amounts of V and Nb are about 0.10 pct V and 0.05 pct Nb at 600 °C for 10,000 h, but shift to 0.18 pct V and 0.05 pct Nb at 650 °C. Nb-bearing steels are preferred to other grades on the short-time side, because NbC precipitation during initial tempering stages delays recovery of martensite. On the long-time side, however, V-bearing steels have higher creep rupture strength. By adding V to the steels, electron microscopic examination reveals a stable microstructure, retardation during creep of the softening of tempered martensite, fine and uniform distribution of precipitates, and promotion of the precipitation of Fe2Mo.

Fujita, T.; Asakura, K.; Sawada, T.; Takamatsu, T.; Otoguro, Y.

1981-06-01

392

Oxidation of hafnium-iron alloys  

International Nuclear Information System (INIS)

Studied has been the oxidation of the hafnium - iron binary alloys (0-38.49% Fe) in the air at 600-1.200 deg C. Through the methods of the microstructural, X-ray microspectral and layer-by-layer X-ray phase analysis the alloys phase composition has been determined, as well as the morphology and structural peculiarities of the scale being formed on these alloys. Plotted have been the kinetic oxidation curves and the curves, reflecting the oxidation of the alloys depending on their composition and on the time factor at various temperatures. It has been established that the oxidizability of the Hf2Fe and HfFe2 intermetallic compounds increases with the growth of the iron content in them. It is shown, that in the particular concentration zone, depending on the temperature, the scale resistance of the hafnium-iron alloys exceeds that of the pure hafnium considerably. The alloys, containing 5-10% Fe, possess the greatest heat resisting capacity

393

Modifying effect of extremal temperature depending on the organism adaptation to this factor on the effect of radiation. 2. Analysis of the potential damages using heat resistance  

International Nuclear Information System (INIS)

It is shown, that the effect of high temperature within the range of 33, 35, 37 and 38 deg C after irradiation (X-rays 3000r) increases the radiation effect, manifesting itself in the loss of X-chromosome of Kanton-C line flies, not adapted to high temperature. It takes place at the expense of reparation process depression and the increase of probability of potential damage realization. The effect on the flies of T-32 line, adapted to high temperature (32 deg C) turned non-effective at the temperature of 33 and 35 deg C. Heat-resistance of reparation ferments in this line is supposed to be higher. The temperature of 37 and 38 deg C has been effective for heat-resistant lines as well as for other lines

394

Effect of impurities on the proneness to temper embrittlement of heat resistant Cr-Mo-V steel  

International Nuclear Information System (INIS)

The authors investigated the effect of most alloying elements which are traditionaly regarded as dangerous in low-alloy structural steels--sulfur, phosphorus, copper, arsenic, antimony, tin--on the proneness to temper embrittlement of steel 25Kh1M1F which is used for making large all-forged rotors of fixed and transport medium-pressure steam turbines. On the basis of the obtained results it may be concluded that from among the investigated alloying elements only phosphorus and antimony have a statistically significant effect on the proneness of fine-grained steel 25Kh1M1F to temper embrittlement, and the embrittling effect of phosphorus is much stronger than the embrittling effect of antimony

395

Development of powder metallurgy Al alloys for high temperature aircraft structural applications, phase 2  

Science.gov (United States)

In this continuing study, the development of mechanically alloyed heat resistant aluminum alloys for aircraft were studied to develop higher strength targets and higher service temperatures. The use of higher alloy additions to MA Al-Fe-Co alloys, employment of prealloyed starting materials, and higher extrusion temperatures were investigated. While the MA Al-Fe-Co alloys exhibited good retention of strength and ductility properties at elevated temperatures and excellent stability of properties after 1000 hour exposure at elevated temperatures, a sensitivity of this system to low extrusion strain rates adversely affected the level of strength achieved. MA alloys in the Al-Li family showed excellent notched toughness and property stability after long time exposures at elevated temperatures. A loss of Li during processing and the higher extrusion temperature 482 K (900 F) resulted in low mechanical strengths. Subsequent hot and cold working of the MA Al-Li had only a mild influence on properties.

Chellman, D. J.

