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A comparison of several surface finish measurement methods as applied to ground ceramic and metal surfaces

Description: Surface finish is one of the most common measures of surface quality of ground ceramics and metal parts and a wide variety of methods and parameters have been developed to measure it. The purpose of this investigation was to compare the surface roughness parameters obtained on the same two specimens from three different types of measuring instruments: a traditional mechanical stylus system, a non-contact laser scanning system, and the atomic force microscope (two different AFM systems were compared). The same surface-ground silicon nitride and Inconel 625 alloy specimens were used for all measurements in this investigation. Significant differences in arithmetic average roughness, root-mean-square roughness, and peak-to-valley roughness were obtained when comparing data from the various topography measuring instruments. Non-contact methods agreed better with the others on the metal specimen than on the ceramic specimen. Reasons for these differences include the effective dimensions and geometry of the probe with respect to the surface topography; the reflectivity of the surface, and the type of filtering scheme Results of this investigation emphasize the importance of rigorously specifying the manner of surface roughness measurement when either reporting roughness data or when requesting that roughness data be provided.
Date: January 1, 1996
Creator: Blau, P.J.; Martin, R.L. & Riester, L.
Partner: UNT Libraries Government Documents Department

Free form fabrication using the laser engineered net shaping (LENS{trademark}) process

Description: Sandia National Laboratories is developing a technology called Laser Engineered Net Shaping{trademark} (LENS{trademark}). This process allows complex 3-dimensional solid metallic objects to be directly fabricated for a CAD solid model. Experiments performed demonstrate that complex alloys such as Inconel{trademark} 625 and ANSI stainless steel alloy 316 can be used in the LENS{trademark} process to produce solid metallic-shapes. In fact, the fabricated structures exhibit grain growth across the deposition layer boundaries. Mechanical testing data of deposited 316 stainless steel material indicates that the deposited material strength and elongation are greater than that reported for annealed 316 stainless steel. Electron microprobe analysis of the deposited Inconel{trademark} 625 material shows no compositional degradation of the 625 alloy and that 100% dense structures can be obtained using this technique. High speed imaging used to acquire process data during experimentation shows that the powder particle size range can significantly affect the stability, and subsequently, the performance of the powder deposition process. Finally, dimensional studies suggest that dimensional accuracy to {+-} 0.002 inches (in the horizontal direction) can be maintained.
Date: December 31, 1996
Creator: Keicher, D.M.; Romero, J.A.; Atwood, C.L.; Griffith, M.L.; Jeantette, F.P.; Harwell, L.D. et al.
Partner: UNT Libraries Government Documents Department

Towards a reliable laser spray powder deposition system through process characterization

Description: A series of experiments have been performed to characterize the laser spray powder deposition tea-one (HAZ) in the process. Goal of these experiments was to minimize the heat affected base substrate while obtaining a maximum build-up rate of the deposited material. Response surface models have been developed to achieve this goal. These models indicate that laser irradiance and component travel speed are both important factors to be considered in optimization of this process. These models suggest that a minimum HAZ can be obtained with a maximum material build-up height by maintaining with a slow travel speed. Although these models are useful in identifying significant factor and process trends, further refinement is required for practical use in industrial applications. Weighting of the response variables used in generating the models is being considered to improve the model robustness. High speed imaging of the deposition process suggests that the powder particle size and/or size distribution affects the stability of this process.
Date: July 1, 1995
Creator: Keicher, D.M.; Jellison, J.L.; Schanwald, L.P.; Romero, J.A. & Abbott, D.H.
Partner: UNT Libraries Government Documents Department

