WorldWideScience
1

Creep properties with short period excessive loadings on a nickel-base heat-resistant alloy Hastelloy XR  

International Nuclear Information System (INIS)

A series of constant load and temperature creep tests and constant temperature creep tests with short period excessive loadings was carried out on a nickel-base heat-resistant alloy Hastelloy XR, which was developed for applications in the High-Temperature Engineering Test Reactor (HTTR), at temperatures ranging from 900 to 1000degC in order to examine the creep behaviors of the alloy under such conditions. The excessive loading levels were the design stress intensity values Sm for Hastelloy XR indicated in the HTTR high-temperature structural design code. Five to six time excessive loadings did not cause significant changes of the minimum creep rate or the time to onset of tertiary creep. About ten time excessive loadings did not cause significant changes of the time to rupture or the rupture elongation. The above-mentioned results suggest that the design stress intensity values Sm for Hastelloy XR have been determined reasonably. (author)

2

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)

3

Carburization of Hastelloy alloy X  

International Nuclear Information System (INIS)

The carburization of Hastelloy X has been studied by the standard tracer techniques using 14C over the temperature range 700 to 11000C in vacuo and helium environment. The 14C activity in the specimen decreases exponentially with the depth of penetration and increases with carburization time. It is observed that carbon diffusion in the alloy is dominated by grain-boundary diffusion. The effect of oxygen in helium gas on carburization is observed. Oxygen has two opposite types of action on carburization of the alloy. One is inhibitive action and the other is accelerative action. (Auth.)

4

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.)

5

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)

6

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)

7

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)

8

Alloying principles for magnesium base heat resisting alloys  

International Nuclear Information System (INIS)

Some binary systems of magnesium-base alloys in which solid solutions are formed, are considered for prospecting heat resistant alloys. It is shown that elements having essential solubility in solid magnesium strongly decreasing with temperature should be used for alloying maqnesium base alloys with high strength properties at increased temperatures. The strengthening phases in these alloys should comprise essential quantity of magnesium and be rather refractory

9

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

Science.gov (United States)

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.

Narita, Toshio

2009-09-01

10

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.)

11

Electron beam welding of dissimilar heat-resistant alloys  

International Nuclear Information System (INIS)

When electron beam welding, which is considered to be suitable to the welding of different materials, was applied to the various combination of the heat resistant alloys for high temperature gas-cooled reactors, the influence that welding conditions exert on the occurrence of welding defects was examined. As the results, porosity occurred in the range of prescribed a(b) value according to the combination of materials, and as heat input was smaller, it was harder to occur. On the other hand, solidifying cracking was frequently observed in the combination with Incoloy 800H, and it did not occur in the range of the prescribed a(b) value. Besides, for the various combination of different materials, the above range of defect occurrence was shown in the figure showing the correlation of the depth of penetration and a(b) value, and the range of adequate welding conditions was determined respectively. As the results, it was clarified that the range of adequate welding conditions covering plate thickness less than 15mm existed except a part of combination. The materials tested were Hastelloy X, Inconel 625, Inconel 617, Incoloy 800H, SUS 316, SUS 304 and 2.25 Cr-1Mo steel, and the test was made by I-type butt welding and X-ray radiography. (Kako, I.)

12

Structure and properties of heat resisting nickel alloys with hafnium  

International Nuclear Information System (INIS)

The effect of modification of heat resistant alloys ZhS6U-VI and ZhS3DK-VI with hafnium (0-1.5 %) on their structure and properties is under study. It is shown that hafnium additions promote decreasing dimensions and quantities of a brittle constituent in fractures as well as interaxial distances of the second order dendrites. Hafnium also changes the morphology of carbides. With hafnium content increase mechanical properties of both alloys and heat resistance of alloy ZhS3DK-VI are improved

13

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 tensi) 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.)

14

Structure and properties of heat resisting titanium alloys  

International Nuclear Information System (INIS)

The principles of preparing heat resistant titanium alloys are considered as well as the structure and properties of existing industrial VT3-1, VT8, VT9, VT18, VT28, VT33, VT35 alloys used at operation temperatures of 300-600 deg C. It is pointed out that ?+? alloys are beneficial for moderate temperatures, while alloys on the base of the ?-phase (pseudo-?-alloys) should be used at high temperatures. The best combination of properties is observed in alloys which have the microstructure of a basket lattice. Durable stay in the ?-range leads to the reduction of strength and ductile properties of the material

15

Determination of allowable stress for a Hastelloy alloy X  

International Nuclear Information System (INIS)

This report presents the initial test results concerning the tensile and creep properties of an Hastelloy alloy X (NC 22 Fe D) solution annealed, and solution annealed then aged. The restrictive test for calculating the structure-size is the stress to cause 1% total elongation for the solution-annealed alloy. The thermal-aging treatments affect the properties of Hastelloy X. The results can be explained by the precipitation of intermetallic molybdenum and tungsten rich phases

16

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)

17

Carbonization and carburization of heat resistant alloys in high pressure helium environment  

International Nuclear Information System (INIS)

Interaction of heat resistant structural alloys with impurities in the coolant of High Temperature Gas Cooled Reactor (HTGR) has been experimentally studied in an autoclave with a high pressure He environment. In order to simulate the environment to that of HTGR, oxidation and carburization potentials in the He gas supplied to the autoclave were adjusted to the actual reactor level. This paper describes the carbonization and carburization of heat resistant structural alloys which are selected from various interesting phenomena observed in this experiment. In the higher temperature range of 800 -- 1,0000C, carbides such as Cr23C6, Cr7C3 and Mo2C were detected on the alloy surfaces by X-ray diffraction technique, and were identified as constituents of white surface layers and particles observed by microscopy. On the other hand, in the lower temperature range of 600 -- 8000C, most alloys such as SUS 304 and Hastelloy X were carburized. This carburization is heavier at 6000C than at 8000C. Interference among oxidation, carbonization and carburization is also discussed. (auth.)

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  

OpenAIRE

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

Compatibility between several heat resistant alloys and sintered Li2O in static helium gas environment  

International Nuclear Information System (INIS)

The reaction of sintered Li2O discs with several commercial heat resistant alloys has been investigated under the conditions of 3.3 x 104 Pa(1/3 atm) static He gas atmosphere in the temperature range of 500 and 7500C. Reaction products were identified by X-ray diffraction analysis to be two phases of Li5FeO4 and LiCrO2. The former was dominant below 6500C and the latter was dominant above 6500C. The activation energies of the reaction were determined by the Arrhenius plots for weight changes and sub-scale thickness measurements. The reactivity of the four Fe-Ni-Cr alloys decreased according to the order of Incoloy 800, 316 SS, Hastelloy X-R and Inconel 600. Grain boundary penetration was observed above 5000C for Incoloy 800, 5000C for 316 SS and 6000C for Inconel 600. There was no grain boundary penetration in Hastelloy X-R. (orig.)

23

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.)

24

Compatibility of heat resistant alloys with boron carbide, 5  

International Nuclear Information System (INIS)

This paper includes an experimental result of out-of-pile compatibility and capsule design for irradiation test in Japan Materials Testing Reactor (JMTR). The compatibility between sheath material and neutron absorber materials for control rod devices (CRD) was examined for potential use in a very high temperature reactor (VHTR) which is under development at JAERI. The purpose of the compatibility tests are preliminary evaluation of safety prior to irradiation tests. Preliminary compatibility evaluation was concerned with three items as follows : 1) Lithium effects on the penetrating reaction of Incoloy 800H alloy in contact with a mixture of boronated graphite and lithium hydroxide powders, 2) Short term tensile properties of Incoloy 800H and Hastelloy XR alloy reacted with boronated graphite and fracture mode analysis, 3) Reaction behavior of both alloys under transient power conditions of a VHTR. It was clear that the reaction rate constant of the Incoloy 800H alloy was accelerated by doping lithium hydroxide into the boron carbide and graphite powder. The mechanical properties of Incoloy 800H and Hastelloy XR alloy reacted with boronated graphite were decreased. Ultimate tensile strength and tensile ductilities at temperatures over 850 deg C were reduced, but there was no change in the proof (yield) stress. Both alloys exhibited a brittle intergranular fracture mode during transient power conditions of a VHTR and also exhibited severe penetration. Irradiation capsules for compatibility test were designed to simulate three irradiation conditions of VHTR: 1) steady state for VHTR, 2) Transient power condition, 3) Service limited life of CRD. Capsule irradiation experiments have been carried out satisfactorily and thus confirm the validity of the capsule design procedure. (author)

25

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.)

26

Structure of granulated heat resisting alloy on nickel base  

International Nuclear Information System (INIS)

Using the methods of electron and light microscopy, electrochemical and roentgenostructural analyses the process of stracture formation ensuring the optimum complex of mechanical properties of granulated heat resisting alloy products is studied. As a material for investigation alloy intermediate products made by hot forming of granules under isostatic conditions at different process parameters are taken. The granules were obtained by sputtering of vacuum induction melted electrodes. Hot isostatic pressing was carried out after heating up to the one-phase ? region temperature. It is shown that to obtain a high level of the mechanical properties during heat treatment of the products made by hot isostatic pressing of nickel heat resisting alloy granules it is necessary to carry out homogenization at temperatures of the one-phase region ensuring the solid solution grain size up to 60-90 ?m. The optimum complex of mechanical properties of the studied alloy is attained after quenching from the two-phase (?+?') region and ageing, in case of two sizes of the ?' phase particles: large ones of the 1.4 ?m size, noncoherent with the matrix, and average ones of the 0.15-0.2 ?m size

27

Study of high-temperature plasticity of heat resistant alloys  

International Nuclear Information System (INIS)

At the 'Serp i molot' works the technological plasticity has been studied of the nickel based heat resisting alloys EHI 828 (non plastic), EHP99 (of low plasticity), EHP202 (more plastic) and EHI437B (of satisfactory plasticity) by rolling rectangular samples into wedged sections with a simultaneous determination of the fracture toughness. This testing permits to determine the maximum possible compression and plasticity (the initation of the first cracks along the edges). The dependence of the hardness HRA characterizing the strain hardening during rolling on the compression epsilon has been studied. The temperature range for the hot deformation is recommended: the beginning of rolling at 1150 deg C, the end of rolling in the rough mill with compression down to 20% per pass at 1100 to 900 deg C depending on the alloy plasticity and rolling in the final mill at 1050 to 800 deg C

28

Principles of alloying of two-phase heat resistant titanium base alloys  

International Nuclear Information System (INIS)

The problems of alloying and heat treatment of heat resistant titanium alloys are considered for alloys VT8, VT9, VT25u taken as an example. It is concluded that high operating properties can be attained if solid solution hardening of the matrix with silicon is provided without silicides formation and precipitation of titanium aluminide particles. It is shown that preliminary precipitation of silicide particles in a grain body prevents formation of Ti3Al. Some recommendations are given on heat treatment conditions and alloy compositions aimed to enhance the level of heat resistance

29

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

30

Influence of heating rate on corrosion behavior of Ni-base heat resistant alloys in simulated VHTR helium environment  

International Nuclear Information System (INIS)

The influence of heating rate on corrosion and carbon transfer was studied for Ni-base heat resistant alloys exposed to simulated VHTR(very high temperature reactor) coolant environment. Special attention was focused to relationship between oxidation and carburization at early stage of exposure. Tests were conducted on two heats of Hastelloy XR with different boron(B) content and the developmental alloys, 113MA and KSN. Two kinds of heating rates, i.e. 80 0C/min and 2 0C/min, were employed. Corrosion tests were carried out at 900 0C up to 500 h in JAERI Type B helium, one of the simulated VHTR primary coolant specifications. Under higher heating rate, oxidation resistance of both heats of Hastelloy XR(2.8 ppmB and 40 ppmB) were equivalent and among the best, then KSN and 113MA followed in the order. Under lower heating rate only alloy, i.e. Hastelloy XR with 2.8 ppmB, showed some deteriorated oxidation resistance while all others being unaffected by the heating rate. On the other hand the carbon transfer behavior showed strong dependence on the heating rate. In case of higher heating rate, significant carburization occured at early stage of exposure and thereafter the progress of carburization was slow in all the alloys. On the other hand only slow carburization was the case throughout the exposure in case of lower heating rate. The carburization in VHTR helium environment was interpreted as to be affected by oxide film formation in the early stage of exposure. The carbon pick-up was largest in Hastelloy XR with 40 ppmB and it was followed by Hastelloy XR with 2.8 ppmB. 113MA and KSN were carburized only slightly. The observed difference of carbon pick-up among the alloys tested was interpreted to be attributed mainly to the difference of the carbon activity, the carbide precipitation characteristics among the alloys tested. (author)

31

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)

32

Peculiarities in structure formation and properties of high-alloy heat resisting niobium base alloys  

International Nuclear Information System (INIS)

Investigation results of the effect of deformation and heat treatment conditions on the structure and properties of niobium alloys with molybdenum content of 15-20% and additionally alloyed with titanium and zirconium in contents of 3 and 1.5% respectively, are presented. Regularities of microalloying effect as efficient way to increase alloy plasticity are considered. It is established that plastic deformation in combination with heat treatment promotes the obtaining of homogenous fine-grain structure and considerable increase of plasticity and technological properties of alloys. To achieve high heat resistance it is advisable to have as large-size grain as possible and the processes of its obtaining must exclude high-temperature polygonization. Microalloying of highly heat-resisting niobium alloys is an efficient means to decrease the tendency to brittle fracture

33

REM effect on mechanical properties and structure of heat resistant alpha-titanium alloy  

International Nuclear Information System (INIS)

Micro alloying with rare-earth metals (La, Dy, Y, Ce) of heat resisting titanium alloy VT18U has been studied for its effect on beta-phase amount, mechanical properties at 20 grad C, long-term rupture strength and creep at 600 grad C. The best results have been obtained for 0.005% La or 0.1%Ce additions. In the latter case along with high heat resistance satisfactory values of plasticity and impact strength are preserved

34

Studies on the quality optimization of hastelloy alloy XR  

International Nuclear Information System (INIS)

Interim results are reported on the multi-lateral joint research program on improving quality and its assurance basis of Hastelloy alloy XR with special emphasis placed on the effect of small amount of boron in the alloy. In the first phase work the exploratory examination on the optimum boron content was made. The results of the tests on several key items yield the optimum range of boron content as 40 to 70 ppm. The second phase work was organized to perform qualification tests on an industrial scale heat, which was specified its boron content (40 ppm) based on the previous phase work. The tests included weldability, tensile and creep-rupture properties, post aging toughness and corrosion and carburization resistance on different type of products. Tests are in progress, in which considerable difference in the degree of improvement was noted between plate and tube. (author)

35

Caused and features of high-temperature of cast heat resisting nickel base alloys  

International Nuclear Information System (INIS)

Experimental data on determining the mechanical properties of ZhS6U alloy in low- and high-temperature regions are presented. Features of structural transformations and physical processes occuring in the alloy under the thermodeformational action are considered. Reasons of burning crack production in cast heat resisting nickel base alloys and ways of their prevention are determined

36

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

37

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)

38

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)

39

Structure and properties of heat resisting coatings of Ni-Cr-Al-Y alloy  

International Nuclear Information System (INIS)

Effect of long-range high-temperature annealings on the structure evolution and properties of heat resisting coatings of the nickel-chromium-aluminium-yttrium alloy used for protection from oxidation and corrosion of heat resisting alloys based on nickel was investigated. It is shown that the ultra-fine-dispersion coating structure provides in an initial state the microduplex structure formation with high ductility and stability at elevated temperatures. The coating exerts no influence on relative elongation and yield strength of the basic ZhS6U alloy at 2 mm sample thickness and more

40

Heat resistant nickel alloys modified with hafnium and zirconium  

International Nuclear Information System (INIS)

Alloys ZhS6U-VI and ZhS3DK-VI modified separately and in combination with zirconium (0.05 %) and hafnium (0.5 %) are under study. It is established that combined alloying increases strength and plastic properties of the alloys. It is shown that alloy ZrS6U-VI tested for a long-term rupture strength demonstrates a rise in microhardness and ?-phase precipitation in the form of lamellar and needle-like particles. Hafnium alloying promotes an increase of lamellar ?phase content whereas zirconium alloying results in needle-like ?-phase formation

41

Investigation into degree of perfection of crystals of nickel heat-resisting alloy  

International Nuclear Information System (INIS)

Using the ZhS6U alloy as an example, the orientation agreement between the matrix of ?-solid solution and the eutectic depositions of ?+?' nickel heat-resistant alloys has been considered. The substructure in different areas of a single crystal of the ZhS6U alloy has been examined by resorting to the metallographic and X-ray analysis methods. The microstructure, diffraction, X -ray topographic pictures of a single crystal of the nickel heat-resistant alloy, are presented. It is shown that a good orientation agreement exists between the matrix of ?-solid solution and ?' phase of the eutectic. The alloy presents X-ray pictures that are characteristic of a fairly perfect single crystal

42

Heat-resisting alloys for hard surfacing and sealing pad welding  

OpenAIRE

The paper deals with heat-resisting alloys used to harden surfaces of elements operating in increased temperatures. It also deals with alloysused to seal cooperating surfaces of elements operating in the conditions of increased temperatures and aggressive utilities. Application methods and properties of thus obtained layers have been presented and adhesion of layers with matrix material has been assessed.

Wielgosz, R. O.

2010-01-01

43

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

44

Physical equations of connection and thermal properties of heat resistant titanium alloys  

International Nuclear Information System (INIS)

Physical equations of connection in the form of analytical dependences to define deformation resistance, as well as equations for defining heat conductivity and specific heat of heat-resisting titanium alloys VT3-1, VT5-1, VT8, VT9, VT18-U and VT20 are presented. 9 refs., 2 figs

45

Heat-resisting alloys for hard surfacing and sealing pad welding  

Directory of Open Access Journals (Sweden)

Full Text Available The paper deals with heat-resisting alloys used to harden surfaces of elements operating in increased temperatures. It also deals with alloysused to seal cooperating surfaces of elements operating in the conditions of increased temperatures and aggressive utilities. Application methods and properties of thus obtained layers have been presented and adhesion of layers with matrix material has been assessed.

R.O. Wielgosz

2010-07-01

46

Phase transformation temperature determining in nickel base heat resistant alloys  

International Nuclear Information System (INIS)

Using the method of thermal differential analysis the temperatures of phase transitions in complex alloyed nickel base materials (KhN43MBTu, KhN56MBYuD, KhN60VMTYu, KhN62VMTYu, KhN65VMBYu, KhN77TYuR) are determined. The alloys were investigated after vacuum arc remelting and subsequent hot plastic deformation. In addition, alloy KhN56MBYuD was studied after various conversions such as electroslag remelting, centrifugal casting, powder spraying and hot isostatic pressing. Studies of thermal curves of alloys allowed to define the temperature of gamma'-phase precipitation and dissolution as well as melting and crystallization points

47

Properties of cobalt heat resisting weld deposited metal of different alloying systems  

International Nuclear Information System (INIS)

Data on mechanical properties and resistance to formation of hot metal cracks in cobalt base alloys with different con-tent of tunasten, nickel, iron, titanium, aluminium, boron, rare earths, weld deposited during are welding, are presented. It is shown, that to increase heat resistance and resistance to formation of hot cracks of cobalt-chromium-nickel weld deposited metal, it is advisable to alloy it with tungsten (up to 8...10%) and yttrium or cerium (up to 0.05%). Iron introduction into the structure of added alloy improves plasticity, reduces heat resistance and resistance of weld deposited metal to hot crack formation. Aluminium, titanium and boron worsen plasticity and reduce resistance to hot crack formation

48

Geometrical product specifications heat-resistant cobalt cast alloy  

OpenAIRE

Geometrical product specification MAR-M509 cast cobalt alloy depend beginning temperature of multilayer ceramic shell moulds (MCS). It has found that go down temperature of MCS from 1000°C to 200°C, the increase surface roughness and its amplitude parameters: Sa, Sz, St, Sq, Sp and Sv.

Lyubimov V.; Opiekun Z.; Bonk C.

2007-01-01

49

Crack resistance in heat resisting steels and alloys under creep  

International Nuclear Information System (INIS)

Model of the local fracture under creep, allowing to analyze and explain the ambiquous critical crack opening dependence on test temperature and time is developed. Using 15Kh1M1F-L, 15Kh11MF, EhI612 steels and EhI437-B alloy it is shown, that steel efficiency may be achieved by increasing the long-term rupture strength at the expense of the melting methods improvement

50

Newly developed heat resistant magnesium alloy by thixomolding  

Energy Technology Data Exchange (ETDEWEB)

Thixomolding of magnesium alloy is an environmentally friendly and safe casting process. This process is capable of near net shape casting from solid feedstock in a single step by injecting metallic slurry into a die cavity with high pressure at semi-solid or fully melted state. In the present work, we investigated the effects of the chemical composition on the creep resistance at elevated temperatures, the corrosion resistance at room temperature and the fluidity during thixomolding about the Mg-Al-Ca-Mm-Sr alloys. Obtained results are the following. (1) The creep resistance increased with increasing additional Ca or Sr content to AM60B. The effect of Ca was larger than that of Sr. The corrosion resistance decreased with increasing Ca content. (2) No significant differences of the corrosion and creep resistance were observed within the Al content of 4 to 8mass% in Mg-Al-3mass%Ca alloys. (3) More than 0.5mass% Mm addition to ACa63 was effective in the corrosion resistant to a certain extent without outstanding decrease of the creep resistance. Moreover, a practical corrosion rate was achieved by more than 0.01mass% Sr addition to ACaE6305. (4) A slight addition (0.01 mass%) of Sr to ACaE6305 was effective in improving the fluidity at a thin wall (1 mm) cavity with thixomolding. (orig.)

Tsukeda, T.; Uchida, R. [Research and Development Group, Magnesium Process Equipment and Products Div., Japan Steel Works, Ltd., Hiroshima (Japan); Suzuki, M.; Koike, J.; Maruyama, K. [Dept. of Materials Science, Graduate School of Engineering, Tohoku Univ., Sendai (Japan)

2003-07-01

51

Modification of heat resistant nickel alloys with disperse particles of refractory compounds  

International Nuclear Information System (INIS)

The paper describes a technology for modifying heat resisting nickel alloys. The basic features of this technology are as follows. Low-dispersed refractory articles of modifiers (carbides, nitrides, carbonitrides) are introduced in the melt in the form of briqnettes. Melt temperature and permissible time of modifier insertion into the melt prior to costing are determined depending or alloy composition and objective to be achieved (grain refinement, improvement of strength or plasticity characteristics). Positive modification results are achieved for ZhS32, ZhS6U, XhS3DK alloys

52

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

53

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

54

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

55

Structure and phase composition of heat resistant granular alloys  

International Nuclear Information System (INIS)

Structure and composition of carbide phases have been investigated in granules of refractory alloys EI698, EP741 and ZhS6U obtained by dispersing of melt in water or in argon and by dispersing of rotating ingot in helium. The most disperse structure has been exhibited by granules obtained by dispersing in water, in all the cases the granules containing (Ti,Nb)(C,N) type carbides. High-temperature annealing (1100-1200 deg C) results in changing of the structure and formation of M6C and MC type carbides

56

On the mechanism of microaddition influence on the resistance to oxidation of heat resisting nickel alloys  

International Nuclear Information System (INIS)

Effect of rare earth metals (yttrium, cerium, praseodymium) on resistance to oxidation of foundry heat-resisting nickel alloys ZhS6K-VI and ZhS6U-VI is considered. It is shown that two mechanisms of microaddition influence of rare earth metals on the resistance to oxidation are possible, namely: rare earth metals additions reduce the concentration of defects in the oxide and change the parameters of its crystal lattice. 5 refs., 2 figs., 4 tabs

57

Estimation methods of crack resistance under heat resistant nickel alloys creep conditions  

International Nuclear Information System (INIS)

Possibility of crack resistance determination under creep conditions of nickel alloy of average heat resistance at 650 and 750 deg C is verified by long-term strength texts of small-zsize samples (10x11x60 mm) with the side unilateral crack (instead of eccentric tensile tests of large-size samples). Thicknesses of the samples at which precritical crack propagation rakes place under plane deformation are determined

58

Determination of ruthenium in heat-resistant nickel alloys by atomic emission spectrometry with inductively coupled plasma  

International Nuclear Information System (INIS)

A technique for measuring 0.5-6.5 mass% ruthenium in heat-resistant nickel alloys using atomic emission spectrometry with inductively coupled plasma was developed. The measurement precision (repeatability and reproducibility) was determined. (author)

59

Internal stress during high-temperature creep of special grade Hastelloy X alloys  

International Nuclear Information System (INIS)

Creep tests and the measurement of internal stress during creep were performed at 9000C for Hastelloy XR and XR-II, i.e. versions of Hastelloy X modified for nuclear applications. Creep rupture time and steady-state creep rate were influenced by the boron content, grain size and heat-treatment temperature of the alloys. It is shown that the difference in the steady-state creep rate is caused by the internal stress dependent on the boron content, grain size and solution-treatment temperature. (orig.)

60

Studies on the permeation of Hydrogen and Tritium through heat resistant alloys  

Science.gov (United States)

At temperatures of 750 to 950°C 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 occurred during the measurements due to a phase transformation.

Schmidt, A. S.; Verfuss, F.; Wicke, E.

1985-04-01

61

Electric effect on formation of gas-circulation coatings on heat resistant alloy  

International Nuclear Information System (INIS)

The formation kinetics for aluminide coating on heat resisting alloy ZhS6U is under study. Polished specimens to be coated were mounted in a reaction chamber with a NiCrAlY powder saturating mixture placed at the bottom. Electric potential was applied between heated ZhS6U alloy specimens and the bottom of the chamber. It is shown that the application of pulsed electric potentials accelerates the growth of diffusion coatings on the alloy. Electric field effect starts at some definite threshold value of direct voltage and manifests itself near the temperature of gamma-phase dissolution in the alloy. The application of pulsed electric potentials makes it possible to form multicomponent coatings of variable composition

62

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.)

63

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

64

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)

65

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

66

Heat-resistant alloys: State-of-the-art and trends of development  

International Nuclear Information System (INIS)

Even today, several decades after inception, nickel-based heat-resistant alloys are still considered to be a class of materials meeting the broadest range of stringent requirements comprising mechanical, process, corrosion-resistant and physico-chemical properties. In the opinion of this author, the opportunities for new alloys to be used are as follows: High-temperature regions in phase diagrams show the compositions which can serve as a basis for new generations of alloys. In addition ceramics based on carbides, nitrides and so on will be used. High-temperature regions are, first of all, connected with utilization of such high-melting intermetallic compounds as NiAl, Co3Ti, TiAl as well as CoAl, Co3Al, Ni3Al and others. (orig./MM)

67

On temperature-force dependence of activation energy for heat-resistant alloys cyclic creep  

International Nuclear Information System (INIS)

Activation energy of the cyclic creep process for heat-resistant nickel alloys at high-temperature (Tsub(isp) approximately equal to 0.5-0.8 Tsub(pl)) low-cyclic (f approximately equal to 35 Hz) loading is determined on the basis of the experimental data processing results in the range of deformation rates from 10-3 to 101 %/h. It is stated that activation energy of the cyclic creep is practically independent of the cycle stresses and temperature and that the stresses of the asymmetric cycle affect the creep rate mainly through changes in the frequency factor

68

Various problems in high temperature strength of heat resistant super-alloys for high temperature gas-cooled reactors  

International Nuclear Information System (INIS)

In July, 1973, the research and development on the direct iron-making technology utilizing high temperature reducing gas were started as a big national project. As the research items, heat resistant super-alloys, high temperature heat exchangers, heat-insulating materials as well as high temperature gas-cooled reactors were enumerated. The aim of the research and development of heat resistant super-alloys is to develop the alloy which has the creep rupture strength for 50,000 hours of higher than 1 kg/mm2 in 1,000 deg C helium atmosphere. This alloy must be worked into tubes of 25 mm outside diameter, 5 mm thickness and at least 7 m length, and the secondary working and welding required for the manufacture of heat exchangers must be possible. The high temperature strength and workability of heat resistant alloys are incompatible properties. The creep rupture strength of heat resistant alloys deteriorates in helium atmosphere. In this paper, the test results on the high temperature strength of ten candiate alloys, which passed the manufacturing test and working test, are reported. The creep rupture strength of H-alloy and I-alloy in 1,000 deg C helium seemed to satisfy the condition. (Kako, I.)