1982-01-01

396

Thermodiffusion Mo-B-Si coating on VN-3 niobium alloy  

International Nuclear Information System (INIS)

Protective properties of complex Mo-B-Si-coating on niobium alloy VN-3 (4.7 mass.% Mo, 1.1 mass.% Zr, 0.1 mass.% C) have been studied. It is established, that the complex Mo-B-Si-coating ensures protection from oxidation of niobium alloys in the temperature range of 800-1200 degC for 1000-1500 hr, at 1600 degC - for 10 hr. High heat resistance of Mo-B-Si - coating at 800-1200 degC is determined by the presence of amorphous film of SiO?2 over the layer MoSi?2 and barrier boride layer on the boundary with the metal protected; decrease in the coating heat resistance at 1600 degC is related to the destruction of boride layer, decomposition of MoSi?2 for lower cilicides and loosening of SiO?2 film

397

Ocorrência de fungos filamentosos termo-resistentes em polpa de tomate envasada assepticamente / Occurrence of heat resistant molds in tomato pulp packed aseptically  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este trabalho teve como objetivo principal determinar a ocorrência de fungos filamentosos termo-resistentes durante o processamento asséptico de polpa de tomate (8° BRIX). Durante o período de safra de tomate foram feitas amostragens em 9 lotes (3 no início, 3 no pico e 3 em fim de safra) e no perío [...] do de entresafra em 5 lotes. Foi feita a enumeração de fungos termo-resistentes nas amostras coletadas durante as diferentes etapas do processo asséptico de cada lote. Foram obtidas contagens médias relativamente baixas, variando entre Abstract in english This work aimed at determining the occurrence of heat resistant molds during the aseptic processing of tomato pulp (8° BRIX). During tomato harvest, 9 lots were sampled (3 at the beginning, 3 at the apex and 3 at the end of harvest) and other 5 lots were sampled between harvest. For each lot, the en [...] umeration of heat resistant molds was carried out in samples collected during the aseptic process. The mean count of heat resistant molds was relatively low, ranging from

Flávio, BAGLIONI; Homero Ferracini, GUMERATO; Pilar Rodriguez, MASSAGUER.

398

Effect of Carbon Content on Microstructure and Mechanical Properties of 9 to 12 pct Cr Ferritic/Martensitic Heat-Resistant Steels  

Science.gov (United States)

Two heats of 9 to 12 pct Cr ferritic/martensitic heat-resistant steels were prepared. One has an ultralow carbon content of 0.01 wt pct, whereas another heat has a normal carbon content of 0.09 wt pct. The effect of carbon content on microstructure and mechanical properties of 9 to 12 pct Cr ferritic/martensitic heat-resistant steels was studied. The results show that the ultralow-carbon steel contains bimodal, nanosized MX precipitates with high density in the matrix but few M23C6 carbide particles in the normalized-and-tempered state. The smaller nanosized MX precipitates have two kinds of typical morphology: One is cubic and another is rectangular. The cubic MX precipitate contains Nb, Ti, and V, whereas the rectangular one only contains Nb and V. The normal carbon steel has abundant M23C6 carbide particles along the grain and lath boundaries and much less density of nanosized MX precipitates after the same heat treatments. After long-term aging at 923 K (650 °C) for 10,000 hours, the stress rupture properties of the ultralow carbon content steel degrades more significantly. The strength degradation mechanism of the 9 to 12 pct Cr ferritic/martensitic heat-resistant steels is discussed in this article.

Yin, Feng-Shi; Tian, Li-Qian; Xue, Bing; Jiang, Xue-Bo; Zhou, Li

2012-07-01

399

Electrode coating effect on composition and properties of nickel-chromium deposited metal alloyed with titanium  

International Nuclear Information System (INIS)

The effect of coating composition with liquid glass as a bond on composition and properties of metal, weld surfaced by electrodes, containing titanium, on Ni heat-resistant alloy, is investigated. Impossibility of producing electrodes with high transformation of titanium with coatings, having liquid glass as a bond, is shown experimentally. It is connected with low resistance and plasticity of surfaced weld metal due to its impurity with silicon and titanium oxides

400

Behavior of ?/?' eutectic in Ni-base alloy under baro-heat treatment  

International Nuclear Information System (INIS)

By metallographic methods, effect of barothermal treatment at 180 MPa and at temperatures near by solidus point on the processes of dissolving and precipitation of ?/?' eutectic in heat-resistant Ni-base alloys have been studied. The correlation between the geometry and concentration of precipitates and parameters of barothermal treatment is established. The barothermal treatment provides a zero porosity material and a decrease of total eutectic amount by a factor of ?5 as compared to initial material

 
 
 
 
401

Effects of B{sub 2}H{sub 6} flow rate and deposition time on superconducting properties of MgB{sub 2}/Hastelloy tapes  

Energy Technology Data Exchange (ETDEWEB)