Irradiation-assisted stress corrosion cracking of HTH Alloy X-750 and Alloy 625

Description: In-reactor testing of bolt-loaded compact tension specimens was performed in 360 C water. New data confirms previous results that high irradiation levels reduce SCC resistance in Alloy X-750. Low boron heats show improved IASCC (irradiation-assisted stress corrosion cracking). Alloy 625 is resistant to IASCC. Microstructural, microchemical, and deformation studies were carried out. Irradiation of X-750 caused significant strengthening and ductility loss associated with formation of cavities and dislocation loops. High irradiation did not cause segregation in X-750. Irradiation of 625 resulted in formation of small dislocation loops and a fine body-centered-orthorhombic phase. The strengthening due to loops and precipitates was apparently offset in 625 by partial dissolution of {gamma} precipitates. Transmutation of boron to helium at grain boundaries, coupled with matrix strengthening, is believed to be responsible for IASCC in X-750, and the absence of these two effects results in superior IASCC resistance in 625.
Date: July 1, 1995
Creator: Bajaj, R.; Mills, W.J.; Lebo, M.R.; Hyatt, B.Z. & Burke, M.G.
Partner: UNT Libraries Government Documents Department

NCSX Vacuum Vessel Fabrication

Description: The National Compact Stellarator Experiment (NCSX) is being constructed at the Princeton Plasma Physics Laboratory (PPPL) in conjunction with the Oak Ridge National Laboratory (ORNL). The goal of this experiment is to develop a device which has the steady state properties of a traditional stellarator along with the high performance characteristics of a tokamak. A key element of this device is its highly shaped Inconel 625 vacuum vessel. This paper describes the manufacturing of the vessel. The vessel is being fabricated by Major Tool and Machine, Inc. (MTM) in three identical 120º vessel segments, corresponding to the three NCSX field periods, in order to accommodate assembly of the device. The port extensions are welded on, leak checked, cut off within 1" of the vessel surface at MTM and then reattached at PPPL, to accommodate assembly of the close-fitting modular coils that surround the vessel. The 120º vessel segments are formed by welding two 60º segments together. Each 60º segment is fabricated by welding ten press-formed panels together over a collapsible welding fixture which is needed to precisely position the panels. The vessel is joined at assembly by welding via custom machined 8" (20.3 cm) wide spacer "spool pieces." The vessel must have a total leak rate less than 5 X 10-6 t-l/s, magnetic permeability less than 1.02μ, and its contours must be within 0.188" (4.76 mm). It is scheduled for completion in January 2006.
Date: October 7, 2005
Creator: Viola, M. E.; Brown, T.; Heitzenroeder, P.; Malinowski, F.; Reiersen, W.; Sutton, L. et al.
Partner: UNT Libraries Government Documents Department

Fatigue acceptance test limit criterion for larger diameter rolled thread fasteners

Description: This document describes a fatigue lifetime acceptance test criterion by which studs having rolled threads, larger than 1.0 inches in diameter, can be assured to meet minimum quality attributes associated with a controlled rolling process. This criterion is derived from a stress dependent, room temperature air fatigue database for test studs having a 0.625 inch diameter threads of Alloys X-750 HTH and direct aged 625. Anticipated fatigue lives of larger threads are based on thread root elastic stress concentration factors which increase with increasing thread diameters. Over the thread size range of interest, a 30% increase in notch stress is equivalent to a factor of five (5X) reduction in fatigue life. The resulting diameter dependent fatigue acceptance criterion is normalized to the aerospace rolled thread acceptance standards for a 1.0 inch diameter, 0.125 inch pitch, Unified National thread with a controlled Root radius (UNR). Testing was conducted at a stress of 50% of the minimum specified material ultimate strength, 80 Ksi, and at a stress ratio (R) of 0.10. Limited test data for fastener diameters of 1.00 to 2.25 inches are compared to the acceptance criterion. Sensitivity of fatigue life of threads to test nut geometry variables was also shown to be dependent on notch stress conditions. Bearing surface concavity of the compression nuts and thread flank contact mismatch conditions can significantly affect the fastener fatigue life. Without improved controls these conditions could potentially provide misleading acceptance data. Alternate test nut geometry features are described and implemented in the rolled thread stud specification, MIL-DTL-24789(SH), to mitigate the potential effects on fatigue acceptance data.
Date: May 1, 1997
Creator: Kephart, A.R.
Partner: UNT Libraries Government Documents Department

Experimental determination of the residual stresses in a Kraft recovery boiler tube

