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Investigation of Rim Cracking in Turbine Wheels with Welded Blades

Description: Rim cracking in turbine wheels with welded blades was evaluated. The problem is explained on the basis of the occurrence of plastic flow in the rim during transient starting conditions when thermal compressive stresses resulting from high-temperature gradients exceed the proportional elastic limit of the material.
Date: February 12, 1947
Creator: Millenson, M. B. & Manson, S. S.
Partner: UNT Libraries Government Documents Department

Experimental investigation of rim cracking in disks subjected to high temperature gradients

Description: Report presenting the results of an experimental investigation of rim cracking in a welded-blade composite gas-turbine wheel, in two carbon-steel disks, and five tool-steel disks. Various characteristics were investigated, including the effectiveness of holes in preventing crack propagation and the influence of hardness and various types of notch on rim cracking.
Date: September 1, 1949
Creator: Wilterdink, P. I.
Partner: UNT Libraries Government Documents Department

Resistance of six cast high-temperature alloys to cracking caused by thermal shock

Description: Report presenting an investigation to determine the relative resistance of six cast high-temperature alloys to cracking caused by thermal shock. The alloys tested included S-816, S-590, Vitallium, 422-19, X-40, and Stellite 6. Results regarding the tabulation of cycles to failure, crack properties, metallographic examination, and some curves of deformation data are provided.
Date: February 1950
Creator: Whitman, M. J.; Hall, R. W. & Yaker, C.
Partner: UNT Libraries Government Documents Department

Origin and development of leading-edge cracks in turbojet engine buckets

Description: Report presenting an investigation to study the origin and development of leading-edge cracking in turbine buckets made of six materials: S-816, M-252, Inconel 550, Inconel 700, Hastelloy R-235, and Jetalloy 1570. Some of the buckets were also given certain stress-relief treatments. Results regarding the development of leading-edge cracks, development of bucket fractures, comparison of performance for the material tested, macro- and microexamination of unfractured and fractured buckets,
Date: May 20, 1957
Creator: Springsteen, D. F.; Gyorgak, C. A. & Johnston, J. R.
Partner: UNT Libraries Government Documents Department

A general kinetic-flow coupling model for FCC riser flow simulation.

Description: A computational fluid dynamic (CFD) code has been developed for fluid catalytic cracking (FCC) riser flow simulation. Depending on the application of interest, a specific kinetic model is needed for the FCC flow simulation. This paper describes a method to determine a kinetic model based on limited pilot-scale test data. The kinetic model can then be used with the CFD code as a tool to investigate optimum operating condition ranges for a specific FCC unit.
Date: May 18, 1998
Creator: Chang, S. L.
Partner: UNT Libraries Government Documents Department

Static strength of cross-grain 7075-T6 aluminum-alloy extruded bar containing fatigue cracks

Description: Report presenting cross-grain specimens made of 7075-T6 aluminum-alloy extrusion were subjected to repeated axial loads until fatigue cracks of various lengths were formed. The specimens were subjected to static tests to determine the residual static strength.
Date: April 1957
Creator: Illg, Walter & McEvily, Arthur J., Jr.
Partner: UNT Libraries Government Documents Department

Factors influencing horizontal cracking in continuously reinforced concrete pavements (CRCP).

Description: This research presents the results on an experimental investigation to identify the significant factors influencing horizontal cracking in continuously reinforced concrete pavements (CRCP). An in-depth analysis of the microstructure, morphological characteristics of the interfacial transition zone (ITZ) and the observation of cracking using the environmental scanning electron microscope (ESEM) was done. Characterization of oxides using Fourier transform infrared spectroscopy (FTIR) and electron dispersive x-ray spectroscopy (EDS) was also performed. Water to cement ratio (w/c) and rebar temperature had a significant influence on the rebar-concrete bond strength. The 28-day shear strength measurements showed an increase in rebar-concrete bond strength as the water to cement ratio (w/c) was reduced from 0.50 to 0.40. There was a reduction in the peak pullout load as the temperature increased from 14oF to 252oF for the corroded and non-corroded rebar experiments. The corroded rebar pullout test results showed a 20-50 % reduction in bond strength compared to the non-corroded rebars. FTIR measurements indicated a presence of lepidocrocrite (γ -FeOOH) and maghemite (γ -Fe2O3) on the ITZ. ESEM images showed the existence of microcracks as early as three days after casting with the bridging of these cracks between coarse aggregate locations in the interfacial zone propagating through the mortar.
Date: August 2008
Creator: Sudoi, Elias K.
Partner: UNT Libraries

