Showing papers on "Inconel published in 1979"

AN INVESTIGATION OF THE CREEP‐FATIGUE‐ENVIRONMENT INTERACTION IN A Ni‐BASE SUPERALLOY

Abstract: — This work was conducted to study the significant increases in fatigue crack growth rates at low frequencies commonly observed at high temperature. Creep tests and fatigue tests at 0·01, 0·1 and 1·0 Hz were conducted at 650°C in air and in helium on samples of INCONEL alloy 718 in two different heat treatments. Creep crack growth rates were 50–100 times greater in air than in helium. Fatigue tests in helium showed little sensitivity to frequency, but tests in air showed considerable increases in crack growth rates at lower frequencies. The results indicate the air environment played a predominant role in both the creep and the fatigue tests. Oxygen diffusion into grain boundaries appeared responsible for the accelerated crack growth in air. An overaging heat treatment reduced the crack growth rates.

Composite material compliant bearing element

Abstract: A compliant fluid film bearing includes a thin, flexible bearing sheet supported on a resilient bump-form support member which is divided into multiple adjacent strips. The bearing sheet and support member are each formed of a composite material made of Inconel X-750 and copper. The Inconel sheet, in annealed condition, is cut and formed in the desired shape and is coated with copper. The sheet is heat treated in an oxygen-free atmosphere to give the Inconel the small grain size for the desired properties of strength and hardness. During the heat treatment, the copper diffuses into the Inconel, producing at the end a composite material of Inconel X-750 having a diffusion of copper into its top portion such that the top surface is about 100% copper, and the copper fraction decreases exponentially with the depth into the Inconel sheet. The bearing elements formed of this composite material provide improved coulomb and viscous damping and improved bearing load capacity and stability at high temperature and speed.

The Effect of Carbon Content and Thermal Treatment on the SCC Behavior of Inconel Alloy 600 Steam Generator Tubing

Abstract: An attempt has been made to improve the SCC performance of Inconel Alloy 600 steam generator tubing by modifying the grain boundary microstructure. Changes in the grain boundary microstruc...

Effect of minor elements on hot workability of nickel-base superalloys

Abstract: Studies have been performed on the effect of five minor elements (S, Ca, Mg, Y, and Zr) on the hot workability of three solid-solution strengthened, nickel-base superalloys: Inconel 600, Hastelloy-X, and a Ni–Cr–W type alloy (NSC-1) for heat-exchanger pipes in high-temperature gas reactors. The hot workability was evaluated from the reduction of area in hot tensile tests using a Gleeble testing machine. Round bar specimens were prepared from near surface portions of alloy ingots melted and cast by vacuum induction melting, vacuum arc remelting, or electroslag remelting. When the sulphur content was increased, a ductility dip appeared for each alloy between 950° and 1150°C; the greater the sulphur content, the deeper the dip. At the same time, the fracture appearance became increasingly intergranular. By adding a small amount of Ca, Mg, Y, or Zr, the hot workability of these alloys changed drastically, and it was found that controlled addition of these minor elements gave a superior hot ductility. ...

The Influence of Thermal Treatment on the SCC Behavior of Inconel Alloy 600 at Controlled Potentials in 10% Caustic Soda Solutions at 315 C

Abstract: Electrochemically controlled test methods have been used to determine the influence of thermal treatment on the stress corrosion cracking (SCC) resistance of Inconel alloy 600 (I-600) in d...

Structure of PWR Primary Corrosion Products

Abstract: The composition and structure of “erud” taken from the fuel elements of various pressurized water reactors (PWR's) were determined by SEM, EDAX, X-ray analysis, infrared spectroscopy, and thermomagnetic analysis. The samples were taken from reactors varying in materials of construction from all stainless steel to mainly Inconel 600 and Zircaloy fuel cladding. It is shown that crud is essentially a nickel ferrite (NixFe3–xO4) with 0.45 < x < 0.75. Calibration of the lattice parameter versus x allows convenient determination of the main constituents of crud samples. Chromium also enters the inverse spinel lattice substitutionally to give a composition CryNixFe3–x–yO4. Aluminum, when present, generally formed amorphous compounds with silicon in the loose crud.

