Showing papers on "Inconel published in 1991"

The Effect of Laves Phase on the Mechanical Properties of Wrought and Cast + HIP Inconel 718

Abstract: The effect of varying amounts of Laves phase on the mechanical properties of wrought and cast + HIP Inconel718 is discussed. When present as a continuous or semicontinuous grain boundary network in wrought Inconel718, Laves phase dramatically reduces room temperature tensile ductility and ultimate tensile strength, with room temperature impact and fracture toughness properties and elevated temperature ductility also reduced. Laves may also act as a preferred crack initiation and propagation site, resulting in reduced low cycle fatigue (LCF) p blty d ca a i i an accelerated fatigue crack growth rates. Laves present as large globular aggregates in cast+HIP Inconel 718 significantly reduces room temperature tensile and elevated temperature stress rupture properties. In addition, the phase acts as a preferred crack initiation and propagation site, resulting in significant reductions in smooth and notch LCF capability and an accelerated fatigue crack growth rate. Methods for controlling Laves phase in wrought and cast +HIP Inconel 718 are discussed. Superalloys 718,625 and Various Derivatives Edited by Edward A. JJxia The Minerals, Metals & Materials Society, 1991

Intergranular Cracking of Ni-16Cr-9Fe Alloys in High Temperature Water

Abstract: The objective of this work is to provide a better understanding of the role of microstructure in intergranular stress corrosion cracking (SCC) of controlled-purity, Inconel 600-type alloys...

Versatile Corrosion Resistance of INCONEL Alloy 625 in Various Aqueous and Chemical Processing Environments

Abstract: INCONEL@ alloy 625 is a nickel-chromium-molybdenum alloy that is used for its high strength, excellent fabricability and weldability, and outstanding corrosion resistance. The outstanding and versatile corrosion resistance of INCONEL alloy 625 under a wide range of temperatures and corrosive environments is the primary reason for its wide acceptance in chemical processing and other applications. This paper will present laboratory and field data related to the resistance of alloy 625 to various aqueous media causing localized corrosion, stress corrosion cracking and other forms of attack. Also the versatility of the alloy for use in oxidizing, carburizing, chlorinated solvents and simulated waste incinerator type environments containing halide species, will be demonstrated. @INCONEL is a trade mark of the Into family of companies. Superalloys 718,625 and Various Derivatives Edited by Edward A. Lmia The Minerals, Metals & Materials Society, 1991

Composition of Surface Films on Nickel Base Superalloys

Abstract: The composition and thickness of the passive film formed on three nickel base superalloys (Inconel 718, Incoloy 925, and MP335N) in an acetate buffer (1 mol l −1 acetic acid/1 mol l −1 sodium acetate) was investigated using the technique of surface analysis by laser ionization (SALI)

Rotary Forge Processing of Direct Aged Inconel 718 for Aircraft Engine Shafts

Abstract: The increase in aircraft engine thrust has required that main engine shaft material exhibit improved tensile strength and cyclic capability. The application of a "Direct Age" heat treatment to a controlled GFM fine grain billet process is discussed. "Direct Aged" tensile and low cycle fatigue properties are presented and compared to fine grain solution and aged material. Improvements in tensile properties were noted at temperatures up to 1200F with the largest improvement occurring at the bar surface. No difference in microstructure or properties was noted along the bar when bars were limited to less than 30' in length. Longitudinal properties were found to be slightly higher than those measured in the tangential direction. It is concluded that application of the "Direct Age" heat treatment to a controlled GFM ingot conversion practice can be used to improve Inconel 718 aircraft engine shaft properties. Superalloys 718,625 and Various Derivatives Edited by Edward A. Im-ia The Minerals, Metals & Materials Society, 1991

Method of producing nickel-alloy honeycomb panels

Abstract: A method for pre-oxidizing a nickel alloy honeycomb core by heating the core while exposing the core to a controlled flow of an oxygen containing gas, such as dry air. The preoxidized core can be brazed in a vacuum furnace to two face sheets to manufacture a honeycomb panel using thin foil brazing material. The methods of preoxidation and panel production for Inconel 718, Rene' 41 and Inconel 625 are specifically described.

Materials for elevated-temperature applications

Abstract: Recent studies have been conducted in an effort to expand the current capabilities of superalloys and to explore materials which may extend application temperatures well beyond the celestial limits of the high temperature materials currently in use. Work on very high melting (melting temperature Tm > 1650 °C) intermetallics has, to some extent, validated the potential of these materials. Specifically, Cr2Nb has been shown to possess both a very high strength at temperatures to 1300 °C and an excellent creep resistance. Efforts directed at intermetallic-intermetallic composite systems such as beryllide-reinforced Fe-40 wt.%Al have shown that the problem of interdiffusional degradation can be significantly inhibited through the formation of a “diffusional lock”. Finally, it has been found that electron beam cold-hearth can significantly enhance performance. Indeed, it has been found that electron beam cold-hearth refining of Inconel 718 resulted in a virtual elimination of inclusions anda sixfold increase in low cycle fatigue life.

Cracking behaviour of heat-resisting steels, alloys and a carbon-fibre-reinforced polymer at elevated temperatures

Abstract: Characterization of creep-dominated fatigue cracking or cavitation in smooth specimens of a type 304 stainless steel is emphasized in terms of the stochastic nature of small-crack initiation and growth. As compared with monometallic ductile steels, a somewhat different cracking behaviour is shown for a titanium alloy Ti-17, an oxide-dispersion-strengthened nickel-base superalloy Inconel MA754 and a grey cast iron FC25. The mechanical behaviour of the large-crack propagation of creep and high temperature fatigue in high strength, low ductility materials is discussed in comparison with ductile materials. A quasi-small-scale creep condition dominates for the creep-fatigue crack propagation of the nickel-base superalloy Inconel 718, and a pure small-scale creep condition is established in the creep crack propagation of an aluminium alloy 2014-T6 and a carbon-fibre-reinforced polymer, namely unidirectional carbon fibres-poly(ether-ether-ketone) composite.

