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Ferrous alloy metallurgy - liquid lithium corrosion and welding. Progress report, January 1-December 31, 1980

Description: Fatigue crack growth has been used to evaluate the interaction between liquid lithium and an imposed stress. Fatigue crack growth data on type 304L stainless steel at 700C and 2 1/4Cr-1Mo steel between 500 and 700C show that for all imposed test conditions (i.e. frequency, temperature, and nitrogen content in the lithium) the interaction of lithium with the strain at the crack tip results in enhanced crack growth rates. The enhanced growth rates result from the effects of either enhanced grain boundary penetration or a change in crack propagation mechanism due to liquid metal embrittlement. Auger spectroscopy of grain boundary penetrated specimen shows that a lithium-oxygen compound forms at the grain boundary. Moessbauer evaluations of the ferrite layer of corroded type 304 stainless steel are being used to develop a model for weight loss in liquid lithium. The welding research in progress is directed to characterize the influence of variations of the austenitic weld metal composition on the microstructural and mechanical properties of dissimilar metal weldments. Weldments of 2 1/4Cr-1Mo steel to 316 stainless steel have been investigated for fusion microstructure, thermal expansion impact strength and characterization of specific long time in-service failures. Modification of weld metal microstructures by microalloy additions is being investigated as a concept to improve weld metal properties. The behavior of a strip electrode in a gas metal arc is being investigated to determine the feasibility of gas metal arc weld strip overlay cladding.
Date: January 1, 1980
Creator: Olson, D. L. & Matlock, D. K.
Partner: UNT Libraries Government Documents Department

Evaluation of laser welding techniques for hydrogen transmission. Final report, September 1977-November 1979

Description: This program was established to determine the feasibility of laser beam welding as a fabrication method for hydrogen transmission and is a precursor in the effort to systematically provide the technological base necessary for large-scale, economic pipeline transmission of fuel for a hydrogen energy system. The study contributes to the technology base by establishing the effect of conventional weld processes and laser beam welding on the mechanical properties of two classes of steels in an air and high pressure gaseous hydrogen environment. Screening evaluation of the tensile, low-cycle fatigue and fracture toughness properties and metallurgical analyses provide the basis for concluding that laser beam welding of AISI 304L stainless steel and ASTM A106B carbon steel can produce weldments of comparable quality to those produced by gas-tungsten arc and electron beam welding and is at least equally compatible with 13.8 MPa (2000 psig) gaseous hydrogen environment.
Date: May 1, 1980
Creator: Mucci, J
Partner: UNT Libraries Government Documents Department

J-controlled crack growth as an indicator of hydrogen-stainless steel compatibility

Description: The J-integral was evaluated as a parameter to characterize fracture of stainless steels and as a measure of hydrogen damage. C-shaped specimens of type 304L, 316, and 21-6-9 stainless steels were tested in high pressure helium and hydrogen. The critical force for crack initiation (Jm), and tearing resistance (dJ/da) were decreased by hydrogen in all three alloys. The J-integral appears useful as a measure of hydrogen compatibility because it is sensitive to both test environment and microstructure.
Date: January 1, 1980
Creator: Dietrich, M.R.; Caskey, G.R. Jr. & Donovan, J.A.
Partner: UNT Libraries Government Documents Department

Fractography of hydrogen-embrittled iron-chromium-nickel alloys

Description: Tensile specimens of iron-chromium-nickel base alloys were broken in either a hydrogen environment or in air following thermal charging with hydrogen. Fracture surfaces were examined by scanning electron microscopy. Fracture morphology of hydrogen-embrittled specimens was characterized by: changed dimple size, twin-boundary parting, transgranular cleavage, and intergranular separation. The nature and extent of the fracture mode changes induced by hydrogen varied systematically with alloy composition and test temperature. Initial microstructure developed during deformation processing and heat treating had a secondary influence on fracture mode.
Date: January 1, 1980
Creator: Caskey, G. R., Jr.
Partner: UNT Libraries Government Documents Department

Hydrogen assisted fracture of sensitized Type 304L austenitic stainless steel

Description: Sensitized specimens of Type 304L stainless steel were tensile tested in atmospheres of hydrogen and helium at high pressure, and in air at ambient pressure. Comparison tensile tests were made with solution-annealed specimens of Type 304L stainless steel in the same atmosphere. When both specimens were tested in high-pressure hydrogen, the sensitized specimens had greater loss in ductility and increased tendency to intergranular fracture. For the sensitized specimens, plastic strain to failure (epsilon/sub p/ = 1n A/sub 0//A/sub f/) in hydrogen at 69 MPa was reduced by 60 to 70% in comparison to similar tests in helium. In addition, a notch with a stress concentration factor of about 3 reduced plastic strain an additional 50 to 60%. In all cases, the nominal tensile strength of Type 304L stainless steel was increased by the notch. There was no evidence of intergranular failure in notched specimens of solution-annealed Type 304L stainless steel tested in high-pressure hydrogen environments.
Date: January 1, 1980
Creator: Caskey, G.R. Jr.
Partner: UNT Libraries Government Documents Department