Description: Neutron diffraction was used to determine the residual stresses in a spiral weld overlay tube used in Kraft recovery boilers by the pulp and paper industry. The specimen was a 2.5 inches OD carbon steel tube covered with a layer of Inconel 625 weld overlay. Residual strains in the carbon steel and weld overlay layers were determined using the ferritic (211) and austenitic (311) reflections, respectively. Residual stresses in each material were derived from the measured strains using Hooke`s law and appropriate elastic constants. Tensile stress regions were found not only in the weld metal but also in the heat affected zone in the carbon steel. The maximum tensile stress was located in the weld overlay layer and was found to be 360 MPa, or about 75% of the yield strength of the weld metal. The experimental data were compared with a finite element analysis based on an uncoupled thermal-mechanical formulation. Overall, the modeling results were in satisfactory agreement with the experimental data, although the hoop strain (stress) appears to have been overestimated by the finite element model. Additional neutron diffraction measurements on an annealed tube confirmed that these welding residual stresses were eliminated after annealing at 900{degrees}C for 20 minutes. 18 refs., 7 figs.
Date: July 1, 1997
Creator: Wang, Xun-Li; Payzant, E.A. & Taljat, B.
Partner: UNT Libraries Government Documents Department

PM alloy 625M for high strength corrosion resistant applications

Description: In applications where the combination of high strength and good corrosion resistance are required, there have been only a few alloys of choice. A new powder metallurgy alloy has been developed, PM 625M, a niobium modification of Alloy 625, as a material to fill this need. One area of particular interest is the nuclear power industry, where many problems have been encountered with bolts, springs, and guidepins. Mechanical properties and stress corrosion cracking data of PM 625M are presented in this paper.
Date: June 1, 1997
Creator: Rizzo, F.J. & Floreen, S.
Partner: UNT Libraries Government Documents Department

Residual stresses in weld overlay tubes: A finite element study

Description: Residual stresses and strains in a tube with circumferential weld overlay were analyzed by the finite element (FE) method. The objective of this work was to develop and verify a FE model, to determine the magnitude and distribution of residual stresses in the weld overlay tube, and to evaluate the significance of two contributing factors to residual stress: (1) difference in material properties between tube and weld material, and (2) thermal gradients in the weld. An axisymmetric FE model was developed to simulate the circumferential two-layer welding process of alloy 625 overlay on SA210 tube. The first layer was modeled as a gas metal arc welding process with filler metal, whereas the autogenous gas tungsten arc welding process was modeled for the second layer. Neutron diffraction technique was used to experimentally determine residual elastic strains in the weld overlay tube. Comparison with the FE results shows overall good agreement. Both the experimental and FE results show high compressive stresses at the inside tube surface and high tensile stresses in the weld overlay. This suggests that weld overlay may be used to relieve tensile or produce compressive stresses at the inside tube surface, which is significant for applications where crack initiation is found at the root pass of the joining weld.
Date: January 3, 1997
Creator: Taljat, B.; Zacharia, T.; Wang, X. L.; Keiser, J. R.; Feng, Z. & Jirinec, M. J.
Partner: UNT Libraries Government Documents Department

Effects of neutron irradiation on deformation behavior of nickel-base fastener alloys

Description: This paper presents the effects of neutron irradiation on the fracture behavior and deformation microstructure of high-strength nickel-base alloy fastener materials, Alloy X-750 and Alloy 625. Alloy X-750 in the HTH condition, and Alloy 625 in the direct aged condition were irradiated to a fluence of 2.4x10{sup 20} n/cm{sup 2} at 264 C in the Advanced Test Reactor. Deformation structures at low strains were examined. It was previously shown that Alloy X-750 undergoes hardening, a significant degradation in ductility and an increase in intergranular fracture. In contrast, Alloy 625 had shown softening with a concomitant increase in ductility and transgranular failure after irradiation. The deformation microstructures of the two alloys were also different. Alloy X-750 deformed by a planar slip mechanism with fine microcracks forming at the intersections of slip bands with grain boundaries. Alloy 625 showed much more homogeneous deformation with fine, closely spaced slip bands and an absence of microcracks. The mechanism(s) of irradiation assisted stress corrosion cracking (IASCC) are discussed.
Date: July 1, 1999
Creator: Bajaj, R.; Mills, W.J.; Kammenzind, B.F. & Burke, M.G.
Partner: UNT Libraries Government Documents Department

