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An atomistic study of the effects of stress and hydrogen on a dislocation lock in nickel

Description: Even though austenitic alloys are commonly used in a hydrogen environment, hydrogen-induced fracture of these alloys has been reported. Most recently it has been shown that the failure of these alloys in hydrogen is initiated by void formation at slip band intersections. It is the object of this work to investigate the atomistic mechanisms that occur at these slip band intersections in the presence of hydrogen. Specifically it has been suggested that dislocation-dislocation interactions may play a large role in the initiation of voids or cracks. Hirth has summarized the various forms of dislocation interactions, traditionally called Lomer-Cottrell Locks (LCLs), that can occur. Baskes et al. have investigated the effects of stress on a LCL using an Embedded Atom Method (EAM) model for nickel developed previously by Angelo et al. The EAM is a well-established semi-empirical method of atomistic calculation that has been successfully used for over a decade to calculate the energetics and structure of defects in transition metals. The work by Angelo et al. established that the trapping of hydrogen to single dislocations had a maximum energy of ca. 0.1 eV while the trapping to a LCL was significantly greater, {approximately}0.33 eV, thus the authors expect that a LCL could be important in explaining the fracture behavior of a fcc material in a hydrogen environment. Baskes et al. found that under uniaxial stress a LCL in the absence of hydrogen underwent a number of transitions, but it did not dissociate or form a crack nucleus. In this work the authors extend the previous work to include the effects of hydrogen. Specifically they will simulate the experiments of Moody et al. for the case of room temperature exposure of Inconel to 190 atm of hydrogen.
Date: March 19, 1998
Creator: Hoagland, R.G. & Baskes, M.I.
Partner: UNT Libraries Government Documents Department

Thermo-Mechanical Processing Parameters for the INCONEL ALLOY 740

Description: In 2000, a Cooperative Research and Development Agreement (CRADA) was undertaken between the Oak Ridge National Laboratory (ORNL) and the Special Metals Corporation (SMC) to determine the mechanical property response of the IN740 alloy to help establish thermo-mechanical processing parameters for the use of this alloy in supercritical and ultra-critical boiler tubes with the potential for other end uses. SMC had developed an alloy, commercially known as INCONEL alloy 740, which exhibited various beneficial physical, mechanical, and chemical properties. As part of SMC's on-going efforts to optimize this alloy for targeted boiler applications there was a need to develop an understanding of the thermo-mechanical response of the material, characterize the resulting microstructure from this processing, and possibly, utilize models to develop the appropriate processing scheme for this product.
Date: November 19, 2007
Creator: Ludtka, G.M. & Smith, G.
Partner: UNT Libraries Government Documents Department

A new metallographic procedure for edge retention of enclosed surfaces

Description: Utilization of a low melting point, metallic alloy that on solidification has provided a reproducible means of preserving edges and accurately measuring deposits on surfaces mounted for metarographic study. In normal laboratory practice the electrically conducting mounting material generates no hazardous waste, needs no special equipment to prepare and is available commercially at a relatively reasonable price. Previous standard edge preservation techniques were found to be 90% inefficient from a time utilization view compared with the new procedure. This new mounting procedure has greatly improved the quality and efficiency of microstructural studies of all materials, especially those on the inside diameters of heat exchanger components. These studies have included reaction products, shallow creep cracks and deposits on tubing, for which the procedure has proved indispensable.
Date: August 1, 1994
Creator: Katz, O. M.
Partner: UNT Libraries Government Documents Department

Nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel and stainless steel alloys

Description: This report presents a nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel alloys from stainless steel alloys as well as an evaluation of cleaning techniques to remove a thermal oxide layer on aircraft exhaust components. The results of this assessment are presented in terms of how effective each technique classifies a known exhaust material. Results indicate that either inspection technique can separate inconel and stainless steel alloys. Based on the experiments conducted, the electrochemical spot test is the optimum for use by airframe and powerplant mechanics. A spot test procedure is proposed for incorporation into the Federal Aviation Administration Advisory Circular 65-9A Airframe & Powerplant Mechanic - General Handbook. 3 refs., 70 figs., 7 tabs.
Date: February 1, 1998
Creator: Moore, D.G. & Sorensen, N.R.
Partner: UNT Libraries Government Documents Department