MgB{sub 2} films were fabricated on polycrystalline Hastelloy tapes. Effects of B{sub 2}H{sub 6} gas flow rate and deposition time on MgB{sub 2} tapes were studied. T{sub c} of the tapes is found unaffected by flow rate but depends on deposition time. High J{sub c} values obtained for MgB{sub 2}/Hastelloy tapes. Hastelloy is a promising metallic substrate for fabrication of MgB{sub 2} conductors. We have investigated the influence of B{sub 2}H{sub 6} gas mixture flow rate and deposition time on superconducting properties of MgB{sub 2} tapes. The MgB{sub 2} tapes are fabricated by growing the MgB{sub 2} films on Hastelloy tapes at a temperature of 520 deg. C by using hybrid physical-chemical vapor deposition (HPCVD) technique. The MgB{sub 2} tapes exhibit transition temperature (T{sub c}) of around 39 K and is found to be unaffected by the gas flow rate but shows a slight dependence on the deposition time. X-ray diffraction analysis revealed that the MgB{sub 2} tapes are polycrystalline in nature. MgB{sub 2} grains of various orientations are observed in the microstructures of the tapes taken by scanning electron microscopy. We obtained much higher J{sub c} values over the wide field range for MgB{sub 2} tapes grown on Hastelloy than the previously reported data on other metallic substrates, such as Cu, SS, and Nb. The critical current density (J{sub c}) of about 10{sup 5} A/cm{sup 2} at 5 K under 3 T is obtained for the MgB{sub 2} tape of thickness 2 {mu}m. These results suggest that the thick MgB{sub 2}/Hastelloy tapes with high J{sub c} values deposited under controlled growth conditions of HPCVD could be useful in high-field applications.

Ranot, M.; Cho, K.; Seong, W.K. [BK21 Physics Division and Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Oh, S. [Material Research Team, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Chung, K.C. [Functional Nano Powder Materials Group, Korea Institute of Machinery and Materials, Changwon 641-010 (Korea, Republic of); Kang, W.N., E-mail: wnkang@skku.edu [BK21 Physics Division and Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

2011-10-15

402

Effects of thermal aging on the mechanical properties of Ni--Cr--Mo--Fe alloy  

International Nuclear Information System (INIS)

The thermal aging of Ni-Cr-Mo-Fe Alloy (Hastelloy Alloy X) at 10000, 12000, 14000, and 16000F (5380, 6490, 7600, and 8710C) for times up to 15,000 h is discussed together with the associated changes in room-temperature impact toughness properties. Effects of 10,000-h aging on room-temperature and elevated-temperature tensile properties, and stress-rupture properties were also evaluated. The alloy exhibits a substantial drop in room-temperature tensile ductility, while elevated-temperature tensile ductility was relatively unaffected by the aging. Stress-rupture properties, while affected by the 16000F (8710C) aging, were relatively unaffected by the lower aging temperatures. The correlation between mechanical properties and microstructure is discussed

403

Corrosion behavior of C-276 alloy in supercritical water at 650 degree C/25 MPa  

International Nuclear Information System (INIS)

The corrosion behavior of nickel-base alloy Hastelloy C-276 was investigated in supercritical water (SCW) at 650 degree C/25 MPa. SEM, EDS, GIXRD and XPS were used to analyze the corrosion morphology, structure and element distribution of oxide film. The results show that the corrosion process of C-276 alloy at 650 degree C/25 MPa in SCW is mainly dissolution of Ni. Since it can not form a uniform and complete oxide film, the alloy in SCW is not well placed to corrosion resistance. The dual-layer oxide film structure which is formed on C-276 is rich in Cr but poor in Ni, Mo. The outer layer consisting of loose and large grains Ni(OH)2 and NiO agrees with dissolution and precipitation mechanism, while the growth of the Cr2O3 inner layer is the result of water through the porous oxides. (authors)

404

Comparative corrosion resistance of some high-nickel, chromium-molybdenum alloys  

International Nuclear Information System (INIS)

The comparative corrosion resistance of alloy C-276 (UNS N10276), alloy 625 (UNS N06625), Hastelloy C-22 (UNS N06022), and ALLCORR (UNS N06110) was studied in sodium chloride-ferric chloride solutions, and nitric, hydrochloric, formic, and sulfuric acids, some with additives such as HF. Butt-welded coupons were used to determine the corrosion characteristics of weldments. In addition to weight loss measurements, crevice and pitting attack were evaluated. For a complex chemical facility to vitrify high-level radioactive wastes, a corrosion study was conducted to select materials of construction for handling the various process streams, several of which were unusually corrosive. Two high-nickel, chromium-molybdenum alloys, C-276 (UNS N10276) and 625 (UNS N06625), were acceptable for much of the processing