Comparison of the crevice corrosion resistance of alloys 625 and 22

Description: The Yucca Mountain Site Characterization Project is concerned with the corrosion resistance of candidate engineered waste package materials. A variety of waste package designs have been proposed for US and Canadian High Level Nuclear Waste Repositories. A common feature of each design is the possibility of utilizing a corrosion resistant material such as a nickel-based super alloy or titanium-based alloy. A suitable corrosion resistant material may provide (a) kinetic immunity if the combination of repository environmental conditions and alloy resistance assure both: (i) a passive condition with negligible chance of localized corrosion stabilization, as well as (ii) low enough passive dissolution rates to insure conventional corrosion allowance over geological times, (b) a second form of ''corrosion allowance,'' if it can be scientifically demonstrated that a mechanism for stifling (i.e., death) of localized corrosion propagation occurs well before waste canisters are penetrated, or (c) such a low probability of initiation and continued propagation that a tolerably low degree of penetration occurs. Unfortunately, a large database on the crevice corrosion properties of alloy 22 does not exist in comparison to alloy 625. Alloy screening tests in oxidizing acids containing FeCl3 indicate that alloy 22 is more resistant to crevice corrosion than 625 as indicated by critical pit and crevice temperatures. Differences in alloying element compositions as expressed by pitting resistance equivalency number calculations support these findings. However, these data only provide the relative ranking of these alloys in terms of crevice corrosion and do not answer the critical questions proposed above.
Date: September 15, 1999
Creator: Palmer, J; Kehler, B; Iloybare, G O & Scully, J R
Partner: UNT Libraries Government Documents Department

Robotic weld overlay coatings for erosion control. Quarterly technical progress report, October 1994--December 1994

Description: Research is presently being conducted to develop a criteria for selecting weld overlay coatings for erosion mitigation in Circulated Fluidized Beds. Initially, eleven weld overlay alloys were selected for erosion testing based upon a literature review. All eleven coatings were deposited on 1018 steel substrates using the plasma arc welding process. Ten samples from each coating were prepared for erosion testing. The coating deposition and sample preparation procedures were described in the second quarterly report. All selected coatings were erosion tested at 400{degree}C and their erosion resistance was evaluated by determining the steady state erosion rate. In addition, the microstructure of each coating was characterized before and after the erosion tests. The results of the tests are discussed in the third quarterly report. No correlations were found between room temperature hardness of the weld overlay coatings and their erosion resistance at elevated temperature. During the last quarter tensile tests were performed at 400{degree}C for the Ultimet, Inconel-625, 316L SS, C-22, and Stellite-6 wrought alloys. The erosion tests for these materials at 400{degree}C are in progress. The results of mechanical and erosion tests will be used to correlate mechanical properties of selected wrought alloys such as tensile toughness, ductility, strain hardening coefficient and yield strength to their erosion resistance at 400{degree}C. Also, the erosion behavior of the wrought alloys compared with similar weld alloys will be analyzed. The experimental procedure and results of the tensile tests are presented in this progress report.
Date: January 25, 1995
Creator: Levin, B. F.; Dupont, J. N. & Marder, A. R.
Partner: UNT Libraries Government Documents Department

The Xu-Tec process of introducing normally solid materials into substrate surfaces. Quarterly technical progress report, July 22, 1992--April 22, 1993

Description: Most of the initial alloying work has been with the interior of pipe segments. The source electrode, an Inconel 625 rod, was inserted into carbon steel pipe segment cathode. Alloy layers were deposited on the interior surfaces of these segments; maximum thickness (8 {mu}) was obtained for a potential difference of 200 V.
Date: December 21, 1992
Creator: Xu, Zhong
Partner: UNT Libraries Government Documents Department

Comparison of calculated and observed cyclic stress-strain relationships for Inconel Alloy 625 at 650 to 1100/sup 0/C

Description: It is concluded that both the bilinear stress-strain and creep laws used with the ANSYS spar element model and the stress relaxation method are able to describe and predict fatigue behavior of Inconel Alloy 625.
Date: June 1, 1983
Creator: Purohit, A.; Ewing, T.F. & Thiele, U.
Partner: UNT Libraries Government Documents Department