Description: A conceptual design is presented for a high power pion production target, based on a rotating band of inconel alloy 718, that is intended to provide a back-up targetry option for the Neutrino Factory Study II. The target band has a 2.5 m radius and has an I-beam cross section that is 6 cm high and with a 0.6 cm thick webbing. The pion capture scenario and proton beam parameters are as specified for the Study II base-line targetry option, i.e. capture into a 20 Tesla tapered solenoidal channel with proton beam fills at 2.5 Hz containing 6 short bunches, each spaced by 20 milliseconds, of 1.67 x 10{sup 13} 24 GeV protons. The target is continuously rotated at 1 m/s to Carey heat away from the production region and through a water cooling tank. The mechanical layout and cooling setup are described and results are presented from realistic MARS Monte Carlo computer simulations of the pion yield and energy deposition in the target and from ANSYS finite element calculations for the corresponding shock heating stresses.
Date: May 4, 2001
Partner: UNT Libraries Government Documents Department


Description: A conceptual design is presented for a high power pion production target for muon colliders that is based on a rotating metal band. Three candidate materials are considered for the target band: inconel alloy 718, titanium alloy 6Al-4V grade 5 and nickel. A pulsed proton beam tangentially intercepts a chord of the target band that is inside a 20 Tesla tapered solenoidal magnetic pion capture channel similar to designs previously considered for muon colliders and neutrino factories. The target band has a radius of 2.5 meters and is continuously rotated at approximately 1 m/s to carry heat away from the production region and through a water cooling tank. The mechanical layout and cooling setup of the target are described, including the procedure for the routine replacement of the target band. A rectangular band cross section is assumed, optionally with I-beam struts to enhance stiffness and minimize mechanical vibrations. Results are presented from realistic MARS Monte Carlo computer simulations of the pion yield and energy deposition in the target and from ANSYS finite element calculations for the corresponding shock heating stresses. The target scenario is found to perform satisfactorily and with conservative safety margins for multi-MW pulsed proton beams.
Date: January 18, 2002
Partner: UNT Libraries Government Documents Department


Description: The ASTM standard B 575 provides the requirements for the chemical composition of Nickel-Chromium-Molybdenum (Ni-Cr-Mo) alloys such as Alloy 22 (N06022) and Alloy 686 (N06686). The compositions of each element are given in a range. For example, the content of Mo is specified from 12.5 to 14.5 weight percent for Alloy 22 and from 15.0 to 17.0 weight percent for Alloy 686. It was important to determine how the corrosion rate of welded plates of Alloy 22 using Alloy 686 weld filler metal would change if heats of these alloys were prepared using several variations in the composition of the elements even though still in the range specified in B 575. All the material used in this report were especially prepared at Allegheny Ludlum Co. Seven heats of plate were welded with seven heats of wire. Immersion corrosion tests were conducted in a boiling solution of sulfuric acid plus ferric sulfate (ASTM G 28 A) using both as-welded (ASW) coupons and solution heat-treated (SHT) coupons. Results show that the corrosion rate was not affected by the chemistry of the materials in the range of the standards.
Date: February 7, 2006
Creator: Fix, D.V.
Partner: UNT Libraries Government Documents Department

Formation and Quantification of Corrosion Deposits in the Power Industry

Description: The presence of deposits on the secondary side of pressurized water reactor (PWR) steam generator systems is one of the main contributors to the high maintenance costs of these generators. Formation and transport of corrosion products formed due to the presence of impurities, metals and metallic oxides in the secondary side of the steam generator units result in formation of deposits. This research deals with understanding the deposit formation and characterization of deposits by studying the samples collected from different units in secondary side system at Comanche Peak Steam Electric Station (CPSES). Fourier transform infrared spectrophotometry (FTIR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) have been used for studying the phases, morphologies and compositions of the iron oxides formed at Unit 1 and Unit 2 of secondary side of steamgenerator systems. Hematite and magnetite were found to be the dominant phases of iron oxides present in the units. Fe, Cr, O, Ni, Si, Cl and Cu were found in samples collected from both the units. A qualitative method was developed to differentiate iron oxides using laser induced breakdown spectroscopy (LIBS) based on temporal response of iron oxides to a high power laser beam. A quantitative FTIR technique was developed to identify and quantify iron oxides present in the different components of the secondary side of the steam generator of CPSES. Amines are used in water treatment to control corrosion and fouling in pressurized water reactors. CPSES presently uses an amine combination of dimethylamine (DMA), hydrazine and morpholine to control the water chemistry. Along with the abovementioned amines, this study also focuses on corrosion inhibition mechanismsof a new amine DBU (1, 8-diazabicyclo [5.4.0] undec-7-ene). Electrochemical impedance spectroscopy and polarization curves were used to study the interaction mechanism between DBU solution and inconel alloys 600 and 690 at steamgenerator operating ...
Date: May 2007
Creator: Namduri, Haritha
Partner: UNT Libraries