Petroleum Refineries, Including Cracking Plants in the United States, January 1, 1948

Description: Report issued by the U.S. Bureau of Mines discussing the petroleum refineries and cracking plants throughout the United States. As stated in the introduction, "in this publication the capacities of petroleum refineries and cracking plants in the United States on January 1, 1948, are listed, according to the latest annual survey of the Bureau of Mines" (p. 1). This report includes tables, and a map.
Date: August 1948
Creator: Lott, F. S.
Partner: UNT Libraries Government Documents Department

Expected radiation effects in plutonium immobilization ceramic

Description: The current formulation of the candidate ceramic for plutonium immobilization consists primarily of pyrochlore, with smaller amounts of hafnium-zirconolite, rutile, and brannerite or perovskite. At a plutonium loading of 10.5 weight %, this ceramic would be made metamict (amorphous) by radiation damage resulting from alpha decay in a time much less than 10,000 years, the actual time depending on the repository temperature as a function of time. Based on previous experimental radiation damage work by others, it seems clear that this process would also result in a bulk volume increase (swelling) of about 6% for ceramic that was mechanically unconfined. For the candidate ceramic, which is made by cold pressing and sintering and has porosity amounting to somewhat more than this amount, it seems likely that this swelling would be accommodated by filling in the porosity, if the material were tightly confined mechanically by the waste package. Some ceramics have been observed to undergo microcracking as a result of radiation-induced anisotropic or differential swelling. It is unlikely that the candidate ceramic will microcrack extensively, for three reasons: (1) its phase composition is dominated by a single matrix mineral phase, pyrochlore, which has a cubic crystal structure and is thus not subject to anisotropic swelling; (2) the proportion of minor phases is small, minimizing potential cracking due to differential swelling; and (3) there is some flexibility in sintering process parameters that will allow limitation of the grain size, which can further limit stresses resulting from either cause.
Date: September 1, 1997
Creator: Van Konynenburg, R.A., LLNL
Partner: UNT Libraries Government Documents Department

Stress corrosion cracking in canistered waste package containers: Welds and base metals

Description: The current design of waste package containers include outer barrier using corrosion allowable material (CAM) such as A516 carbon steel and inner barrier of corrosion resistant material (CRM) such as alloy 625 and C22. There is concern whether stress corrosion cracking would occur at welds or base metals. The current memo documents the results of our analysis on this topic.
Date: March 1, 1998
Creator: Huang, J.S.
Partner: UNT Libraries Government Documents Department

Comparison of asymmetric with symmetric feed oil injection parameters in a riser reactor.

Description: A computational fluid dynamic (CFD) computer code was used to determine the effects of product yields of three feed injection parameters in a fluidized catalytic cracking (FCC) riser reactor. This study includes the effects of both symmetrical and non-symmetrical injection parameters. All these parameters have significant effects on the feed oil spray distribution, vaporization rates and the resulting product yields. This study also indicates that optimum parameter ranges exist for the investigated parameters.
Date: April 20, 1999
Creator: Bowman, B. J.; Chang, S. L.; Lottes, S. A. & Zhou, C. Q.
Partner: UNT Libraries Government Documents Department

Some Observations on Stress-Corrosion Cracking of Single Crystals of AZ61X Magnesium Alloy

Description: Note presenting exploratory tests of the stress-corrosion cracking of single crystals of solution-treated AZ61X magnesium alloy in distilled water, in hydrofluoric acid, and in a salt-chromate solution. The results of this paper show that failures often start and run on planes other than the basal plane and are inconsistent with previously generated hypotheses. Results regarding the pilot tests on polycrystalline specimens and single-crystal tests are provided.
Date: July 1957
Creator: Meller, F. & Metzger, M.
Partner: UNT Libraries Government Documents Department

