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Corrosion performance of structural alloys.

Description: Component reliability and long-term trouble-free performance of structural materials are essential in power-generating and gasification processes that utilize coal as a feedstock. During combustion and conversion of coal, the environments encompass a wide range of oxygen partial pressures, from excess-air conditions in conventional boilers to air-deficient conditions in 10W-NO{sub x} and gasification systems. Apart from the environmental aspects of the effluent from coal combustion and conversion, one concern from the systems standpoint is the aggressiveness of the gaseous/deposit environment toward structural components such as waterwall tubes, steam superheaters, syngas coolers, and hot-gas filters. The corrosion tests in the program described in this paper address the individual and combined effects of oxygen, sulfur, and chlorine on the corrosion response of several ASME-coded and noncoded structural alloys that were exposed to air-deficient and excess-air environments typical of coal-combustion and gasification processes. Data in this paper address the effects of preoxidation on the subsequent corrosion performance of structural materials such as 9Cr-1Mo ferritic steel, Type 347 austenitic stainless steel, Alloys 800, 825, 625, 214, Hastelloy X, and iron aluminide when exposed at 650 C to various mixed-gas environments with and without HCI. Results are presented for scaling kinetics, microstructural characteristics of corrosion products, detailed evaluations of near-surface regions of the exposed specimens, gains in our mechanistic understanding of the roles of S and Cl in the corrosion process, and the effect of preoxidation on subsequent corrosion.
Date: July 15, 1999
Creator: Natesan, K.
Partner: UNT Libraries Government Documents Department

Corrosion performance of structural alloys in oxygen/sulfur/chlorine-containing environments.

Description: Component reliability and long-term trouble-free performance of structural materials are essential in power-generating processes that utilize coal as a feedstock. The combustion environments encompass a wide range of oxygen partial pressures, from excess-air conditions in conventional systems to air-deficient conditions in low-NO{sub x} systems. Apart from the environmental aspects of the effluent from coal combustion, one concern from the systems standpoint is the aggressiveness of the combustion environment toward boiler structural components such as waterwall tubes and steam superheaters. The corrosion tests in this program address the individual and combined effects of oxygen, sulfur, and chlorine on the corrosion response of several ASME-coded and noncoded boiler materials exposed to air-deficient and excess-air combustion conditions. Data in this paper address the corrosion behavior of structural materials such as Type 347 stainless steel, Alloys 800, 825, 625, 214, and Hastelloy X when exposed at 650 C to excess-air combustion conditions with and without HCl. Thermodynamic calculations were made to evaluate the gas chemistries formed from coal combustion. The results of such calculations, coupled with oxygen/sulfur/chlorine thermochemical diagrams, were used to select the gas environments for the laboratory test program. Results are presented for weight change, thickness loss, microstructural characteristics of corrosion products, mechanical integrity and cracking of scales, and the mechanistic understanding gained on the role of sulfur and chlorine in the corrosion process.
Date: June 22, 1998
Creator: Natesan, K.
Partner: UNT Libraries Government Documents Department

Thermal stability of high temperature structural alloys

Description: High temperature structural alloys were evaluated for suitability for long term operation at elevated temperatures. The effect of elevated temperature exposure on the microstructure and mechanical properties of a number of alloys was characterized. Fe-based alloys (330 stainless steel, 800H, and mechanically alloyed MA 956), and Ni-based alloys (Hastelloy X, Haynes 230, Alloy 718, and mechanically alloyed MA 758) were evaluated for room temperature tensile and impact toughness properties after exposure at 750 C for 10,000 hours. Of the Fe-based alloys evaluated, 330 stainless steel and 800H showed secondary carbide (M{sub 23}C{sub 6}) precipitation and a corresponding reduction in ductility and toughness as compared to the as-received condition. Within the group of Ni-based alloys tested, Alloy 718 showed the most dramatic structure change as it formed delta phase during 10,000 hours of exposure at 750 C with significant reductions in strength, ductility, and toughness. Haynes 230 and Hastelloy X showed significant M{sub 23}C{sub 6} carbide precipitation and a resulting reduction in ductility and toughness. Haynes 230 was also evaluated after 10,000 hours of exposure at 850, 950, and 1050 C. For the 750--950 C exposures the M{sub 23}C{sub 6} carbides in Haynes 230 coarsened. This resulted in large reductions in impact strength and ductility for the 750, 850 and 950 C specimens. The 1050 C exposure specimens showed the resolution of M{sub 23}C{sub 6} secondary carbides, and mechanical properties similar to the as-received solution annealed condition.
Date: March 1, 1999
Creator: Jordan, C.E.; Rasefske, R.K. & Castagna, A.
Partner: UNT Libraries Government Documents Department

Inelastic analysis of two plates under deformation dependent loads

Description: Cover plates are used in current designs for high temperature gas-cooled reactors to compress the mineral fiber insulation against the inside of the liner of the prestressed concrete pressure vessel. In the upper plenum, these plates are hexagonal and specified as carbon steel; in the lower cross ducts, the plates are square and made of Hastelloy X. The General Atomic Company has specified both damage and safety limit criteria for these plates. These plates have been analyzed at these limits using the inelastic finite element computer program EPACA. The results indicate that the total strains for the square plate were within the specified values; however, the maximum deformations at the free corners indicate separation from the insulation and failure to achieve one of the design requirements. Since no material data were available for carbon steel at the limiting temperatures, it was assumed that the hexagonal plates were constructed of 2$sup 1$/$sub 4$ percent Cr--1 percent Mo material. Although this material was found to produce satisfactory performance, extrapolation of available information would lead to the conclusion that the performance of carbon steel plates would not be satisfactory at the specified conditions. (auth)
Date: February 1, 1976
Creator: Iskander, S.K.; Collins, C.W. & Sanders, J.P.
Partner: UNT Libraries Government Documents Department