69

Influence of liquid copper-silver brazing alloy on properties of high-strength and heat resistant alloys and steels  

International Nuclear Information System (INIS)

The influence of temperature, heating rate, microstructure, the duration of Cu-Ag melt attack during brazing, the thickness and the material of barrier coating on properties of materials (Ni-Cr alloys, Cr-Ni steals, a Fe-Ni base EhJ-702 alloy) being brazed is studied. The tests of specimens with a brazing alloy are carried out in the temperature range of 780-1000 deg C. It is revealed that heat resistant alloys under brazing conditions experience brittle fracture. Multiphase structure coarse grain, increased hydrogen content mechanical stress concentrators are found to intensity embrittlement of the materials. The use of barrier coating displaying a chemical affinity to the brazing alloy results in a decrease of the tendency to embrittlement

70

Vapor deposited and deposition diffusion coatings for turbine blades of directionally crystallized heat resistant alloys  

International Nuclear Information System (INIS)

Comparative studies were made for the structure and properties of two types of coatings intended to protect a heat resistant nickel base alloy against high temperature gaseous corrosion. The coating of the first type was of Ni-20%Cr-12%Al-0,5Y composition and was vapor deposited using ion-plasma technique. The second type coating had a two-layer structure with an outer layer of Ni-24%Al-5%-Cr composition produced by diffusion saturation. The inner layer was analogous to the first type coating. Corrosion tests of the model alloy (Ni-12%W-10%Co-6%Al-5%Cr-1%Ti) with above-mentioned coatings showed that the two-layer coating processes higher heat and corrosion resistance and has no detrimental effects on strength properties of a directionally solidified substrate. 3 refs., 4 figs., 2 tabs

71

Microstructural characterization of dissimilar welds between alloy 800 and HP heat-resistant steel  

International Nuclear Information System (INIS)

In this study, dissimilar welds between HP heat-resistant steel and Incoloy 800 were made with four different filler materials including: 309 stainless steel and nickel-based Inconel 82, 182 and 617. The microstructure of the base metals, weld metals and their interfaces were characterized by utilizing optical and scanning electron microscopy. Grain boundaries migration in the weld metals was studied. It was found that the migration of grain boundaries in the Inconel 82 weld metal was very extensive. Precipitates of TiC and M23C6 (M = Cr and Mo) in the Inconel 617 weld metal are identified. The necessary conditions for the formation of cracks close to the fusion line of the 309-HP joints are described. Furthermore unmixed zone near the fusion line between HP steel base metal and Inconel 82 weld metal is discussed. An epitaxial growth is characterized at the fusion line of the 309-Alloy 800 and Inconel 617-Alloy 800 joints

72

Study of long-term strength of nickel heat resisting alloy monocrystals  

International Nuclear Information System (INIS)

Effect of orientation and direction of growing of ZhS-6U alloy crystals on long-term strength is studied. Fracture mode and crystal structure, formed at high-temperature creep, are also studied. It is established that [111] orientation has considerable advantages for long-term strength of monocrystals of ZhS-6U nickel heat- resistant alloy in comparison with [001] and [011] orientations. Structure with subgrain sizes from 0.1 to 0.2 mm is formed in crystals under creep. Transition from secondary to tertiary creep is not connected with formation of macrodiscontinuities in monocrystals. Cracks are formed mainly along the carbide precipitations at the end of the third stage

73

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

74

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

75

The role of rare earth elements on the high-temperature oxidation of heat-resisting alloys  

International Nuclear Information System (INIS)

Recently, the working temperature of boilers, engines, chemical installations and nuclear reactors rises gradually for improving their efficiency, and the demands of endurable temperature and time to the heat-resisting alloys used for these machinery and equipments have increased remarkably. The mechanical strength, thermal fatigue endurance and corrosion resistance of heat-resisting alloys at high temperature must be satisfactory in the using environment of constant temperature and thermal cycles. When rare earth elements are added to heat-resisting alloys and steels, their properties are affected, and the many improving effects have been reported. It has been known since long ago that the corrosion resistance in high temperature oxidizing gas atmosphere is remarkably improved. In this paper, the results of researches on this subject are given, and the points of problem are pointed out, to give a clue for clarifying the role of rare earth elements in the high temperature oxidation of heat-resisting alloys. The formation and growth of oxide films, the control of oxidation rate, the adhering property of oxide films, the effect of adding rare earth elements on the diffusion rate in oxides and alloys, the wedging effect of oxide films owing to internal oxides, the effect due to the obstruction of void formation, and the negative effect of adding rare earth elements are explained. (Kako, I.)

76

Effect of method for plastic working procedure on deformability of heat resisting alloys  

International Nuclear Information System (INIS)

Presented are the results of investigation of deformability of the heat resisting KhN56BMTYUR, KhN67BMTYU alloys at the wire drawing and rolling. The deformability has been evaluated by the results of macro- and micro-analyses, by the change of metal density and mechanical properties in the process of deformation. It is found that by the rolling it is possible to obtain 3-6 mm diameter wire with high surface quality avoiding intermediate heat treatments, cleaning and grinding the wire surface. The production of the wire of the same diameter by drawing is connected with intermediate heat treatments and with the presence of surface and internal defects in the form of longitudinal and transverse cracks, tears, laminations

77

Installation for mechanical tests of heat-resisting alloys under super-plasticity conditions  

International Nuclear Information System (INIS)

An mechanical test installation designed on the base of the P-5 serial machine to investigate heat-resisting alloys under superplasticity conditions is described. The range of the deformation velocity is from 0.1 to 1000 mm/min with accuracy not worse than 1%. Suggested is a specimen heating system with three-zone resistance furnace, three-step heat and automatic temperature control; the system provides at +-3 deg C temperature variations a 3 deg C gradient over 280-300 mm furnace length in the temperature range from 9O0 to - 1300 deg C when measuring with 0.05 % accuracy. A high-sensitive electrical strain dynamometer permits to register tensile forces within the limits from 0.1 to 500 kg with 0.5% accuracy

78

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

International Nuclear Information System (INIS)

Research highlights: ? The segregation concentration is much higher in dimples that at grain boundaries. ? The prominent segregation of tin and tellurium is observed during rupture test. ? The cracking initiates at the grain boundary carbide interface. - Abstract: Reheat or stress relief cracking phenomena have been reassessed in 2.25Cr1.5W heat-resistant alloys. During rupture test, time to intergranular failure increases with decreasing temperature and tensile stress and is shorter in the alloy containing a higher bulk content of phosphorus. Also the time to intergranular failure can be expressed by t = t0.?-n.exp(Q/RT) where t0 is the proportional constant, n the stress exponent and Q the activation enthalpy. Matrix softening is accelerated under tensile stress and an active carbide growth occurs at grain boundaries oriented normal to the tensile stress direction. Because impurities segregate actively to dimples frequently observed at reheat intergranular fracture surfaces, the dimples are not micro-ductile fracture areas but the grain boundary carbide interfaces. The segregation concentration of the impurities is much higher at the grain boundary carbide interfaces than the carbide-free grain boundaries. The phosphorus segregation at the carbide interfaces of the alloy containing the higher bulk content of phosphorus is mainly replaced by the segregation of nitrogen, tin and tellurium in the alloy containing a lower bulk cone 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.

79

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 precipitationsble amount of coagulated precipitations of about 0.2 ?m size

80

Tension and creep design stresses of the 'Hastelloy-X' alloy for high-temperature gas cooled reactors  

International Nuclear Information System (INIS)

To provide the design data for the Hastelloy-X alloy, the tensile and creep test data was obtained experimentally, and a number of creep data was also collected through literature surveys. All of the experimental and collected data was combined to determine a minimum design value for a tensile stress and to predict a long-term life for a creep rupture time. The design yield and ultimate tensile stress curves for the Hastelloy-X alloy were determined by a best fitting all of the data up to 1000 deg. C. Creep master curves based on the Larson-Miller parameter were obtained for the standard deviations of 1?, 2? and 3?. The creep-rupture life for up to 105 h was predicted for the Hastelloy-X alloy

81

The welding metallurgy of HASTELLOY alloys C-4, C-22, and C-276  

Science.gov (United States)

The welding metallurgy (solidification and solid state transformations) of HASTELLOY* Alloys C-4, C-22, and C-276 has been determined. Varestraint hot-cracking tests performed on commercial alloys revealed a weldability ranking as follows: C-4 > C-22 > C-276. All alloys would be expected to have good weldability, with Alloy C-4 having a very low hot-cracking tendency, comparable to 304L stainless steel. Microstructures of gas-tungsten-arc welds of these alloys have been characterized by scanning electron microscopy and analytical electron microscopy. Intermetallic secondary solidification constituents have been found associated with weld metal hot cracks in Alloys C-276 and C-22. In Alloy C-276, this constituent is a combination of P and ? phases, and in Alloy C-22, this constituent is composed of ?, P, and ? phases. With phase composition data obtained by AEM techniques and available ternary (Ni-Cr-Mo) phase diagrams, an equivalent chemistry model is proposed to account for the microstructures observed in each alloy's weld metal.

Cieslak, M. J.; Headley, T. J.; Romig, A. D.

1986-11-01

82

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

83

Formation of carbides in the cast heat-resistant nickel alloy  

International Nuclear Information System (INIS)

The study results on a carbide phase nature, its composition and distribution in the Ni+9%Co+5%Al+2%Nb+1%Mo+10%W+1%Fe cast heat-resistant nickel alloy of ZhS6U type are reported. Investigated alloy demonstrates a high dispersion, fine structure of carbide phase with retention of even distribution in the outlying districts of a heat-treated casting. Tungsten is included into initial carbides as well as in heat-treated and deformed ones. Initial carbides consist from (Ti0,51Ni0,34W0,08)C and a heat-treated and deformed ones have (Ti0,57 Nd0,24W0,12)C composition. From the obtained results one can conclude that a carbide phase composition change is connected with a composition and share of ?'-phase and matrix. Change of carbide phase composition and dispersion improvement are interrelated and determined by carbide formation kinetics

84

Design fatigue curve for Hastelloy-X  

International Nuclear Information System (INIS)

In the design of components intended for elevated temperature service as the experimental Very High-Temperature gas-cooled Reactor (VHTR), it is essential to prevent fatigue failure and creep-fatigue failure. The evaluation method which uses design fatigue curves is adopted in the design rules. This report discussed several aspects of these design fatigue curves for Hastelloy-X (-XR) which is considered for use as a heat-resistant alloy in the VHTR. Examination of fatigue data gathered by a literature search including unpublished data showed that Brinkman's equation is suitable for the design curve of Hastelloy-X (-XR), where total strain range ? epsilon sub(t) is used as independent variable and fatigue life Nsub(f) is transformed into log(log Nsub(f)). (author)

85

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)

86

Glow discharge mass spectrometric analysis of nickel-based heat-resisting alloys  

International Nuclear Information System (INIS)

GD-MS analysis of nickel-based heat-resisting alloys has been performed using a VG 9000 glow discharge (GD) mass spectrometer. Concentrations of not only alloying elements (Al, Si, Ti, V, Cr, Mn, Fe, Co, Cu, Y, Nb, Mo and W) but also trace elements (B, C, Mg, P, S, Zn, Ga, As, Zr, Cd, Sn, Sb, Te, Pb and Bi) were successfully determined in disk shaped samples. The examination of spectral interference confirmed the following. The influence of manganese argide (55Mn40Ar+) on the ion beam intensity of 95Mo+ was negligible because manganese content of the alloys is usually less than 1 mass%. Mass spectra of 31P+ and 32S+ may be affected by the spectral interference of 62Ni2+ and 64Ni2+, respectively, due to the matrix element. However, these ion species were sufficiently separated at the mass resolution 5000 (m/?m, at 5% peak height) used in this study. Relative sensitivity factors (RSFs) were determined by analyzing standard reference materials: JAERI CRMs, a NIST SRM, a BS CRM, BCS CRMs and the alloys prepared in our Institute. The average RSF-values obtained for Ni=1 were 0.436 for Al, 0.826 for Si, 0.281 for Ti, 0.375 for V, 1.480 for Cr, 1.122 for Mn, 0.754 for Fe, 0.653 for Co, 3.321 for Cu, 0.303 for Y, 0.436 for Nb, 0.862 for Mo, 0.935 for Ta and 1.052 for W. The analytical accuracy (?d) obtained was comparable (?d) obtained was comparable to that of FP-XRF analysis, except for chromium and iron determinations. Relative standard deviations (RSDs) of five replicate measurements were within about 2.5%, except for phosphorus (P; 0.003 mass%, RSD; 3.31%) and sulfur (S; 0.005 mass%, RSD; 3.08%). GD-MS analytical values for ODS MA6000 alloy were obtained using a RSF correction program, and the values were in good agreement with those obtained by FP-XRF and by chemical analysis (author)

87

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%.

88

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

89

Influence of melt heat treatment and modifying on structure and properties of heat resistant alloy ZhS6U  

International Nuclear Information System (INIS)

The structure and properties of a heat resistant nickel base alloy (ZhS6U) were investigated depending on melting conditions. It is shown that simultaneous application of high temperature melt treatment and modifying results in a decrease of crystallization temperature range, in an increase of solidus temperatures and the temperature of secondary phase complete dissolution. The combined melt treatment permits forming the optimal cast metal structure with uniformly distributed globular carbides

90

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

91

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

92

Creep behavior of Hastelloy X, 2 1/4 Cr--1 Mo steel, and other alloys in simulated HTGR helium  

International Nuclear Information System (INIS)

Creep tests on several materials both in environments of air and in helium containing small amounts of H2, CH4, CO, and H2O are reported. Tests have been run on Hastelloy X at 650 to 8700C for times to 20,000 h, and although it does carburize in helium, its creep properties are very similar in both environments. Tests have been run on 2 1/4 Cr--1 Mo steel at 482 to 6500C for times to 20,000 h, and its creep strength is less in helium than in air, likely because of the decarburization that occurs in helium. Limited creep tests have been run on 9 Cr--1 Mo steel, alloy 800H, Hastelloy S, and alloy 617. The results show no large environmental creep effects but are insufficient to conclude that such effects do not exist. A test sample of Ni-7% Cr-12% Mo-4% Fe-2% Ti completely resisted carburization under conditions where Hastelloy X increased in carbon content from 0.0993 to 0.436%. Most of the creep tests described in this report are continuing. Samples of Hastelloy X and alloy 617 for subsequent testing are aging; one set has accumulated 17,000 h in air, and one set has accumulated 7000 h in helium

93

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.)

94

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 the diffusing carbon reached the center of the specimen

95

Low alloy light-weight heat-resistant high-temperature materials on the base of Ni3Al intermetallic compound  

International Nuclear Information System (INIS)

Comparative analysis of domestic alloys of VKNA type on the basis of Ni3Al intermetallic compound with different types of structure and modern nickel alloys was conducted. Advantages of VKNA type alloys as compared to industrial nickel alloys are shown: higher observation temperatures, lower density, economy of deficient heavy alloying elements. VKNA type alloys are characterized by higher gas corrosion resistance, higher heat resistance and higher ultimate strength

96

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

OpenAIRE

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 kineti...

Wang Haitao; Wang Yuqing; Yu Huashun

2009-01-01

97

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

98

Prediction of the high-temperature creep behavior for Hastelloy-X alloy  

International Nuclear Information System (INIS)

The nickel-based Hastelloy X alloy is one of the candidate materials for structural components of the High Temperature Gas-cooled Reactor (HTGR). Its creep data was obtained from the creep tests under several stress levels at 950 .deg. C, and using this data, the creep behavior was investigated by the ?-projection model. The proper fitting range was determined from the creep curves at any stress level because the ?1-parameters are dependent on a fitting strain range. A stress dependency for the ?-parameters was established to accurately predict the creep curve of a low stress level. The time to 1%-low strains was predicted for various stress levels, and the ratios between the time to 1%-low strain and time to rupture were lower than 15%. Also, a predicted minimum creep rate revealed a good agreement with the experimental data

99

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

International Nuclear Information System (INIS)

To model the creep curves of the Hastelloy-X alloy which is being considered as a candidate material for the VHTR (Very High Temperature gas-cooled Reactor) components, full creep curves were obtained by constant-load creep tests for different stress levels at 950 C degrees. Using the experimental creep data, the creep curves were modeled by applying the Theta projection method. A number of computing processes of a nonlinear least square fitting (NLSF) analysis was carried out to establish the suitably of the four Theta parameters. The results showed that the ?1 and ?2 parameters could not be optimized well with a large error during the fitting of the full creep curves. On the other hand, the ?3 and ?4 parameters were optimized well without an error. For this result, to find a suitable cutoff strain criterion, the NLSF analysis was performed with various cutoff strains for all the creep curves. An optimum cutoff strain range for defining the four Theta parameters accurately was found to be a 3% cutoff strain. At the 3% cutoff strain, the predicted curves coincided well with the experimental ones. The variation of the four Theta parameters as the function of a stress showed a good linearity, and the creep curves were modeled well for the low stress levels. Predicted minimum creep rate showed a good agreement with the experimental data. Also, for a design usage of the Hastelloy-X alloy, the plot of the log stress versus lo, 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)

100

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

101

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.)

102

Creep rupture properties and their degradation of heat resistant alloys for nuclear steel making in helium and reducing gas atmospheres  

International Nuclear Information System (INIS)

Creep rupture properties of heat resistant alloys with carbide or carbide and ?' precipitates were investigated in the temperature range from 900 0C to 1050 0C in He and reducing gas atomospheres. The degradation of the rupture strengths took place in the allays, which have carbide as a strengthener, due to decarburization in He atmosphere at temperature higher than 1000 0C. In the alloy which was strengthened mainly by ?', the dissolution of ?' led to the degradation of the rupture strengths, but to the restoration of the rupture ductilities in greater extent. A new method to predict the rupture life, steady state creep rate, etc. from 0.2 % proof stress was proposed. In most cases, the method was found to be satisfactory in the sense that it represents the degradation behaviour of the alloys according to various causes. (author)

103

X-ray fluorescence analysis of nickel-based heat-resisting alloys by matrix correction using theoretical alpha coefficients  

International Nuclear Information System (INIS)

The study of the X-ray fluorescence analysis of main component and alloying elements in nickel-based heat-resisting alloys has been performed. The calibration curves were made by using NBS SRM's, JAERI and home-made nickel-based standard samples and the correction was made for the matrix effects using theoretical alpha coefficients. Accuracies (?d) for respective element obtained from those curves with correction were improved, especially for chromium and iron, in comparison with uncorrected ones. The relative standard deviation for each element was in the ragne of 0.25 ? 1.27 % with the exception of aluminum (0.26 Al%; r.s.d. 3.01 %). The analytical ranges were as follows; Cr(12.75 ? 26.49 %), Mo(1.09 ? 9.18 %), W(0.019 ? 4.57 %), Co(0.39 ? 8.90 %), Ti(0.35 ? 3.44 %), Al(0.15 ? 6.68 %), Nb(0.88 ? 5.38 %), Fe(0.12 ? 23.2 %), Mn(0.01 ? 0.65 %). The analytical values of nickel-based heat-resisting alloys such as Inconel 713LC, Mar-M247 and so on, showed good agreement with those determined by chemical analysis. (author)

104

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

105

Effect of cyclic and static stresses on cyclic creep of heat resistant nickel alloys under multicycle loading  

International Nuclear Information System (INIS)

The process of cyclic creep of heat-resistant nickel alloys under asymmetric multicycle loading is studied as affected by cyclic ?sub(a) and static ?sub(m) stresses. It is stated that an increase in cyclic ?sub(a) and static ?sub(m) stresses produces a decrease in the life time of materials studied, thus essentially rising cyclic creep rate epsilonsub(?)(t). It is shown that dependence of the minimum cyclic creep rate epsilon''sub(?) on the static component ?sub(m) is fairly approximated by a power or exponential dependences, the dependence mentioned on the cyclic component ?sub(a) is approximated by an exponential one

106

The diffusion model of pores vacancy dissolution at gaseous isostatic pressing of heat resistant nickel alloy monocrystal  

International Nuclear Information System (INIS)

Diffusion model of vacancy dissolution of pores under the action of all-round compression stresses (gas isostatic pressing) and capillar forces is proposed. The experiments are carried out using a nickel base heat resistant alloy single crystal. At the initial stage of the process the external pressure effect is shown to be predominant. The time of dissolution is in inverse proportion to the stress and depends quadratically on the initial pore size. At the final stage (a pore radius less than 100 nm) the pore disappears rapidly under the action of capillar forces

107

Corrosion behavior of nickel base heat resisting alloys for nuclear steelmaking system in high-temperature steam  

International Nuclear Information System (INIS)

The corrosion behavior of nickel base heat resisting alloys is investigated in steam at 8000C and 40 atm, simulating the superheated steam of the nuclear steelmaking system. The alloys tested are five new alloys developed for the nuclear steelmaking system and one commercial alloy Inconel 617. A protective surface oxide scale, consisting of Cr2O3 mainly and of MnCr2O4, forms on the alloys except Inconel 617. Internal oxides, consisting of Al and Ti oxides, also form in the alloys containing Al. For Inconel 617, nodular oxides, consisting of NiO in the outer region and Cr internal oxides in the inner region, form in addition to Cr2O3 and MnCr2O4 after 1000 h. No decarburization occurs in each alloy. The effect of alloy compositions on the corrosion behavior is discussed. The rate of Cr depletion resulting from the formation of Cr2O3-rich scale is found to be influenced by the presence of MnCr2O4 layer outside the Cr2O3 scale, and is described by a parabolic rate law for the alloys with thin MnCr2O4 layer and by a cubic rate law for the alloys with thick MnCr2O4 layer. Al and Ti, which are reactive more than Cr, are found to improve a resistance to spalling of the Cr2O3-rich scale, through a key-on effect by the internal oxides and by the enriect by the internal oxides and by the enrichment of Ti oxides at the Cr2O3 scale/alloy interface. (author)

108

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)

109

Effect of yttrium on the oxide scale adherence of pre-oxidized silicon-containing heat-resistant alloy  

International Nuclear Information System (INIS)

Highlights: ? AE experiment shows yttrium has a beneficial effect on the pre-oxidized HP40 alloy. ? Yttrium facilitates the formation of internal oxide after 10 h of oxidation. ? Internal oxide changes the rupture behaviour of the oxide scale. ? Twins form in the internal oxide and improve the binding strength of the scale. - Abstract: This paper investigates the effect of the rare earth element yttrium on the rupture behaviour of the oxide scale on the silicon-containing heat-resistant alloy during cooling. After 10 h of oxidation, yttrium is found to facilitate the formation of internal oxides (silica) at the scale-matrix interface. Due to the twinning observed by scanning transmission electron microscopy (STEM) in silica, the critical strain value for the scale failure can be dramatically improved, and the formation of cracks at the scale-matrix interface is inhibited.

110

Weld metal hot-cracking of Hastelloy alloys C-22 and C-276: a study by analytical electron microscopy  

International Nuclear Information System (INIS)

Weld metal hot-cracking in multi-component alloy systems is often the result of the formation of small volume fractions of nonequilibrium constituents along solidification grain boundaries. These constituents arise as a result of the segregation phenomenon accompanying weld solidification and often serve to extend the solidification temperature range well below the equilibrium solidus. Purpose of this study was to identify and characterize (crystal structure and composition) by analytical electron microscopy (AEM) the phases associated with weld metal hot-cracking in Hastelloy alloys C-22 and C-276

111

Effects of cyclic aging on mechanical properties and microstructures of hastelloy alloy X  

International Nuclear Information System (INIS)

In attempt of application to the high temperature structural components for the very high temperature gas cooled-reactor (VHTR), microstructural stability of Hastelloy alloy X and its influence to the room temperature toughness were investigated. The mechanical property changes, particularly aged by thermal cycling to be expected in the reactor operation were examined by tensile tests, Charpy impact tests, hardness tests, EPMA analysis and TEM observation. In addition to isothermal aging, cyclic aging was given up to 125 cycles with peak temperature at 700 -- 10000C. Holding time was given for 8 hours at each peak temperature so that total accumulated time at the peak reached 1000 hours. The results indicate that the changes in ductility of the cyclically aged materials are generally enhanced relative to those of isothermally aged. The observed trend was consistent with the enhanced carbide precipitation. For the peak aging temperature up to 9000C, the ductility loss of the cyclic case is higher than that of the isothermal, while the relation is reversed at 10000C. (author)

112

Design of super heat-resisting Nb-based alloys for nuclear applications  

International Nuclear Information System (INIS)

Nb-based alloys are ones of the promising materials for structural applications in advanced nuclear power systems. A systematic estimation for high-temperature tensile strength, high-temperature creep strength, corrosion resistance to liquid sodium and alloy density was performed in order to get useful information for the design of the Nb-based alloys, as was similarily done for Mo-based alloys. The high-temperature micro-hardness and the high-temperature tensile strength were found to be predictable using the same calculation method employed in the Mo-based alloys. The differences in the atomic radius and in the Young's modulus between the Nb atom and alloying elements were taken into account in the prediction. The melting temperature was calculated readily by taking the compositional average of melting temperatures for constituent metals, and used as an indication for the creep strength of alloys. The corrosion resistance to liquid Na was also found to be significantly lower in the Nb-based alloys than in the Mo-based alloys. In addition, the corrosion resistance of Nb-based alloys were largely varied with alloying elements. From a series of corrosion tests with various Nb-M binary alloys, alloying elements which are effective in improving the corrosion resistance were selected. Furthermore, alloy densities were estimated by taking the compositional average of the densities for constituent metals in alloy. Based on these results, a Nb-W-V-Zr system was selected as tults, a Nb-W-V-Zr system was selected as the most promising alloy for nuclear power plants. The specific properties were estimated with varying alloy compositions, even though extensive investigation is further needed to draw a conclusion on the corrosion resistance of these alloys. Finally, it was concluded that the present predicting method could provide an useful indication for the efficient design of Nb-based alloys. (author)

113

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

114

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.)

115

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

116

Resistance to thermal fatigue of heat resistant alloys with protective coating  

Energy Technology Data Exchange (ETDEWEB)

Blades of gas turbines are calorized for protection against corrosion and erosion in a gas stream in an atmosphere of combustion products. However, such a coating also reduces the plasticity of the surface layer and has been found to reduce, under sufficiently high static loads, the fatigue resistance of ZhS6KP heat resistant steel under cyclic thermomechanical loads. A study was made to determine the effect of various coatings on ZhS6U heat resistant steel under a deformation of 0.6 to 3% and 100 reversible 950/sup 0/C temperature cycles with holding for 1.5 min at 950/sup 0/C. The most effective crack inhibitor under these conditions was the NiCoCrAlY coating (50 to 80 ..mu..m thick) with an ..cap alpha.. + ..beta.. phase structure. With Ni-15Al-35Cr-Y and CoCrAlY coatings, cracks were found to propagate radially into the base metal and to shorten the life most appreciably. In air at a large deformation (> 0.8%) the life of specimens decreased by 30 to 50% and at a small deformation (< 0.6%) after 10/sup 3/ cycles the life of specimens remained the same with or without coating. 8 references, 5 figures.

Bokshteyn, S.Z.; Bychkov, N.G.; Dul' nev, R.A.; Zaytsev, G.N.; Ol' shanskaya, E.Ya.; Rybina, T.V.

1980-04-01

117

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

118

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

119

Influence of structure of heat-resistant nickel alloy ZhS6U on its weldability in the solid state  

Energy Technology Data Exchange (ETDEWEB)

A study was made of the influence of various structural characteristics of heat-resistant alloys and the phenomenon of superplasticity on the formation of a welded joint by diffusion welding. Studies were performed on heat resistant alloy ZhS6U in the cast state and the same alloy obtained from granules by powder metallurgy. Tests were performed in the 960-1200/sup 0/C temperature interval at deformation rates of 1 x 10/sup -4/ - 1 x 10/sup -1/ S/sup -1/ and showed significant differences in mechanical properties of the alloys obtained by different methods, related to the structural state of the alloy. The cast alloy has low ductility and high resistance to plastic deformation, whereas the powder metallurgy product shows all the signs of superplasticity at 1050-1150/sup 0/C. The structure formed upon heating to the welding point has decisive influence on the weldability of heat-resistant nickel alloys. The best-quality welded joint is obtained under temperature and speed conditions corresponding to the range of superplastic deformation of the alloy.

Golubev, V.N.; Sharif' yanov, F.Sh.; Vlasova, A.V.

1985-02-01

120

High temperature crevice corrosion of heat-resistant Ni-base alloy in the simulated HTR helium  

International Nuclear Information System (INIS)

Interaction between a Ni-base heat-resistant alloy and the simulated HTR primary coolant environment was examined with emphasis on the reactions inside narrow crevice gaps. A new method using Mo crevice cells was developed to obtain reproducible quantitative results. The test environment was characterized by the low oxidizing species as trace gaseous impurities. Series of sequential phenomena were observed: i.e. the preferential consumptions of oxidizing species in the outer part of the crevice, followed by the lack of oxide film and the resultant extensive carburization further inside the crevice. A model on the possible phenomena occurring at tips of the cracks formed during creep or fatigue tests and low flow rate portions in the reactor primary circuit as well. The feasibility of the interpretation was checked referring to the existing numerical formula and using the experimental results obtained parameters. Calculations reproduced penetration curves of the Cr- oxidation with reasonable accuracy. (author)

121

High-temperature tensile-hold crack-growth behavior of HASTELLOY® X alloy compared to HAYNES® 188 and HAYNES® 230® alloys  

Science.gov (United States)

The creep-fatigue crack-growth tests of HASTELLOY® X alloy were carried out at the temperatures of 649°C, 816°C, and 927°C in laboratory air. The experiments were conducted under a constant stress-intensity-factor-range (? K) control mode with a R-ratio of 0.05. In the constant ? K tests, a ? K of 27.5 MPa sqrt{m} and a triangular waveform with a frequency of 0.333 Hz were used. Various tensile hold times at the maximum load were imposed to study fatigue and creep-fatigue interactions. Crack lengths were measured by a direct current potential drop method. In this paper, effects of hold time and temperature on the crack-growth rates are discussed. Furthermore, the crack-growth rates of the HASTELLOY® X alloy are compared to those of the HAYNES® 188 and HAYNES® 230® superalloys.

Lee, S. Y.; Lu, Y. L.; Liaw, P. K.; Choo, H.; Thompson, S. A.; Blust, J. W.; Browning, P. F.; Bhattacharya, A. K.; Aurrecoechea, J. M.; Klarstrom, D. L.

2008-03-01

122

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

123

Corrosion performance of heat resistant alloys in Na2SO4-V2O5 molten salts  

International Nuclear Information System (INIS)

The corrosion resistant of three heat resistant alloys in molten vanadium pentoxide (V2O5), sodium sulfate (Na2SO4) and 80(mol%) V2O5-20Na2SO4 has been evaluated using the weight loss technique. Materials included Fe-25Cr-35Ni-0.45C, Fe-35Cr-45Ni with 0.12 and 0.45C alloys. Temperatures included 600, 700 and 800 deg. C for V2O5 and the 80V2O5-20Na2SO4 mixture, and 800, 900 and 1000 deg. C for Na2SO4. The tests were supplemented by detailed electronic microscopy and microanalysis studies. In all cases, the least resistant alloy was the Fe-25Cr-35Ni-0.45C one whereas the most resistant was the Fe-35Cr-45Ni-0.12C one. The results are discussed in terms of the acidic dissolution of the external protective Cr2O3, Al2O3 and SiO2 layers, by the salts and internal sulfidation

124

Improving effect of rare earth elements on the high temperature oxidation resistance of sintered heat resisting-alloys  

Energy Technology Data Exchange (ETDEWEB)

In order to clarify the improving effect of rare earth elements on the oxidation resistance, various additive methods, i. e. metallic addition, dispersion of oxide and superficial application of oxide particles were investigated. The influence of rare earth elements on the ionic defect structure of Cr/sub 2/O/sub 3/ was also studied. Oxide weight increase and film exfoliation rate were investigated on Ni-20Cr alloy at conditions of atmospheric oxidation, 1273K and rare earth metallic addition, and effects on oxidation rate lowering and film exfoliation rate reduction due to the addition of rare earth elements were verified. In case of oxide dispersion, much larger effect than metallic addition could be verified for Fe-20Cr, Ni-20Cr, Ni-15Cr and sintered IN-100. Similar results were obtained in case of superficial application on the sintered Fe-20Cr alloy. Two improving effects of rare earth elements on lowering oxidation rate and suppressing the scale spalling on heat resistant alloys were much stronger than those of other reactive elements. (8 figs, 1 photo, 37 refs)

Nagai, Hiroshi

1987-11-25

125

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

126

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

127

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  

OpenAIRE

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...