Using the Laser Engineered Net Shaping (LENS{trademark}) process to produce complex components from a CAD solid model

Description: The Laser Engineered Net Shaping (LENS{trademark}) process, currently under development, has demonstrated the capability to produce near-net shape, fully dense metallic parts with reasonably complex geometrical features directly from a Computer-Aided Design (CAD) solid model. Using a highly localized laser beam, metal powders are used to produce very fine grain high strength structures. Results to date show that excellent mechanical properties can be achieved in alloys such as 316 stainless steel and Inconel 625. Significant increases in yield strength have been achieved with no loss in ductility. The current approach lends itself to produce components with a dimensional accuracy of {+-} 0.002 inches in the deposition plane and {+-} 0.015 inches in the growth direction. These results suggest that the LENS{trademark} process will provide a viable means for direct fabrication of metallic hardware.
Date: August 1, 1997
Creator: Smugeresky, J.E.; Keicher, D.M.; Romero, J.A.; Griffith, M.L. & Harwell, L.D.
Partner: UNT Libraries Government Documents Department

Metallurgical Bonding Development of V-4Cr-4Ti Alloy for the DIII-D Radiative Divertor Program

Description: General Atomics (GA), in conjunction with the Department of Energy`s (DOE) DIII-D Program, is carrying out a plan to utilize a vanadium alloy in the DIII-D tokamak as part of the DIII-D Radiative Divertor (RD) upgrade. The V-4Cr-4Ti alloy has been selected in the U.S. as the leading candidate vanadium alloy for fusion applications. This alloy will be used for the divertor fabrication. Manufacturing development with the V-4Cr-4Ti alloy is a focus of the DIII-D RD Program. The RD structure, part of which will be fabricated from V-4Cr-4Ti alloy, will require many product forms and types of metal/metal bonded joints. Metallurgical bonding methods development on this vanadium alloy is therefore a key area of study by GA. Several solid state (non-fusion weld) and fusion weld joining methods are being investigated. To date, GA has been successful in producing ductile, high strength, vacuum leak tight joints by all of the methods under investigation. The solid state joining was accomplished in air, i.e., without the need for a vacuum or inert gas environment to prevent interstitial impurity contamination of the V-4Cr-4Ti alloy.
Date: June 1, 1998
Creator: Smith, J.P.; Johnson, W.R. & Trester, P.W.
Partner: UNT Libraries Government Documents Department

Causes and solutions for cracking of coextruded and weld overlay floor tubes in black liquor recovery boilers

Description: Cracking of coextruded, black liquor recovery boiler floor tubes is both a safety and an economic issue to mill operators. In an effort to determine the cause of the cracking and to identify a solution, extensive studies, described in this and three accompanying papers, are being conducted. In this paper, results of studies to characterize both the cracking and the chemical and thermal environment are reported. Based on the results described in this series of papers, a possible mechanism is presented and means to lessen the likelihood of cracking or to totally avoid cracking of floor tubes are offered.
Date: September 1, 1998
Creator: Keiser, J.R.; Taljat, B. & Wang, X.L.
Partner: UNT Libraries Government Documents Department

Compatibility of ITER candidate materials with static gallium

Description: Corrosion tests have been conducted to determine the compatibility of gallium with candidate structural materials for the International Thermonuclear Experimental Reactor (ITER) first wall/blanket systems, e.g., Type 316 stainless steel (SS), Inconel 625, and Nb-5 Mo-1 Zr. The results indicate that Type 316 SS is least resistant to corrosion in static gallium and Nb-5 Mo-1 Zr alloy is most resistant. At 400 C, corrosion rates for Type 316 SS, Inconel 625, and Nb-5 Mo-1 Zr alloy are {approx} 4.0, 0.5, and 0.03 mm/yr, respectively. Iron, nickel, and chromium react rapidly with gallium. Iron shows greater corrosion than nickel at 400 C ({ge} 88 and 18 mm/yr, respectively). The present study indicates that at temperatures up to 400 C, corrosion occurs primarily by dissolution and is accompanied by formation of metal/gallium intermetallic compounds. The growth of intermetallic compounds may control the overall rate of corrosion.
Date: September 1995
Creator: Luebbers, P. R. & Chopra, O. K.
Partner: UNT Libraries Government Documents Department