Summary of Dissimilar Metal Joining Trials Conducted by Edison Welding Institute

Description: Under the direction of the NASA-Glenn Research Center, the Edison Welding Institute (EWI) in Columbus, OH performed a series of non-fusion joining experiments to determine the feasibility of joining refractory metals or refractory metal alloys to Ni-based superalloys. Results, as reported by EWI, can be found in the project report for EWI Project 48819GTH (Attachment A, at the end of this document), dated October 10, 2005. The three joining methods used in this investigation were inertia welding, magnetic pulse welding, and electro-spark deposition joining. Five materials were used in these experiments: Mo-47Re, T-111, Hastelloy X, Mar M-247 (coarse-grained, 0.5 mm to several millimeter average grain size), and Mar M-247 (fine-grained, approximately 50 {micro}m average grain size). Several iterative trials of each material combination with each joining method were performed to determine the best practice joining method. Mo-47Re was found to be joined easily to Hastelloy X via inertia welding, but inertia welding of the Mo-alloy to both Mar M-247 alloys resulted in inconsistent joint strength and large reaction layers between the two metals. T-111 was found to join well to Hastelloy X and coarse-grained Mar M-247 via inertia welding, but joining to fine-grained Mar M-247 resulted in low joint strength. Magnetic pulse welding (MPW) was only successful in joining T-111 tubing to Hastelloy X bar stock. The joint integrity and reaction layer between the metals were found to be acceptable. This single joining trial, however, caused damage to the electromagnetic concentrators used in this process. Subsequent design efforts to eliminate the problem resulted in a loss of power imparted to the accelerating work piece, and results could not be reproduced. Welding trials of Mar M-247 to T-111 resulted in catastrophic failure of the bar stock, even at lower power. Electro-spark deposition joining of Mo-47Re, in which the deposited material was ...
Date: November 18, 2005
Creator: Lambert, MJ
Partner: UNT Libraries Government Documents Department

Helium blistering of ceramic coatings on Hastelloy X and Nb--1% Zr

Description: The surface damage of insulating ceramic coatings on Hastelloy X and Nb-- 1 percent Zr held at room temperature and at 300$sup 0$C was studied for both 100 keV and 250 keV helium ion irradiation for a dose range from 3.7 x 10$sup 18$ to 1 x 10$sup 19$ ions cm$sup -2$. Blisters were observed after room temperature irradiation with both 100 keV and 250 keV helium ions. However, for irradiation at 300$sup 0$C no blisters could be observed. The sharp rise in the helium permeation with temperature, observed by others for some glasses and ceramics, is thought to be responsible for this behavior. These results suggest that for the energy range studied helium blistering has a negligible surface erosion effect on such coatings if they are operated at temperatures above 300$sup 0$C. (auth)
Date: January 1, 1975
Creator: Kaminsky, M.; Das, S.K. & Ekern, R.
Partner: UNT Libraries Government Documents Department

Filter systems for IGCC applications

Description: The objectives of this program were to identify metallic filter medium to be utilized in the Integrated Gasification Combined Cycle process (IGCC). In IGCC processes utilizing high efficiency desulfurizing technology, the traditional corrosion attack, sulfidation, is minimized so that metallic filters are viable alternatives over ceramic filters. Tampa Electric Company`s Polk Power Station is being developed to demonstrate Integrated Gasification Combined Cycle technology. The Pall Gas Solid Separation (GSS) System is a self cleaning filtration system designed to remove virtually all particulate matter from gas streams. The heart of the system is the filter medium used to collect the particles on the filter surface. The medium`s filtration efficiency, uniformity, permeability, voids volume, and surface characteristics are all important to establishing a permeable permanent cake. In-house laboratory blowback tests, using representative full scale system particulate, were used to confirm the medium selection for this project. Test elements constructed from six alloys were supplied for exposure tests: PSS 310SC (modified 310S alloy); PSS 310SC heat treated; PSS 310SC-high Cr; PSS 310SC-high Cr heat treated; PSS Hastelloy X; and PSS Hastelloy X heat treated.
Date: November 1, 1995
Creator: Bevan, S.; Gieger, R.; Sobel, N. & Johnson, D.
Partner: UNT Libraries Government Documents Department

Preparation of Metal Filter Element for Fail Safety in IGCC Filter Unit

Description: Metal filter elements as the fail safety filter are fabricated by the methods using cold isostatic pressure (compress method) and binder (binder method) to form the filter element and tested in a experimental and bench units. The fail safety filter on the filtration system is mounted additionally in order to intercept the particle leak when the main filter element is broken. So it should have two contrary functions of a high permeability and being plugged easily. The filter element having high porosity and high plugging property was fabricated by the bind method. It has the porosity more than 50%, showed very small pressure drop less than 10mmH2O at the face velocity of 0.15m/s, and plugged within 5 minutes with the inhibition of the particle leak larger than 4 {micro}m. The test result of corrosion tendency in IGCC gas stream at 500 C shows SUS310L material is very reasonable among SUS310, SUS316, Inconel 600, and Hastelloy X.
Date: September 18, 2002
Creator: Choi, J-H.; Ahn, I-S.; Bak, Y-C.; Bae, S-Y.; Ha, S-J. & Jang, H-J.
Partner: UNT Libraries Government Documents Department