Graneix Jérémie; Beguin Jean-Denis; Pardeilhan François; Masri Talal; Alexis Joël

2013-01-01

128

Technological foundations of surface modification of the parts made from heat-resistant Ni-based alloys with heat-resistant NiCrAlY coating with the use of power pulsed electron beams  

International Nuclear Information System (INIS)

Experimental data on the effect of power pulsed electron irradiation on the surface structure and exploitation properties of gas-turbine blades produced from heat-resistant Ni-base alloys with NiCrAlY coatings have been analysed. Mechanisms of the effect of electron-beam treatment on the blade material properties are considered. It is shown that choice of optimal parameters of electron irradiation and final heat treatment provide a significant improvement of fatigue properties and corrosion resistance of compressor and turbine blades

129

Creep behavior for Hastelloy-XR  

International Nuclear Information System (INIS)

Creep-rupture tests for Hastelloy-XR, a Ni-base heat resistent alloy, were conducted in air at the temperature of 650 to 900 deg C. Times to rupture ranged from 1000 to 16000 h. As results of tests, creep curves were observed to vary depending on both temperature and stress, particularly on temperature. Namely, they showed typical classical shapes consisting of primary, secondary and tertiary creep at 650 to 700 deg C. The regions of primary and secondary creep decreased gradually as the temperature became higher and in one case of 900 deg C and high stress, only tertiary creep was observed. Metallurgical observation by optical microscope showed the similar inclination. Some differences were found concerning rupture morphology and void shape between temperatures below 750 deg C and above 850 deg C. (author)

130

Oxidizing atmosphere effect on the surface layer structure of complex heat resisting alloys  

International Nuclear Information System (INIS)

Long-term strength of the ZhS6U refractory alloy has been tested at 975 deg C for 120 hrs, and crack generation, structure and surface composition of the alloy were studied by microscopy, local X-ray spectral analysis and microhardness measurements. The surface layer has been found to be rich in alloying elements such as Al, Cr, Ti , which diffuse from the bulk to meet the flow of oxygen and nitrogen atoms to and from oxides and nitrides. Formation of micropores involved in diffusion facilitates the oxygen access into the bulk of the metal. Oxidation of grain boundaries crossing the surface contributes to crack generation

131

Phase transformations in heat resisting nickel alloy ZhS6U after fatigue testing  

Energy Technology Data Exchange (ETDEWEB)

The phase transformations and alloying element distribution between the phases in the ZhS6U alloy weakened in the process of fatigue testing are investigated. It is shown by the methods of physico-chemical phase analysis and electron microscopy that stresses acting at working temperatures contribute to the coagulation of ..gamma..'-phase, raise its chemical heterogeneity and contribute to the decay into ..gamma../sub 1/ and ..gamma../sub 2/ fractions, the latter differing in their composition and structural stability. The ..gamma../sub 1/ to ..gamma../sub 2/ fraction relationship directly depends on high-temperature testing duration and alloy strength level.

Kishkin, S.T.; Morozova, G.I.; Belyaev, M.S.; Gnevsheva, A.I.; Sorokina, L.P.

1984-12-01

132

Phase transformations in heat resisting nickel alloy ZhS6U after fatigue testing  

International Nuclear Information System (INIS)

The phase transformations and alloying element distribution between the phases in the ZhS6U alloy weakened in the process of fatigue testing are investigated. It is shown by the methods of physico-chemical phase analysis and electron microscopy that stresses acting at working temperatures contribute to the coagulation of ?'-phase, raise its chemical heterogeneity and contribute to the decay into ?1 and ?2 fractions, the latter differing in their composition and structural stability. The ?1 to ?2 fraction relationship directly depends on high-temperature testing duration and alloy strength level

133

The Crystal Structure at Room Temperature of Six Cast Heat-Resisting Alloys  

Science.gov (United States)

The crystal structures of alloys 61, X-40,X-50, 422-19, 6059, and Vitallium, derived from x-ray diffraction, are discussed. The alloys have been, or are being considered for use in gas turbine applications. The predominant phase was a solid solution of the face centered cubic type of the principal constituent elements.The lattice parameters were found to be between 3.5525 and 3.5662.

Rosenbaum, Burt M.

1947-01-01

134

Niobium and molybdenum effect on heat resistance of vanadium precipitation-hardening alloys  

International Nuclear Information System (INIS)

Effect of niobium (0.5-15%) and molybdenum (2-3%) on the V-Zr-C alloys properties were investigated. Tensile tests were carried out at 900 deg C. It has been established that alloying with niobium and molybdenum leads to a considerable increase in long-term strength. Strengthening occurs at the expense of precipitation of carbide phase particles. Molybdenum and niobium promote carbide phase refining

135

Superplasticity and structure of heat resisting alloy ZhS6U  

International Nuclear Information System (INIS)

Regularities of superplastic deformation of ZhS6U nickel alloy in connection with peculiarities of its structure are investigated. All the properties of superplastic deformation are shown to be characteristic for the ZhS6U alloy in the 8.3x10-4-8.3x10-2 s-1 range of rates and at the temperatures of 1050-1150 deg C. Formation of fine grain, structure containing grains of #betta#- and #betta#'-phases is the structural reason for manifestation of superplasticity effect in the alloy. Slipping over the grain boundaries in combination with grain-boundary diffusion and with intracrystalline dislocation slipping are the main deformation mechanisms

136

Superplasticity and structure of heat resisting alloy ZhS6U  

Energy Technology Data Exchange (ETDEWEB)

Regularities of superplastic deformation of ZhS6U nickel alloy in connection with peculiarities of its structure are investigated. All the properties of superplastic deformation are shown to be characteristic for the ZhS6U alloy in the 8.3x10/sup -4/-8.3x10/sup -2/ s/sup -1/ range of rates and at the temperatures of 1050-1150 deg C. Formation of fine grain, structure containing grains of ..gamma..- and ..gamma..'-phases is the structural reason for manifestation of superplasticity effect in the alloy. Slipping over the grain boundaries in combination with grain-boundary diffusion and with intracrystalline dislocation slipping are the main deformation mechanisms.

Kabyshev, O.A.; Sharif' yanov, E.Sh.; Valiev, R.Z.; Notkin, A.B. (Ufimskij Aviatsionnyj Inst. (USSR))

1982-01-01

137

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

138

Subsurface microstructural changes in a cast heat resisting alloy caused by high temperature corrosion  

OpenAIRE

A cast HP ModNb alloy (Fe–25Cr–35Ni–1Nb, wt.%) was oxidised and carburised in CO–CO2 corresponding to aC = 0.1 and pO2 = 3 1016 atm at 1080 C. Formation of an external, chromium-rich oxide scale led to depletion of this metal in a deep alloy subsurface zone. Within that zone, secondary chromium-rich carbides dissolved, primary carbides oxidised, solute silicon and aluminium internally oxidised, and extensive porosity developed. Pore volumes correspond to the difference be...

Oquab, Djar; Xu, Nan; Monceau, Daniel; Young, David

2010-01-01

139

Die-casting capabilities of heat resistant Mg-Al-Ca alloys  

Energy Technology Data Exchange (ETDEWEB)

Various amounts of Ca were added to AZ91D magnesium alloy, and their effects on the die-casting abilities were investigated. It was observed that fluidity as die filling ability tends to decrease by Ca additions except for about 2%Ca. This reduction of fluidity by Ca was more significant at high superheats probably due to the high affinity between Ca and oxygen. Contrary to expectation, hot cracking resistance was found to increase by Ca additions. High Ca alloys showed some die-sticking tendency. However, the tendency was not observed below 2%Ca. (orig.)

Kim, J.M.; Park, B.K.; Jun, J.H.; Kim, K.T.; Jung, W.J. [Advanced Materials Development Center, Korea Inst. of Industrial Technology, Yeonsu-Ku, Incheon (Korea)

2005-07-01

140

Time-dependent crack growth in a heat-resistant alloy Inconel 617  

International Nuclear Information System (INIS)

Inconel alloys have been used extensively as heat exchange tubing materials in the power generation industry because of their excellent mechanical properties as elevated temperatures. Evaluation of the alloys for High Temperature Gas-Cooled Reactor (HTGR) applications has proved that Ni-Cr-Co alloys have good high temperature strength, creep properties and weldability. In this work, the cyclic fatigue behavior and creep crack growth rate of Inconel 617 alloy were tested for analysis of time-dependent crack propagation characteristics at 650degC. Microstructural examination was performed for observation of grain boundary carbide precipitation growth and the coalescence of intergranular microcracks that would enhance the crack propagation rate. It was observed that at higher temperatures, low fatigue frequency, and higher R-ratio (mean-stress), the effects of dynamic recovery tended to become stronger because the mobility of dislocation increased with increasing temperature. As a result, the subgrain grew to a larger size. Eventually, the influence of time-dependent processes on crack growth rate can effectively represent the overall effects on a creep ductile material at elevated temperatures. (author)

141

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

142

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

143

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.)ported later. (Kako, I.)

144

Influence of coating on the properties of heat resistant gas turbine alloys. Pt. 2. Microstructures  

Energy Technology Data Exchange (ETDEWEB)

Differences in the creep behaviour of some Ni base alloys were interpreted by a metallographic examination of broken specimens of a creep rupture test. If the fracture of uncoated specimens is initiated by an oxidation from the surface, by coating the time until rupture is elongated. If the fracture of uncoated specimens is unsensitive to an oxidation from the surface, there is no influence of a coating except one melt of the alloy IN-792 coated with RT 22. Improvements or deteriorations in creep resistance of coated specimens compared with uncoated mainly are caused by the heat treatments during or after coating. Different casting techniques influence the orientation of dendrites and size, position and arrangement of pores which partly have a decisive influence on the creep behaviour. Differences in creep limits up to a factor of 2 in time in general could not be interpreted by the metallographic observations used.

Sachova, E.; Hougardy, H.P.

1988-10-01

145

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.)

146

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

147

Creep-rupture properties and corrosion behavior of 2 1/4 Cr-1 Mo steel and Hastelloy X alloys in simulated HTGR environment-interim report  

International Nuclear Information System (INIS)

Hastelloy X and 21/4 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 21/4 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

148

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; Rittenhouse, P. L.

1977-01-01

149

Structure of heat resistant nickel alloys after temperature-time treatment of melt  

International Nuclear Information System (INIS)

Consideration is given to the influence of liquid metal treatment on macro- and microstructure of nickel base alloy type ZhS6U. The melt was treated according to following regimes: 1600 deg C, 5 min; 1650 deg C, 20 min; 1700 deg C, 20 min; 1750 deg C, 20 min; 1830 deg C, 10 min. It was shown that melt treatment results in more homogeneous distribution of secondary phase over dendritic cells. This allows one to abandon homogenizing annealing of castings. Microstructural changes are revealed to be due to more equilibrium state of melt prior to crystallization. 11 ref.; 3 figs.; 1 tab

150

On the reproducibility and detection limit of neutron activation method of oxygen determination in heat resisting alloys  

International Nuclear Information System (INIS)

A neutron activation technique for the determination of low oxygen content in the nickel base heat resisting alloys. The most perspective possibility to improve the reproducibility and to increase the detection limit is increase the neutron flux that may be achieved by using the NGI-12 neutron pulse generator. The generator's parameters are as follows: neutron energy is equal to 14 MeV, the neutron flux is in the limits from 3x109 to 1010 neutr./s. (at pulse frequency of 20 p/s.), the feeder line voltage is 220 v., frequency is 50 Hz, power consumed is not more than 1.5 kW. The analysis results of powder-like and compact samples on the oxygen content are estimated. It is shown that the reproducibility of the analysis results of compact samples is higher than that of powders. The detection limit for powders is equal to approximately 0.004% of masses, whereas for compact samples the detection limit is 0.002% of masses

151

Pulsed Nd:YAG Laser Welding of Ni-Alloy Hastelloy C-276 Foils  

Science.gov (United States)

In this study a pulsed Nd:YAG laser was used to join Hastelloy C-276 thin foil with 100 microns thickness. Pulse energy was varied from 1.0 to 2.25 J at small increments of 0.25 J with a 4 ms pulse duration. The macro and microstructures of the welds were analyzed by optical and electronic microscopy, tensile shear test and microhardness. Sound laser welds without discontinuities were obtained with 1.5 J pulse energy. Results indicate that using a precise control of the pulse energy, and so a control of the dilution rate, it is possible to weld Hastelloy C-276 thin foil by pulsed Nd:YAG laser.

Ventrella, Vicente Afonso; Berretta, José Roberto; de Rossi, Wagner

152

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

153

General principles of thermomechanical treatment in producing disk pressings for gas-turbine engines from high heat-resistant nickel alloys  

International Nuclear Information System (INIS)

The general principles of producing forgings of heat resistant nickel base alloys (Ni-Cr-Co-W-Mo-Nb-Al-Ti-C) are formulated. They include the requirements to chemical composition, structure, mechanical and processing properties of initial die-forgings, heating conditions for blanks to be worked, hot working and cooling conditions, recommendations on hardening heat treatment of the die-forgings with regard to their high tendency to hot cracking as well as the methods of acceptance control

154

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

155

Evaluation on materials performance of Hastelloy Alloy XR for HTTR uses. 3. Manufacture of filler metal and its weldability  

International Nuclear Information System (INIS)

Weldability on Hastelloy Alloy XR base metals and filler metals for the High Temperature Engineering Test Reactor (HTTR) components was examined by means of chemical analysis of deposited metals, optical microscopy, hardness measurements, FISCO and bend test. All of the results obtained by each test showed favorable performance. In particular, in the bend test which is considered to be critical pass, the optimization of B and C contents in the filler metal resulted in low susceptibility to weld cracking. Therefore, it is concluded that the excellent performance of the filler metal used and the effectiveness of narrowing groove are confirmed, and there is no problem from the viewpoint of engineering with respect to HTTR application. (author)

156

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)

157

Morphology and crystallography of M5B3 boride formation during high temperature ageing of heat resisting type ZhS6U alloys  

International Nuclear Information System (INIS)

Electron diffraction method is used to identify phases forming during long-term high-temperature (950 deg C) ageing of heat-resisting ZhS6U nickel alloy. The precipitated phase is identified as M3B3 type tungsten-chromium boride. Dimensional and orientation relations between crystal lattices of ?-solid solution and M5B3 phase are ascertained. The obtained results should be taken into account during high temperature experiments and utilization of products made of ZhS6U alloy

158

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.)

159

Creep rupture properties under varying load/temperature conditions on a nickel-base heat-resistant alloy strengthened by boron addition  

International Nuclear Information System (INIS)

A series of constant load and temperature creep rupture tests and varying load and temperature creep rupture tests was carried out on Hastelloy XR whose boron content level is 60 mass ppm at 900 and 1000 C in order to examine the behavior of the alloy under varying load and temperature conditions. The life fraction rule completely fails in the prediction of the creep rupture life under varying load and temperature conditions though the rule shows good applicability for Hastelloy XR whose boron content level is below 10 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 test conditions from 1000 to 900 C. The trend observed in the tests from 900 to 1000 C can be qualitatively explained by the mechanism that the oxide film which is formed during the prior exposure to 900 C plays the role of the protective barrier against the boron dissipation into the environment. (orig.)

160

Creep rupture properties under varying load/temperature conditions on a nickel-base heat-resistant alloy strengthened by boron addition  

International Nuclear Information System (INIS)

A series of constant load and temperature creep rupture tests and varying load and temperature creep rupture tests was carried out on Hastelloy XR whose boron content level is 60 mass ppm at 900 and 1000degC in order to examine the behavior of the alloy under varying load and temperature conditions. The life fraction rule completely fails in the prediction of the creep rupture life under varying load and temperature conditions though the rule shows good applicability for Hastelloy XR whose boron content level is below 10 mass ppm. The modified life fraction rule has been proposed based on the dependence of the creep rupture strength on the born content level of the alloy. The modified rule successfully predicts the creep rupture life under the test conditions from 1000degC to 900degC. The trend observed in the tests from 900degC 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. (author)

161

Comparison of laser, electron beam and argon arc welding of heat resisting KhN68VMTYuK nickel alloy  

International Nuclear Information System (INIS)

Comparison of the effect of laser, electron beam and argon arc welding (LW, EBW, AAW) on weld geometry, effectiveness of penetration and welded joint properties has been made. It has been shown that an aplication of laser welding for heat resisting KhN68VMTYuK alloy 1.5 m thick under rigid conditions conduces to a formation of high quality metal weld. This type of welding increases the process effectiveness, resistance to hot cracking and mechanical properties as compared to AAW and LW at small rates. It is inferior to EBW in all technological properties

162

Creep-rupture properties of Incoloy 800H, 2-1/4 Cr-1 Mo, and Hastelloy X alloys in simulated HTGR environment  

International Nuclear Information System (INIS)

Results of creep-rupture tests performed in a simulated HTGR helium environment (design basis helium) are presented and compared with available air data for Incoloy 800H, Hastelloy X, and 21/4 Cr--1 Mo steel. Tests were performed at temperatures representative of HTGR operating conditions for each alloy (900 to 16000F). Test durations to date were generally less than 4000 h. Results indicate that creep-rupture properties of these alloys in the test environment are consistent with the expected properties in air. Additional tests of 10,000 h duration are planned. 10 figures, 4 tables

163

Improvement of creep strength of TIG welded hastelloy X alloy joint  

International Nuclear Information System (INIS)

The creep strength of the TIG welded joints of Hastelloy X is sometimes weaker than that of the parent material. Especially in the internal pressure creep test using cylindrical test pieces, this phenomenon appears conspicuously. This is because in the case of the cylinders having circumferential joints, the rupture time becomes short due to the enhanced creep phenomenon, in which the welded metal is pulled by the parent material having large creep rate, and its creep rate increases. In order to improve this defect, it was attempted to improve the creep strength of the welded metal by adding B, Zr and rare earth elements to the welding rods. As the result, by adding several tens ppm of B, the weldability was not harmed, and the remarkable effect of improvement was observed. Also it was found that rare earth elements were considerably effective. In the cylindrical test pieces having joints, for which these improved welding rods were used, the joints which broke in the parent material were able to be obtained. As for the case of the cylindrical test pieces having circumferential and longitudinal joints, the comparison of creep strength was carried out, but nearly the same strength was shown, and it was proposed to regard the circumferential joints as important similarly to the longitudinal joints. (Kako, I.)

164

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)

165

Characteristics and experimental evaluation of super-heat-resisting Nb-based and Mo-based alloys  

Energy Technology Data Exchange (ETDEWEB)

Nb-based and Mo-based alloys have been investigated in order to develop the frontiers of materials technique which will be utilized in the environment of high-temperature liquid alkali metals. In this study, both mechanical properties and corrosion resistance to liquid Li were evaluated for two designed Mo-based alloys, Mo-15Re-0.1Zr and Mo-15Re-0.1Zr-0.1Ti. In addition, a series of corrosion test was performed with provisionally designed Nb-based alloys, Nb-(1-4)Hf. High-temperature tensile properties: The designed Mo-based alloys were found to have more excellent high-temperature tensile properties, compared to the commercial TZM alloy. High-temperature creep properties: The designed Mo-based alloys were superior in the high-temperature creep properties to other solid solution hardening Mo-based alloys. Workability: The designed Mo-based alloys exhibited an excellent workability, irrespective of the Ti addition. Corrosion resistance to liquid Li: The Nb-1Hf alloy was chosen as a promising alloy of having the highest corrosion resistance among the Nb-based alloys. Also, the Mo-15Re-0.1Zr-0.1Ti alloy was superior to Mo-15Re-0.1Zr alloy, in view of the corrosion resistance to liquid Li. (J.P.N.)

Morinaga, Masahiko; Furui, Mitsuaki; Noda, Kenji; Oda, Masaaki [Nagoya Univ. (Japan). School of Engineering

1997-03-01

166

Effect of crystallization character of a casting nickel alloy type ZhS6 on its heat resistance  

Energy Technology Data Exchange (ETDEWEB)

Results of studies in long-term strength and ductility are presented for a ZhS6U casting alloy with an equiaxial and directed structure. It is established that directed crystallization of the alloy raises its strength characteristics.

Golubovskij, E.R.; Bulygin, I.P.; Timofeeva, L.N.; Shershen-kova, E.Yu.

1982-05-01

167

Effect of crystallization character of a casting nickel alloy type ZhS6 on its heat resistance  

International Nuclear Information System (INIS)

Results of studies in long-term strength and ductility are presented for a ZhS6U casting alloy with an equiaxial and directed structure. It is established that directed crystallization of the alloy raises its strength characteristics

168

Relationship of H2O and CH4 supply rates in HTGR helium to the carburization of Hastelloy-X and alloy 800H  

International Nuclear Information System (INIS)

A detailed study of the carburization of Hastelloy-X and alloy 800H in high-temperature gas-cooled reactor helium was made to determine the cause of the wide variability of data generated in retorts. Data for 10000C and 2500-h exposure show that up to an order of magnitude difference in the carburization levels can be caused by changes in the flow rate of the test gas and/or the position of the corrosion specimen in the gas stream. The results are unambiguously explained by the parameters S(H2O) and S(CH4), the supply rates of water and methane, respectively

169

Influence of iron and beryllium additions on heat resistance of silicide coatings on TsMB-30 molybdenum alloy  

International Nuclear Information System (INIS)

Alloying of titanium modified silicide coatings on TsMB-30 molybdenum alloy with iron or beryllium is stated to improve their protective properties. Coatings with low content of alloying elements have the best protective properties. Service life of coatings is determined by the formed oxide film and phase transformations taking place in the coating

170

Optimization of the structure and composition of heat resisting alloys on the basis of Al-Cu-Mn-Zr-Cr system  

International Nuclear Information System (INIS)

The effects of composition and manufacturing technique on structure, low-temperature mechanical properties and heat resistance of the Al-Cu-Mn-Zr-Cr system as ingots and hot-rolled sheets are studied. It is established that in billets of 20 x 40 x 180 mm in size the solubility of zirconium and chromium in aluminium-copper solid solution can achieve 0.8% (mass) under the certain conditions. As a promising composition the composition Al-2.5% Cu-1% Mn-0.4% Zr-0.4% Cr is proposed which in form of hot-rolled sheets exceeds D 20 type alloy in low-temperature mechanical properties and high-temperature strength index at 400 deg C

171

Control method of purification system of helium coolant for suppressing decarburization of heat-resistant alloy used in very high temperature gas cooling reactors  

International Nuclear Information System (INIS)

It is important to control the chemistry of the helium coolant used in high-temperature gas-cooled reactors (HTGRs). The effect of a decarburizing environment on the creep rupture properties tends to decrease the creep rupture life of the heat-resistant alloy used in heat exchangers. In this paper, we describe an active control method for the concentration of impurities using the existing helium purification system, which consists of a helium heater, a copper oxide trap (CuOT), a molecular sieve trap, a cold charcoal trap, and a bypass line. Analysis showed that the efficiency control of CuOT is effective in improving the decarburizing atmosphere. The efficiency control of CuOT increases the concentrations of carbon monoxide and hydrogen. It was found that both the enrichment of carbon monoxide suggested in previous studies and the enrichment of hydrogen are also effective in forming the carburizing atmosphere. (author)

172

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

173

Evaluation on materials performance of Hastelloy Alloy XR for HTTR uses-6. Tensile and creep properties of heat exchanger tube base materials and its welded-joints  

International Nuclear Information System (INIS)

Tensile and creep properties of heat exchanger tube base materials and its welded-joints were investigated as a series of evaluation tests on Hastelloy Alloy XR heat exchanger tube and filler metal for the High Temperature Engineering Test Reactor (HTTR) components. As for tensile properties after thermal aging of base materials and welded joints, ductility was remarkably reduced at room temperature while it was raised at 950degC. On creep properties, the difference between base materials and welded joints in creep rupture strength was relatively small. Creep rupture elongation tended to decrease with increasing rupture time, and rupture elongation of welded joint had a tendency to be lower than that of base material. On the other hand, a comparison of plate with tube on high temperature tensile ductility after thermal aging was found to be higher in tube than in plate while its difference was slight at room temperature. As for creep properties, base materials and welded joints of tube had a tendency to be slightly shorter in rupture time at lower stress and long terms than those of plate. However, it is concluded that this is not problematic in practical uses from the fact that the rupture time in tube is comparable or greater than that of Hastelloy Alloy XR master curve and that it is much longer than that of design creep rupture strength =SR=. (author)

174

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

175

High-Temperature tensile and creep properties of hastelloy-X superalloy for the HTGR  

International Nuclear Information System (INIS)

The design of the metallic components for a High Temperature Gas cooled Reactor (HTGR) such as hot gas ducts, Intermediate Heat eXchanger (IHX) tube, and steam reformer tubes is principally carried out using the mechanical strength values of the tensile and creep properties. Elevated tensile and creep data for candidate alloys are needed to design the structural components operated at 900 to 1000 .deg. C. Hastelloy-X is a candidate heat-resistant alloy for the HTGR. In this study, the tensile and creep properties were investigated at the high temperature test conditions; 600 to 1000 .deg. C in tensile and 950 .deg. C in creep. A lot of data were collected through literature survey, and the data were analyzed in the viewpoint of the design of the HTGR structures. The fractured micrographs were also observed

176

Characterization of oxide layers of heat-resisting alloys in oxidizing and oxidizing/sulfidizing atmospheres by deuterium permeation measurement  

International Nuclear Information System (INIS)

Deuterium permeation measurements are suitable to characterize the integrity of layers, which are preoxidized or in-situ oxidized on high temperature alloys. The permeation through metal alloys with a growing oxidized layer is described by a model with a time dependence of the permeation flux related to the growth of the oxide layer. The behaviour of the layers, which are oxidized at different oxidizing atmospheres, are investigated in this work. By permeation test, parabolic rate constants, impeding factors, as well as permeability, diffusivity and the solubility of deuterium for the oxide layers are obtained. The measurement are continued in sulfidizing atmosphere for testing such layers as corrosion barrier. In correlation with microstructural post examinations it is found that permeation measurement can be utilized as a method for investigating high-temperature corrosion. (orig.)

177

Influence of coating on the properties of heat resistant gas turbine alloys. Pt. 1. Creep-rupture behaviour  

Energy Technology Data Exchange (ETDEWEB)

The influence of coatings and coating thermal cycles on the creep and creep-rupture behaviour of several nickel based gas turbine blade and vane alloys was evaluated. As a result of creep-rupture tests, the scatter bands of the rupture stress and of the stress to reach 0.2% plastic strain show in comparison to the uncoated materials decreased mean values and even more decreased lower bound values. At an austenitic steel for exhaust valves, no influence of coating was observed.

Ebeling, W.; Granacher, J.; Kloos, K.H.; Hagedorn, K.E.

1988-10-01

178

Effect of mechanical surface treatment on oxidation and carburization of some austenitic heat resisting alloys in the simulated HTGR helium environment  

International Nuclear Information System (INIS)

Influence of mechanical surface finishing on corrosion was studied with some austenitic heat resisting alloys exposed to the simulated HTGR helium environment. The exposure tests were made at 900 and 10000C for 500 and 1500h. Contrary to the prediction based on the trend of some conventional experimental results on the oxidation of cold worked material at comparatively low temperatures, severe cold working, e.g. shot-blasting, was found to accelerate oxidation and carburization. Although, in some cases, moderate surface grinding showed results almost comparable to the surface abraded with fine emery papers, most mechanical surface finishing were recognized as to promote oxidation and carburization at 900 and 10000C in the simulated HTGR helium. The oxide film formed on the ground or shot-blasted specimen tended to spall more easily during cooling after isothermal exposure at 10000C. Based on the metallographic observation mechanisms of the acceleration of oxidation and carburization was discussed. The surface cold work was considered to cause not only enhanced chromium diffusion to the surface but also considerable degree of inhomogeneity of the degree of working in the microscopic scale, resulting in rather rapid oxide build-up and spallation. Some of the surface finishing in practice with severe cold working, thus, were concluded to be harmful to the integrity of HTGR structural components. (author)

179

Fixed time integration-emission spectrochemical analysis of nickel-base alloys and heat resisting steels for minor amount of elements  

International Nuclear Information System (INIS)

The emission spectrochemical analysis of nickel-base alloys and heat resisting steels by the fixed time integration method has been developed. Nickel contents of 9 to 76% in the samples were examined in this study. For such samples, the internal standard method was inadequate, while the fixed time integration method gave good accuracy in the determination of minor elements in these samples. Elements analysed were C, P, S, B, Si, Ta, Co, Fe, Mn, Nb, Cu, Ti, Zr and Al. At first, ternary alloys containing a constant amount of cobalt (0.5, 1.0, 3.0, 6.0, 10.0, or 20.0%) with changing amounts of nickel and iron were prepared in order to examine the effect of nickel and iron content on the determination of these elements. It was found that the samples should be classified to two groups according to the nickel content, that is one group corresponding to 9 - 60% nickel and the other to 60 - 76%, and calibration curves had to be made separately. The equations of calibration curves were given in the regression lines of the first order in the determination of minor elements. For correcting the effect of neighbouring lines, coefficients of correction were derived by the multiple regression analysis. The relation between the sensitivity of analysis and the coefficient of correction was examined. As the sensitivity, the gradient of calibration curves was chosen, and it was observed that there was a linear correlation between the gradient and the partial regression coefficient. Afted the partial regression coefficient. After all, the relation of hyperbola was concluded to exist between the gradient and the coefficient of correction in the determination of most elements. The gradients of calibration curves in the two groups were almost the same, but the gradients of the group containing more amount of nickel were a little larger than those of the other. (author)

180

Vacuum-Induction, Vacuum-Arc, and Air-Induction Melting of a Complex Heat-Resistant Alloy  

Science.gov (United States)

The relative hot-workability and creep-rupture properties at 1600 F of a complex 55Ni-20Cr-15Co-4Mo-3Ti-3Al alloy were evaluated for vacuum-induction, vacuum-arc, and air-induction melting. A limited study of the role of oxygen and nitrogen and the structural effects in the alloy associated with the melting process was carried out. The results showed that the level of boron and/or zirconium was far more influential on properties than the melting method. Vacuum melting did reduce corner cracking and improve surface during hot-rolling. It also resulted in more uniform properties within heats. The creep-rupture properties were slightly superior in vacuum heats at low boron plus zirconium or in heats with zirconium. There was little advantage at high boron levels and air heats were superior at high levels of boron plus zirconium. Vacuum heats also had fewer oxide and carbonitride inclusions although this was a function of the opportunity for separation of the inclusions from high oxygen plus nitrogen heats. The removal of phosphorous by vacuum melting was not found to be related to properties. Oxygen plus nitrogen appeared to increase ductility in creep-rupture tests suggesting that vacuum melting removes unidentified elements detrimental to ductility. Oxides and carbonitrides in themselves did not initiate microcracks. Carbonitrides in the grain boundaries of air heats did initiate microcracks. The role of microcracking from this source and as a function of oxygen and nitrogen content was not clear. Oxygen and nitrogen did intensify corner cracking during hot-rolling but were not responsible for poor surface which resulted from rolling heats melted in air.