Comparison of the crevice corrosion resistance of Alloys 625 and 22 in concentrated chloride solution from 60 to 95 degrees C

Description: The effects of electrolyte composition and oxide film age on the crevice corrosion properties of alloys 625 and 22 were studied at temperatures ranging from 60 to 95 C in concentrated chloride electrolytes. Critical potentials were determined using conventional current density thresholds and comparisons were made between 625 and 22 on the basis of these critical potentials. Air aged 22 specimens exhibited the highest resistance to crevice corrosion at 95 C in terms of critical crevice potentials, while freshly polished 22 exhibited the lowest resistance. Studies over the entire, temperature range showed that air aged 22 is more resistant to crevice corrosion than air aged 625 as evidenced by higher critical crevice potentials. As the temperature was lowered from 95 to 8O C, critical crevice potentials for 22 either approached or exceeded experimentally determined Cr (Mo, Ni) transpassive potentials.
Date: December 6, 1999
Creator: Kehler, B A; Illevbare, G O & Scully, J R
Partner: UNT Libraries Government Documents Department

Supercritical water oxidation benchscale testing metallurgical analysis report

Description: This report describes metallurgical evaluation of witness wires from a series of tests using supercritical water oxidation (SCWO) to process cutting oil containing a simulated radionuclide. The goal of the tests was to evaluate the technology`s ability to process a highly chlorinated waste representative of many mixed waste streams generated in the DOE complex. The testing was conducted with a bench-scale SCWO system developed by the Modell Development Corporation. Significant test objectives included process optimization for adequate destruction efficiency, tracking the radionuclide simulant and certain metals in the effluent streams, and assessment of reactor material degradation resulting from processing a highly chlorinated waste. The metallurgical evaluation described herein includes results of metallographic analysis and Scanning Electron Microscopy analysis of witness wires exposed to the SCWO environment for one test series.
Date: February 1, 1993
Creator: Norby, B.C.
Partner: UNT Libraries Government Documents Department

Advanced Turbine Systems Program -- Conceptual design and product development. Quarterly report, August 1--October 31, 1995

Description: The objective of Phase 2 of the Advanced Turbine Systems (ATS) Program is to provide the conceptual design and product development plan for an ultra high efficiency, environmentally superior and cost competitive industrial gas turbine system to be commercialized by the year 2000. A secondary objective is to begin early development of technologies critical to the success of ATS. This quarterly report, addresses only Task 4, conversion of a gas turbine to a coal-fired gas turbine, which was completed during the quarter and the nine subtasks included in Task 8, design and test of critical components. These nine subtasks address six ATS technologies as follows: catalytic combustion; recuperator; autothermal fuel reformer; high temperature turbine disc; advanced control system (MMI); and ceramic materials.
Date: December 31, 1995
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

Robotic weld overlay coatings for erosion control. Final technical progress report, July 1992--July 1995

Description: The erosion behavior of weld overlay coatings has been studied. Eleven weld overlay alloys were deposited on 1018 steel substrates using the plasma arc welding process and erosion tested at 400{degrees}C at 90{degrees} and 30{degrees} particle impact angles. The microstructure of each coating was characterized before erosion testing. A relative ranking of the coatings erosion resistance was developed by determining the steady state erosion rates. Ultimet, Inconel-625, and 316L SS coatings showed the best erosion resistance at both impact angles. It was found that weld overlays that exhibit good abrasion resistance did not show good erosion resistance. Erosion tests were also performed for selected wrought materials with chemical composition similar to weld overlays. Eroded surfaces of the wrought and weld alloys were examined by Scanning Electron Microscopy (SEM). Microhardness tests were performed on the eroded samples below the erosion surface to determine size of the plastically deformed region. It was found that one group of coatings experienced significant plastic deformation as a result of erosion while the other did not. It was also established that, in the steady state erosion regime, the size of the plastically deformed region is constant.
Date: October 15, 1995
Creator: Levin, B. F.; DuPont, J. N. & Marder, A. R.
Partner: UNT Libraries Government Documents Department