405

Role of internal stresses in evolution of gamma-phase particle morphology in nickel alloys under high temperature creep  

International Nuclear Information System (INIS)

Relationships of dislocation structure evolution to morphological changes of gamma'-phase at the secondary and transient stages of creep at 1000 deg C have been investigated theoretically and experimentally for heat resisting nickel base alloys. The dislocation structure which is formed at interphase boundaries under deformation of two-phase alloys is under consideration along with dislocation-induced stress fields. These latter are shown to be reponsible for formation of lamellar structure of the initial creep stage and to promote perfecting of lamellar shape at the secondary stage in the alloys with negative lattice discrepancy

406

Effect of Mg-Zn-Nd spherical quasi-crystals on microstructure and mechanical properties of ZK60 alloy  

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To improve the strength, toughness, heat-resistance and deformability of magnesium alloy, the microstructure and mechanical properties of ZK60 alloy strengthened by Mg-Zn-Nd spherical quasi-crystal phase (I-phase) particles were investigated. Mg40Zn55Nd5 (I-phase) particles in addition to ?-Mg, MgZn phase and MgZn2 phases can be obtained in ZK60-based composites under normal casting condition by the addition of quasi-crystal containing Mg-Zn-Nd master alloy. The experimental results show tha...

Zhang Jinshan; Wang Xing; Zhang Zhaoguang

2011-01-01

407

Fracture toughness of a X alloy under static load  

International Nuclear Information System (INIS)

In the High Temperature Reactor research programm of the French CEA, Hastelloy alloy plates contain mineral fibers used as insulating material and as such prevent the concrete core vessel from receiving excess heat. Due to the high pressure exerted on this insulating materials, the Hastelloy plates are heavily stressed and, therefore, it is important to know their fracture strength. In the case of an elastic, brittle material, the fracture toughness is commonly defined through the Ksub(1c) parameter. But, for plastic materials, measuring Ksub(1c) requires very large samples and it was found more convenient to measure the fracture parameter Jsub(1c) instead of Ksub(1c). Two independent ways were followed to measure Jsub(1c): in the first one the shape of the crack after loading was made apparent by some fatigue cycles; after complete fracture of the sample, the amount of crack extension appears clearly and it becomes possible to generate a J resistance curve. As an alternative, we partially unloaded the specimen to get its compliance: the change in compliance was then supposed to coincide with the start of the crack extension. Finally a finite element code was used to compute the specimen state at the beginning of the crack extension. So we are able to obtain the shape of the Load-Displacement curve and to compare it with the experimental one

408

Study of laser heat resistant carbide coatings tribological characteristics in conditions of one-direction continuous sliding  

International Nuclear Information System (INIS)

The comparative investigation of tribological characteristics of laser high-temperature carbide coatings and cast high-temperature materials in conditions of continuous one-directed sliding at 1000 deg C temperature in the range of 5 ... 18 MPa thrust was carried out. At the loads less than 5 MPa wear of chromium carbide-based coatings was shown to be several times lower than of cast alloys. With loads increasing up to 12 ... 18 MPa the carbide coatings remained serviceability while the samples of most advanced cast high-temperature alloy ZhS-26 sticked together. The conclusion that laser coatings could provide the serviceability of machine parts in harder conditions was made

409

Tellurium corrosion of nickel-based alloys in fuel salts  

International Nuclear Information System (INIS)

For high-temperature molten salt reactors corrosion of the metallic container alloy in primary circuit is the concern. This paper summarizes results of an experimental investigation conducted recently to understand the mechanism and to develop a means of controlling tellurium embrittlement in the nickel-based alloys. The addition of a chromium telluride to salt can be used to provide small partial pressures of tellurium simulating a reactor environment where tellurium appears as a fission product. Tellurium corrosion of Ni-based alloys in stressed and unloaded conditions studies was tested in molten LiF-NaF-BeF2 and LiF-BeF2-ThF4-UF4 (mole%) salt mixtures at temperatures up to 700degC with measurement of the redox potential. Following Hastelloy N-type modified alloys: HN80M-VI with 1.5% Nb, HN80MTY with 1% Al and MONICR with about 2% Fe were used for the study in the LiF-NaF-BeF2 corrosion facilities. Materials investigated in LiF-BeF2-ThF4-UF4 fuel salt include, in addition to mentioned above, high temperature HN80MTB (77Ni-10Mo-6W-7Cr) and EM-721 (65Ni-28W-7Cr) alloys. (author)