Decker, R. F.; Rowe, John P.; Freeman, J. W.

1959-01-01

181

Oxidation and creep tests of hastelloy-S in VHTR helium environment  

International Nuclear Information System (INIS)

Hastelloy-S, developed by Cabot Corp. for the applications involving severe cyclic heating condition, was tested for its potential applicability to VHTRs as one of the structural alloys. It is said that the alloy has excellent microstructural stability, low thermal expansion and outstanding oxidation resistance. The corrosion test and creep test of the alloy-S were carried out in simulated VHTR helium environment, and the results were compared with those of Hastelloy-XR ehich is one of the candidate materials for VHTR structural components. The results obtained were as follows. The oxidation resistance of the alloy-S was better than that of the alloy-XR. The oxidation resistance was increased by lowering the Cr content and increasing the relative ratio of Mn to Cr in Ni-base alloys. Localized oxidation was observed in the alloy-S at grain boundaries due to the internal oxidation of Al contained in the alloy. The creep strength of the alloy-S was lower than that of the alloy-XR. The comparison of creep property was made between the as-received material and the material with coarse grains formed by heat treatment. From the results obtained so far, it was judged that the alloy-S has not sufficient capability to be substituted for the alloy-XR. (Kako, I.)

182

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.)

183

Creep property of hastelloy X and incoloy 800 in a helium environment  

International Nuclear Information System (INIS)

To clarify the mechanism of the effect of helium environment on the creep properties of heat resistant alloys, relations of creep curves to the surface finish of test specimens, the development of creep cracks and oxidation kinetics etc. have been examined. Incoloy 800 at the temperature of 7500C indicates scarecely any environmental effect within the range of primary and secondary creep zones. Enhancement in the creep rate is noticed, however, at the tertiary creep zone under the helium environment. This finding is correlated to the fact that the crack, once initiated on the surface of the test specimen, propagates more easily because of the less oxidation under the helium environment. Importance of process control shall be emphasized for the manufacture of Hastelloy X since it has become clear that the effect of grain size on the creep strength is more pronounced than that of environment. (author)

184

Creep curve formularization at 950degC for Hastelloy XR  

International Nuclear Information System (INIS)

Creep tests under constant stress were conducted on a nickel-base heat-resistant alloy, Hastelloy XR, in air at 950degC. Minimum creep strain rate, time to the onset of tertiary creep and time to rupture were obtained as a function of applied stress. Then, a creep constitutive equation was made based on the Garofalo formula for primary and secondary creep and based on the Kachanov-Rabotnov formula for tertiary creep, which could represent fairly well the experimental creep deformation curves under the constant stress conditions. The creep deformation under the constant load condition corresponding to the stress increment was analysed using the creep constitutive equation and strain hardening law. Then the calculated creep strain showed slightly higher value than the experimental creep strain, and the calculated life was shorter than the experimental one. (author)

185

Tungsten powder alloys with carbide hardening as materials for reinforcing fibres in heat resistant composite materials. Communication 1.Manufacture of powder tungsten carbide-hardened alloys  

International Nuclear Information System (INIS)

Factors affecting the possibility of stabilization in tungsten powder alloys of high-melting hardening interstitial phases (carbides, borides and nitrides of 4 group metals) are considered: presence of oxygen from the atmosphere and that asorbed on the surface of powder particles within W-MeC(MeB2, MeN) system; temperature of sintering occurrence of interstitial elements or phases interacting with oxygen more actively that the phase (HfC) that should be stabilized in the system. Measures allowing to prepare tungsten powder alloys using standard process equipment are suggested

186

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)

187

Research for developing heat resistant superalloys  

International Nuclear Information System (INIS)

For the purpose of developing economical heat resistant alloys of Fe base by the casting dispersion of TiC, the composition of the base metal was examined. As the result, it was found that Fe-35Ni-20Cr was the strongest. Also, as the amount of dispersion of TiC, it was clarified that from 8 to 10 % was most suitable. As the base of Ni base heat resistant alloys of solid solution strengthening type, the result that Ni-Cr-W was the most excellent was obtained. Also the elements of very small amount were examined, and it was shown that the combined use of Nb and B was the most effective, but in the addition of Nb more than 1.6 %, harmful intermetallic compound was formed. The effect of elements added to Ni-20 Cr alloy on its creep rupture life in He was examined, and as the result, it was found that the life time tended to deteriorate in He as compared with in the atmosphere. As the reason, the stress concentration due to the sharpening of crack tips in He and the selective oxidation of added elements mainly at grain boundaries were conceivable. Ni-20Cr-3W alloy showed abnormally large creep rupture life and elongation on low stress side in oxidizing atmosphere at 1000 deg C, and this was due to the obstruction of crack propagation in accelerating creep stage by oxidation. (Kako, I.)

188

Fundamental studies on electron beam welding of heat-resistant superalloys for nuclear plants, (3)  

International Nuclear Information System (INIS)

Hot cracks are apt to occur in the electron beam welds of heat-resistant superalloys for nuclear plants as Hastelloy-type, Inconel-type, Incoloy-type ones, etc. The authors experimentally produced a new type of Inconel 617 by the addition of Nb to improve the sensitivity to microcracking of commercial Inconel 617 which was proved to be most susceptible to microcracking. Thereafter, its electron beam welds were examined for sensitivity to hot cracking. Results show that the liquation of the main precipitate NbC hardly takes place when Nb is added at approximately 2% level or more, and microcracks satisfactorily disappear with the addition of Nb at approximately 4% level. Therefore, it is generally considered to be effective as one of the preventive measures against microcracks to add this alloying element so that both melting temperature of the precipitate, and the temperature to start eutectic reaction between precipitate and matrix, ? fall above the temperature at which the matrix begins to melt. (author)

189

Thermal treatment of a heat resistant gas-thermal coating  

International Nuclear Information System (INIS)

Specimens of heat resistant cast alloy ZhS6U with gas-thermal coatings containing aluminium and chromium are taken to study the effect of heat treatment on the coating structure and the state of a coating - substrate interface. It is revealed that the heating of the substrate up to 900 deg C, when ZhS6U alloy coating, promotes hardening of the heat resisting coating and doubles adhesion strength. Vacuum annealing at 1000 deg C for 2 h decreases the level of residual stresses by a factor of 3 and provides needed adhesion between the substrate and the coating in gas turbine blades

190

Nickel Alloy, Corrosion and Heat-Resistant, Sheet, Strip, and Plate 72Ni - 15.5Cr - 0.95 (Cb (Nb) + Ta) - 2.5Ti - 0.70Al - 7.0Fe Consumable Electrode, Remelted or Vacuum Induction Melted, Solution Heat Treated, Precipitation-Hardenable  

CERN Document Server

Nickel Alloy, Corrosion and Heat-Resistant, Sheet, Strip, and Plate 72Ni - 15.5Cr - 0.95 (Cb (Nb) + Ta) - 2.5Ti - 0.70Al - 7.0Fe Consumable Electrode, Remelted or Vacuum Induction Melted, Solution Heat Treated, Precipitation-Hardenable

SAE Aerospace Standards. London

2012-01-01

191

Prediction of regularities in changes of properties of nickel-base heat resistance alloys in dependence on chromium, cobalt, niobium and tungsten contents  

International Nuclear Information System (INIS)

Dependence of specific electric resistance of Ni-Al-Ti-Nb-Cr-Co-W system alloys on temperature and content of alloying elements is studied to obtain calculation ratios permitting to predict the dependence of physical properties on the chemical composition. It is shown, that the alloy has the maximum value of electric resistance at maximum Cr, W, Nb contents and at minimum Co content. Character of temperature dependence is connected mainly with processes on the boundaries of ?- and ?'-phases. Experimental data are presented in the form of mathematical dependences

192

Corrosion behavior of aged hastelloy C-276  

International Nuclear Information System (INIS)

The alloy containing Ni, Cr, Mo, Fe, W, named Hastelloy C-276, has applications in corrosive media at high temperatures, Commercially available Hastelloy C-276 has been aged at 850 degree C for different intervals of time form 24 to 192h to investigate the corrosion behavior after ageing. Samples are subjected to corrosion in the boiling ferric sulfate sulfuric acid solution unto 30h. Corrosion rate was determined after every six hour of immersion. SEM examination of corrosion tested specimens reveals that preferential attack has taken place at the grain boundaries and the precipitates. Reduction in Mo and W concentration in the precipitates indicates that meu-phase precipitates, produced during heat treatment, are preferentially attacked by the medium. (author)

193

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

International Nuclear Information System (INIS)

In order to carry out the structural design of high temperature pipings, intermediate heat exchangers and isolating valves for a multipurpose high temperature gas-cooled reactor, in which coolant temperature reaches 1000 deg C, the creep characteristics of Hastelloy X used as the heat resistant material must be clarified. In addition to usual creep rupture life and the time to reach a specified creep strain, the dependence of creep strain curves on time, temperature and stress must be determined and expressed with equations. Therefore, using the creep data of Hastelloy X given in the literatures, the creep constitutive equation was made. Since the creep strain curves under the same test condition were different according to heats, the sensitivity analysis of the creep constitutive equation was performed. The form of the creep constitutive equation was determined to be Garofalo type. The result of the sensitivity analysis is reported. (Kako, I.)

194

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)

195

Effect of low-temperature thermomechanical treatment on the heat resistance of low alloys of the Mo-Zr-C and Mo-Zr-Nb-C systems  

International Nuclear Information System (INIS)

Investigated was the low-temperature thermomechanical treatment (hardening from 2100 deg C, hydraulic extrusion with a reduction of 40% + ageing at 1200 deg C) upon the long-term strength at 1100 and 1300 deg C of molybdenum alloys with additions of zirconium and niobium. It was found, that the treatment enhances the long-term strength of alloys of the Mo-Zn-C and Mo-Zr-Nb-C systems at the test temperature of 1100 deg C 1.7-2 times as compared to hardening and ageing. At 1300 deg C, the considerable increment of the long-term strength is observed only during short test. The addition of 0.2 weight % Nb raises the long-term strength of the Mo-Zr-C alloys

196

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

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer Determining the intermetallics of the Mg-4Al-2Sr-1Ca alloy in as-cast and as-annealed state. Black-Right-Pointing-Pointer Grain boundary phases play an important role during creep. Black-Right-Pointing-Pointer 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 {alpha}-Mg and grain boundary intermetallics, predominantly lamellar eutectic C14-Mg{sub 2}Ca and bulky Mg-Al-Sr ternary phase. In addition, small amounts of C36-(Mg, Al){sub 2}Ca and Mg{sub 17}Sr{sub 2} phases were also observed. Annealing at 400 Degree-Sign 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 Degree-Sign C and applied stresses between 50 and 80 MPa. Annealing at 400 Degree-Sign 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.

Bai Jing, E-mail: baijing@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Jiangning, 211189, Nanjing (China); Sun Yangshan; Xue Feng; Zhou Jian [School of Materials Science and Engineering, Southeast University, Jiangning, 211189, Nanjing (China)

2012-01-01

197

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

198

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

199

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

200

Precipitation studies in hastelloy C-276  

International Nuclear Information System (INIS)

Commercially available Hastelloy C-276 has been examined for precipitation behavior and mechanical properties. The alloy has been aged at 650 and 850 C for 1-240 hrs time intervals. Hardness has been measured as a function of ageing time. Hardness increases with time at higher ageing temperature while it remains constant at lower temperature. Electron microscope examination revels Mo rich precipitates at 850 C and their density being increase with time. Preliminary results on the fracture toughness shows that the materials fails mainly through brittle mode. (author)

201

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

202

Kinetics of evaporation and ablation of goods made from heat-resistant alloys with protective coatings under irradiation with high-power ion beams  

International Nuclear Information System (INIS)

The kinetics of ablation of the surface layers of the specimens and gas-turbine engine (GTE) vanes made from the Ti- and Ni-based alloys with erosion-resistant coatings under the action of power pulse ion beams (PPIB) at different pulse current density has been studied. The basics of ecology-pure ion-beam technologies of repairing GTE vanes with different protective coatings are developed. It is shown that a powerful ion beam of millimicrosecond duration is quite an efficient tool for repairing compressor blades and a turbine with protective coatings. PPIB application makes it possible to remove the surface layers of 0.04 (TiSiB) up to 1 ?m (ZrN) thickness for one impulse

203

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

204

Influence of temperature, environment, and thermal aging on the continuous cycle fatigue behavior of Hastelloy X and Inconel 617  

International Nuclear Information System (INIS)

Results are presented for strain-controlled fatigue and tensile tests for two nickel-base, solution-hardened reference structural alloys for use in several High-Temperature Gas-Cooled Reactor (HTGR) concepts. These alloys, Hastelloy X and Inconel 617, were tested from room temperature to 8710C in air and impure helium. Materials were tested in both the solution-annealed and the preaged conditios, in which aging consisted of isothermal exposure at one of several temperatures for periods of up to 20,000 h. Comparisons are given between the strain-controlled fatigue lives of these and several other commonly used alloys, all tested at 5380C. An analysis is also presented of the continuous cycle fatigue data obtained from room temperature to 4270C for Hastelloy G, Hastelloy X, Hastelloy C-276, and Hastelloy C-4, an effort undertaken in support of ASME code development

205

The new alloy Thermon 4972 (NiCr22W12Fe) for high temperature components of gas-cooled reactors  

International Nuclear Information System (INIS)

A new heat resistant Fe-Ni-Cr-W alloy - Thermon 4972 - was developed within the scope of the prototype nuclear process plant project. This new alloy not only shows mechanical properties and creep rupture properties similar to those of the nickel-based alloy Inconel 617 but in addition, the new alloy forms protective oxide layers in atmospheres with very low O2 partial pressures. Experimental test results carried out in so called PNP-helium for durations up to 2000 h in the temperature range of 750 and 950 deg. C are compared with those of the alloy Inconel 617. Furthermore the mechanical properties of these two alloys as also the alloys Hastelloy X and Incoloy 800 H have been compared. (author). 5 refs, 18 figs, 2 tabs

206

Creep properties of Hastelloy-X in impure helium environments  

International Nuclear Information System (INIS)

In impure helium environments, Hastelloy-X is susceptible to carburization and oxidation. These effects are investigated separately, and are related to the creep behavior of the alloy. Experiments were carried out at 9000C in both helium and air. Carburization resulted in a slight increase of the creep strength up to the onset of the tertial creep. Suppression of the creep crack growth by oxidation was confirmed using notched plate specimens of Inconel alloy 600 and Hastelloy-X. Although the difference of creep strength in air and in helium was very small and considered to be inclusive in the usual scatter, a pessimistic ratio of rupture stress in helium to that in air was estimated to be 0.9

207

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

208

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)

209

High-temperature stress rupture performance of Hastelloy C-276  

Energy Technology Data Exchange (ETDEWEB)

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)

Ma, Y.; Lu, D.G. [North China Electric Power Univ., School of Nuclear Science and Engineering, Beijing (China)

2010-07-01

210

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)

211

Creep properties and simulation of weld repaired low alloy heat resistant CrMo and Mo steels at 540 deg C. Sub project 1 - Ex-serviced parent metal and virgin weld metals  

Energy Technology Data Exchange (ETDEWEB)

Many existing power generating and process plants, where low alloy heat resistant CrMo(V) steels are extensively used for critical components, have exceeded their design lifetime of usually 100,000 hours. Assessment of residual lifetime and extension of economic life by weld repair have become increasingly important and attractive. This project aims at i) performing weld repair and determining the degree of mismatching, ii) evaluating the creep properties of weld repairs, iii) analysing creep behaviour of weld repair and providing necessary data for further reliable simulations of weld repair creep behaviour in long term service, and iv), simulating and assessing lifetime and creep damage evolution of weld repair. Weld repair using 10 CrMo 9 10, 13 CrMo 4 4 and 15 Mo 3 consumables has been carried out in a service-exposed 10 CrMo 9 10 pipe. Creep specimens have been extracted from the service-exposed 10 CrMo 9 10 parent metal (PM), from the virgin 10 CrMo 9 10 weld metal (WM), from the virgin 13 CrMo 4 4 WM as well as from the virgin 15 Mo 3 WM. Iso-thermal uniaxial creep tests have been performed at 540 deg C in air. Pre- and post-metallography are carried out on the selected samples. FEM simulations using obtained creep data are executed. Pre-test metallography shows normal and acceptable weld repairs at given welding conditions. Creep tests demonstrate that the virgin 10 CrMo 9 10, 13 CrMo 4 4 and 15 Mo 3 WMs have apparently longer creep lifetime than the service-exposed CrMo 9 10 PM at higher stresses than 110 MPa. Among the weld metals, the longest creep lifetime is found in 10 CrMo 9 10. Higher creep strength and lower creep strain rate in the weld metals indicate an overmatch weld. At 95 MPa, however, lifetime of 13 CrMo 4 4 WM is surprisingly short (factors which may shorten lifetime are discussed and one more test will start to verify creep strength at low stress) and tests are still running for other two weld metals. More results regarding low stress creep behaviour will therefore be available at phase 2 of the project. Together with the results of creep tests on the crosswelds and simulations, concrete conclusions and recommendations will be also given at phase 2 of the project. Transgranular failure is predominant, independent of stresses and materials. Pores/cavities are only found adjacent to the fracture. FEM simulations using obtained creep data predict fracture in corresponding weld metal. Extrapolation of the creep results to service stress, i.e. 35 MPa, results in undermatched welds for repairs with 13 CrMo 4 4 and 15 Mo 3 weld metals. Norton's law, Monkman-Grant relation and {phi}- and {omega}-models (strain-strain rate) are valid for both parent and weld metals. These models can be utilised for lifetime assessment and reproduction of creep curves. Using {phi}- and {omega}-models, creep curves have been successfully reproduced and the reproduced creep curves are comparative with the experiments. Creep tests on the weld metals at low stress as well as on cross-weld specimens at phase 2 of the project are expected to provide more results, comprehensive understanding of creep behaviour in weld repair as a whole and reliable simulations.

Rui Wu; Storesund, Jan; Borggreen, Kjeld; Weilin Zang

2006-10-15

212

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

213

Creep properties of heat-resistant superalloys for nuclear plants in helium  

International Nuclear Information System (INIS)

In order to estimate the creep and rupture strengths of candidate alloys for the intermediate heat exchanger of VHTR, creep and stress rupture tests in impure helium were conducted on Hastelloy X, Inconel 617, Inconel 625, Incoloy 800 and Incoloy 807 at 9000C. The results were discussed in comparison with those in air and the alloys were examined from the point of view of the elevated temperature structural design. The main results obtained are summarized as follows: (1) No appreciable decrease in creep and rupture strengths in helium as compared with those in air is observed on Hastelloy X and Inconel 625. On the contrary, the creep and rupture strengths of Inconel 617 in helium decrease slightly as compared with those in air. In the case of Incoloy 807, the creep strength to cause 1 percent total strain and that to initiate secondary creep increase remarkably in helium as compared with those in air. However, the creep strength to cause initiation of tertiary creep and the rupture strength in helium remarkably decrease as compared with those in air. (2) The order of magnitude of the S0 value for each material in helium is as follows; Hastelloy X > Inconel 617 > Incoloy 807 > Inconel 625 > Incoloy 800 Meanwhile, that of the S sub(t) value in helium is; Inconel 617 > Hastelloy X > Incoloy 807 > Inconel 625 > Incoloy 800. (author)

214

Composition of eta carbide in Hastelloy N after aging 10,000 hr at 8150C  

International Nuclear Information System (INIS)

The composition of the eta carbide in Hastelloy N containing 0.7 wt percent Si in the alloy approaches M12C, rather than M6C as indicated in the alloy literature. The silicon content of the eta phase in this case was about 25 at. percent, much higher than has been observed in less highly alloyed material. The data do not permit a definition of the limiting compositions of the phases

215

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.

Brinkman, C. R.; Rittenhouse, P. L.

1976-01-01

216

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

217

Effect of temperature upon the fatigue-crack propagation behavior of Hastelloy X-280  

International Nuclear Information System (INIS)

The techniques of linear-elastic fracture mechanics were employed to characterize the effect of temperature upon the fatigue-crack propagation behavior of Hastelloy X-280 in an air environment. Also included in this study are survey tests to determine the effects of thermal aging and stress ratio upon crack growth behavior in this alloy

218

The corrosion behavior of molybdenum and Hastelloy B in sulfur and sodium polysulfides at 623 K  

International Nuclear Information System (INIS)

An experimental study was completed to determine the corrosion behavior of molybdenum and Hastelloy B, a nickel-based alloy with high molybdenum content, in sulfur and sodium polysulfides (Na/sub 2/S/sub 3/,Na/sub 2/S/sub 4/, Na/sub 2/S/sub 5/) at 623 K. In sulfur, molybdenum corrodes very slowly, with a parabolic rate constant of 3.6 x 10/sup -9/ cm s/sup -1/2/. Hastelloy B shows no measurable corrosion after 100h of exposure to sulfur. The corrosion reaction of molybdenum in Na/sub 2/S/sub 3/ is characterized by the formation of a protective film that effectively eliminates further corrosion after the first 100h of exposure. Hastelloy B, however, corrodes rapidly in Na/sub 2/S/sub 3/, with corrosion rates approaching those of pure nickel under the same conditions. After the first 4h of exposure, the kinetics for the corrosion of Hastelloy B in Na/sub 2/S/sub 3/ follows a linear rate law. The scale morphology has multiple spalled layers of NiS/sub 2/, with some crystallites of NiS/sub 2/ appearing on the leading face of the scale and between the individual scale layers. This spalling causes smaller coupons of the Hastelloy B to corrode faster than larger coupons

219

Creep properties of heat-resistant superalloys for nuclear plants in helium  

International Nuclear Information System (INIS)

Creep properties of candidate superalloys for VHTR components in a helium environment at both temperatures of 8000C and 9000C were compared with those of the same alloys in the atmospheric condition, and the superalloys were contrasted with each other from the viewpoint of high temperature structural design. At 8000C, no significant effect of a helium environment on creep properties of the superalloys is observed. At 9000C, however, creep strength of Inconel 617, Incoloy 800 and Incoloy 807 in the helium environment decrease more than in the atmospheric environment. In Hastelloy X and Inconel 625, there is no significant difference between creep strengths in helium and those in the atmospheric condition. Concerning So and St values in helium at 9000C, Inconel 617 and Hastelloy X are clearly superior to other superalloys. (author)

220

Alloys For Flexible Hoses In A Corrosive Environment  

Science.gov (United States)

High-nickel alloy resists pitting corrosion. Report evaluates metal alloys for flexible hoses in corrosive environment. Tested to find alternatives to 304L stainless steel. Nineteen alloys selected for testing on basis of reputation for resistance to corrosion. Top five, in order of decreasing resistance to corrosion: Hastelloy(R) C-22, Inconel(R) 625, Hastelloy(R) C-276, Hastelloy(R) C-4, and Inco(R) alloy G-3. Of these, Hastelloy(R) C-22 found best for flexible-hose application.

Macdowell, Louis G., III; Ontiveros, Cordelia

1992-01-01

221

CORN CULTIVAR IDENTIFICATION THROUGH HEAT RESISTANT PROTEINS  

Directory of Open Access Journals (Sweden)

Full Text Available Stable and polymorphic markers are required for the identification and registration of the cultivars. The purpose of this research was to evaluate the heat resistant proteins polymorphism and stability of seeds from corn lines harvested in different years and dried under natural and artificial conditions, in order to employ such proteins in the identification and registration of the cultivars. The seeds showed different physiological quality when evaluated by germination test and the heat resistant proteins were extracted from embryonic axis from seeds of each line, in Tris-HCl 0,05 M buffer. The eletrophoretic patterns of these proteins in SDS-PAGE showed stable bands for each genotype even for the lines with higher variation in the germination test. The most similar corn inbred lines were distinguished, at least by two bands, showing that these proteins were highly polymorphic. The stability and the high level of polymorphism of the heat resistant proteins, make them potential markers in corn cultivars registration and identification programs.

SOLANGE CARVALHO BARRIOS ROVERI JOSÉ

2004-04-01

222

Exposure of heat resistant materials in a synthetic biogas  

Energy Technology Data Exchange (ETDEWEB)

Uncooled specimens of nine heat resistant alloys have been exposed to a gas, similar to that occurring in biomass gasification. The test temperature wax {approx} 900 deg C and the exposure time {approx} 2000 hours. The flow rate of the gas was so high that it never reached its equilibrium composition. Thermodynamical evaluations indicated that, besides oxidation, both sulphidation and carbon pick-up were possible corrosion modes. In the post test examinations, however, only oxidation could be confirmed. Most alloys were only slightly attacked, since a protective chromia rich oxide layer was formed on all specimens as a result of the low oxygen partial pressure of the gas. However, in Alloys 601 and 800, the low oxygen activity led to the formation of an internal grain boundary alumina network. 353 MA was even more severely attacked. The formation of an internal silica network seems to have initiated catastrophic oxidation attacks on several locations. This unexpected behaviour is probably a result of the sheet specimen`s being heavily cold deformed and not annealed afterwards. 11 refs, 16 figs, 2 tabs

Ivarsson, Bo [Avesta Sheffield Research and Development (Sweden)

1996-08-01

223

Anodic corrosion of Hastelloy-C in sulfuric acid solution  

International Nuclear Information System (INIS)

The corrosion behavior of anodically polarized Hastelloy-C was investigated in an 1N sulfuric acid solution by using various methods as follows; e.g. potentiostatic and potentiokinetic polarization characteristic measurements, colorimetric analyses of the dissolved alloy elements and ESCA method. Both of the two kinds of polarization characteristic measurements gave results indicating that the alloy behaved in three different ways according to the potential from -0.2 to 1.0 Volt vs S.C.E. Below 0.2 V, although iron tended to selectively dissolve, the total amount of dissolution was very slight and the alloy was almost maintained in a passive state. At the potential between 0.2 and 0.8 V, local attack of the alloy and selective dissolution of molybdenum were observed. The electrolytic current reached its maximum value at 0.6 V, and a steep rise of the current was observed at about 0.9 V. Above the latter potential, the alloy was uniformly attacked and all elements dissolved in proportional manner to their alloy contents. Different ESCA spectra were also obtained according to the polarization potential. (auth.)

224

Nickel aluminide base alloys  

International Nuclear Information System (INIS)

The possibility to replace commercial heat resisting nickel base alloys of ZhS6U type with nickel aluminide base ones is under consideration. The alloys based on Ni3Al and NiAl are examined and ways to increase their ductility, heat resistance and strength in a wide temperature range are determined

225

Investigation of the creep behaviour of heat resistant gas turbine alloys. [Materials: Inconel 718, FSX 414, Udimet 500, IN-713C, IN-100, IN-738LC, IN-939, Nimonic 101  

Energy Technology Data Exchange (ETDEWEB)

The high temperature deformation behaviour of typical investment cast materials and wrought alloys is measured in tensile tests, continuous and interrupted creep tests and annealing tests. In a special evaluation method the strain values determined in the different tests are combined. Examples for characteristic creep values and for creep equations are given.

Kloos, K.H.; Granacher, J.; Bartsch, H.

1986-06-01

226

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

227

Effect of forced cooling during welding on thermal cracking of heat resistant precipitation-hardened materials  

International Nuclear Information System (INIS)

A method has been suggested for preventing base-metal cracks in welding of age-hardening Ni-based heat resistant alloy. The said method consists in forced cooling of welds by liquid-coolants (water, liguid nitrogen or argon). It was shown that the above method enhances resistance of welds to cracking on reheatings. The resistance of the heat affected zone to thermal cracking increases with the increase in cooling rate in the temperature range of intensive ageing

228

Creep of heat resisting materials under thermal cycling  

International Nuclear Information System (INIS)

Investigation results for creep of heat resisting materials (0Kh16N15M3B austenitic steel, the ZhS-6U nickel base alloy) under thermal cycling conditions are presented. The investigations have been carried out at the constant temperature and under conditions of saw-like temperature cycle at the constant load. Cyclic tests of the austenitic steel have been carried out in the temperature range of 400 reversible 700 deg C, the ZhS-6U alloy has been tested in the temperature range of 600 reversible 1100 deg C. Expe netal confirmation of the suggested conception of the account of cyclic change of the mechanical properties of the material under conditions of non-isothermal creep is obtained. Application possibility for the hypothesis of the transformed time to calculate the steady creep rate under thermal cycling conditions according to the results of isothermal tests for the materials having weak dependence of the yield limit on the temperature is shown

229

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

230

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

OpenAIRE

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...

Graneix Jérémie; Beguin Jean-Denis; Pardheillan François; Alexis Joël; Masri Talal

2014-01-01

231

Corrosion behavior of Hastelloy C-276 in supercritical water  

International Nuclear Information System (INIS)

The corrosion behavior of a nickel-based alloy Hastelloy C-276 exposed in supercritical water at 500-600 deg. C/25 MPa was investigated by means of gravimetry, scanning electron microscopy/energy dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. An oxide scale with dual-layer structure, mainly consisting of an outer NiO layer and an inner Cr2O3/NiCr2O4-mixed layer, developed on C-276 after 1000 h exposure. Higher temperature promoted oxidation, resulting in thicker oxide scale, larger weight gain and stronger tendency of oxide spallation. The oxide growth mechanism in SCW seems to be similar to that in high temperature water vapor, namely solid-state growth mechanism.

