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RESUME OF INFORMATION ON HYDROGEN IN TITANIUM ALLOYS AND ITS IMPLICATIONS TO HRP

Description: A summary is presented of available information on the nature of H embrittlement in Ti, its control, and effects on other Ti properties. Most data also apply to Zr. Types of embrittlement are discussed, along with H sources and effects on mechanical properties. Also, the effects of H on forming heat treatment, and joining are discussed as well as Ti production and processing and methods of H removal. Finally, H in-service pickup is considered, and methods for establishing the extent of this reaction are discussed. (J.R.D.)
Date: February 12, 1958
Creator: Hammond, J.P.
Partner: UNT Libraries Government Documents Department

Creep properties of forged 2219 T6 aluminum alloy shell of general-purpose heat source-radioisotope thermoelectric generator

Description: The shell (2219 T6 aluminum forging) of the General Purpose Heat Source-Radioisotope Thermoelectric Generator was designed to retain the generator under sufficient elastic stress to secure it during space flight. A major concern was the extent to which the elastic stress would relax by creep. To determine acceptability of the shell construction material, the following proof tests simulating service were performed: 600 h of testing at 270/sup 0/C under 24.1 MPa stress followed by 10,000 h of storage at 177/sup 0/C under 55.1 MPa, both on the ground; and 10,000 h of flight in space at 270/sup 0/C under 34.4 MPa stress. Additionally, systematic creep testing was performed at 177 and 260/sup 0/C to establish creep design curves. The creep tests performed at 177/sup 0/C revealed comparatively large amounts of primary creep followed by small amounts of secondary creep. The early creep is believed to be abetted by unstable substructures that are annealed out during testing at this temperature. The creep tests performed at 270/sup 0/C showed normal primary creep followed by large amounts of secondary creep. Duplicate proof tests simulating the ground exposure conditions gave results that were in good agreement. The proof test simulating space flight at 270/sup 0/C gave 0.11% primary creep followed by 0.59% secondary creep. About 10% of the second-stage creep was caused by four or five instantaneous strains, which began at the 4500-h mark. One or two of these strain bursts, occurred in each of several other tests at 177 and 260/sup 0/C but were assessed as very moderate in magnitude. The effect is attributable to a slightly microsegregated condition remaining from the original cast structure.
Date: December 1, 1981
Creator: Hammond, J.P.
Partner: UNT Libraries Government Documents Department

Ductility minimum and its reversal with prolonged aging in cobalt- and nickel-base superalloys

Description: The cobalt-base superalloys Haynes alloy No. 25 and Haynes alloy No. 188 and the nickel-base superalloy Inconel 625 show a pronounced ductility minimum at temperatures of 760 and 704/sup 0/C, respectively, in the solution-annealed condition. However, after prolonged (11,000 h) aging at 816/sup 0/C (1500/sup 0/F), copious precipitates form to completely reverse the behavior. These precipitates reduce tensile ductility drastically up to temperatures where the ductility dip is observed for the solution-annealed condition; then the brittle behavior from aging gives way to greatly enhanced ductility. This behavior in Haynes alloy No. 25 is examined in detail. Its tensile properties in the solution-annealed and 816/sup 0/C-aged conditions are correlated with mode of fracture and the amounts, identity, and morphology of the precipitates. The latter were assessed by optical and scanning electron metallography, microhardness, electron microprobe, and x-ray diffraction. The minimum and its reversal are explained by thermally activated processes, which began with the onset of recovery.
Date: January 1, 1978
Creator: Hammond, J. P.
Partner: UNT Libraries Government Documents Department

Ductility minimum and its reversal with aging in cobalt-base superalloys

Description: Good mechanical properties in the face of long-term aging at high temperatures are required of superalloys for nuclear and solar power-conversion applications. Of special concern are losses in ductility and toughness resulting from microstructural instability. The report compares the tensile ductility responses in two cobalt-base superalloys for the solution annealed and aged conditions and endeavors to rationalize results with contemporary concepts. The cobalt-base superalloys Haynes alloy No. 25 and Haynes alloy No. 188 show a pronounced ductility minimum at 760/sup 0/C for the solution annealed condition. However, after prolonged (11,000 h) aging at 816/sup 0/C, copious precipitates form and completely reverse this behavior. These precipitates drastically reduce tensile ductility up to the temperature at which the ductility begins to dip for the solution annealed condition; then the brittle behavior from aging gives way to greatly enhanced ductility. This behavior in Haynes alloy No. 25 was examined in detail. Tensile properties in the solution annealed and 816/sup 0/C-aged conditions are correlated with mode of fracture and the amounts, identity, and morphology of the precipitates. The latter were assessed by optical and scanning electron metallography, microhardness, electron microprobe, and x-ray diffraction. The minimum and its reversal are explained by thermally activated processes that began with the onset of recovery.
Date: January 1, 1979
Creator: Hammond, J. P.
Partner: UNT Libraries Government Documents Department