Corrosion of high Ni-Cr alloys and Type 304L stainless steel in HNO/sub 3/-HF

Description: Nineteen alloys were evaluated as possible materials of construction for steam heating coils, the dissolver vessel, and the off-gas system of proposed facilities to process thorium and uranium fuels. Commercially available alloys were found that are satisfactory for all applications. With thorium fuel, which requires HNO/sub 3/-HF for dissolution, the best alloy for service at 130/sup 0/C when complexing agents for fluoride are used is Inconel 690; with no complexing agents at 130/sup 0/C, Inconel 671 is best. At 95/sup 0/C, six other alloys tested would be adequate: Haynes 25, Ferralium, Inconel 625, Type 304L stainless steel, Incoloy 825, and Haynes 20 (in order of decreasing preference); based on composition, six untested alloys would also be adequate. The ions most effective in reducing fluoride corrosion were the complexing agents Zr/sup 4 +/ and Th/sup 4 +/; Al/sup 3 +/ was less effective. With uranium fuel, modestly priced Type 304L stainless steel is adequate. Corrosion will be most severe in HNO/sub 3/-HF used occasionally for flushing and in solutions of HNO/sub 3/ and corrosion products (ferric and dichromate ions). HF corrosion can be minimized by complexing the fluoride ion and by passivation of the steel with strong nitric acid. Corrosion caused by corrosion products can be minimized by operating at lower temperatures.
Date: April 1, 1980
Creator: Ondrejcin, R.S. & McLaughlin, B.D.
Partner: UNT Libraries Government Documents Department

Attack of high-strength, oxidation-resistant alloys during in-can melting of simulated waste glasses

Description: The restistance of candidate canister alloys to penetration under the most severe conditions expected during in-can melting was directly proportional to the chromium content of the alloy, and inversely proportional to the Na/sub 2/O content of the glass melt. Specimens were exposed for 24 hours, which is the time required for in-can melting full-size waste-glass forms based on tests carried out at Pacific Northwest Laboratories (PNL) and at SRL. The penetration resistance to Frit 211 at 1150/sup 0/C for 24 hours of most alloys tested was satisfactory. The amount of penetration would not affect the integrity of the waste form. Inconel 625, Hastelloy X, and Inconel 601 were penetrated < 20 mils. This was considered excellent. Incoloy 801, Type 310 stainless steel, Type 304L stainless steel, Inconel 600, and Type 347 stainless steel were penetrated < 40 mils. This was considered good. Hastelloy C-4 was penetrated > 100 mils by a glass composed of 65 wt % Frit 21 and 35 wt % composite sludge (with uranium) at 1150/sup 0/C for only 7 hours. This amount of penetration of an in-can melting canister would not be satisfactory. 12 figures.
Date: January 1, 1980
Creator: Rankin, W.N.
Partner: UNT Libraries Government Documents Department

Corrosion in lithium-stainless steel thermal-convection systems

Description: The corrosion of types 304L and 316 austenitic stainless steel by flowing lithium was studied in thermal-convection loops operated at 500 to 650/sup 0/C. Both weight and compositional changes were measured on specimens distributed throughout each loop and were combined with metallographic examinations to evaluate the corrosion processes. The corrosion rate and mass transfer characteristics did not significantly differ between the two austenitic stainless steels. Addition of 500 or 1700 wt ppM N to purified lithium did not increase the dissolution rate or change the attack mode of type 316 stainless steel. Adding 5 wt % Al to the lithium reduced the weight loss of this steel by a factor of 5 relative to a pure lithium-thermal-convection loop.
Date: January 1, 1980
Creator: Tortorelli, P.F.; DeVan, J.H. & Selle, J.E.
Partner: UNT Libraries Government Documents Department

Response to annealing and reirradiation of AISI 304L stainless steel following initial high-dose neutron irradiation in EBR-II. [LMFBR]

Description: The object of this study was to measure the stability of irradiation-induced microstructure upon annealing and, by selectively annealing out some of these features and reirradiating the material, it was expected that information could be gained concerning the role of microstructural changes in the void swelling process. Transmission electron microscopic examinations of isochronally annealed (200 to 1050/sup 0/C) AISI 304L stainless steel, which had been irradiated at approximately 415/sup 0/C to a fast (E > 0.1 MeV) neutron fluence of approximately 5.1 x 10/sup 26/n/m/sup 2/, verified that the two-stage hardness recovery with temperatures was related to a low temperature annealing of dislocation structures and a higher temperature annealing of voids and solute redistribution.
Date: January 1, 1980
Creator: Porter, D.L.; McVay, G.L. & Walters, L.C.
Partner: UNT Libraries Government Documents Department

GCFR core cladding temperature limits

Description: This paper reviews the phenomena that affect selection of the GCFR cladding faulted temperature limit. The limiting effects are determined to be clad melting, strength and oxidation rate. The selected temperature limit is 1300/sup 0/C (2370/sup 0/F). The limits for normal, upset and emergency events are also breifly reviewed, and some changes under consideration are discussed.
Date: May 1, 1980
Creator: Day, J.M. & LaBar, M.P.
Partner: UNT Libraries Government Documents Department