232

Corrosion behavior of Hastelloy C-276 in supercritical water  

Energy Technology Data Exchange (ETDEWEB)

The corrosion behavior of a nickel-based alloy Hastelloy C-276 exposed in supercritical water at 500-600 deg. C/25 MPa was investigated by means of gravimetry, scanning electron microscopy/energy dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. An oxide scale with dual-layer structure, mainly consisting of an outer NiO layer and an inner Cr{sub 2}O{sub 3}/NiCr{sub 2}O{sub 4}-mixed layer, developed on C-276 after 1000 h exposure. Higher temperature promoted oxidation, resulting in thicker oxide scale, larger weight gain and stronger tendency of oxide spallation. The oxide growth mechanism in SCW seems to be similar to that in high temperature water vapor, namely solid-state growth mechanism.

Zhang Qiang [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, P.O. Box 436, Chendu 610041 (China); Tang Rui [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, P.O. Box 436, Chendu 610041 (China)], E-mail: xajttr@163.com; Yin Kaiju; Luo Xin [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, P.O. Box 436, Chendu 610041 (China); Zhang Lefu [College of Nuclear Science and Technology, Shanghai Jiaotong University, Shanghai 200240 (China)

2009-09-15

233

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

234

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)

235

Disk-laser welding of Hastelloy X cover on René 80 turbine stator blade  

Science.gov (United States)

Nickel-base alloys, such as Hastelloy X and René 80, are among the most common ones for aerospace applications, due to their mechanical strength at high temperatures and oxidation resistance properties, although processing for missile and space vehicle applications requires extensive fusion and resistance welding for fastening. Laser welding using a Yb:YAG disk laser in continuous mode emission is investigated in this paper for overlap joining of Hastelloy X plates on René 80 samples resulting from waste turbine blades. An explorative study is carried out in order to find an appropriate processing window as well as discussing bead features and common issues. Special fixtures for clamping have been specifically developed and tested. A 3-factors study with power, welding speed and focus position as governing parameters has been arranged; 2 levels have been chosen for each factor. Geometric features, defects and indications are discussed referring to the parameters main effects.

Caiazzo, Fabrizia; Corrado, Gaetano; Alfieri, Vittorio; Sergi, Vincenzo; Cuccaro, Luigi

2012-01-01

236

Fatigue and uniaxial deformation behavior of Hastelloy XR at elevated temperatures  

International Nuclear Information System (INIS)

Fully reversed continuous cycling tests and tensile tests were conducted on Hastelloy XR at temperatures ranging from 600 deg C to 950 deg C in air. Fatigue life of Hastelloy XR depends on temperature. A series of SEM observation revealed that transgranular fracture with evident striation formation was dominant at temperatures below 800 deg C, while intergranular cracking was found above 900 deg C. These results suggest that creep mechanism takes place in the fatigue behavior of this alloy above 900 deg C. Numerical analyses of deformation behavior during fatigue and tensile tests were conducted to interpret the experimental results. Conventional elastic-creep constitutive equation gave a good prediction of this deformation process. (author)

237

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)

238

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.)

239

Creep properties of 20% cold worked hastelloy XR  

International Nuclear Information System (INIS)

Creep properties of Hastelloy XR, in 20% cold worked or solution treated condition, were studied at 800, 900 and 1000degC. The results obtained are as follows: (1) At 800degC, creep rupture time of 20% cold worked Hastelloy XR is longer than that of solution treated one. However, the effect disappears above 900degC. At 1000degC, it becomes shorter than that of solution treated Hastelloy XR. (2) Rupture elongation and reduction of area of 20% cold worked Hastelloy XR are smaller than those of solution treated one. While these values of 20% cold worked Hastelloy XR are lowest at 900degC, they recover considerably at 1000degC. (3) Nonclassical creep curves which have the region with low creep rate at an early stage of creep were observed at high temperatures for Hastelloy XR, in 20% cold worked or solution treated condition. (4) Minimum creep rate, ?m, of 20% cold worked Hastelloy XR is decreased by as much at a factor of 20 to 50 at 800 and 900degC. On the other hand, ?m of 20% cold worked Hastelloy XR is increased by as much as a factor of 2 at 1000degC. (5) Although 20% cold work enhances creep resistance of Hastelloy XR at 800 and 900degC, the effect becomes detrimental at 1000degC where dynamic recrystallization occurs during creep. (author)

240

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

241

Improved Ni--Cr--Mo alloy for corrosion service  

International Nuclear Information System (INIS)

A new Ni-Cr-Mo corrosion resistant alloy, Hastelloy alloy C-4, has been developed that does not precipitate an intermetallic Mu phase upon aging in the 650 to 10900C temperature range. This further improvement of Hastelloy alloy C-276 has evolved from a detailed study of the effects of the substitutional and interstitial elements on the precipitation of intermetallic and carbide phases. Data have been generated to show that Hastelloy alloy C-4 is basically equivalent in corrosion resistance to its predecessors in both oxidizing and reducing media

242

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

243

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

244

Effect of grain size on high temperature creep properties of Hastelloy X  

International Nuclear Information System (INIS)

The effect of grain size, ranged from 37 to 1220 ?m, on creep behavior of Hastelloy X was studied at temperatures of 950, 1000 and 10500C. A steady state creep rate, epsilon* sub(s) (*: radical), of the alloy decreased with the increase of the grain size, reached a minimum at the grain size of 100 -- 200 ?m, L sub(M), and increased with the increase of that. From measurements of friction stress (?sub(f)) and observations of microstructures, it is concluded that the increase in epsilon* sub(s) (*: radical) under a given applied stress with the decrease of the grain size is attributable to the increase of an effective stress, ?sub(e)(= ?sub(a) - ?sub(f)), where ?sub(a) is the applied stress). On the other hand, recrystallization induced by a high stress concentration at grain boundary triple points in the coarse-grained alloys seems to accelerate the creep. By comparing the results in the Hastelloy X with those in carbon free 17Cr-14Ni steel, it is suggested that the grain size dependence of the epsilon* sub(s) (*: radical) of the Hastelloy X having finer grains than L sub(M) is more remarkable than that of carbon free 17Cr-14Ni steel because of the decrease of fine precipitates within grains in the former alloy, while the dependence of the alloy having coarser grains than L sub(M) is minor than that of carbon free 17Cr-14Ni steel because of preventing the stress concentration at the triple points by the grain boundary precipitates. (author)y precipitates. (author)

245

Heat resistance of bacillus spores at various relative humidities.  

Science.gov (United States)

The thermal resistance characteristics of spores from strains of five different Bacillus species were determined in phosphate buffer and at relative humidities ranging from <0.001 to 100% in a closed-can system. Spores tested in the closed-can system showed a marked increase in heat resistance over those in phosphate buffer, with the greatest increases occurring at relative humidities between 1 and 50%. When estimates of the time to reduce the initial spore concentration 99.99% (F value) at eight different relative humidities were plotted against temperature, three different types of heat resistance profiles were obtained, with maximum resistances at relative humidities of 1, 7, and 30%. When the various strains of spores were heated at the relative humidity of their maximum heat resistance, their relative order of heat resistance was different from that seen in buffer. Spores from the soil isolate were most resistant under these conditions (F(121.1) = 99.5 h). PMID:16345868

Reyes, A L; Crawford, R G; Wehby, A J; Peeler, J T; Wimsatt, J C; Campbell, J E; Twedt, R M

1981-10-01

246

High temperature failures of heat resistant cast steel; Hochtemperaturschaeden bei hitzebestaendigem Stahlguss  

Energy Technology Data Exchange (ETDEWEB)

Heat resistant cast steel can fail by high temperature, the atmosphere, deposits and mechanical stresses. High temperature corrosion by gas atmospheres can be oxidation, nitriding, carburization, metal dusting, sulphur and chlorine attack. Corrosion by deposits as oil ash or chromates and liquid metals as copper base alloys, lead, tin and zinc leads to a rapid reduction in wall thickness. Besides there are mechanical stresses which lead to failures by stress rupture cracks or thermoshock. The additional effect by material aging should be considered as well. (orig.)

Steinkusch, W. [Pose-Marre Edelstahlwerk GmbH, Erkrath (Germany)

1998-02-01

247

ISOLATION OF HEAT RESISTANT FUNGI FROM CANNED FRUITS  

OpenAIRE

-Increase in the consumption of canned fruit juice rather than the fruit itself raises alarmonto the safety of these canned juices as they are stored for longer period of time unlike the fruit and dormant if spores present could germinate and cause spoilage. Heat-resistant molds are characterized by the production of ascospores or similar structures with heat resistance, in some instances comparable to bacterial spores. This enables them to survive even when they are thermally...

Sani Ibrahim; Anusha, M. B.; Udhayaraja, P.

2014-01-01

248

ISOLATION OF HEAT RESISTANT FUNGI FROM CANNED FRUITS  

Directory of Open Access Journals (Sweden)

Full Text Available -Increase in the consumption of canned fruit juice rather than the fruit itself raises alarmonto the safety of these canned juices as they are stored for longer period of time unlike the fruit and dormant if spores present could germinate and cause spoilage. Heat-resistant molds are characterized by the production of ascospores or similar structures with heat resistance, in some instances comparable to bacterial spores. This enables them to survive even when they are thermally processed.

Sani Ibrahim

2014-05-01

249

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

250

Tensile properties of Hastelloy X and Incoloy 800 exposed to air and helium at high temperature  

International Nuclear Information System (INIS)

The effect of corroded surface layer on the tensile properties at room and high temperatures was studied for Hastelloy X and Incoloy 800 by comparing the properties of corroded specimens with those of aged specimens. Corroded specimens were those subjected to 3,000-h and 50,000-h exposures at 1,0000C to air and VHTR helium. A small effect of exposure was observed both to helium and air in the case of Hastelloy X. In the case of Incoloy 800, however, exposure to air was found to reduce tensile properties markedly whereas exposure to helium scarcely reduced. Metallographic observation indicated that reduction of tensile properties was caused by intergranular oxidation. The ratio of the tensile strength (corroded specimen/aged specimen) being plotted against the amount of intergranular oxidation, data of the two alloys were superimposed on the same curve. Ductility minimum point observed on the solution treated materials at intermediate temperature was not detected on the aged and the corroded Hastelloy X, but was detected on the aged and the corroded Incoloy 800. (author)

251

Permeability of hydrogen isotope through Hastelloy XR in the HTTR hydrogen production system  

International Nuclear Information System (INIS)

Permeation of hydrogen isotope through a high-temperature alloy as used heat exchanger and reformer tubes is an important problem in the hydrogen production system connected to be the high-temperature engineering test reactor (HTTR). The objective of this test is to investigate a governing process of hydrogen permeation and effective methods of reducing an amount of permeated hydrogen isotope through the tubes. This paper described the governing process of hydrogen permeation in the HTTR hydrogen production system and permeability of hydrogen and deuterium of Hastelloy XR. A diffusion process in a solid metal limited the amount of permeated hydrogen isotope in the HTTR hydrogen production system. An activation energy for hydrogen permeation of Hastelloy XR was almost equal to that of Hastelloy X. It was found that an oxide film produced during 140 h heating under helium gas circumference has an effect of reducing the amount of permeated hydrogen isotope. We obtained the permeability of hydrogen and deuterium for Hastelloy XR as follows. Hydrogen : Temperature=570-820degC, Partial pressure=1.06 x 102 - 3.95 x 103 Pa. Activation energy, E0 = 67.2 ± 1.2 (kJ·mol-1). Pre-exponential factor, F0 = (1.0 ± 0.2) x 10-4 (cm3 (NTP)·cm-1·s-1·Pa-0.5). Deuterium : Temperature = 670 - 820degC, Partial pressure : 9.89 x 102 - 4.04 x 103Pa. Activatio- 4.04 x 103Pa. Activation energy, E0 = 76.6 ± 0.5 (kJ·mol-1). Pre-exponential factor, F0 = (2.5 ± 0.3) x 10-4 (cm3 (NTP)·cm-1·s-1·Pa-0.5). (author)

252

Torsional creep characteristics of Hastelloy X  

International Nuclear Information System (INIS)

Nonlinear analysis method can be applied for rationalized design of nuclear component at elevated temperature, verification of constitutive equation is required under the multi-axial cyclic loading. In our company, high-temperature tension-torsion testing machine has been developed to understand multi-axial material characteristics at elevated temperature and to verify nonlinear constitutive equation. In this paper, torsional creep characteristics of Hastelloy X at 900degC are reported and applicability of nonlinear analysis method to actual design is discussed. (author)

253

Hydrogen permeation through nickel and Hastelloy X  

International Nuclear Information System (INIS)

Hydrogen permeation through materials is one of the major problems in the fusion reactor design. In this study, hydrogen permeabilities of nickel and Hastelloy X were measured with a permeation method. For nickel, the dependence of hydrogen permeability on hydrogen pressure and sample thickness was investigated systematically, and for Hastelloy X, the effects of sample treatments, mainly heat treatment, were studied. Main results are as follows: (1) Hydrogen permeability in nickel was obtained within the temperature range of 473 to 973 K, the hydrogen pressure range of 3.4 x 102 to 8.67 x 104 Pa and the sample thickness of 0.20 to 0.80 mm, which is as follows: P = (5.94 +- 0.22) x 10-5 exp(-(51.5 +- 0.3)kJ.mol-1/RT)cm3(NTP).cm-1.s-1.Pasup(-1/2). (2) Because of the good reproducibility of the data, the effectiveness of the apparatus was established. (3) It was confirmed that the bulk diffusion is the rate-limiting step of hydrogen permeation through nickel and the dissolution of hydrogen into nickel depends on Sieverts' law. (4) Within the temperature range of 673 to 873 K, hydrogen permeabilities of Hastelloy X were obtained as follows: For a sample without heat treatment P = (5.62 +- 1.29) x 10-5 exp(-(58.2 +- 1.7)kJ.mol-1/RT)cm3(NTP).cm-1.s-1.Pasup(-1/2); for a sample heated at 1023 K for 30 h before measurements P = (3.14 +- 1.07) x 10efore 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.)

254

Segregation Characteristics of Pulsed Laser Butt Welding of Hastelloy C-276  

Science.gov (United States)

The microsegregation/macrosegregation of Hastelloy C-276 weld joint in pulsed laser welding was investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electron probe microanalyzer (EMPA). The results indicated that during pulsed laser welding, the microsegregation was weakened compared with other welding process, and then the Brody-Flemings (BF) model with revised k was proposed to evaluate the element microsegregation in solid-solution strengthened Ni-based alloys. Also, no phenomenal macrosegregation was observed in the weld joint compared with the base metal.

Ma, Guangyi; Wu, Dongjiang; Guo, Dongming

2011-12-01

255

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)

256

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

257

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

258

Strain vs. strain rate relationships for Incoloy 800, Hastelloy X and Hastelloy N  

International Nuclear Information System (INIS)

Strain versus strain rate data for unirradiated and irradiated Incoloy 800, Hastelloy X, and Hastelloy N were collected and plotted. All readily available data, both biaxial and uniaxial, between 1200 and 14000F were included regardless of chemistries, heat treatment, aging effects, etc. Several general conclusions were drawn from these data: (1) For unirradiated material, the strain to rupture decreases with decreasing strain rate (below tensile rates). This is also seen in 316 SS. (2) There appears to be a minimum in the curves for uniaxial tests on irradiated material. No such minimum is apparent in the biaxial data. (3) Biaxially stressed specimens (unirradiated) tested at low strain rates give the most accurate prediction of what the stress rupture ductility may be following irradiation. (U.S.)

259

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)

260

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

261

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.

262

Creep and rupture behavior of a special grade Hastelloy-X in simulated HTGR helium  

International Nuclear Information System (INIS)

Creep and rupture tests were conducted for Hastelloy-XR (a modified version of the conventional Hastelloy alloy X) at 800, 900, and 10000C in simulated high-temperature gas-cooled reactor helium. Creep testing machines with special control of helium chemistry were used. As a result, the scatter of creep-rupture data could be reduced, and the variability of creep-rupture behavior due to manufacturing history could be resolved. Results of metallography and carbon analysis of ruptured specimens showed that the material improved resistance to corrosion in the helium environment, and carbon intrusion during the steady-state creep stage was suppressed to a negligible level. Under refined test conditions combined with the quality controlled material, it was demonstrated that there was little significant difference between helium and air in the creep-rupture results obtained at 800 to 10000C up to about 104h. The importance of maintaining the protective function of the surface oxide film of alloys was stressed in securing reproducibility and predictability of long-time creep performance

263

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

264

Cholesterol and heat shock protein levels in heat resistant lines  

International Nuclear Information System (INIS)

Increases in either the cholesterol content of cellular membranes or in the levels of heat shock proteins have independently been proposed as mechanisms of conferring heat resistance on cells. These two hypotheses were explored in a series of four stable heat resistant lines isolated from wild type and surface variants of B16 melanoma cells. The results can be summarized as follows: The free cholesterol content, expressed on a unit protein basis or as a molar ratio to phospholipid (C:PL ratio) in the heat resistant lines was similar to that in the respective parent lines with values for the C:PL ratio of 0.13 to 0.17 in the different lines. Analysis of the constitutive levels of heat shock proteins was done by measurement of the radioactivity in protein bands separated by gel electrophoresis following a two day exposure of cells to radioactive amino acids. Protein levels were quantified either by densitometer scanning of radiographs of the gels or by serial sectioning. Within the limits of resolution of the technique, no significant increases in constitutive levels of the three major heat shock proteins with subunit molecular weights of 68, 70, or 89 kilodaltons were observed in the heat resistant lines

265

Humidity affects genetic architecture of heat resistance in Drosophila melanogaster  

DEFF Research Database (Denmark)

Laboratory experiments on Drosophila have often demonstrated increased heritability for morphological and life-history traits under environmental stress. We used parent-offspring comparisons to examine the impact of humidity levels on the heritability of a physiological trait, resistance to heat, measured as knockdown time at constant temperature. Drosophila melanogaster were reared under standard nonstressful conditions and heat-shocked as adults at extreme high or low humidity. Mean knockdown time was decreased in the stressful dry environment, but there was a significant sex-by-treatment interaction: at low humidity, females were more heat resistant than males, whereas at high humidity, the situation was reversed. Phenotypic variability of knockdown time was also lower in the dry environment. The magnitude of genetic correlation between the sexes at high humidity indicated genetic variation for sexual dimorphism in heat resistance. Heritability estimates based on one-parent-offspring regressions tended to be higher under desiccation stress, and this could be explained by decreased environmental variance of heat resistance at low humidity. There was no indication that the additive genetic variance and evolvability of heat resistance differed between the environments. The pattern of heritability estimates suggests that populations of D. melanogaster may have a greater potential for evolving higher thermal tolerance under arid conditions.

Bubliy, Oleg A; Kristensen, Torsten Nygård

2012-01-01

266

R and D of the heat-resistant LH antenna  

International Nuclear Information System (INIS)

Two different types of Lower Hybrid Current Drive (LHCD) antenna having high-heat resistant property are developed according to a pulse length and/or working frequency. In the first type of LH antenna, heat resistive material is installed at the antenna mouth only and should be attachable using bolts. This heat-resistant mouth is exchanged for a new one when it is damaged. The heat-resistant mouth is made of Carbon Fiber Composite (CFC)-block bonded with stainless steel-base machined to fit the waveguides. This mouth has no Cu-plating for reducing rf-losses, because the antenna is designed to operate during 10-100 s injection of 2 GHz in JT-60SC. The second antenna consists of a compact multi-junction (MJ) part and a power divider designed for the next generation tokamak machine like ITER. This MJ must be made of low-Z material as a plasma facing component allowing no degradation in confinement. The test module for the MJ is made of rods and plates of CFC with Cu-plating ?30 cm in length. The test module shows transmitted power availability up to 45 MW/m2 over 1000 s with cooling at 3.7 GHz. For improvement of transmitted power availability, R and D of strong Cu-plating on CFC surface has been progressed using an electrochemical method

267

Development of heat-resistant polyethylene tubular containers  

International Nuclear Information System (INIS)

In order to develop heat-resistant polyethylene (PE) tubular containers which are retort-sterilizable or hot-packable, and have excellent flexibility, the modifications using radiation crosslinking methods were carried out. The improvement in the heat resistance is attributed to a three-dimensional structure of molecules caused by radiation crosslinking. However, three-dimensional structured PE is generally not melted even at a temperature higher than its melting point, it is poor in fusibility when fused by means of heat sealing, and cause a decrease of heat-seal strength. To avoid the low heat-seal strength, the tubular container was irradiated by a low energy electron accelerator. It was found that low energy electron beam irradiation impart heat resistance without reducing the heat seal strength. This is due to the fact that the PE tubular forms cross-link only on its surface using low energy accelerator. In fact, the PE tubular container having a wall thickness of 0.48 mm was irradiated with 3.0 MeV electron beam. As the absorption dose increased, the gel fraction increased and heat-seal strength decreased. On the contrary irradiation with 270 keV electron beam is superior for fusibility and hence heat sealing. Accordingly, it is concluded that low energy electron beam irradiation is effective for PE tubular containers to improve the heat-resistance without impairing the heat-sealability. (author)

268

Electrochemical impedance spectrometry using 316L steel, hastelloy, maraging, Inconel 600, Elgiloy, carbon steel, TiN and NiCr. Simulation in tritiated water. 2 volumes; Spectrometrie d`impedance electrochimique sur acier 316L, hastelloy, maraging inconel 600, elgiloy, acier au carbone, TiN, NiCr. Simulations en eau tritiee. 2 volumes  

Energy Technology Data Exchange (ETDEWEB)

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.

Bellanger, G.

1994-03-01

269

Controlling the Microstructure of Hastelloy-X Components Manufactured by Selective Laser Melting  

Science.gov (United States)

Selective Laser Melting (SLM) is steadily gaining acceptance across the manufacturing industry. Techniques for manufacturing components with complex geometries layer by layer have proven to be very effective in accelerating product development and hence reducing time to market. To build components by SLM from a nickel based super-alloy requires an understanding of process parameters and how they influence the microstructure, the degree of porosity and the properties. In this work, it was found that the as-fabricated density of parts manufactured from Hastelloy-X by SLM could be increased from 77 to 99% by decreasing the laser scan speed, and that the degree of cracking can be reduced by decreasing the amount of minor alloying additions such as Mn and Si.

Tomus, D.; Jarvis, T.; Wu, X.; Mei, J.; Rometsch, P.; Herny, E.; Rideau, J.-F.; Vaillant, S.

270

Creep and creep rupture properties of Hastelloy X in air and helium at 9000C  

International Nuclear Information System (INIS)

Effect of environment on creep and creep rupture behaviors was studied on Hastelloy X. Creep and creep rupture tests were carried out in air and He at 9000C for durations of up to 10,000 hr. Lever type testing machines were used for tests in air, however, in He, directly loaded type testing machines were used for the sake of load precision. Metallographic analyses were carried out for ruptured specimens. Main results obtained are as follows. (1) No effect of environment was detected on creep and creep rupture properties such as minimum creep rate or rupture life. (2) Both environments caused a small amount of decarburization, in the degree of which there was no difference between them. (3) It is considered that little difference in creep behaviors between both environments is mainly due to lower susceptibility to local oxidation of this alloy than that of alloys containing Al, Ti and so on. (auth.)

271

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

272

Long-term behaviour of heat-resistant steels and high-temperature materials. Langzeitverhalten warmfester Staehle und Hochtemperaturwerkstoffe  

Energy Technology Data Exchange (ETDEWEB)

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).

1987-01-01

273

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

274

Creep properties of EB welded joint on Hastelloy X  

International Nuclear Information System (INIS)

In order to clarify the creep properties of EB welds on Hastelloy X which is one of the candidate alloys for components of VHTR, creep tests on EB weld metal and welded joint were carried out. The results were discussed in comparison with those of base metal and TIG welds. Further, EB welds were evaluated from the standpoint of high temperature structural design. The results obtained are summarized as follows. 1) Both creep rupture strengths of EB weld metal and EB welded joint are almost equal to that of base metal, but those of TIG welds are lower than base metal. As for the secondary creep rate, EB weld metal is higher and TIG weld metal is lower than base metal. As for the time to onset of tertiary creep, no remarkable difference among base metal, EB weld metal and TIG weld metal is observed. 2) In case of EB weld metal, although anisotropy is slightly observed, the ductility is same or more as compared with base metal. In case of TIG weld metal, on the contrary, anisotropy is not observed and the ductility is essentially low. 3) Such rupture morphology of EB weld metal as appears to have resulted from interconnection of voids which occurred at grain boundary is similar to base metal. In case of TIG weld metal, however, many cracks with sharp tips are observed at grain boundary, and the rupture appears to have occurred in brittle by propagation and connection of the cracks. 4) It can be said from the standpoint of high temperature structural design that EB weldingperature structural design that EB welding is very suitable to welding for structure where creep effects are significant, because both of the creep ductility and the rupture strength are almost equal to those of base metal. (author)

275

Martensite-austenite transformation kinetics of high Cr ferritic heat-resistant steel  

Energy Technology Data Exchange (ETDEWEB)

The isochronal transformation behavior from martensite ({alpha}') to austenite ({gamma}) of modified high Cr ferritic heat-resistant steel was analyzed using the kinetic information extracted from differential thermal analysis results. The thus obtained {alpha}' {yields} {gamma} transformation kinetic process has been described by a JMAK-like model including three overlapping processes: site saturation nucleation, diffusion-controlled growth, and impingement correction for random distribution of nuclei. It is found that both the diffusion of alloying components and the inhibition of carbide precipitates strongly affect the {alpha}' {yields} {gamma} transformation kinetic processes. The {alpha}' {yields} {gamma} transformation (at relatively low heating rates) is of diffusion-controlled nature, and the obstruction of carbides during the migration of the {alpha}'/{gamma} interface leads to a decrease in the pre-exponential factor of diffusion coefficient. (orig.)

Ma, Qiujia [Tianjin Univ. (China). State Key Lab. of Hydraulic Engineering Simulation and Safety; Tianjin Univ. (China). School of Materials Science and Engineering; Shao, Yi; Liu, Yongchang; Gao, Zhiming; Yu, Liming [Tianjin Univ. (China). State Key Lab. of Hydraulic Engineering Simulation and Safety

2013-10-15

276

Comparative evaluation of the fracture toughness of heat-resisting steels in creep conditions  

International Nuclear Information System (INIS)

An approach to the evaluation of the fracture toughness of heat-resistant steels is proposed which employs an energy parameter (Jc integral) determined at the final stage of fracture. The method is demonstrated by applying it to 15Kh1M1FL steel in creep. It is shown that the fracture toughness of the steel in the temperature range 510-565 C is largely determined by its initial structure. It is also shown that a reduction of the yield stress during long-term service is not accompanied by an adequate increase in fracture toughness, which is explained by the embrittlement of the alloy during long-term service. 6 references

277

Enumeration of byssochlamys and other heat-resistant molds.  

Science.gov (United States)

Methods for the detection of low numbers of heat-resistant molds on fruits were studied by using cultures of Byssochlamys and a number of unidentified mold isolates. Ascospore dormancy had a marked effect on viable recoveries, and the medium in which ascospores were heated influenced activation rates. Best results were obtained when fruit homogenates were heated for 60 min at 70 C in Concord grape juice, followed by culturing on acidified Potato Dextrose Agar. PMID:16349886

Splittstoesser, D F; Kuss, F R; Harrison, W

1970-09-01

278

Precipitation Behavior of ?-FeCr Phases in Hastelloy C-2000 Superalloy Under Plastic Deformation and Aging Treatment  

Science.gov (United States)

Precipitation behavior and structural feature of the ?-FeCr phase in Hastelloy C-2000 alloy under plastic deformation and aging treatment are investigated using scanning electron microscopy, transmission electron microscope, and x-ray diffraction. The plate-shaped ?-FeCr phase can precipitate in the alloy by plastic deformation and aging treatment because of the increase of both defect density and heterogeneity of alloying elements. This phase is distributed along the interface between matrix and deformation twins. The appearance of unidirectional faults on surface of the ?-FeCr phase indicates that it may be a metastable-phase. Because of the precipitation of the brittle ?-FeCr phase and the increase of defects' density such as dislocation and deformation twins in the matrix, mechanical properties of the alloy are improved remarkably.

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

2014-12-01

279

Void swelling in electron irradiated Hastelloy-X  

International Nuclear Information System (INIS)

The electron-irradiation studies on Hastelloy-X in the temperature range of 400 -- 6000C to a dose of about 40 dpa have revealed that Hastelloy-X is much more resistant to void swelling compared to Type 316 stainless steel. The low void swelling in Hastelloy-X is attributable to small void size which arises from long incubation period for void nucleation and low climbing rate of dislocations. The magnitude of the incubation period depends on the stability of void embryo; the void in Hastelloy-X is not considered to be stabilized with solute atom segregation as seen in Type 316 stainless steel, and then, the high dislocation density is essential for the void nucleation. The stabilization of void embryo also affects the void number density, especially at high temperature where vacancy supersaturation rate is low. And the small void number density in Hastelloy-X results in very small void swelling at a high temperature (6000C). (auth.)

280

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)

281

Creep-fatigue interaction correlations for Hastelloy X and Inconel 617  

International Nuclear Information System (INIS)

Hastelloy X and Inconel 617 are the materials for very high temperature gas-cooled reactors for multiple purposes, aiming at the maximum working temperature of 1000 deg C, and the collection of the data on their high temperature strength and the establishment of the fracture criteria as the basis of structural design have become the important subjects. However, especially the data concerning fatigue and creep fatigue are very few. As for the actual design method for high temperature structures concerning fatigue and creep fatigue, there is the ASME Boiler and Pressure Vessel Code, Section 3, Case 1592, but the temperature range of application is not higher than 1400 deg F, and the materials are limited to AISI 304, 316 and Alloy 800 H. In this study, high temperature low cycle fatigue test was carried out on Hastelloy X and Inconel 617, and the mutual effect of fatigue and creep was investigated. As for the high temperature low cycle fatigue test, strain-controlling test, cyclic creep rupture test and load-controlling test were carried out. Moreover, the parameters controlling the damage due to the accumulation of macroscopic strain in one direction were investigated, and the law of damage when the damage due to repeated strain and the damage due to the accumulation of strain in one direction arise simultaneously was studied. The results are reported. (Kako, I.)