Los Alamos Neutron Science Center Area-A beam window heat transfer alalysis

Description: Several analyses that investigate heat transfer in the Area-A beam window were conducted. It was found that the Area-A window should be able to withstand the 1-mA, 3-cm beam of the accelerator production of tritium materials test, but that the margins to failure are small. It was also determined that when the window is subjected to the 1-mA, 3-cm beam, the inner window thermocouples should read higher than the current temperature limit of 900{degrees}C, although it is possible that the thermocouples may fail before they reach these temperatures. Another finding of this study was that the actual beam width before April 1997 was 20 to 25% greater than the harp-wire printout indicated. Finally, the effect of a copper-oxide layer on the window coolant passage was studied. The results did not indicate the presence of a large copper-oxide layer; however, the results were not conclusive.
Date: July 1, 1997
Creator: Poston, D.
Partner: UNT Libraries Government Documents Department


Description: Inconel can be used for thermal neutron flux measurements by means of its cobalt impurity or its chromium constituent where conventional monitors are unsuitable. The use of cobalt should also be applicable to other nickel alloys. Discriminatory counting is required. (auth)
Date: March 16, 1959
Creator: Guss, D.E. & Leddicotte, G.W.
Partner: UNT Libraries Government Documents Department


Description: A study of the behavior of Inconel at 1500 deg F under realistic dynamic stress states was performed to critically evaluate present criteria used to solve low-cycle fatigue problems and to demonstrate their applicability for the more complex situations. The relative agreement between the static complex stress- creep-rupture results and the low-cycle fatigue data is demonstrated. From the relationships developed for static complex stress-creep-rupture data, it is demonstrated that the magnitudes of the effects of stress state and frequency on low-cycle fatigue can be determined. (auth)
Date: March 21, 1963
Creator: Kennedy, C.R.
Partner: UNT Libraries Government Documents Department


Description: The inert--gas arc-spray method was studied in an effort to develop a continuous process for coating metals with calcium. Duplex electrode arc-spray equipment was used throughout the investigation. While the process appeared feasible, vapors produced during arc spraying and generally poor adhesion of the calcium to the base metal were considered the major deterrerts to the process. Other methods studied or investigated disclosed that the plasma-jet process improved the bonding between calcium and base metal, but that further research would be necessary to effect uniform coatings of calcium. The present state in Europe of arc-metal spraying was reviewed. No information on specific techniques was located in the literature. (auth)
Date: August 24, 1959
Creator: Haskins, A.F. & Evans, R.M.
Partner: UNT Libraries Government Documents Department


Description: Metal corrosion tests were conducted with four high waste loading non-Fe-limited HLW glass compositions. The results at 1150 C (the WTP nominal melter operating temperature) show corrosion performance for all four glasses that is comparable to that of other typical borosilicate waste glasses, including HLW glass compositions that have been developed for iron-limited WTP streams. Of the four glasses tested, the Bi-limited composition shows the greatest extent of corrosion, which may be related to its higher phosphorus content. Tests at higher suggest that a moderate elevation of the melter operating temperature (up to 1200 C) should not result in any significant increase in Inconel corrosion. However, corrosion rates did increase significantly at yet higher temperatures (1230 C). Very little difference was observed with and without the presence of an electric current density of 6 A/inch{sup 2}, which is the typical upper design limit for Inconel electrodes. The data show a roughly linear relationship between the thickness of the oxide scale on the coupon and the Cr-depletion depth, which is consistent with the chromium depletion providing the material source for scale growth. Analysis of the time dependence of the Cr depletion profiles measured at 1200 C suggests that diffusion of Cr in the Ni-based Inconel alloy controls the depletion depth of Cr inside the alloy. The diffusion coefficient derived from the experimental data agrees within one order of magnitude with the published diffusion coefficient data for Cr in Ni matrices; the difference is likely due to the contribution from faster grain boundary diffusion in the tested Inconel alloy. A simple diffusion model based on these data predicts that Inconel 690 alloy will suffer Cr depletion damage to a depth of about 1 cm over a five year service life at 1200 C in these glasses.
Date: November 5, 2009
Partner: UNT Libraries Government Documents Department