Corrosion Behavior of Selected Structural Materials in a Simulated Steam-Cycle High-Temperature Gas-Cooled Reactor Helium Environment

Abstract: Corrosion of carbon steel, 2 1/4 Cr--1 Mo, Types 422, 304, and 316 stainless steel, Alloy 800 (Grade 2), Alloy 800 H, Inconel 617, and Hastelloy X by gaseous impurities in a simulated steam-cycle high-temperature gas-cooled reactor helium environment was investigated. The corrosion tests were conducted at various temperatures for up to 5000 h. Oxidation was observed in all the alloys investigated except carbon steel as predicted by thermodynamic calculations. Other gas-metal reactions observed included carbon deposition on carbon steel and 2 1/4 Cr--1 Mo, and carburization in Type 316 stainless steel with the as-received surface condition (i.e., annealed and pickled). Thermodynamic considerations were given to rationalize the chemical reaction(s) that dominates the carbon potential in the test environment and to provide a basis for making thermodynamic predictions as to the occurrence of carbon deposition, carburization, and/or decarburization.

The Fatigue-Crack Propagation Response of Two Nickel-Base Alloys in a Liquid Sodium Environment

Abstract: The elevated temperature fatigue-crack propagation response of Inconel 600 and Inconel 718 was characterized within a linear-elastic fracture mechanics framework in air and low-oxygen liquid soium environments. The crack growth rates of both nickel-base alloys tested in liquid sodium were found to be considerably lower than those obtained in air. This enhanced fatigue resistance in sodium was attributed to the very low oxygen content in the inert sodium environment. Electron fractographic examination of the Inconel 600 and Inconel 718 fatigue fracture surfaces revealed that operative crack growth mechanisms were dependent on the prevailing stress intensity level. Under low growth rate conditions, Inconel 600 and Inconel 718 fracture surfaces exhibited a faceted, crystallographic morphology in both air and sodium environments. In the higher growth rate regime, fatigue striations were observed; however, striations formed in sodium were rather ill-defined. These indistinct striations were attributed to the absence of oxygen in the liquid sodium environment. Striation spacing measurements were found to be in excellent agreement with macroscopic growth rates in both environments.

Heatttreatment method for niibased alloy

Abstract: PURPOSE:To increase resistance to intercrystalline stress corrosion cracking through the development of metal carbides in the grain boundary by a specified heat-treatment of a corrosion resistant Ni-based alloy such as inconel 600.

Build up welding method

Abstract: PURPOSE: To improve resistances to stress, corrosion, and crack of the nuclear reactor pressure vessel, by using the Inconel material, which has the stability parameter of a specific value or more when it is melt-stuck, in the last build up layer or the surface layer which is brought into contact with high-temperature water CONSTITUTION: The inside face of the nuclear reactor pressure vessel of the boiled water type nuclear reactor is subjected to build up welding with the Inconel material of the Ni-Cr-Fe system including 15W20% Cr and 70W75% Ni, and Inconel melt- stuck metal layer of the first layer 2 and the second layer 3 is formed on base metal 1 Next, the Inconel material where the ratio (stability parameter) of the number of atoms of the contained stabilized element forming the MC type carbide to the number of atoms of contained carbon becomes 20 or more when it is welded is used to form last build up layer 5 or the surface layer COPYRIGHT: (C)1981,JPO&Japio

High temperature sulfidation of six alloys

Abstract: Six ferrous alloys were exposed for 100 h to a gas mixture containing 1 pct hydrogen sulfide and 3 pct steam at a temperature of 650 °C. Their relative resistances to corrosive attack were in the order: plain carbon (worst), Inconel 600, Incoloy 800, 316 stainless, 304 stainless and Armco 18SR (best).