282

High-Temperature Low-Cycle Fatigue Property of Heat-Resistant Ductile-Cast Irons  

Science.gov (United States)

This study examined the high-temperature degradation behavior of two types of heat-resistant Si-Mo ductile cast iron (Fe-3.4C-3.7Si-0.4Mo and Fe-3.1C-4.5Si-1.0Mo) with particular attention paid to the mechanical properties and overall oxidation resistance. Tension and low-cycle fatigue properties were examined at 600 °C and 800 °C. The mechanical tests and metallographic and fractographic analyses showed that cast iron containing higher Si and Mo contents had a higher tensile strength and longer fatigue life at both temperatures than cast iron with lower levels due to the phase transformations of pearlite and carbide. The Coffin-Manson type equation was used to assess the fatigue mechanism suggesting that the higher Si-Mo alloy was stronger but less ductile than the lower Si-Mo alloy at 600 °C. However, similar properties for both alloys were observed at 800 °C because of softening and oxidation effects. Analysis of the isothermal oxidation behavior at those temperatures showed that mixed Fe2SiO4 layers were formed and the resulting scaling kinetics was much faster for low Si-Mo containing iron. With increasing temperature, subsurface degradation such as decarburization, voids, and cracks played a significant role in the overall oxidation resistance.

Kim, Yoon-Jun; Jang, Ho; Oh, Yong-Jun

2009-09-01

283

Low-cycle fatigue of Hastelloy X and Hastelloy XR in simulated VHTR helium coolant environment at elevated temperature  

International Nuclear Information System (INIS)

Strain-controlled low-cycle fatigue tests were conducted on Hastelloy X and its modified version, Hastelloy XR, at 900 sup( o)C in the flowing simulated VHTR helium environment. The results of this study provide the following conclusions; 1) Hastelloy X and Hastelloy XR exhibited essentially the same low-cycle fatigue characteristics under the given test conditions, where marked difference was observed in the oxidation performance between those materials. The results obtained in the present work were in good accordance with the following equation proposed by Manson and Coffin ? epsilon sub(t) = ? epsilon sub(e) + ? epsilon sub(p) = 0.00228 Nsub(f)sup(-0.00732) + 0.447 Nsub(f)sup(-0.604) 2) The ratio of Nsup(f) in impure helium to Nsup(f) in 1--3 x 10-6 Pa vacuum were examined, and the results were equally about 0.7 for both materials. 3) Both transgranular fracture mode with ductile striations and intergranular fracture mode were recognized in the fracture surfaces, with the former mode being predominant. 4) The results obtained in the present work were situated on the line corresponding to the approximate average level of the available fatigue data in literature on Hastelloy X tested under similar test conditions. (author)

284

Heat-resistant coatings for the high-pressure turbine blades of promising GTEs  

Science.gov (United States)

Heat-resistant coatings are considered for the external surface of high-pressure turbine (HPT) single-crystal blades for promising gas turbine engines (GTEs) made from carbon-free nickel superalloys with rhenium or rhenium plus ruthenium. Nickel superalloys covered with heat-resistant coatings consisting of heat-resistant connecting layers and an external ZrO2-(7-8 wt %)Y2O3 ceramic layer are subjected to heat resistance and high-temperature tests. The test results are used to choose the heat-resistant layer that ensures the highest properties of a composition heat-resistant coating. The use of sequential chemical and physical deposition methods for coating layers is shown to be required to protect HPT blades in promising GTEs. Medium-frequency magnetron plasmachemical deposition of ceramic layers in heat-resistant coatings with a low thermal conductivity is found to be promising.

Kablov, E. N.; Muboyadzhyan, S. A.

2012-01-01

285

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

286

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

287

Heat Resistance of Bacillus Spores at Various Relative Humidities  

OpenAIRE

The thermal resistance characteristics of spores from strains of five different Bacillus species were determined in phosphate buffer and at relative humidities ranging from <0.001 to 100% in a closed-can system. Spores tested in the closed-can system showed a marked increase in heat resistance over those in phosphate buffer, with the greatest increases occurring at relative humidities between 1 and 50%. When estimates of the time to reduce the initial spore concentration 99.99% (F value) at e...

Reyes, Antolin L.; Crawford, Ronald G.; Wehby, Albert J.; Peeler, James T.; Wimsatt, John C.; Campbell, Jeptha E.; Twedt, Robert M.

1981-01-01

288

Increasing austenitic steel heat resistance by laser coating  

International Nuclear Information System (INIS)

Capabilities for increasing austenitic steel heat resistance (long-term strength, creep resistance) by laser oxide coating are considered. The experimental data on strengthening of 18/9 type steel with Cr2O3 coating are given. It is shown that laser coating of 18/9 type austenitic steel on the Cr2O3 base strengthens the specimen surface and makes it more resistant to temperature and corrosion environmental effects, and, therefore, considerably improves (2-3 times) its durability and reduces the creep rate without causing its embrittlement

289

High temperature embrittlement of Hastelloy X after low fluence neutron irradiation  

International Nuclear Information System (INIS)

In an irradiation program aimed at qualifying a tube material for the absorber rods of a pebble-bed high temperature gas cooled reactor (HTGR), tensile and creep test specimens of the nickel-chromium based, solid solution strengthened, high temperature alloy Hastelloy X were irradiated at 673 or 873 K in six reactor experiments to accumulate thermal neutron fluences between 1.2 x 1022 and 3.1 x 1025 m -2. In addition, 110 ?m thick foils were homogeneously implanted with helium from a cyclotron to helium concentrations of 10, 150, and 480 atomic parts per million (appm), corresponding to helium contents expected in the high fluence neutron irradiation experiments. Tensile and creep rupture tests were performed with irradiated and implanted samples as well as virgin controls in the temperature range 300 to 1123 K. The results are presented

290

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)

291

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

292

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.)

293

Hemispherical total emissivity of Hastelloy N with different surface conditions  

Energy Technology Data Exchange (ETDEWEB)

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.

Gordon, Andrew J.; Walton, Kyle L. [Particulate Systems Research Center, Nuclear Science and Engineering Institute, University of Missouri, Columbia, MO 65211 (United States); Ghosh, Tushar K., E-mail: ghoshT@missouri.edu [Particulate Systems Research Center, Nuclear Science and Engineering Institute, University of Missouri, Columbia, MO 65211 (United States); Loyalka, Sudarshan K.; Viswanath, Dabir S.; Tompson, Robert V. [Particulate Systems Research Center, Nuclear Science and Engineering Institute, University of Missouri, Columbia, MO 65211 (United States)

2012-07-15

294

Weldability evaluations and weldment properties of Hastelloy X  

International Nuclear Information System (INIS)

Studies of weldability and weldment properties were conducted on commerical heats of Hastelloy X. Weldment preparation was done using several combinations of welding techniques and filler metals. Evaluation methods employed included hot cracking susceptibility and tensile and creep properties measured both before and after aging at 593 to 8710C for up to 10,000 h

295

Hemispherical total emissivity of Hastelloy N with different surface conditions  

Science.gov (United States)

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.

Gordon, Andrew J.; Walton, Kyle L.; Ghosh, Tushar K.; Loyalka, Sudarshan K.; Viswanath, Dabir S.; Tompson, Robert V.

2012-07-01

296

Weldability evaluations and weldment properties of Hastelloy X  

International Nuclear Information System (INIS)

Studies of weldability and weldment properties were conducted on commerical heats of Hastelloy X. Weldment preparation was done using several combinations of welding techniques and filler metals. Evaluation methods employed included hot cracking susceptibility and tensile and creep properties measured both before and after aging at 593 to 8710C for up to 10,000 h. (Auth.)

297

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.

298

Study of rigid cross-linked PVC foams with heat resistance.  

Science.gov (United States)

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. PMID:23519258

Shi, Aihua; Zhang, Guangcheng; Zhao, Chenhui

2012-01-01

299

Study of Rigid Cross-Linked PVC Foams with Heat Resistance  

Directory of Open Access Journals (Sweden)

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

300

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)

301

Oxidation phenomena of nickel-base alloys in high temperature water  

International Nuclear Information System (INIS)

Surface oxidation of nickel-base and iron-base super alloys in high temperature low dissolved oxygen water environment was investigated by FE-SEM and X-ray diffraction analysis. Observed oxides on the surface of the alloys were as follows, =Incoloy 800; spinel type oxide (M3O4), Inconel 625; spinel type oxide + nickel oxide + chromium hydroxide, Hastelloy C22; nickel oxide + chromium hydroxide, Hastelloy B2; nickel oxide= Compared to high iron content Incoloy 800, Hastelloy B2 showed large weight loss, and it was assumed that iron is very important element for producing the stable oxide in the low oxygen content high temperature water environment. (author)

302

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

303

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

304

Integrated Thermal Protection Systems and Heat Resistant Structures  

Science.gov (United States)

In the early stages of NASA's Exploration Initiative, Snecma Propulsion Solide was funded under the Exploration Systems Research & Technology program to develop integrated thermal protection systems and heat resistant structures for reentry vehicles. Due to changes within NASA's Exploration Initiative, this task was cancelled early. This presentation provides an overview of the work that was accomplished prior to cancellation. The Snecma team chose an Apollo-type capsule as the reference vehicle for the work. They began with the design of a ceramic aft heatshield (CAS) utilizing C/SiC panels as the capsule heatshield, a C/SiC deployable decelerator and several ablators. They additionally developed a health monitoring system, high temperature structures testing, and the insulation characterization. Though the task was pre-maturely cancelled, a significant quantity of work was accomplished.

Pichon, Thierry; Lacoste, Marc; Glass, David E.

2006-01-01

305

Heat-resistant ferritic steels for advanced power plants  

International Nuclear Information System (INIS)

Substantial progress is being made in Japan in improving the high-temperature mechanical properties of heat-resistant high-chromium ferritic steels. These steels are attracting the attention of the materials community because of their potential use in advanced energy-producing systems, such as ultra-supercritical power plants, fast breeder reactors, and nuclear-fusion reactors, that must operate at higher temperatures to ensure efficiency. Use of high-chromium ferritics has been restricted to service temperatures below 550 to 600 degrees C (1.20 to 1,110 degrees F). New compositions and heat treatments, however, have raised this limit to 650 degrees C (1,200 degrees F). This article focuses on several developments in high-chromium ferritic steels for advanced power plants. Most of then originated at the University of Tokyo and its industrial research partners

306

Creep equations for heat-resistant power plant steels  

International Nuclear Information System (INIS)

For design and in-service monitoring of high-temperature components used in power plants and industrial installations, information is required on the in-service deformation of the heat-resistant steels relating to all applications and particularly to the relevant intended service lives and the resulting low stress levels. Comprehensive long-term creep tests have to be m[e in order to derive the creep data. Modern calculation methods call for data describing ste[y lo[ and deformation behaviour by means of creep equations. This approach in general requires as a basis experimentally verified data on at least one typical steel. As a second step, the equations are [justed to describing average creep behaviour of the steel. The paper discusses the development of creep equations for the steels 14 MoV 6 3, No.1, and X 19 CrMoVNbN 11 1, No. 7. (orig./CB)

307

Characteristics of heat resistance of metal of certain grade  

International Nuclear Information System (INIS)

Modern development of power machine construction is accompanied by continuous increase of operation parameters and service time of power machine elements. Under the conditions heat resistance characteristics, evaluated by extrapolation for the calculated service time on the basis of restricted duration tests play the decisive role. Pipeline systems (steam supply lines and steam superheaters) are the most metal-consuming elements of modern thermal power plants. Results of the tests are generalized, their statistical processing using the M 220 and ES computers, is realized. According to the method suggested parameters of long-term strength equations for commercial steels are given. Pearlitic, aystenitic and high-chromium steels were considered. 30 comercial series of 12Kh1MF steel were tested by various organizations and the results were processed. Total number of tested samples exceeded 700

308

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.

309

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-22 Fe-18 Mo (Hastelloy-X) and Ni-Cr-22 Co12 Mo (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

310

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

311

Characterization of Hastelloy thin films deposited by pulsed laser ablation  

International Nuclear Information System (INIS)

Hastelloy thin films have been deposited on carbon steel substrates at room temperature by pulsed laser ablation of bulk Hastelloy targets. Different numbers of laser pulses were used in order to obtain films of various thicknesses. Scanning electron microscopy (SEM) was used to analyze the surface morphology of the deposited films. Energy dispersion X-ray (EDX) spectroscopy and X-ray diffraction (XRD) have shown that the laser ablation process was almost congruent, and the crystallographic structure was retained in the films. In order to relate the microstructure of the film surface with its corrosion behavior, electrochemical tests in aqueous CO2 environment, such as potentiodynamic curves and linear polarization resistance, were performed. The film characteristics and their dependence on deposition parameters are presented and discussed

312

The viscoplastic behavior of Hastelloy-X single crystal  

Science.gov (United States)

A viscoplastic constitutive model for simulating the behavior of Hastelloy-X single crystal material was derived based on crystallographic slip theory. To determine the appropriate constitutive model constants and to test the predictions of the model, tests on Hastelloy-X crystals were carried out, including the rate sensitivity, cyclic hardening, nonproportional hardening, relaxation, and strain rate dip tests. It was found necessary to include cube slip in the model in order to correlate the uniaxial behavior of the single crystal, to incorporate the interaction effects in both the hardening and the dynamic recovery evolution equations for the drag stress, and to successfully capture correct strain rate sensitivity under biaxial tension-torsion loading conditions.

Jordan, Eric H.; Shi, Shixiang; Walker, Kevin P.

1993-01-01

313

Electrochemistry Corrosion Properties of Pulsed Laser Welding Hastelloy C-276  

Science.gov (United States)

Based on the welding quality requirement of Hastelloy C276 in the extreme environment, the electrochemistry corrosion property of laser welding Hastelloy C276 was evaluated in the neutral, acid and alkaline solutions, and the corroded surface was observed by the co-focal laser scanning microscope to confirm the corrosion mechanism. The results indicated, the corrosion trend of the weld was weaker than that of base metal in the neutral and acid solutions, but in the alkaline solutions, the corrosion trend of the base metal was weaker. However, the corrosion rate of the weld was much slower than that of base metal in all solutions. At the point of corrosion mechanism, in the acid and alkaline solutions, the base metal and weld showed the uniform corrosion. However, in the neutral solution, the selective corrosion and intergranular corrosion occurred in the base metal and the weld, respectively.

Ma, G.; Niu, F.; Wu, D.; Qu, Y.

314

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

315

Corrosion behavior of zirconia-coated Hastelloy X in a high-temperature helium environment  

International Nuclear Information System (INIS)

The corrosion behavior of Hastelloy X coated with (NiCrAl)/(ZrO2-CaC2) was examined, after serving as the liner tube of helium engineering demonstration loop (HENDEL) hot gas duct. The Hastelloy X with the ceramic coating system was exposed to high-temperature helium gas for --6000 h. The compositions of oxide films formed on Hastelloy X were entirely different between the noncoated and ceramic-coated tubes

316

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)

317

Physical properties of Hastelloy® C-276™ at cryogenic temperatures  

Science.gov (United States)

In recent years, the Ni-Mo-Cr superalloy Hastelloy® C-276™ has been used as a substrate material for fabricating superconducting tapes such as YBCO and MgB2 coated conductors. With increasing piece length, these coated conductors are within reach of large scale commercial applications. However, data on the physical properties of Hastelloy C-276 at temperatures relevant for these applications are not yet available. In this work, physical properties including magnet succeptibility, specific heat, electrical resistivity, and the Seebeck coefficient are measured from 2to300K and thermal conductivity from 2to200K. Our results show that Hastelloy C-276 exhibits Curie paramagnetism between 4 and 300K with a Curie constant C =0.091K. A spin-glass-like behavior is observed below 3K. The electrical resistivity has a minimum at ˜12K, and shows a linear weak T dependence at higher temperatures. The specific heat Cp between 15 and 40K follows Cp=?T+AT3. Below ˜10K, an upturn in Cp/T with decreasing T is interpreted by the existence of very small ferromagnetic clusters. We found relatively strong phonon contribution to the thermal conductivity in the measured temperature range. In addition, we present the thermal diffusivity as a function of temperature calculated from the thermal conductivity and the Cp data. The Seebeck coefficient is found to be proportional to temperature. The results of our measurements provide important data not only for the specific applications of the superconducting coated conductors that use Hastelloy C-276 as substrates, but also for many other potential cryogenic temperature applications.

Lu, J.; Choi, E. S.; Zhou, H. D.

2008-03-01

318

Feasibility of EB Welded Hastelloy X and Combination of Refractory Metals  

Science.gov (United States)

As NASA continues to expand its horizon, exploration and discovery creates the need of advancement in technology. The Jupiter Icy Moon Orbiter's (JIMO) mission to explore and document the outer surfaces, rate the possibility of holding potential life forms, etc. within the three moons (Callisto, Ganymede, and Europa) proves to be challenging. The orbiter itself consists of many sections including: the nuclear reactor and the power conversion system, the radiator panels, and the thrusters and antenna. The nuclear reactor serves as a power source, and if successfully developed, can operate for extended periods. During the duration of my tenure at NASA Glenn Research Center's (NASA GRC) Advanced Metallics Branch, I was assigned to assist Frank J. Ritzert on analyzing the feasibility of the Electron Beam Welded Hastelloy X (HX), a nickel-based superalloy, to Niobium- 1 %Zirconium (Nb-1 Zr) and other refractory metals/alloys including Tantalum, Molybdenum, Tungsten, and Rhenium alloys. This welding technique is going to be used for the nuclear reactor within JIMO.

Martinez, Diana A.

2004-01-01

319

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

Energy Technology Data Exchange (ETDEWEB)

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 {mu}-phase was observed in the MZ after a tempering treatment at 950 deg. C.

Ahmad, M. [Physics Research Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan)]. E-mail: maqomer@yahoo.com; Akhter, J.I. [Physics Research Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan); Akhtar, M. [Physics Research Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan); Iqbal, M. [Physics Research Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan); Ahmed, E. [Physics Research Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan); Choudhry, M.A. [Department of Physics, Islamia University, Bahawalpur (Pakistan)

2005-03-22

320

Behaviour of heat-resistant steels under multistage fatigue stress  

International Nuclear Information System (INIS)

Four heat-resistant steels (10 CrMo 9 10, 28 CrMoNiV 4 9, X 22 CrMoV 12 1, X 6 CrNiMo 17 13), were used to examine the fatigue under multistage rectangular cyclic stress. The load cycles were made to be similar to the stress affecting power plant components. These are mainly cycles with decreasing and/or increasing stresses, with the temperature or both variables at the same time having been varied in some cases. As characteristical parameters of the modified life-fraction rule, the relative fracture life and for characterizing strains the relative strain life as well were determined. For the assessment of the relative life under any multistage stress, a new step hypothesis, applicable to all possible elementary stress steps, was developed. This hypothesis is able to predict even a consequential effect by means of additional rules. In comparison to this hypothesis, the simple life fraction rule which is unapt for single-stage stress, results in a somehow better prognosis of the fraction time and strain endurance limits under multistage stress. (orig./MM)

321

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)

322

A new class of bio-heat resisted polymer blend.  

Science.gov (United States)

Increasing in oil prices and environmental concerns is a driving force to seek out alternative materials. A completely biodegradable starch is a candidate for the alternative materials. Since the starch is brittle, it must be mixed with other polymers. In order to make a thermoplastic starch (TPS), we need a bio-compatiblizer to increase a degree of compatibilization. The biocompatibilzer can be a small molecules or nanoparticles with the small molecules, which leads to improved material properties. In order to demonstrate a possible biocompatibilzer, we first developed a corn-based starch impregnated with non-halogenated flame retardant formulations. The starch was blended with Ecoflex, a biodegradable polymer. Using SAXS and USAXS we characterized structures of the compounds with different amount of Ecoflex by weight. Furthermore, the addition of 5% nanoparticles in the compounds increased the Young's Modulus and impact toughness significantly. The compounds also did flame test. It is indicated that the compound with the addition of the nanopaticles would pass with a UL-94V0 rating. Therefore, the procedure for producing these TPS compounds can be applied to any biodegradable polymers, manufacturing a new bio-heat resisted compound.

Pack, Seongchan; Kashiwagi, Takashi; Koga, Tadanori; Rafailovich, Miriam

2009-03-01

323

Influence of pH on heat resistance of Bacillus licheniformis in buffer and homogenised foods.  

Science.gov (United States)

The influence of pH of heating menstruum (McIlvaine buffer) on the heat resistance of Bacillus licheniformis was investigated and compared with the heat resistance in homogenised tomato and asparagus at pH 7 and 4 in a wide range of temperatures. Heat resistance was in all mestrua smaller at acid pH. At 99 degrees C and pH 4, heat resistance was 1/20 lower than at pH 7. However, the magnitude of this effect decreased as heat treatment temperatures were increased almost disappearing at 120 degrees C. z values increased from 6.85 at pH 7, to 10.75 at pH 4. At 99 degrees C the effect of pH on heat resistance was constant along the range of pH's tested. The increase of one pH unit increased D99 by 180%. At pH 7 and 4, heat resistance was the same in buffer as in tomato and asparagus homogenates at all temperatures tested. The diminishing influence of the acidification of some foods on the heat resistance of B. licheniformis sterilisation temperatures should be taken into account when a raise in temperature is considered to shorten the duration of heat processes. PMID:8722182

Palop, A; Raso, J; Pagán, R; Condón, S; Sala, F J

1996-02-01

324

Bacillus sporothermodurans and other highly heat-resistant spore formers in milk.  

Science.gov (United States)

A recent example of a micro-organism causing undesired growth in consumer milk is Bacillus sporothermodurans producing highly heat-resistant spores (HRS) which may survive ultra-high temperature (UHT) treatment or industrial sterilization. Molecular typing showed a heterogeneous group of farm isolates (non-HRS strains), but a clonal group of UHT isolates from diverse European countries and other continents (HRS-clone) suggesting a common source. During a survey of Belgian dairy farms for the presence of potentially highly heat-resistant spore formers, high numbers of these spores were detected in filter cloth, green crop and fodder samples. The strain collection showed a high taxonomic diversity with 18 potentially new species and with Bacillus licheniformis and Geobacillus pallidus as predominating species overall. Seventeen B. sporothermodurans isolates were identified, mainly originating from feed concentrate. Heat resistance studies showed the UHT resistance of B. sporothermodurans spores present in industrially contaminated UHT milk, but a lower heat resistance of laboratory-grown strains (HRS and non-HRS). Hydrogen peroxide, used as sanitizer in the dairy industry, was found to induce higher heat resistance of laboratory-grown B. sporothermodurans strains to a certain level. This indicates that sublethal stress conditions may affect the heat resistance. By transmission electron microscopy, structural differences at the spore level were found between HRS and non-HRS strains. The data indicate that the attainment of extreme heat resistance is rather multifactorial. PMID:16907805

Scheldeman, P; Herman, L; Foster, S; Heyndrickx, M

2006-09-01

325

SR X-ray analysis of Ni-based alloys corroded in molten fluoride salt  

International Nuclear Information System (INIS)

Corrosion test of Ni-based high temperature alloys of Inconel 600, Hastelloy X and Hastelloy c-276 were performed in molten fluoride salt(LiNaKF) at 750 degree C for up to 320 h. The virgin and corroded samples were imaged by scanning electron microscope, analyzed by synchrotron radiation microbeam X-ray fluorescence(?-XRF) and characterized by X-ray diffraction(XRD). The ?-XRF results show that corrosion of the Ni-based alloy in molten fluoride salt is mainly due to the erosion of alloying element Cr. The XRD results show that the alloying element Mo of Hastelloy c-276 formed the Mo2C structure, which can enhances anti-corrosive performance of the alloy in molten fluoride salt. (authors)

326

Electron Microscopic Analysis of Heterogeneous Precipitates in Hastelloy C-276  

Science.gov (United States)

Three distinct second phases were observed to form heterogeneously at grain and deformation twin boundaries when Hastelloy C-276 was aged in the temperature range of 923 to 1173 K. The most abundant was the faulted, molybdenum rich ? phase. The next most abundant phase was molybdenum rich M6C carbides, and the third phase, which was observed very infrequently, was tentatively identified as the P phase. The compositions of these phases were remarkably similar, and the need to employ several electron microscopy techniques is emphasized. The origin of the ? phase is discussed in the light of its chemistry.

Raghavan, M.; Berkowitz, B. J.; Scanlon, J. C.

1982-06-01

327

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

328

Trends in the development of heat resistant steels for seamless tubes in power station construction  

International Nuclear Information System (INIS)

The requirements for heat resistant steels for power station construction have changed. Good properties in relation to resistance to heat are taken for granted; today the key points of interest are ductility at low temperatures and weldability requirements. The erratic increases in the price of fossil fuels lead to increase in steam temperature and pressure just as the construction of advanced reactors automatically leads to the use of heat-resistant austenitic steels. (orig.)

329

Incidence and Diversity of Potentially Highly Heat-Resistant Spores Isolated at Dairy Farms  

OpenAIRE

The presence of highly heat-resistant spores of Bacillus sporothermodurans in ultrahigh-temperature or sterilized consumer milk has emerged as an important item in the dairy industry. Their presence is considered undesirable since they hamper the achievement of commercial sterility requirements. By using a selective 30-min heat treatment at 100°C, 17 Belgian dairy farms were screened to evaluate the presence, sources, and nature of potentially highly heat-resistant spores in raw milk. High n...

Scheldeman, Patsy; Pil, Annelies; Herman, Lieve; Vos, Paul; Heyndrickx, Marc

2005-01-01

330

Carburization of heat resistant austenitic FeNiCr steel at 850 - 1000{sup o}C  

Energy Technology Data Exchange (ETDEWEB)

This doctoral thesis discusses carburization in FeNiCr steel. Carburization is a corrosion process involving dissolution and diffusion of carbon into the alloy. It is often found in industrial processes involving high temperatures and carbon containing gases, such as thermal cracking of mixtures of propane, butane and water vapour to form ethylene. In this work, carburization of three heat resistant FeNiCr steels in mixtures of CH{sub 4}+H{sub 2} in the temperature interval 850-1000{sup o}C was studied by thermogravimetry and different solid state characterization techniques. The process involved carbon deposition on the outer surface of the alloy, dissolution and diffusion of carbon into the alloy as well as carbide formation. The rate determining step was diffusion of carbon into the alloy. Two models based on Fick`s 2. law were applied to the results. Wagner`s model for internal oxidation, which gives an analytical solution of Fick`s 2. law, did not fit the results. A good fit was obtained basing the model on a finite difference technique. This model solves Fick`s 2. law numerically. However, the kinetic and thermodynamic data obtained by fitting deviate from those found in the literature. Cavities more or less filled with graphite and Fe particles were found just beneath the outer surface of the alloys. The formation of these cavities are attributed to a reaction between the outer Fe-rich regions of (Cr,Fe){sub 7}C{sub 3} and carbon in solid solution to form Fe and graphite and is a type of metal dusting. 137 refs., 74 figs., 19 tabs.

Forseth, S.

1995-12-01

331

High temperature strength of hastelloy x welded joints  

International Nuclear Information System (INIS)

In the design of high temperature structures such as ASME Code N-47, the high temperature strength characteristics of welded joints become the problem. Also, the design of the welded parts in high temperature structures in the present state is according to the standard in which the bimetallic behavior of welded parts is not considered, accordingly, it is much problematic. In this paper, the high temperature strength characteristics of Hastelloy X welded joints are described, and the problems in the present design are pointed out, moreover, some comment is given to the evaluation of high temperature strength for the future. In the ASME Code, Case N-47, the strength of welded joints is required to be the same as that of parent metals. Therefore, the data on the high temperature strength of welded joints must be collected. The results of tensile test at room temperature, 700, 800, 900 and 1000 deg C on the parent metal and EB and TIG welded joints of Hastelloy X are shown. Also, the characteristics of mono-axial creep rupture, internal pressure creep rupture, and high temperature, low cycle fatigue are reported. The lowering of strength in the tension, creep and fatigue of welded joints must be examined and evaluated in view of the combined behavior of parent metals and weld metals. (Kako, I.)

332

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

333

On one algorithm of searching optimum alloying complex  

International Nuclear Information System (INIS)

The algorithm prepared determines the optimum combination of the alloying elements on the basis of the apriori information methods and Monte-Carlo method provides for calculating the expected properties at the given combination of the alloying elements. The tests carried out on the heat-resisting nickel alloys have proved that the calculations almost coincide with the experimental data

334

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

Directory of Open Access Journals (Sweden)

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

335

High temperature oxidation of hastelloy X in high velocity impurified helium  

International Nuclear Information System (INIS)

High temperature oxidation of Hastelloy X, to be used as in-pile tubing material in a high-temperature helium gas loop (OGL-1), has been tested in high-velocity imprified helium gas at 8000, 9000 and 1,0000C. It was observed that, under these conditions, the outer layer of the oxide film covering the metal surface tended to be blown away, and that both ends of the specimen oxidized to appreciable extent. The oxide film was found upon examination to be constituted of three layers - (a) a boundary zone between base metal and the oxide film proper, (b) an inner layer consisting of Cr2O3, and (c) an outer layer mainly comprising spinel oxides of Cr and Mn. It was also revealed that, under the same experimental conditions, the oxidation penetration rate obeyed the cubic rate law at 9000C and the parabolic rate law at 1,0000C. This difference of behavior according to temperature could be ascribed to a change occurring in the type of oxygen diffusion in the alloy phase. (auth.)

336

Swelling in neutron irradiated nickel-base alloys  

International Nuclear Information System (INIS)

Inconel 625, Incoloy 800 and Hastelloy X were neutron irradiated at 500 to 7000C. It was found that of the three alloys investigated, Inconel 625 offers the greatest swelling resistance. The superior swelling resistance of Inconel 625 relative to that of Hastelloy-X is probably related to differences in the concentrations of the minor rather than major alloy constituents, and can involve (a) enhanced recombination of defects in the Inconel 625 and (b) preferential attraction of vacancies to incoherent precipitates. (U.S.)

337

Principles of alloying of Ni superalloys resistant to high-temperature corrosion  

International Nuclear Information System (INIS)

The effect of alloying elements (Cr, Ti, Al, Co, W, Nb) on resistance against high-temperature corrosion of the nickel alloys, applied in the gas turbine building, is studied. The diagram of the alloys heat resistance level dependence on the alloying elements concentration is plotted, wherein three areas are separated: 1) the area of improved heat resistance due to the solid solution and dispersion strengthening; 2) the area of decreasing heat resistance due to formation of the carbide net by the grain boundaries; 3) the area of catastrophic decrease in the heat resistance by separation of the embrittlement topologically close-packed phases. The class of the high-temperature corrosion-resistant nickel alloys with different chromium content (13-30%), the Ti/Al > 1 concentration ratio and balanced content of high-melting and rare earth elements is created

338

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

339

Heat treatment of nickel alloys  

International Nuclear Information System (INIS)

A heat treating process is described that can be used to produce desired combinations of strength, ductility, and fabricability characteristics in heat resistant age-hardenable alloys having precipitation-hardening amounts of niobium, titanium, and/or tantalum in a nickel-containing matrix. (U.S.)