Biomass Gas Cleanup Using a Therminator

Description: The objective of the project is to develop and demonstrate a novel fluidized-bed process module called a “Therminator” to simultaneously destroy and/or remove tar, NH3 and H2S from raw syngas produced by a fluidized-bed biomass gasifier. The raw syngas contains as much as 10 g/m3 of tar, 4,000 ppmv of NH3 and 100 ppmv of H2S. The goal of the Therminator module would be to use promising regenerable catalysts developed for removing tar, ammonia, and H2S down to low levels (around 10 ppm). Tars are cracked to a non-condensable gas and coke that would deposit on the acid catalyst. We will deposit coke, much like a fluid catalytic cracker (FCC) in a petroleum refinery. The deposited coke fouls the catalyst, much like FCC, but the coke would be burned off in the regenerator and the regenerated catalyst would be returned to the cracker. The rapid circulation between the cracker and regenerator would ensure the availability of the required amount of regenerated catalyst to accomplish our goal. Also, by removing sulfur down to less than 10 ppmv, NH3 decomposition would also be possible in the cracker at 600-700°C. In the cracker, tar decomposes and lays down coke on the acid sites of the catalyst, NH3 is decomposed using a small amount of metal (e.g., nickel or iron) catalyst incorporated into the catalyst matrix, and H2S is removed by a small amount of a metal oxide (e.g. zinc oxide or zinc titanate) by the H2S-metal oxide reaction to form metal sulfide. After a tolerable decline in activity for these reactions, the catalyst particles (and additives) are transported to the regenerator where they are exposed to air to remove the coke and to regenerate the metal sulfide back to metal oxide. Sulfate formation is avoided by running the regeneration with slightly sub-stoichiometric quantity ...
Date: March 6, 2012
Creator: Dayton, David C.; Kataria, Atish & Gupta, Rabhubir
Partner: UNT Libraries Government Documents Department

Partial control of complex processing systems

Description: The past year saw substantial advances in the development of a model of Fluidized Catalytic Crackers, which now allows one to calculate both steady state and dynamic behavior of the system as basis for control studies. The first goal was to elucidate nonlinear features using the model. The model shows that adding a combustion promoter that catalyzes the CO-CO[sub 2] reaction reduces chances for multiple steady states within the range of desirable operating conditions; by adding enough promoter, one can also eliminate them. Conventional control structure can lead to input multiplicities.
Date: January 1, 1993
Creator: Shinnar, R.
Partner: UNT Libraries Government Documents Department

Entrained-Flow, Fast Ablative Pyrolysis of Biomass - Annual Report, 1 December 1984 - 31 December 1985

Description: The ablative, fast pyrolysis system was relocated to SERI's new, permanent Field Test Laboratory. Pyrolysis system modifications were made to increase the energy available to the vortex reactor and to enhance the collection efficiency of primary pyrolysis vapors. Mathematical modeling of the vapor cracker has resulted in the ability to accurately predict experimental results with respect to the thermal cracking of the primary vapors, the generation of noncondensible gases, and the gas composition. The computer algorithm of this model can be readily used to perform experimental simulation and/or reactor scale-up due to its fundamental nature. Preliminary screening tests with pure ZSM-5 zeolite catalyst, supplied by Mobil Research and Development Corporation, have shown promise for the conversion of primary pyrolysis oil vapors to aromatic hydrocarbons; i.e., gasoline.
Date: July 1, 1986
Creator: Diebold, J. P.; Scahill, J. W. & Evans, R. J.
Partner: UNT Libraries Government Documents Department

The Effect of Weld Residual Stress on Life of Used Nuclear Fuel Dry Storage Canisters

Description: With the elimination of Yucca Mountain as the long-term storage facility for spent nuclear fuel in the United States, a number of other storage options are being explored. Currently, used fuel is stored in dry-storage cask systems constructed of steel and concrete. It is likely that used fuel will continue to be stored at existing open-air storage sites for up to 100 years. This raises the possibility that the storage casks will be exposed to a salt-containing environment for the duration of their time in interim storage. Austenitic stainless steels, which are used to construct the canisters, are susceptible to stress corrosion cracking (SCC) in chloride-containing environments if a continuous aqueous film can be maintained on the surface and the material is under stress. Because steel sensitization in the canister welds is typically avoided by avoiding post-weld heat treatments, high residual stresses are present in the welds. While the environment history will play a key role in establishing the chemical conditions for cracking, weld residual stresses will have a strong influence on both crack initiation and propagation. It is often assumed for modeling purposes that weld residual stresses are tensile, high and constant through the weld. However, due to the strong dependence of crack growth rate on stress, this assumption may be overly conservative. In particular, the residual stresses become negative (compressive) at certain points in the weld. The ultimate goal of this research project is to develop a probabilistic model with quantified uncertainties for SCC failure in the dry storage casks. In this paper, the results of a study of the residual stresses, and their postulated effects on SCC behavior, in actual canister welds are presented. Progress on the development of the model is reported.
Date: August 1, 2013
Creator: Ballinger, Ronald G.; Ferry, Sara E.; Black, Bradley P. & Teysseyre, Sebastien P.
Partner: UNT Libraries Government Documents Department