Analysis of unclad and sub-clad semi-elliptical flaws in pressure vessel steels

Description: This study was conducted to support warm prestressing experiments on unclad and sub-clad flawed beams loaded in pure bending. Two cladding yield strengths were investigated: 0.6 Sy and 0.8 Sy, where Sy is the yield strength of the base metal. Cladding and base metal were assumed to be stress free at the stress relief temperature for the 3D elastic-plastic finite element analysis used to model the experiments. The model results indicated that when cooled from the stress relief temperature, the cladding was put in tension due to its greater coefficient of thermal expansion. When cooled, the cladding exhibited various amounts of tensile yielding. The degree of yielding depended on the amount of cooling and the strength of the cladding relative to that of the base metal. When subjected to tensile bending stress, the sub-clad flaw elastic-plastic stress intensity factor, K{sub I}(J), was at first dominated by crack closing force due to tensile yielding in the cladding. Thus, imposed loads initially caused no increase in K{sub I}(J) near the clad-base interface. However, K{sub I}(J) at the flaw depth was little affected. When the cladding residual stress was overcome, K{sub I}(J) gradually increased until the cladding began to flow. Thereafter, the rate at which K{sub I}(J) increased with load was the same as that of an unclad beam. A plastic zone corrected K{sub I} approximation for the unclad flaw was found by the superposition of standard Newman and Raju solutions with those due to a cladding crack closure force approximated by the Kaya and Erdogan solution. These elastic estimates of the effect of cladding in reducing the crack driving force were quite in keeping with the 3D elastic-plastic finite element solution for the sub-clad flaw. The results were also compared with the analysis of clad beam experiments by Keeney and the conclusions ...
Date: June 1, 1996
Creator: Irizarry-Quinones, H.; Macdonald, B.D. & McAfee, W.J.
Partner: UNT Libraries Government Documents Department


Description: The project started on September 1, 2001. During last 4 months, one post-doctor has been hired for this project. We have received TBC samples (YSZ/CoNiCrAlY/ Inconel 601) from Tohoku University, Japan, while processing of the TBC samples was delayed in GE Corp. Research and Development. The TBC preparation in Japan was based on our technical requirement by plasma spray. Bond coat CoNiCrAlY and the YSZ was produced by low-pressure plasma spray and air plasma spray respectively. The morphology of the surface and the microstructure of cross-section of the sample was observed and analyzed by SEM and EDX. XRD was also used to detect the phases in the YSZ. Currently we are processing the overlay Al{sub 2}O{sub 3} on the TBC samples by EB-PVD and high velocity oxy-fuel (HVOF) spray techniques in collaboration with Penn State University and State University of New York at Stony Brook. We will finish comparing the hot corrosion behavior of the Al{sub 2}O{sub 3}/YSZ/CoNiCrAlY/superalloy system with the YSZ/CoNiCrAlY/superalloy system. The mechanism of hot corrosion will be investigated. The processing-structure-properties relationship of the overlays will be determined.
Date: January 31, 2002
Creator: Mao, Scott X.
Partner: UNT Libraries Government Documents Department


Description: The heat exchanger and steam generator for the U. S. Atomic Energy Commission Sodium Components Project will be constructed entirely of type 316 stainless steel. Because of the susceptibility of this alloy to stress corrosion cracking, it is proposed to clad all areas of the steam generator with Inconel where the stainless steel will be exposed to water and steam. A discussion is presented of the work to justify the selection of Inconel for this service. A discussion of Inconel type welding alloys is also included. (auth)
Date: March 1, 1961
Creator: Phillips, L.E. & Vawter, F.F.
Partner: UNT Libraries Government Documents Department


Description: Results are presented of research and development work performed in conjunction with the 70-Mw design of a sodium-to- sodium intermediate heat exchanger and a sodium-to-water steam generator. Kanigen plating was substituted for Inconel overlays. A program to evaluate this plating was undertaken. Elimination of tube end ferrules, mechanical behavior of sine wave tubes, tube-to- tube sheet welded connections, metallurgical examination of bimetallic tubes, transition weld test, bayonet tube test, and bayonet tube weld cap test are discussed. (M.C.G.)
Date: October 30, 1960
Partner: UNT Libraries Government Documents Department

ZT-40M system design, modification, and installation

Description: ZT-40 is a reversed field pinch experiment which had been operated as originally designed, with a ceramic discharge tube until November 1980. At that time, the experiment was shut down for major modifications. This paper will describe these modifications in general and discuss in detail the design of the energy system.
Date: January 1, 1981
Creator: Hammer, C.F.
Partner: UNT Libraries Government Documents Department