340

AC losses of YBCO strips on YSZ/hastelloy substrates  

Science.gov (United States)

The effect of subdividing superconducting YBCO films on YSZ-buffered hastelloy substrates into arrays of parallel strips on the AC loss was investigated. Measurements of the loss component of the AC susceptibility, ??, revealed that the frequency-independent hysteretic contribution to ??, which is dominant at low frequencies ( f ? 1 kHz), decreased by a factor 1/ N when the film was subdivided into N parallel strips. As the strips were made wider or the separation between them made smaller, the hysteretic ?? increased. The eddy current contribution to ??, which originates from the metallic substrate, was found to become dominant with increasing frequency and approached a linear frequency dependence at high frequencies. The experimental findings are in close agreement with theoretical predictions of the AC loss in x-arrays of YBCO strips on metallic substrates.

Herrmann, J.; Müller, K.-H.; Savvides, N.; Gnanarajan, S.; Thorley, A.; Katsaros, A.

341

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)

342

Fabrication of dense heat resisting ceramics of hafnium dioxide  

International Nuclear Information System (INIS)

Given are investigation results on CaO and Y2O3 binding in solid solutions with HfO2 depending on the type and quantity of introduced stabilizing additions, temperature. Technology of thermostable product manufacturing out of hafnium dioxide has been developed. It is shown that introduction of 2% (mol) of stabilizing additions improves HfO2 sintering, but does not ensure the necessary material stabilization degree. To obtain HfO2, stabilized at 1750 deg C by 70%, it is necessary to introduce 6% (mol) of Y2O3 or 8% (mol) of CaO. Hafnium dioxide crucibles, obtained by the method of slip casting according to the developed technology, are tested in the course of melting different metals and alloys of the Ta-Si system at 2500-2550 deg C with positive results

343

Production of heat-resistant metal-ceramic coatings on the basis of titanium silicide and nitride by thermoreactive electrospark surface strengthening  

International Nuclear Information System (INIS)

Coatings on the basis of Ti5Si3 titanium silicide have been produced using the Thermoreactive Electrospark Surface Strengthening (TRESS) method. Their formation took place by applying a charge exothermic layer of specified composition (Ti-Si, Ti-Si3N4) onto a substrate and the subsequent chemical conversion in it that is maintained by energy of pulsed discharges. A series of investigations of structure, composition and properties (microhardness, thickness, integrity, and wear-resistance) of TRESS-coatings on OT4-1 titanium alloy was carried out. A dependence of depth of chemical conversion in charge layers on energy processing mode was found. It was established that the coatings produced during optimal processing mode (E = 0,3 J) facilitate an increase in microhardness, wear-resistance and heat-resistance of OT4-1 alloy

344

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

345

Regularities of changes of high-temperature hardness in Nb-ZrN and Nb-HfN system alloys  

International Nuclear Information System (INIS)

Heat resistance of casted niobium alloys of two quasibinary systems is studied by the method of high-temperature hardness. The composition heat resistance curve is calculated for the case of short-term hardness taking into consideration structural peculiarities of studied alloys and all possible hardening mechanisms-dispersed, compositional and deformation hardening. The calculated curve is shown to be in a good correlation with the experimental one. A conclusion is made that a character of composition-heat resistance curve for two- phase alloy systems is determined mainly by the size change of strengthening phase at the increase of its volume content

346

Electroslag welding of large diameter tubes of heat resisting chromium-molybdenum-vanadium steels  

International Nuclear Information System (INIS)

The results are presented of comparative mechanical tests of welds of large-diameter pipes from warm-resistant 15Kh1M1F steel performed by electroslag and automatic submerged arc welding with the use of 08KhMF filler wire. It is shown that electroslag welding is a most efficient technique where welds are normalized and tempered, no pre-welding heating being required. The coefficient of heat resistance of welds is 0.8. Electroslag welding of pipes with the use of a filler wire of a composition similar to that of the base metal will result in welds of a coefficient of heat resistance close to unity

347

Comparison of Pressure Resistances of Spores of Six Bacillus Strains with Their Heat Resistances  

OpenAIRE

The pressure resistances of the spores of six Bacillus strains were examined at 5 to 10(deg)C and were compared with their heat resistances. The pressure treatments (at 981 MPa for 40 min and at 588 MPa for 120 min) did not inactivate the spores of B. stearothermophilus IAM12043, B. subtilis IAM12118, and B. licheniformis IAM13417. However, these spores had large differences in heat resistance. The spores of B. megaterium IAM1166 were 9.3 times more pressure resistant but 246 times less heat ...

Nakayama, A.; Yano, Y.; Kobayashi, S.; Ishikawa, M.; Sakai, K.

1996-01-01

348

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.)

349

New progress in the theory and practice of heat-resisting concretes  

International Nuclear Information System (INIS)

The main properties of heat-resistant cellular, light and heavy concretes based on high-alumina-, alumina- and Portland cements, liquid glass, alumo-phosphate binder and other binding materials containing different fine-ground additives and fillers are considered. The data of foreign and national investigations are presented concerning the effect of heating and mineral composition of cements and fine-ground mineral additions on the phase composition and structure of the cement stone and tensile properties of concretes. The foreign and national experience in the utilization of heat-resistant concretes when constructing thermal units in various branches of industry is described, as well as the economic effectiveness obtained herewith

350

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)

351

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

352

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.)

353

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

Science.gov (United States)

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

354

Study of radiative properties of heat resisting metals and alloys, (1)  

International Nuclear Information System (INIS)

The heat radiative properties of Ni, Co, and Cr were investigated. The test samples were made of electrolytic nickel, rolled cobalt sheet and chromium ingot. The purities of Ni and Co were 99.9 percent, and that of Cr 99 percent. The spectroscopic properties of the samples were measured and analyzed. In the case of Ni, the light absorption mechanism by the conductive electrons was dominant in the wavelength region of near-infrared and infrared radiation, and the temperature region up to 1700 degree K. The values of the radiation properties vary continuously. In the case of Co, a wide absorption band of the inter-band quantum transition appeared in the near-infrared region in the hcp region below 500 degree K. In the transformation temperature region, remarkable heat hysteresis characteristics were seen. In the case of Cr, a wide absorption band was also seen in the near-infrared region. However, the phase transformation and the thermal hysteresis were not observed. The optical constants of Ni, Co and Cr are well explained by a dispersion formula and the formulas concerning its parameters. (Kato, T.)

355

Simple bond-order-type interatomic potential for an intermixed Fe-Cr-C system of metallic and covalent bondings in heat-resistant ferritic steels  

Science.gov (United States)

It is known that M23C6(M = Cr/Fe) behavior in heat-resistant ferritic steels affects the strength of the material at high temperature. The ability to garner direct information regarding the atomic motion using classical molecular dynamics simulations is useful for investigating the M23C6 behavior in heat-resistant ferritic steels. For such classical molecular dynamics calculations, a suitable interatomic potential is needed. To satisfy this requirement, an empirical bond-order-type interatomic potential for Fe-Cr-C systems was developed because the three main elements to simulate the M23C6 behavior in heat-resistant ferritic steels are Fe, Cr, and C. The angular-dependent term, which applies only in non-metallic systems, was determined based on the similarity between a Finnis-Sinclair-type embedded-atom-method interatomic potential and a Tersoff-type bond-order potential. The potential parameters were determined such that the material properties of Fe-Cr-C systems were reproduced. These properties include the energy and lattice constants of 89 crystal structures; the elastic constants of four realistic precipitates; the bulk moduli of B1, B2, and B3 crystals; the surface energies of B1 and B2 crystals; and the defect-formation energies and atomic configurations of 66 Fe-Cr-C complexes. Most of these material properties were found to be reproduced by our proposed empirical bond-order potentials. The formation energies and lattice constants of randomly mixed Fe-Cr alloys calculated using the interatomic potentials were comparable to those obtained through experiments and first-principles calculations. Furthermore, the energies and structures of interfaces between Cr carbide and ?-Fe as predicted through first-principles calculations were well reproduced using these interatomic potentials.

Kumagai, Tomohisa; Nakamura, Kaoru; Yamada, Susumu; Ohnuma, Toshiharu

2014-12-01

356

Effect of grain size on creep and creep-rupture properties of hastelloy X  

International Nuclear Information System (INIS)

Effect of grain size variation between 60 ?m and 350 ?m on creep and creep-rupture properties was studied on Ni-base alloy Hastelloy X. Creep and creep-rupture tests were carried out at 800, 900 and 10000C for durations up to about 103 h. At the same time, measurements of the number and size of grain boundary cavities were conducted through longitudinal sections of specimens which were unloaded during creep deformation by means of optical microscopy of 100 sup( x) magnification, and the relation between grain boundary cavitation and creep deformation was obtained. Rupture life decreased with increase of grain size at 8000C, but, at 10000C,increased with increase of grain size. Rupture life at 9000C was little affected by grain size variation. Grain boundary cavities below 20/mm2 initiated at the time of starting of the tertiary creep range. The higher rupture strength of finer grain size materials at 8000C corresponded to the phenomena that the number and size of grain boundary cavities at constant crept time and the number of grain boundary cavities at constant creep strain decreased as grain size decreased. These phenomena at 8000C show the ease of initiation and growth of grain boundary cavities in coarser grain size materials and are considered to be due to cohesion of the carbides near the grain boundaries. The higher rupture strength of coarser grain size materials at 10000C corresponded to the phenomena that the number and size of grain boundary cavities at constant crept time decreased as grain size increased and linkage of the cavities occurred in the early creep region for finer grain size materials. These phenomena at 10000C which show difficulty of initiation and growth of grain boundary cavities in coarser grain size materials may be attributed to a continuous precipitation of the carbides at the grain boundaries. (author)

357

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)

358

Creep behaviour of heat-resistant power plant steels under rectangular cyclic stress  

International Nuclear Information System (INIS)

The modified life component rule is suitable for describing, to a great extent, the rectangular cyclic creep behaviour of a series of typical heat-resistant steels. In order to predict fracture time or expansion boundary time, the data of a stress cycle are necessary in addition to the normal creep values of a steel. (orig.)

359

Creep fatigue behavior of heat resistant steels under service-type strain cycling at high temperature  

International Nuclear Information System (INIS)

On three typical heat resistant steels the creep fatigue behaviour is investigated up to about 10000 h test duration using a service-type strain cycle. In a creep fatigue life analysis the cyclic deformation behaviour and the applicability of the generalized damage accumulation rule are investigated and possibilities of long-term creep fatigue prediction are studied. (orig.)

360

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

361

Heat resisting scintillation counters with optical contact on the base of low-molecular polyorganosiloxane elastomers  

International Nuclear Information System (INIS)

The results of development of spectrometric scintillators with a heat resistance up to +150 deg C are presented. Optical glues based on polymethyldephenyl (demethyl) siloxane rubber and a catalyst for cold curing of organooxymoxysilanes were used as an optical contact. The results of quality testing of the optical contact are given, as well as the results of thermo- and vibrotests of the detectors

362

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

363

Effects of 10 MeV electron irradiation at high temperature of a Ni-Mo-based Hastelloy.  

Science.gov (United States)

A Hastelloy alloy was irradiated with 10 MeV electrons at 650 degrees C for 700 h to a total dose of 2 x 10(-3) displacements per atom (dpa). The microstructure of irradiated and non-irradiated specimens of this alloy were investigated by transmission electron microscopy (TEM). The non-irradiated specimens were analyzed by 3-D atom probe tomography (APT) in a local-electrode atom-probe (LEAP). TEM analysis before the irradiation detects small precipitates with a mean diameter of 22 nm, which are coherent with the FCC matrix. The number density of these precipitates is approximately 7 x 10(18) m(-3). Electron diffraction patterns from these precipitates exhibit superlattice reflections corresponding to the L1(2) ordered structure. The chemical composition of the precipitates, as measured by APT, is around 75 at% Ni with additions of Al, Ti and Mo. After electron irradiation, small precipitates with an irregular morphology are observed. The number density of these new precipitates about 10(20) m(-3) is greater than that of the L1(2) ordered precipitates before irradiation. The L1(2) superlattice reflections disappear completely, instead diffuse diffraction spots are observed at 1(1/2)0(FCC), which is attributed to compositional short-range order (SRO). The results are discussed with respect to the influence of the electron irradiation on the morphology and structure of the ordered precipitates. PMID:17403580

Wanderka, N; Bakai, A; Abromeit, C; Isheim, D; Seidman, D N

2007-09-01

364

Hydrogen transport in nickel base stainless alloys  

Science.gov (United States)

Hydrogen transport parameters have been measured in two nickel base stainless alloys, HASTELLOY Alloys C-276 and G. Hydrogen diffusivity and permeability were determined by means of the electrolytic permeability technique over the temperature range of 17 to 90 °C. Although the two alloys are similar in composition and structure, they exhibited dramatically different hydrogen behavior. For Alloy C-276, the diffusivity in both the cold worked and annealed conditions decreased by a factor of two following low temperature (500 °C) aging. That behavior was related to ordering in the alloy. Unexpectedly, hydrogen trapping was not observed in Alloy C-276. An analysis of hydrogen transport in Alloy G indicated reversible and irreversible trapping of hydrogen by niobium substitutional atoms and second phase carbides, respectively. The hydrogen transport results were related to the hydrogen embrittlement tendencies of the two nickel base alloys.

Mezzanotte, David A.; Kargol, James A.; Fiore, Nicholas F.

1982-07-01

365

Dispersion ageing of the Mo-Zr-C alloys  

International Nuclear Information System (INIS)

Kinetics of forming of superfine heat-resistant structures in molybdenum alloys with carbide phases, appearing in the process of senescence and directed crystallization, is studied. The two stages character of ageing alloys is set. Conditions of cleaning of molybdenum matrix from a carbon at the simultaneous alloying by dispersion carbides are exposed. More high thermal stability of eutectic fibres (plates) on comparison with the dispersion particles of ageing alloys is shown

366

Carburization behaviour of high temperature alloys in carburizing environment  

International Nuclear Information System (INIS)

In studying the carburization behaviour of high temperature alloys, carburization tests in heavy carburizing environment were undertaken on several potential candidate alloys for uses in HTR system. The alloys tested were R 4286 developed by ERANS (Engineering Research Association of Nuclear Steel-making) programme, Ni-18.5 % Cr-21.5 % W as identified F alloy, Hastelloy XR and Hastelloy XR-II, and the test environment conditions employed were (Ar + 10 % CH4) gas at 800, 850, 900 and 950 deg C for up to 100 hours. It is shown that when no protective surface oxide layer is formed, the carburization kinetics follows a parabolic rate law, and the alloying additions of Al and Ti have a beneficial effect in dry environment (very low oxidizing) on the carburization resistance due to the formation of Al-Ti-based oxide and without formation of Cr-based oxide. In the comparison of the carburization resistance of the alloys tested, R 4286 containing 2 % Al and 2.5 % Ti exhibits the best resistance due to the formation of the protective Al-Ti-based oxide and the F alloy shows a moderate resistance, while Hastelloys XR and XR-II are found to have the lowest resistance. (author)

367

Heat-resistance of Hamigera avellanea and Thermoascus crustaceus isolated from pasteurized acid products.  

Science.gov (United States)

Products containing sugar or fruit derivatives are usually subjected to a pasteurization process that can anyway be ineffective to kill ascospores from heat-resistant molds. Although the most occurring and economically relevant heat-resistant species belong to Byssochlamys, Neosartorya, Talaromyces, and Eupenicillium genera, an increasing number of uncommon heat-resistant isolates have been recently detected as spoiling microorganisms in such products. Since Hamigera spp. and Thermoascus spp. were those more frequently isolated at SSICA, heat resistance of Hamigera avellanea and Thermoascus crustaceus strains from pasteurized acid products was studied in apple juice, in blueberry and grape juice and in a buffered glucose solution. Data obtained from thermal death curves and statistical elaboration of raw data showed that D values of H. avellanea may vary between 11.11 and 66.67 min at 87°C, between 4.67 and 13.51 at 90°C, and between 0.43 and 1.52 min at 95°C. Similarly, D values of T. crustaceus may vary between 18.52 and 90.91 min at 90°C, between 2.79 and 19.23 at 93°C, and between 1.11 and 2.53 min at 95°C. For both strains studied, the z-values calculated from the decimal reduction time curves did not prove to be significantly influenced by the heating medium, that being 4.35°C, 5.39°C or 5.27°C for H. avellanea and 4.42°C, 3.69°C or 3.37°C for T. crustaceus, respectively in apple juice, in blueberry and grape juice or in the buffered glucose solution. Considering the pasteurization treatments industrially applied to fruit-based foods, the variation of thermal parameters does not seem to be a possible way to avoid product spoilage by these two species and only good practices applied to reduce the original load of heat-resistant fungi can help producers to prevent losses in contaminated finished products, as usually happens for other heat resistant molds. PMID:24239977

Scaramuzza, Nicoletta; Berni, Elettra

2014-01-01

368

Influence of test temperature on post irradiation, high temperature tensile and creep properties of X8CrNiMoNb1616, X10NiCrAlTi3220 (alloy 800) and NiCr22Fe18Mo (Hastelloy X)  

International Nuclear Information System (INIS)

To extend the database of potential HTGR control rod tube materials, three austenitic alloys X8CrNiMoNb 16 16, X10NiCrAlTi 32 20 and NiCr22Fe18Mo were irradiated in the form of tensile and creep test specimens at 400, 500 and 600degC to a thermal neutron fluence of 3x1025 m-2. The main aim was to quantify the influence of the irradiation temperature on the materials' short-term mechanical properties between RT and 900degC, but additional information should be gained regarding the possible influence of neutron spectra, the materials' high temperature notch sensitivity and the influence of upset temperatures on the materials high temperature embrittlement. The irradiation behaviour, especially of Alloy 800, is very complex. Both strength and ductility values between RT and 800degC are influenced by the irradiation temperature, and in case of the unirradiated controls, by the annealing temperature, an indication for intricate precipitation behaviour. The high temperature embrittlement can be very severe and was already evident at test temperatures of 400degC. There are indications that a high-energy neutron spectrum increases the materials' strength values in tensile testing. (orig.)

369

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

370

Physical Simulation of Friction Stir Welding and Processing of Nickel-Base Alloys Using Hot Torsion  

Science.gov (United States)

The Gleeble hot torsion test was utilized in an attempt to simulate the friction stir-processed microstructure of three Ni-base alloys: Hastelloy X, Alloy 625, and Alloy 718. The simulation temperatures were based on actual thermal cycles measured by embedded thermocouples during friction stir processing of these alloys. Peak process temperatures were determined to be approximately 1423 K (1150 °C) for Hastelloy X and Alloy 625 K and 1373 K (352 °C and 1100 °C) for Alloy 718. The peak temperature and cooling rates were programed into the Gleeble™ 3800 thermo-mechanical simulator to reproduce the stir zone and thermo-mechanically affected zone (TMAZ) microstructures. The TMAZ was successfully simulated using this technique, but the stir zone microstructure could not be accurately reproduced, with hot torsion samples exhibiting larger grain size than actual friction stir processing trials. Shear stress and strain rates as a function of temperature were determined for each material using hot torsion simulation.

Rule, James R.; Lippold, John C.

2013-08-01

371

Creep properties of hastelloy x and their application to the structural design  

International Nuclear Information System (INIS)

In the creep curve of Hastelloy X, it was difficult to divide it into the three stages of creep. However, these stages were made distinguishable by plotting the relationship between creep rates and time in double-logarithmic coordinates. All the creep data of Hastelloy X, except the isochronous stress-strain curves, required for determining the design stress intensities S sub(o) and S sub(t) were arranged through the Larson-Miller parameter. The isochronous stress-strain curves for a heat of Hastelloy X were derived from the constitutive equations obtained from short-term data. A fairly good agreement between the predicted data and the experimental data was obtained. (auth.)

372

High temperature low-cycle fatigue strength of Hastelloy X  

International Nuclear Information System (INIS)

Isothermal low-cycle fatigue tests including both load controlled and strain controlled tests were conducted on Hastelloy X, one of the materials for VHTR (Very High Temperature Gas Cooled Reactor). The effects of temperature, atmosphere, strain rate and hold time were studied. Special attention was given to the creep-fatigue criteria. The results are summarized as follows. (1) In the simulated VHTR He gas, the fatigue life increases as compared with that in air for the test without any strain hold time, but remains almost unchanged for the test with a long strain hold time. (2) In the temperature range from 800 to 10000C, the Coffin-Manson relationship holds between plastic strain range and fatigue life, but it does not agree well with the result estimated from the tensile test. (3) The relationships between plastic strain range and fatigue life obtained from the strain controlled test under different strain rates and strain hold times are almost equal. The fatigue life under the strain controlled test can be estimated using these relationships. (4) The result of the load controlled test agrees well with that obtained by applying the linear damage rule on the assumption that the total damage consists of the two kinds of damages caused by cyclic plastic strain and by accumulation of creep strain on one side. The both damages can be calculated by applying the life fraction rule to the relationship between plastic strain range and fatigue life and to that betain range and fatigue life and to that between stress and creep rupture ductility, respectively. (auth.)

373

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.)

374

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

Energy Technology Data Exchange (ETDEWEB)

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 H/sub 2/SO/sub 4/ 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.

Bort, H.; Wolf, I.; Leistikow, S.

1987-07-01

375

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

Science.gov (United States)

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 H 2SO 4 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.

Bort, H.; Wolf, I.; Leistikow, S.

1987-07-01

376

Temperatures and the condensate heat resistance in dropwise condensation of multicomponent mixtures with inert gases  

Energy Technology Data Exchange (ETDEWEB)

The temperature variations occurring in dropwise condensation at condenser plates of a compact, polymer heat exchanger are studied using instantaneous infrared temperature field recordings. An averaging procedure in time and an assessment of extreme values is proposed and carried out. With the results, the heat resistance of the condensate is quantified. It is found that mixing and convection in the condensate, caused by coalescence and drainage of drops, reduces the condensate heat resistance by a factor 4 as compared with purely conductive heat transfer. This reduction is comparable, both in nature and in magnitude, to the effect of enhanced mixing due to turbulence in the liquid film of filmwise condensation. A second condensable species has been added to the gas mixture in order to study the contribution of Marangoni convection due to concentration gradients to the condensate heat transfer resistance. No contribution is found. (Author)

Ganzevles, F.L.A.; Geld, C.W.M. van der [Eindhoven University of Technology (Netherlands). Faculty of Mechanical Engineering

2002-07-01

377

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

378

Does enhanced heat resistance of irradiated insects represent greater ability to adapt  

International Nuclear Information System (INIS)

Previous work from this lab demonstrated that irradiated flour beetles (Tribolium) develop resistance to oxygen with similar kinetics: greater sensitivity for about 1 week, increasing resistance over the next week, and resistance persisting for 3-6 months. This is in contrast to the rapid development of heat resistance in yeast exposed to UV or ionizing radiation and to rapid induction of heat-stress proteins in E. coli exposed to UV or nalidixic acid. The authors' early work did not distinguish between intrinsic heat resistance and enhanced ability to adapt. They tried to resolve this problem by comparing response of irradiated and of control beetles to challenge at 450C with or without brief exposure to 410C just prior to challenge. Mean lethal exposure time at 450C was increased to about the same extent in both populations after 15 min at 410C, suggesting that irradiation increases insectors' intrinsic resistance to stress rather than their ability to adapt

379

Ordered mesoporous silica materials (SBA-15) with good heat-resistant magnetism  

International Nuclear Information System (INIS)

A series of highly ordered mesoporous materials (CF-SBA-15) with heat-resistant magnetism have been successfully prepared from impregnation of cobalt salt, iron salt, and citric acid with as-synthesized SBA-15. XRD and N2 isotherms indicate that these materials have highly ordered hexagonal mesoporous symmetry and open pore systems. The measurement of magnetic property shows that these materials are ferromagnetic even if calcined at 550 deg. C for 10 h in air, indicating their good heat-resistant magnetism. These results would be very important for recycle and regeneration of adsorbents and catalysts in practical applications. Moreover, this method may be useful for other mesoporous materials with thermally stable magnetism from a combination of other mesoporous materials such as MCM-41 with magnetic nanoparticles of MnFe2O4 and NiFe2O4

380

The mean condensate heat resistance of dropwise condensation with flowing inert gases  

OpenAIRE

The quantification of the condensate heat resistance is studied for dropwise condensation from flowing air-steam mixtures. Flows are essentially laminar and stable with gas Reynolds numbers around 900 and 2000. The condensate shaping up as hemispheres on a plastic plane wall and the presence of inert gases make it possible that thermocapillary convection occurs making the resistance less than the mean condensate thickness (ca. 0.185 mm) divided by the heat conduction coef...

Geld, C. W. M.; Brouwers, H. J. H.

1995-01-01

381

Comparative evaluation of forecasting techniques for heat resisting materials in power machine-building  

International Nuclear Information System (INIS)

The technique of forecasting heat resistance of materials used in power machine building is suggested and tested. The 15Kh1M1F and Kh18NM4Mo steels have been tested to prove the possibility of using the equations suggested for the extrapolation of results of tests lasting from 10-50 th h to 100-200 th h. A program in the FORTRAN language is developed for the computer processing of dependences used

382

New heat-resistant chromium steels for a promising objects of power engineering  

Science.gov (United States)

Data are presented on new-grade 12Kh10M1V1FBR and 10Kh9V2MFBR heat-resistant chromium steels for turbine rotors, boiler tube systems, and pipelines of ultrasupercritical steam parameters. The operating properties of new steels are assessed in comparison with those of 12Kh1MF, 15Kh1M1F, and 10Kh9MFB steels.

Dub, A. V.; Skorobogatykh, V. N.; Shchenkova, I. A.

2008-07-01

383

Injection Molded Optical Lens Using a Heat Resistant Thermoplastic Resin with Electron Beam Cross-Linking  

Science.gov (United States)

The poor heat resistant properties of a transparent thermoplastic resin was improved by electron beam irradiation cross-linking. A correcting aspheric lens for a 635-nm laser diode was fabricated using an injection molding machine, and was irradiated with an electron beam. The near field pattern (NFP), the far field pattern (FFP) at the focus position and the transmittance of the lens did not change after exposure to a 260 °C reflow process for 60 s.

Tomomi Sano,; Yoshitomo Iyoda,; Takayuki Shimazu,; Michiko Harumoto,; Akira Inoue,; Makoto Nakabayashi,; Hiroshi Ito,

2010-05-01

384

Creep of heat resistant steels under various temperature-force conditions  

International Nuclear Information System (INIS)

12Kh1MF and 15Kh1M1F steels are studied for changes in the fine structure and for failure under creep. The results of creep tests are presented. The temperature-force regions are investigated where various kinetic regularities and different mechanisms of creep processes are observed. A diagram suggested for 12Kh1MF steel permits estimation of the temperature force test conditions proceeding from service conditions in order to predict long-term heat-resistant properties

385

Automated system for studying heat resistance of ceramic and refractory materials  

International Nuclear Information System (INIS)

Automated system is described intended for testing ceramic and refractory materials under their thermal loading with simultaneous recording of acoustic emission which accompanies the process of specimen destruction. The presented results of tests prove it possible not only to determine the fracture moment of specimens but also to localize the macrocrack initiation zone in them. The results also testify to the effect of mechanical processing of specimens on their heat resistance

386

Incidence and diversity of potentially highly heat-resistant spores isolated at dairy farms.  

Science.gov (United States)

The presence of highly heat-resistant spores of Bacillus sporothermodurans in ultrahigh-temperature or sterilized consumer milk has emerged as an important item in the dairy industry. Their presence is considered undesirable since they hamper the achievement of commercial sterility requirements. By using a selective 30-min heat treatment at 100 degrees C, 17 Belgian dairy farms were screened to evaluate the presence, sources, and nature of potentially highly heat-resistant spores in raw milk. High numbers of these spores were detected in the filter cloth of the milking equipment and in green crop and fodder samples. About 700 strains were isolated after the selective heating, of which 635 could be screened by fatty acid methyl ester analysis. Representative strains were subjected to amplified ribosomal DNA restriction analysis, 16S rRNA gene sequencing, percent G+C content, and DNA-DNA reassociations for further identification. The strain collection showed a remarkable diversity, with representatives of seven aerobic spore-forming genera. Bacillus licheniformis and Bacillus pallidus were the most predominant species overall. Twenty-three percent of the 603 spore-forming isolates proved to belong to 18 separate novel species. These findings suggest that the selective heating revealed a pool of unknown organisms with a higher heat-resistant character. This study showed that high spore counts can occur at the dairy farm and that feed and milking equipment can act as reservoirs or entry points for potentially highly heat-resistant spores into raw milk. Lowering this spore load by good hygienic measures could probably further reduce the contamination level of raw milk, in this way minimizing the aerobic spore-forming bacteria that could lead to spoilage of milk and dairy products. Assessment and characterization of this particular flora are of great importance to allow the dairy or food industry to adequately deal with newly arising microbiological problems. PMID:15746351

Scheldeman, Patsy; Pil, Annelies; Herman, Lieve; De Vos, Paul; Heyndrickx, Marc

2005-03-01

387

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

388

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

Energy Technology Data Exchange (ETDEWEB)

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. [Physics Research Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan); Akhter, J.I. [Physics Research Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan)]. E-mail: jiakhter@yahoo.com; Iqbal, M. [Physics Research Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan); Akhtar, M. [Physics Research Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan); Ahmed, E. [Physics Research Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan); Shaikh, M.A. [Physics Research Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan); Saeed, K. [Nuclear Materials Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan)

2005-01-01

389

Applying Tep Measurements to Assess the Response of Hastelloy to Long Time Aging  

Science.gov (United States)

Hastelloy C-276 service temperature is restricted due to precipitation of the intermetallic compound ?. Time-temperature curves indicate that the highest precipitation rate is obtained at about 870° C. Thermoelectric Power (TEP) measurements were applied to monitor the precipitation kinetics during aging at 870° C. The TEP was found to be well correlated with the amount of ? phase formed during aging and with the reduction in impact energy and ductility. It was demonstrated that TEP measurements could be used to monitor aging of Hastelloy C-276.