410

Carbon corrosion of alloys at high temperature  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Alloys used at high temperature must resist both creep and corrosion. Design for corrosion resistance is based on the formation of a slow-growing, protective oxide scale by selective oxidation of an appropriate alloy component, usually chromium or aluminium. A successful scale will exclude other cor [...] rodents, notably carbon, which can otherwise cause extremely rapid corrosion at high temperatures. Selective oxidation of an alloy component necessarily lowers the concentration of that metal in the alloy subsurface region. Under thermal cycling conditions, mechanical damage to the scale leads to renewed oxide growth and accelerated alloy depletion. Eventually, a point is reached where diffusion of a corrodent into the alloy becomes competitive with the outward diffusion of alloy metal to repair the protective scale. Two examples of alloy failure by carbon attack are considered. In the steam cracking (pyrolysis) process, centrifugally cast tubes of heat-resisting alloy are exposed to a gas stream of hydrocarbon and steam, at a carbon activity of unity. Formation and repair of the surface chromia scale causes alloy depletion, Kirkendall void formation, and subsequent internal precipitation of chromium-rich carbides. Their formation makes chromia scale formation much more difficult, and generates internal stress. Eventually, the tubes fail by creep rupture. In other processes (e.g. steam reforming, heat treatment), synthesis gases are supersaturated with carbon at intermediate temperatures. Once the alloy's protective scale is breached, carbon attacks the depleted substrate. In the case of ferritic alloys, it forms a surface scale of Fe3C. As this scale thickens, the supersaturated carbon precipitates as graphite within its outer regions. The resulting volume expansion causes disintegration of the cementite in a process known as metal dusting. In the case of austenitic alloys, no metal carbide is formed. Instead, carbon dissolves in the depleted metal to diffuse inward and precipitate as graphite within the metal matrix. Again, volume expansion causes disintegration of the alloy, and metal dusting results. Dusting occurs at an extraordinarily rapid rate, and leads to failure by section loss or even penetration.

D.J., Young; J., Zhang.

411

Carbon corrosion of alloys at high temperature  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Alloys used at high temperature must resist both creep and corrosion. Design for corrosion resistance is based on the formation of a slow-growing, protective oxide scale by selective oxidation of an appropriate alloy component, usually chromium or aluminium. A successful scale will exclude other cor [...] rodents, notably carbon, which can otherwise cause extremely rapid corrosion at high temperatures. Selective oxidation of an alloy component necessarily lowers the concentration of that metal in the alloy subsurface region. Under thermal cycling conditions, mechanical damage to the scale leads to renewed oxide growth and accelerated alloy depletion. Eventually, a point is reached where diffusion of a corrodent into the alloy becomes competitive with the outward diffusion of alloy metal to repair the protective scale. Two examples of alloy failure by carbon attack are considered. In the steam cracking (pyrolysis) process, centrifugally cast tubes of heat-resisting alloy are exposed to a gas stream of hydrocarbon and steam, at a carbon activity of unity. Formation and repair of the surface chromia scale causes alloy depletion, Kirkendall void formation, and subsequent internal precipitation of chromium-rich carbides. Their formation makes chromia scale formation much more difficult, and generates internal stress. Eventually, the tubes fail by creep rupture. In other processes (e.g. steam reforming, heat treatment), synthesis gases are supersaturated with carbon at intermediate temperatures. Once the alloy's protective scale is breached, carbon attacks the depleted substrate. In the case of ferritic alloys, it forms a surface scale of Fe3C. As this scale thickens, the supersaturated carbon precipitates as graphite within its outer regions. The resulting volume expansion causes disintegration of the cementite in a process known as metal dusting. In the case of austenitic alloys, no metal carbide is formed. Instead, carbon dissolves in the depleted metal to diffuse inward and precipitate as graphite within the metal matrix. Again, volume expansion causes disintegration of the alloy, and metal dusting results. Dusting occurs at an extraordinarily rapid rate, and leads to failure by section loss or even penetration.

D.J., Young; J., Zhang.

2013-02-01

412

Chromium and vanadium effect on the tendency to delayed fracture in the low-alloy heat resisting steel after welding heating  

International Nuclear Information System (INIS)

Effect of the change of chromium and vanadium content is considered in limits, admissible by technical conditions, on structure and properties of the 15Kh2NMFA steel. Investigation of the tendency to formation of cold near-weld cracks is carried out at samples with initation heat-affected zone. Recommendations on thermal regime of the 15Kh2NMFA steel welding in dependence on vanadium and chromium content are made on the basis of investigation, carried out

413