BELLOWS FAILURE IN SOLIDS SEPARATION LOOP OF THE HRT MOCKUP

Description: The failure of the valve bellows would appear to be due to a combination of stress corrosion nnd crevice corrosion. Stress corrosion occurred as evidenced by the transgranular branched cracking found in the bellows and in the base which was joined to the bellows. It seems probable that chlorides were present, which, along with the residual stresses present in the bellows assembly, created the necessary conddtions for stress corrosion to occur. Crevice corrosion occurred probably due to heavy deposits of solids at the base of the bellows, which created a condition of oxygen impoverishment. While the crater in the base may have been related to a galvanic effect created by the gold gasket, the contour of the crater would suggest that the cause of the crater was due more to crevice corrosion. (auth)
Date: February 1, 1957
Creator: Kegley, T.M. Jr. & Hammond, J.P.
Partner: UNT Libraries Government Documents Department

Predicted strains in austenitic stainless steels at stresses above yield

Description: Tensile results on austenitic stainless steels were analyzed to develop means for predicting strains at stresses above yield for reactor regulatory applications. Eight heats each of types 316 and 304 were tested at 24, 93, 204, and 316/sup 0/C as mill-annealed and at 24/sup 0/C after reannealing. The effects of heat-to-heat variations on total strain (to 5%) at discrete stress levels were portrayed by a rational polynomial incorporating three constants that relate to the basic features of the true-stress-true-strain diagram. Because these constants usually are interrelated, a single parameter, yield strength (YS), proved adequate to predict results. For predictions analytical expressions of yield strength, an average value (YSa), and a lower bound value (YSa - 1.65SEE (standard error of estimate)) were used. Using the rational polynomial with these parameters we determined (1) limits of total maximum strain and (2) ratios of strain of material of lower bound YS to that of average YS. These are recorded at regular increments of stress (34 MPa (5 ksi)) and at ASME Code-related stresses (S/sub y), S/sub m/, 1.2S/sub m/ and 1.5S/sub m/). At intermediate stresses, strain penalties for using material of lower bound strength were large, generally larger for type 316 than type 304. For mill-annealed type 316 at 24, 93, 204, and 316/sup 0/C, the maximum ratios of strain were 8.8, 13.0, 14.1, and 14.9, respectively, whereas for type 304 they were 3.5, 3.4, 5.6, and 4.6. At 1.5S/sub m/ and 316/sup 0/C, a maximum strain of 2.08% was predicted for type 316 and 1.66% for type 304, as contrasted to values of 0.14 and 0.39% for average strain (YSa).
Date: January 1, 1977
Creator: Hammond, J.P. & Sikka, V.K.
Partner: UNT Libraries Government Documents Department

SWAGING OF URANIUM-MOLYBDENUM ALLOY POWDERS CONTAINING 10 TO 15 WT % MOLYBDENUM

Description: Uranium --molybdenum alloy rods containing from 10 to 15 wt% Mo and 1/16- in. in diameter were successfully fabricated by hot rotary swaging, followed by machining to remove the protective sheathing (Inconel with molybdenum barrier). Structurally strong rods with densities greater than 95% of theoretical were produced from both calciumreduced uranium mixed with hydrogen-reduced molybdenum and acid-cleaned, prealloyed shot when reduced in area about 55% at 1050 or 1100 deg C. Alloy homogeneity was good with prealloyed powders; however, traces of molybdenum -rich, gamma phase persisted in the elemental uranium -molybdenum material after swaging at 1100 deg C. Swagings embodying hydride uranium or oxide- contaminated prealloyed shot were unsatisfactory because of insufficient consolidation or poor interparticle bonding. (auth)
Date: September 11, 1963
Creator: Rabin, S.A.; Lotts, A.L. & Hammond, J.P.
Partner: UNT Libraries Government Documents Department

FABRICATION DEVELOPMENT OF U-Mo-UO$sub 2$ AND U-Mo-UC DISPERSION FUELS FOR THE ENRICO FERMI FAST-BREEDER REACTOR

Description: The fabricability of dispersion fuels using UO/sub 2/ or UC as the dispersoid and uranium combined with 10 to 15 wt% Mo as the matrix was investigated. Cores containing l7.8 wt% UO/sub 2/ dispersed in U-- 15 wt.% Mo were successfully fabricated to about 80% of theoretical density by cold pressing at 50 tsi, sintering at 1100 deg C, and cold coining at 50 tsi. Comparable results were obtained with UC as the dispersoid. Core fabrication results varied greatly with the type of matrix powder used. Occluded gases, pour density, and surface cleanliness bore important relations to the fabrication behavior of powders. Suitable pressing and sintering results were obtained with prealloyed, calcium-reduced U--Mo powder and with molybdenum and calcium-reduced uranium as elemental powders. Shotted prealloyed powders were difficult to press and sinter, as were elemental and prealloyed powders prepared by hydriding. The cores containing UO/sub 2/ were picture-frame, hot-roll-clad as miniature plates. Molybdenum, Fansteel 82, and Zr--3 wt% Al were investigated as cladding materials. While each bonded well to itself, only the molybdenum-clad core, rolled at 1150 deg C to 10/1 reduction, resulted in dispersions free of ruptures and UO/sub 2/ fragmentation and in strong bonding to the core, evaluated by metallography, mechanical peel, and thermal shock tests. The matrix phase was homogeneous, but the UO/sub 2/ dispersoid showed stringering characteristic of cores worked by hot rolling. Core densities as high as 99% of theoretical were obtained. (auth)
Date: June 24, 1963
Creator: Rabin, S.A.; Martin, M.M.; Lotts, A.L. & Hammond, J.P.
Partner: UNT Libraries Government Documents Department