Ifergane, S.; Gelbstein, Y.; Dahan, I.; Pinkas, M.; Landau, A.

2009-03-01

390

Change in the heat-resistance of sunflower plants under the local effect of soft X-rays  

International Nuclear Information System (INIS)

The local effect of soft X-rays on the growth and heat-resistance of sunflower plants was studied. Irradiation of the main point of growth with doses of 27 and 36 Gr was found to raise the limit of heat-resistance of the plants by 2.5-3.0 deg C. This is apparently related to the accumulation of the dry mass of the leaves owing to the inhibited growth of the stem. A direct correlation was established between the heat-resistance of the plants and the content of firmly bound wat.er in the leaves

391

Dependence of heat resistance of Drosophila on ambient temperature and relationship of this property to mutation process  

International Nuclear Information System (INIS)

It has been demonstrated that thermosensitvity of the gametes in Drosophila line T correlates with the heat resistance of the flies. This property of the gametes is determined during ontogenesis, depending on the temperature during development and not by genotypic preadaptation as such, i.e., affinity of the females to the heat resistance line T. The ability of females to acquire heat resistance during the adult phase (in the first three days after emergence), i.e., by acclimatization to a temperature different from the temperature during development does not change the response of the gametes to extreme temperature which had developed during ontogenesis under a particular temperature

392

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

393

Heat resistance of Listeria monocytogenes in vacuum packaged pasteurized fish fillets.  

Science.gov (United States)

The heat resistance of two strains of Listeria monocytogenes in sous-vide cooked fillets of cod and salmon was investigated. Fish sticks of 5 g were inoculated, vacuum-packed and heated at different combinations of time and temperature (58-80 degrees C). Time-temperature combinations allowing survival and time-temperature combinations at which the bacteria were destroyed, were used to determine D- and z-values. D-values were in the range of what has been published for other food products. D60-values were between 1.95 and 4.48 min depending on the strain and the fish. Both strains were one-four-times more heat resistant in salmon than in cod, showing the importance of the heating menstruum. This difference may be due to the higher fat content in salmon as compared to cod. Z-values were calculated to be 5.65 and 6.4 degrees C, respectively, for the two strains. The suitability of methods for heat resistance experiments and the survival of L. monocytogenes in sous-vide cooked fish fillets are discussed. PMID:8268058

Ben Embarek, P K; Huss, H H

1993-11-01

394

Development of high Cr heat-resistant steel for realization of fast breeder  

International Nuclear Information System (INIS)

To realize fast breeder reactor until 2050, high Cr heat-resistant steel has been developed for materials of the cooling system and fuel cladding. Mod. 9Cr-1Mo steel, precipitation hardening ferritic steel, was used to the cooling system. Chemical compositions, history, the present statue of research activities about Mod. 9Cr-1Mo steel and application to fast breeder reactor are described. 9Cr-ODS (Oxide dispersion strengthened ferritic steel) for the fuel cladding is reported with background, history, the present statue of researches, fine structure, production process, and development plan. Illustrated are the outline of realization of fast breeder reactor in Japan, compactification of fast breeder reactor plant by application of high Cr heat-resistant steel, heat-resistant and irradiation-resistant property of ODS, fine structures of 9Cr-ODS, production process of ODS, improvement of cooling work and strength by controlling the cooling rate, the short-time strength and internal pressure creep rupture strength of 9Cr-ODS, PNC-316 and PNC-FMS, and development plan of ODS. (S.Y.)

395

Two distinct groups within the Bacillus subtilis group display significantly different spore heat resistance properties.  

Science.gov (United States)

The survival of bacterial spores after heat treatment and the subsequent germination and outgrowth in a food product can lead to spoilage of the food product and economical losses. Prediction of time-temperature conditions that lead to sufficient inactivation requires access to detailed spore thermal inactivation kinetics of relevant model strains. In this study, the thermal inactivation kinetics of spores of fourteen strains belonging to the Bacillus subtilis group were determined in detail, using both batch heating in capillary tubes and continuous flow heating in a micro heater. The inactivation data were fitted using a log linear model. Based on the spore heat resistance data, two distinct groups (p < 0.001) within the B. subtilis group could be identified. One group of strains had spores with an average D120 °C of 0.33 s, while the spores of the other group displayed significantly higher heat resistances, with an average D120 °C of 45.7 s. When comparing spore inactivation data obtained using batch- and continuous flow heating, the z-values were significantly different, hence extrapolation from one system to the other was not justified. This study clearly shows that heat resistances of spores from different strains in the B. subtilis group can vary greatly. Strains can be separated into two groups, to which different spore heat inactivation kinetics apply. PMID:25481058

Berendsen, Erwin M; Zwietering, Marcel H; Kuipers, Oscar P; Wells-Bennik, Marjon H J

2015-02-01

396

Fundamental studies on electron beam welding on heat-resistant superalloys for nuclear plants, (3)  

International Nuclear Information System (INIS)

In this report, microcracks in the electron beam welds of the superalloys for nuclear plants were metallurgically investigated. Obtained conclusions can be summarized as follows; 1) The precipitates adjacent to the fusion line of Hastelloy X, Inconel 617 and Incoloy 807 which accompany microcracks change and melt clearly. On the other hand, those of Inconel 625 and SUS 316 in which microcracks never occur remain unchanged, and the precipitates remain nearly in the original condition in the case of Incoloy 800 which accompanies microcracks. 2) Main precipitates identified for every superalloy are M23C6 and M6C for Hastelloy X, M6C for Inconel 617, NbC and Ti(C,N) for Incoloy 807, NbC for Inconel 625, Ti(C,N) for Incoloy 800 and M23C6 for SUS 316. 3) The liquation of precipitates is considered to take place only when either melting temperature of precipitates or eutectic temperature between precipitates and matrix ? is lower than the temperature of matrix to start melting. 4) It is easily presumed that a microcrack will initiate at the melted precipitate at the grain boundary of the heat affected zone adjacent to the fusion line where the distribution of temperature, stress and strain is of peculiar characteristics. This distribution will be described in the following report in details. (author)

397

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)

398

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.)

399

High temperature crevice corrosion of hastelloy x in helium environment containing several kinds of impurities  

International Nuclear Information System (INIS)

Interaction between a Ni-base heat-resistant alloy and simulated HTR primary coolant environment, which contained controlled concentrations of both oxidizing and carburizing impurities, was examined with emphasis placed on the reactions inside narrow crevice gaps. A test method of providing artificial crevice using a Mo container was developed to obtain quantitative results with resonable reproducibility. The test environment was helium of low oxidizing potential with trace amount of gaseous impurities: H2, H2O, CO2 and CH4. The state of oxidation on the inner surfaces of the crevice was examined by measuring the change in concentration of Cr on the specimen surface using EPMA. Significant difference in the change of the surface was seen along with the distance from the crevice entrance. There was a preferential consumption of oxidizing species in the outer part of the crevice due to the formation of continuous oxide film, leading to porous or discontinuous oxide film formation, and the resultant extensive carburizations in the inner part of the crevice. Vaporization was noted far inside the crevice where oxide film was scarecely formed. The zone of continuous oxide film formation was found to extend into the crevice as a function of the 1/4 power of exposure time, and its reaching distance in a given time was proportional to the square root of opening of crevice gap. These relations were consistent with a model with an assu were consistent with a model with an assumption that the diffusion of reactants through the gas was a rate determining step. The model based on the results obtained will be applied to the crevices with the similar geometrical effects such as the internals of fatigue and creep cracks and also actual crevice formed on the surface of heat exchanger tubes. (author)

400

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

401

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

Science.gov (United States)

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

2011-02-01

402

Superconductivity mediated by a soft phonon mode: specific heat, resistivity, thermal expansion and magnetization of YB6  

OpenAIRE

The superconductor YB6 has the second highest critical temperature Tc among the boride family MBn. We report measurements of the specific heat, resistivity, magnetic susceptibility and thermal expansion from 2 to 300 K, using a single crystal with Tc = 7.2 K. The superconducting gap is characteristic of medium-strong coupling. The specific heat, resistivity and expansivity curves are deconvolved to yield approximations of the phonon density of states, the spectral electron-p...

Lortz, R.; Wang, Y.; Tutsch, U.; Abe, S.; Meingast, C.; Popovich, P.; Knafo, W.; Shitsevalova, N.; Paderno, Yu B.; Junod, A.

2005-01-01

403

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

404

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

405

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

406

Model aids alloy life prediction  

International Nuclear Information System (INIS)

Over the years, a number of mathematical models designed to analyze rupture data have been developed and widely used by processing engineers to project material strength, set allowable design stresses and predict the longevity of heat resistant alloys. Until recently, the mathematical models most commonly applied to heat resistant alloy rupture analysis have been open to error. Now, however, a mathematical model has been developed that removes a great deal of the subjective limitations of traditional models in the parametric statistical analysis of creep rupture data. This model is called ''The Bi-Linear Method For Parametrical Statistical Analysis of Creep Rupture Data'', and is available to the industry. The penalties for failure to accurately predict optimum allowable stresses can be (1) premature failure, in the case of under designing, (2) increased thermal stress in thicker sections of equipment components, and (3) waste due to over designing

407

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

408

Creep properties of Hastelloy X and their application to structural design  

International Nuclear Information System (INIS)

Creep and stress rupture tests on three heats of Hastelloy X differing in the manufacturing process were carried out at 8000C, 9000C and 10000C. Interpretation of the observed creep properties was made, and a method for predicting necessary design data from the experimentally obtained results was discussed. The results are as follows. (1) It was difficult to separate the primary, secondary and tertiary creep stages in the creep curve of Hastelloy X of the present tests. However, those were made distinguishable by plotting the results in a double-logarithmic coordinates. From these creep rate curves, the primary and secondary creep rates and the times to the initiation of secondary and tertiary creeps were derived. (2) It is considered that the same stress and temperature dependences between the primary and secondary creep rates exist in the creep behaviour of Hastelloy X of the present tests. (3) All the creep data, except the isochronous stress-strain curve, required for the design such as stress vs. rupture time, stress vs. secondary creep rate and stress vs. time to initiation of tertiary creep could be arranged through the Larson-Miller parameter. On the other hand, the isochronous stress-strain curve was figured out by estimating creep curves. The constitutive equations of creep for a heat of Hastelloy X proposed in this paper and the isochronous stress-strain curves derived from these constitutive equations were consistent with tstitutive equations were consistent with the experimental data obtained for the corresponding material. (auth.)

409

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.)

410

Heat resistance of gametes of marine invertebrates in relation to temperature conditions under which the species exist  

Energy Technology Data Exchange (ETDEWEB)

The possible role of the heat resistance level of mature gametes and embryos of poikilotherms in the adaptation of a species to environmental temperature conditions was investigated. Within a species, heat resistance of gametes does not undergo any recognizable change even in the presence of significant fluctuations in temperature. Evidence in support of this statement was obtained on gametes of invertebrates belonging to different populations of the same species collected in different seasons, and on invertebrates maintained under different temperatures. The heat resistance of gametes is correlated with the degree of thermophily of the species concerned. Species living under similar temperature conditions exhibit minimal, if any, differences in heat resistance. Hence, the heat resistance level of their gametes is a function of temperature conditions of formation and existence of the species as a whole. During the ontogenesis of poikilotherms, eggs, zygotes and early stages of embryonic development are most susceptible to heat injury. The upper thermal limit for the normal development of eggs and embryos is only 1 to 3/sup 0/C higher than the temperatures encountered under natural conditions. It is concluded that the heat resistance level of gametes and embryos represents an adjustment to temperatures at which spawning, fertilization and earlier embryonal development occur. Temperatures which, throughout the year, exceed the upper thermal limit or remain below the lower thermal limit for the development of embryos, act as limiting factors for the species' distribution.

Andronikov, V.B.

1975-04-30

411

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

412

High-temperature strength of molybdenum base alloys  

International Nuclear Information System (INIS)

Results of studies on high-temperature strength in high vacuum at temperatures of 1473-1873 K are presented for molybdenum-base alloys of MBN, TsM6 and TsM10 type. The TsM6 alloy in the studied temperature range is shown to possess higher heat-resistance characteristics than those of the MBN and TsM10 alloys

413

Creep crack growth behavior of several structural alloys  

Science.gov (United States)

Creep crack growth behavior of several high temperature alloys, Inconel 600, Inconel 625, Inconel X-750, Hastelloy X, Nimonic PE-16, Incoloy 800, and Haynes 25 (HS-25) was examined at 540, 650, 760, and 870 °C. Crack growth rates were analyzed in terms of both linear elastic stress intensity factor and J*-integral parameter. Among the alloys Inconel 600 and Hastelloy X did not show any observable crack growth. Instead, they deformed at a rapid rate resulting in severe blunting of the crack tip. The other alloys, Inconel 625, Inconel X-750, Incoloy 800, HS-25, and PE-16 showed crack growth at one or two temperatures and deformed continuously at other temperatures. Crack growth rates of the above alloys in terms ofJ* parameter were compared with the growth rates of other alloys published in the literature. Alloys such as Inconel X-750, Alloy 718, and IN-100 show very high growth rates as a result of their sensitivity to an air environment. Based on detailed fracture surface analysis, it is proposed that creep crack growth occurs by the nucleation and growth of wedge-type cracks at triple point junctions due to grain boundary sliding or by the formation and growth of cavities at the boundaries. Crack growth in the above alloys occurs only in some critical range of strain rates or temperatures. Since the service conditions for these alloys usually fall within this critical range, knowledge and understanding of creep crack growth behavior of the structural alloys are important.

Sadananda, K.; Shahinian, P.

1983-07-01

414

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)

415

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

416

Studies of thermal-cycle endurance of heat resistant materials under asymmetric thermomechanical loading  

International Nuclear Information System (INIS)

Results of experimental investigation of thermal-cycle endurance of heat resistant materials under conditions of asymmetric thermo-mechanical loading are presented. Using the maximum-likelyhood fit statistical evaluation of the parameters of logarithmically normal distribution of the sample endurance are obtained with an account of the parameter dependence on the level of stresses. A mathematical model of endurance based on the approximation of diagrams of limiting stresses in the case of asymmetric thermo-mechanical loading with the equation of inclined ellipse is suggested. Comparison of the calculated endurance, obtained with an aid of the model with the experiment results is made

417

Utilization of heat-resistance cables with mineral insulation in nuclear-power installations  

International Nuclear Information System (INIS)

The survey reflects accumulated experience in utilization of heat- and radiation-resistant cables with mineral insulation in the monitoring and control system of nuclear power and research reactors, in particular as necessary component parts of intrareactor detectors. Results are reported for several investigations of electrical conductivity in mineral insulation and background effects in cables under intense irradiation and at high temperatures; data on other electrical properties of cables are also generalized. Designs of heat-resistant cables and cable shoes are described and certain technological aspects of their utilization are considered

418

Heat resistance and local structure of FeCl2-absorbed crosslinked poly(?-glutamic acid)  

International Nuclear Information System (INIS)

Fiber of Japanese food natto (Bacillus subtilis) is known to be superabsorbent poly(?-glutamic acid) (PGA). NaCl particles precipitate in FeCl2-absorbed crosslinked PGA when heated at crystallization temperature of 320 deg C for 10 to 60 min. After heat treatment the Moessbauer spectrum of FeCl2-crosslinked PGA consists of a quadrupole doublet due to FeCl2 x 2H2O. The Moessbauer spectrum of anhydrous FeCl2 reagent heated under the same condition shows an intense sextet due to ?-Fe2O3. These results prove that the superabsorbent polymer, crosslinked PGA, has higher heat resistance. (author)

419

Using flame spraying to increase heat resistance of slit radiant recuperator  

International Nuclear Information System (INIS)

The possibility is shown to use ferrosilicium coating produced by flame spraying as a protective layer of the inner cylinder of slit radiation recuperator. Ferrosilicium spraying procedures and optimal particle sizes are determined; heat resistance of samples of the St. 3 sp carbon steel with and without coating as well as that of Kh23N18 steel samples are studied. It is shown that it is advantageous to use coated St. 3 steel for recuperator fabrication instead of the Kh23N18 stainless steel

420

The Further Development of Heat-Resistant Materials for Aircraft Engines  

Science.gov (United States)

The present report deals with the problems involved in the greater utilization and development of aircraft engine materials, and specifically; piston materials, cylinder heads, exhaust valves, and exhaust gas turbine blading. The blades of the exhaust gas turbine are likely to be the highest stressed components of modern power plants from a thermal-mechanical and chemical standpoint, even though the requirements on exhaust valves of engines with gasoline injection are in general no less stringent. For the fire plate in Diesel engines the specifications for mechanical strength and design are not so stringent, and the question of heat resistance, which under these circumstances is easier obtainable, predominates.

Bollenrath, Franz

1946-01-01

421

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

422

Kinetics and mechanisms of crack propagation under creep in heat resisting steel  

International Nuclear Information System (INIS)

Distribution of creep cracks is studied for rotor heat resisting steel within the temperature range of 460...560 deg C and test duration up to 3000 h. A considerable growth of cracks for 1000 h is observed with the values of stress intensity factors 3-7 times lower than the Ksub(Ic) value. Intergranular fracture is observed with comparatively high values of Ksub(I), crack growth being of a discontinuous character; with comparatively small value of Ksub(I) the crack growth occurs due to the growth of pores, their coalescence and convergence with the crack tip

423

Assessment of molybdenum influence on long-term heat resistance of selected austenitic steel grades  

International Nuclear Information System (INIS)

Analysis gave evidence that an increase in the long-term heat resistance by addition of approximately 2.5% molybdenum is, in the long run, more efficient in unstabilized austenitic CrNiMo(N) steels of the AISI 316 type than in stabilized X 6 CrNiMoTi 17 12 steel. The effect of molybdenum can be intensified or reduced by factors such as the stabilization ratio and grain size in stabilized CrNiMoTi steels, and the boron, nitrogen and carbon contents in unstabilized CrNiMo(N) steels. (Z.S.). 6 tabs., 6 figs., 62 refs

424

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)

425

Characteristics of the heat resistant FBG sensor under laser cladding condition  

Science.gov (United States)

We have developed heat resistant strain sensors using laser processing techniques. The application is aimed at structural health monitoring for high temperature piping systems. This situation requires extraordinary durability such as radiation resistance and noise isolation due to adverse conditions caused by nuclear reactions or electro-magnetic pulses. We proposed that a Fiber Bragg Grating (FBG) sensor made by femtosecond laser processing could be the best candidate. The combination of fabric reinforcement and a heatproof adhesive mold successfully protected the fragile optical fiber once the fiber was installed on the piping material's surface. To make the best use of the heat-resistant characteristic, we fixed the FBG sensor by metal mold. A groove was processed onto the surface of a SUS metal plate with a grindstone. We used a Quasi-CW laser to weld a filler wire onto the plate. The optical fiber was situated under the filler wire before was heated by laser pulses with 10 joule energy and a duration of 10 ms. A series of weld pool formed a sealing clad on the groove. The FBG sensor was buried at a depth of 1 mm over a length of 1 cm. No degradation in its reflection spectra was detected before and after the processing. The FBG sensor can detect the vibration of the plate caused by impact shocks. In this paper, the Bragg peak shift of the FBG sensor under laser cladding condition has been discussed.

Nishimura, A.; Terada, T.

2014-02-01

426

Development and properties of new 10Cr-2Mo-V-Nb heat resisting steel  

International Nuclear Information System (INIS)

For the development of a new ferritic heat resisting steel which shows excellent characteristics in creep rupture strength, weldability, resistance to oxidation, and corrosion resistance to sodium and steam at the service temperature of 5000 to 6000C, extensive studies have been carried out. The main results are as follows: (1) 0.05C-10Cr-2Mo-0.1V-0.05Nb steel is obtained, whose creep rupture strength at 6000C is superior to that of SUS 304 (18-8 stainless steel). (2) This steel comprises two phases: delta-ferrite and tempered martensite. Main precipitates after longer term at 6000 to 7000C are M23C6 and Fe2Mo. Fe2Mo, a stable precipitate in ferrite, contributes to the creep rupture strength at longer term. (3) Ferritic heat resisting steel of this type is promising not only for the boiler tube use but for the fast breeder reactor steam generator use, since it has excellent high temperature strength and the resistance to oxidation and corrosion. (author)

427

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

428

Study of heat-resistant coatings by ionplating; Ionplating ni yoru taikyusei hogo himaku no kaihatsu  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study is to develop a preparation technique of composite protective coatings including ceramic hard coatings by means of ionplating, and to apply them to metal molds and gold plating products which require the heat resistance. Conditions of gas phase synthesis of silicon nitride and its performance were investigated. As a result, coatings have been obtained, which are stable at 800 centigrade and have the Vickers hardness over 1,000. Silicon nitrides synthesized in gas phase were all amorphous. Among them, the silicon nitride with a composition of Si3N4 exhibited the most excellent heat resistance. It was shown that titanium is suitable for the adhesive layer between the base material and coating. In addition, aluminum oxide and silicon oxide protective coatings for gold plating were examined. It was made clear that the silicon oxide with a thickness of about 0.15 {mu}m keeps the most natural gold color. This protective coating exhibited several ten times of abrasion resistance when comparing with the gold plating surface. 4 refs., 12 figs., 9 tabs.

Yamamoto, J.; Tamura, M.; Kono, T. [Kochi Prefectural Industrial Technology Center, Kochi (Japan)

1994-10-01

429

Development of Semi-Stochastic Algorithm for Optimizing Alloy Composition of High-Temperature Austenitic Stainless Steels (H-Series) for Desired Mechanical and Corrosion Properties.  

Energy Technology Data Exchange (ETDEWEB)

The goal of this project was to adapt and use an advanced semi-stochastic algorithm for constrained multiobjective optimization and combine it with experimental testing and verification to determine optimum concentrations of alloying elements in heat-resistant and corrosion-resistant H-series stainless steel alloys that will simultaneously maximize a number of alloy's mechanical and corrosion properties.

Dulikravich, George S.; Sikka, Vinod K.; Muralidharan, G.

2006-06-01

430

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

OpenAIRE

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 pa...

Khidhir, Basim A.; Bashir Mohamed; Younis, Mahmoud A. A.

2010-01-01

431

Study ofof weld morphology on thin Hastelloy C-276 sheet of Study weld morphology on thin Hastelloy C-276 sheet of pulsed laser welding pulsed laser welding  

Science.gov (United States)

In this paper, it was indicated that the laser welding was well suitable to joining of thin Hastelloy C-276 sheet (0.5 mm thickness), and also the fine grain were observed in welding zone with invisible HAZ (heat affected zone). In addition, the smooth weld joint could be controlled by means of the laser parameter adjustment. On the other hand, it's proposed that Ni-Cr-Co-Mo and austenite CFe15.1 cubic face-centered crystal structure should be existed in as-received and welding samples, as well as the cause of FWHM (Full Width at Half Maximum) widened and peak offset of joined samples were analyzed.

Wu, Dongjiang; Ma, Guangyi; Guo, Yuquan; Guo, Dongming

432

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

Directory of Open Access Journals (Sweden)

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

433

Absorption of molten fluoride salts in glassy carbon, pyrographite and Hastelloy B  

Science.gov (United States)

Materials performance is one of the issues of the accelerator driven transmutation technology (ADTT). Identification of the materials, which would satisfy the strength and integrity requirements for the target-blanket assembly (e.g. corrosion and radiation resistance), is a significant challenge. We report on the study of the interaction (i.e. penetration and capture) of molten fluoride salts with glassy carbon, pyrolitic graphite, and Hastelloy B, which are considered as candidates for structural materials of the ADTT systems. Massive penetration into and capture of molten fluorides within a several micrometer thick surface layer was observed for all inspected specimens. The incorporation rate of the molten fluorides depends on the exposure time and temperature of the molten fluoride bath. The corrosion resistance of the specimens was verified in stationary conditions. Whereas excellent resistance has been found for pyrolitic graphite, evident corrosion was observed for glassy carbon and particularly for Hastelloy B.

Vacik, J.; Naramoto, H.; Cervena, J.; Hnatowicz, V.; Peka, I.; Fink, D.

2001-03-01

434

AC losses in stacks and arrays of YBCO/hastelloy and monofilamentary Bi-2223/Ag tapes  

Science.gov (United States)

Formulae are presented for the eddy current AC power loss and the AC hysteresis loss of z-stacks and x-arrays made of metal-superconductor strips. The AC self-field case and the applied AC magnetic field case are examined for different stacking spacings of a z-stack and different lateral spacings of an x-array. The effect of different metal-to-superconductor width-ratios on the losses is investigated. Numerical values are given for the two losses in YBCO/hastelloy and in monofilamentary Bi-2223/Ag tapes. At 50 Hz, the eddy current loss in a z-stack or an x-array made of YBCO/hastelloy tapes is small compared to the hysteresis loss while in a z-stack or an x-array made of monofilamentary Bi-2223/Ag tapes, the eddy current loss contributes significantly at small current or small magnetic field amplitudes.

Müller, K.-H.

1999-01-01

435

Interfacial Reactions of Ion Beam Mixed SiC film deposited onto Hastelloy X substrate  

International Nuclear Information System (INIS)

As we reported previously, the materials used for the SO3 decomposer in Iodine-Sulfur cycle for Nuclear Hydrogen Production System require excellent mechanical properties as well as a high corrosion resistance in SO2/SO3 environment at an elevated temperature up to 950 .deg. C. So far, no metallic materials have been proved to be useful in such an environment. We have studied a surface modification of Hastelloy X by a SiC coating and an ion beam mixing. It is expected that only deposited SiC film is easily peeled off during heating at the elevated temperature. However, the SiC coating on Hastelloy X followed by ion beam mixing (IBM) is sustained at the elevated temperature above 900 .deg. C. The mechanisms of the good adhesion at the interface was studies using X-TEM, AES, XPS, XRD, X-SEM and EDS are presented

436

Effects of high temperature environment on creep properties of hastelloy X  

International Nuclear Information System (INIS)

In order to clarify the creep properties of Hastelloy X, that is one of the materials discussed for use in VHTR, in helium at extremely high temperature, creep and rupture tests in helium and in air were carried out on Hastelloy X at temperatures of 9000C and 10000C. No remarkable differences between primary and secondary creep rates in helium and those in air were observed. On the other hand, the initiation of tertiary creep was slower and the period of tertiary creep shorter in helium than in air. Moreover, rupture ductilities decrease in helium as compared with those in air. Those differences are considered to be dependent of less internal oxidation and sharper crack tips in helium than in air. (author)

437

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

438

Guidelines for experimental design protocol and validation procedure for the measurement of heat resistance of microorganisms in milk.  

Science.gov (United States)

Studies on the heat resistance of dairy pathogens are a vital part of assessing the safety of dairy products. However, harmonized methodology for the study of heat resistance of food pathogens is lacking, even though there is a need for such harmonized experimental design protocols and for harmonized validation procedures for heat treatment studies. Such an approach is of particular importance to allow international agreement on appropriate risk management of emerging potential hazards for human and animal health. This paper is working toward establishment of a harmonized protocol for the study of the heat resistance of pathogens, identifying critical issues for establishment of internationally agreed protocols, including a harmonized framework for reporting and interpretation of heat inactivation studies of potentially pathogenic microorganisms. PMID:25305440

Condron, Robin; Farrokh, Choreh; Jordan, Kieran; McClure, Peter; Ross, Tom; Cerf, Olivier

2015-01-01

439

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

440

Creep-rupture tests of internally pressurized Hastelloy-X tubes  

Science.gov (United States)

Seamless Hastelloy-X tubes with 0.375-in. outside diameter and 0.025-in. wall thickness were tested to failure at temperatures from 1400 to 1650 F and internal helium pressures from 800 to 1800 psi. Lifetimes ranged from 58 to 3600 hr. The creep-rupture strength of the tubes was from 20 to 40 percent lower than that of sheet specimens. Larson-Miller correlations and photomicrographs of some specimens are presented.

Gumto, K. H.; Colantino, G. J.

1973-01-01

441

Effect of structure factors on the restriction of production possibility of economical articles of complex nickel alloys by casting and hot working of ingots  

International Nuclear Information System (INIS)

Possibilities of conventional casting and hot working techniques are analyzed for further improvement of production of high nickel alloys with elevated heat resistance. Analysis of investigation results has shown that progress achieved in the field of melting and hot working has no further possibilities for nickel alloys with low degree of structure heterogeneity and, therefore, for alloys with low heat resistance. Further development of compositions of nickel alloys on the base of conventional technology is inefficient or impossible from the economic point of view. Thus, the development and application of principally new technological processes is necessary

442

Effect of NaCl on Heat Resistance, Antibiotic Susceptibility, and Caco-2 Cell Invasion of Salmonella  

OpenAIRE

This study evaluated the effects of NaCl on heat resistance, antibiotic susceptibility, and Caco-2 cell invasion of Salmonella. Salmonella typhimurium NCCP10812 and Salmonella enteritidis NCCP12243 were exposed to 0, 2, and 4% NaCl and to sequential increase of NaCl concentrations from 0 to 4% NaCl for 24?h at 35°C. The strains were then investigated for heat resistance (60°C), antibiotic susceptibility to eight antibiotics, and Caco-2 cell invasion efficiency. S. typhimurium NCCP10812 sh...

Yohan Yoon; Mi-Hwa Oh; Beom-Young Park; Hyunjoo Yoon; Kyoung-Hee Choi

2013-01-01

443

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

Directory of Open Access Journals (Sweden)

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

444

Thermal, epithermal and thermalized neutron attenuation properties of ilmenite-serpentine heat resistant concrete shield  

International Nuclear Information System (INIS)

Experimental measurements were carried out to study the attenuation properties of low-energy neutrons transmitted through unheated and preheated barriers of heavy-weight, highly hydrated and heat-resistant concrete shields. The concrete shields under investigation have been prepared from naturally occurring ilmenite and serpentine Egyptian ores. A collimated beam obtained from an Am-Be source was used as a source of neutrons, while the measurements of total thermal, epithermal, and thermalized neutron fluxes were performed using a BF-3 detector, multichannel analyzer and Cd filter. Results show that the ilmenite-serpentine concrete proved to be a better thermal, epithermal and thermalized neutron attenuator than the ordinary concrete especially at a high temperature of concrete exposure. (Author)

445

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