EFFECTS OF LASER SHOCK PEENING ON SCC BEHAVIOR OF ALLOY 600

Description: In this study, the effects of laser shock peening (LSP) on stress corrosion cracking (SCC) behavior of Alloy 600 in tetrathionate solution were investigated. The degree of sensitization was quantified using double loop electrochemical potentiokinetic reactivation (DLEPR) tests. The sensitized Alloy 600 was demonstrated to be susceptible to intergranular SCC in tetrathionate solution. Following LSP, residual stresses and the amount of plastic strain introduced in Alloy 600 were characterized. The effects of LSP on SCC susceptibility of Alloy 600 in tetrathionate solution were evaluated by slow strain rate tests and constant load tests. Results indicate a significant increase in resistance to crack initiation and decreased susceptibility to SCC after LSP.
Date: August 1, 2013
Creator: Telang, Abhishek; Gill, Amrinder; S.R.Mannava; Vasudevan, Vijay K.; Qian, Dong & Teysseyre, Sebastien P.
Partner: UNT Libraries Government Documents Department

Attrition Resistant Fischer-Tropsch Catalysts Based on FCC Supports

Description: Commercial spent fluid catalytic cracking (FCC) catalysts provided by Engelhard and Albemarle were used as supports for Fe-based catalysts with the goal of improving the attrition resistance of typical F-T catalysts. Catalysts with the Ruhrchemie composition (100 Fe/5 Cu/4.2 K/25 spent FCC on mass basis) were prepared by wet impregnation. XRD and XANES analysis showed the presence of Fe{sub 2}O{sub 3} in calcined catalysts. FeC{sub x} and Fe{sub 3}O{sub 4} were present in the activated catalysts. The metal composition of the catalysts was analyzed by ICP-MS. F-T activity of the catalysts activated in situ in CO at the same conditions as used prior to the attrition tests was measured using a fixed bed reactor at T = 573 K, P = 1.38 MPa and H{sub 2}:CO ratio of 0.67. Cu and K promoted Fe supported over Engelhard provided spent FCC catalyst shows relatively good attrition resistance (8.2 wt% fines lost), high CO conversion (81%) and C{sub 5}+ hydrocarbons selectivity (18.3%).
Date: February 5, 2010
Creator: Adeyiga, Adeyinka
Partner: UNT Libraries Government Documents Department

Materials Degradation and Detection (MD2): Deep Dive Final Report

Description: An effort is underway at Pacific Northwest National Laboratory (PNNL) to develop a fundamental and general framework to foster the science and technology needed to support real-time monitoring of early degradation in materials used in the production of nuclear power. The development of such a capability would represent a timely solution to the mounting issues operators face with materials degradation in nuclear power plants. The envisioned framework consists of three primary and interconnected “thrust” areas including 1) microstructural science, 2) behavior assessment, and 3) monitoring and predictive capabilities. A brief state-of-the-art assessment for each of these core technology areas is discussed in the paper.
Date: February 1, 2013
Creator: McCloy, John S.; Montgomery, Robert O.; Ramuhalli, Pradeep; Meyer, Ryan M.; Hu, Shenyang Y.; Li, Yulan et al.
Partner: UNT Libraries Government Documents Department

Shock induced multi-mode damage in depleted uranium

Description: Recent dynamic damage studies on depleted uranium samples have revealed mixed mode failure mechanisms leading to incipient cracking as well as ductile failure processes. Results show that delamination of inclusions upon compression may provide nucleation sites for damage initiation in the form of crack tip production. However, under tension the material propagates cracks in a mixed shear localization and mode-I ductile tearing and cracking. Cracks tips appear to link up through regions of severe, shear dominated plastic flow. Shock recovery experiments were conducted on a 50 mm single stage light gas gun. Serial metallographic sectioning was conducted on the recovered samples to characterize the bulk response of the sample. Experiments show delaminated inclusions due to uniaxial compression without damage propagation. Further results show the propagation of the damage through tensile loading to the incipient state, illustrating ductile processes coupled with mixed mode-I tensile ductile tearing, shear localization, and mode-I cracking in depleted uranium.
Date: January 1, 2009
Creator: Koller, Darcie D; Cerreta, Ellen K & Gray, Ill, George T
Partner: UNT Libraries Government Documents Department