Stress corrosion cracking of Inconel 600 tubing in deaerated high temperature water

Abstract: Inconel 600 will undergo stress corrosion cracking (SCC) at grain boundaries when subjected to a high stress and exposed to water without oxygen at high temperature. Very few service failures have occurred but extensive intergranular cracking has also occurred in plants that experienced denting. All of these cracks were from the primary side. The process of denting produced high strains and stresses in the tubing, as well as slow strain rates during deformation. The literature is silent on effects of slow strain rates or cyclic stresses on SCC of Inconel 600 in deaerated, high temperature aqueous media such as pure or primary water. Because of the importance of avoiding primary-to-secondary leaks through the Inconel 600 pressure boundary, a research program was started at BNL in an attempt to improve the qualitative and quantitative understanding of factors influencing SCC in deaerated high temperature aqueous media. These data also predict service performance under given sets of conditions. Preliminary results which indicate that intergranular SCC is produced quite readily in some heats of tubing when exposed at (a) constant deflection, (b) when slightly cold worked and subjected to straining at low rates, (c) when subjected to slow cyclic stress, or (d) when themore » electrochemical potential of stressed pieces is controlled. Cracking has now been produced in Inconel 600 under conditions that had not been examined and reported before. First trends of temperature dependence of SCC are discussed. Some tentative correlations are made with microstructural variables, although a simple relationship with such structure or prior processing has not been defined. Heating at 700/sup 0/C for about 15 hours improved the SCC resistance dramatically. Future tests will include primary and secondary water ingredients and some impurities.« less

Creep Properties of Heat-Resistant Superalloys for Nuclear Plants in Helium

Abstract: In order to estimate the creep and rupture strengths of candidate alloys for the intermediate heat exchanger of VHTR, creep and stress rupture tests in impure helium were conducted on Hastelloy X, Inconel 617, Inconel 625, Incoloy 800 and Incoloy 807 at 900°C. The results were discussed in comparison with those in air and the alloys were examind from the point of view of the elevated temperature structural design.The main results obtained are summarized as follows:(1) No appreciable decrease in creep and rupture strengths in helium as compared with those in air is observed on Hastelloy X and Inconel 625. On the contrary, the creep and rupture strengths of Inconel 617 in helium decrease slightly as compared with those in air. Meanwhile, the creep and rupture strengths of Incoloy 800 in helium are remarkably lower than those in air. In the case of Incoloy 807, the creep strength to cause 1 percent total strain and that to initiate secondary creep increase remarkably in helium as compared with those in air. However, the creep strength to cause initiation of tertiary creep and the rupture strength in helium remarkably decrease as compared with those in air.(2) The order of magnitude of the So value for each material in helium is as follows; Hastelloy X>Inconel 617>Incoloy 807>Inconel 625>Incoloy 800Meanwhile, that of the St value in helium is; Inconel 617>Hastelloy X>Incoloy 807>Inconel 625>Incoloy 800.

Static and dynamic crack toughness of brazed joints of Inconel 718 nickel-base alloy

Abstract: The crack toughness of brazed joints of Inconel 718 nickel-base alloy was investigated at different strain rates. The brazing filler metal used was BNi5. The results were compared with those obtained on specimens made of the base material. The brazed joints were heat-treated after the brazing process in order to achieve a desirable distribution of the brittle phases in the joint.

Tungsten wire-reinforced superalloys for 1093 C (2000 F) turbine blade applications

Abstract: Various combinations of fiber and matrix materials were fabricated and evaluated for the purpose of selecting a specific combination that exhibited the best overall properties for a turbine blade application. A total of seven matrix alloys, including Hastelloy X, Nimonic 80A, Inconel 600, Inconel 625, IN-102, FeCrA1Y, were investigated reinforced with either 218CS tungsten, or W-Hf-C fibers. Based on preliminary screening studies, FeCrA1Y, Inconel 600 and Inconel 625 matrix composites systems were selected for extended thermal cycle tests and for property evaluations which included stress rupture, impact, and oxidation resistance. Of those investigated, the FeCrA1Y matrix composite system exhibited the best overall properties required for a turbine blade application. The W-Hf-C/FeCrA1Y system was selected for further property evaluation. Tensile strength values of up to 724 MPa (105,000 psi) were obtained for this material at 982 C and 607 MPa at 1093 C.