An analysis of the creep-environment interaction of Inconel alloy X-750 exposed at 1150°C

Abstract: The effect of exposure of Inconel alloy X-750 to air at 1150°C on creep at 700°C and 400 MPa has been investigated. Contrary to the findings for exposure at 1050°C, exposure to air at 1150°C does not impair creep ductility. This is attributable to oxygen diffusion into the alloy at 1150°C being impeded. Evidence is given here to show that during exposure to air at 1150°C diffusion of chromium is fast enough to reach the surface and form a chromium oxide scale, which acts as a barrier to further oxygen diffusion.

Creep Deformation of Inconel Alloy 718 in the 650C to 760C Temperature Regime

Abstract: The steady-state creep behavior of a commercial grade Inconel alloy 718 has been studied over the temperature range of 650°C to 760°C at initial applied stress levels ranging from 276 MPa up to 724 MPa. Two age heat treatments were also compared and found to exhibit comparable stress exponents and apparent creep activation energies indicating that the fundamental steady-state creep deformation mechanisms were independent of age heat treatment. In the case of both heat treatments, the creep stress exponents and activation energies are significantly higher than those of pure Ni (i.e. n=5 and Qc=Q,=280 kJ/mole) assuming dislocation creep as the rate limiting deformation mechanism. The high stress exponents reflect the strengthening imparted by the Y" precipitates while the high creep activation energy is controlled y N suggested to reflect multi-component diffusion precipitate coarsening as rate limiting for steady-state creep deformation.

Tensile Properties of Ni-Base Alloys in High Pressure Hydrogen at Room Temperature.

Abstract: The tensile properties of Inconel 718 and Udimet 720 Ni-base alloys being used for liquid hydrogen fueled rocket engine materials were investigated in a high pressure hydrogen of 19.7MPa at room temperature. The results obtained are as follows;(1) Elongation, reduction of area and ultimate tensile strength in hydrogen were smaller than those in argon for both Inconel 718 and Udimet 720. The effect of hydrogen on the tensile properties increased with decreasing strain rate.(2) Dimple rupture was mainly observed in argon both of Inconel 718 and Udimet 720. In hydrogen, the fracture along the interface between δ phase and γ matrix for Inconel 718 and that along the interface between γ' phase and γ matrix for Udimet 720 were observed on the fracture surface, respectively.(3) For Inconel 718, the crack initiation occurred at carbide and then the crack propagated along the interface between δ phase and γ matrix in hydrogen. For Udimet 720, the crack initiation occurred at precipitate and then the crack propagated along the interface between γ' phase and γ matrix in hydrogen.

Study on transient liquid insert metal diffusion bonding of Ni-base superalloys, (Part 4). Analysis of homogenizing process of alloying elements on transient liquid insert metal diffusion bonding.

Abstract: This study evaluated homogenizing process of alloying elements such as aluminum, titanium and chromium during Transient Liquid Insert Metal Diffusion Bonding (TLIM-bonding) of Ni-base superalloys such as MM007, Mar-M247, Inconel 713C and IN939 with a Ni-15%Cr-4%B amorphous insert metal.The detailed analysis at the bonded interlayer of TLIM-bonded joint was performed quantitatively using electron probe microscopy (EPMA) technique. From the experimental results, the concentrations at the center of the bonded interlayer (Ct) of aluminum and titanium increased and that of chromium decreased dependent on the holding time during homogenizing process due to elements diffusion from the base metal to the bonded interlayer. Further, increasing temperature decreased the holding time for completion of homogenizing process.Homogenizing process was calculated analytically by applying one-dimensional diffusion model considering the base metal dissolution, thereby equations were derived for estimating the concentration Ct of aluminum, titanium and chromium.The calculated values corresponded well with the experimental ones, except in the early stage of homogenizing process. It follows that the equation by applying one-dimensional diffusion model can estimate the holding time for completion of homogenizing process in fabrication.

Crack Propagation of Oxide Dispersion Strengthened Superalloy Inconel MA754 in Creep-Fatigue.

Abstract: Crack propagation behavior was examined in creep-fatigue at high temperatures using center cracked plate (CCP) specimens of an oxide (Y2O3) dispersion strengthened (ODS) superalloy, Inconel MA754, manufactured by mechanical alloying and a Ni-base superalloy without oxide dispersion, Nimonic 75. The Inconel MA754 has coarse elongated grains whereas the Nimonic 75 has fine homogeneous ones. The results obtained are summarized as follows.(1) The transverse crack propagation of the Inconel MA754 at 1273K and 1173K was strongly affected by the microstructure. The crack arrested temporarily at the grain-boundaries perpendicular to the propagation direction while it propagated fast at the midway.(2) The average crack length through the thickness of specimen, which included about 15 grains, was measured by means of the DC potential drop technique during the test of Inconel MA754. The length increased smoothly without the crack arrest and the propagation rate was correlated well with the creep J-integral range.(3) Little difference was observed in the dl/dN-ΔJc relations between the Inconel MA754 and the Nimonic 75 (at 1173K and 1073K).(4) The crack propagation of the Inconel MA754 was much slower than that of the Nimonic 75. This high resistance of ODS superalloy against creep-fatigue crack propagation was caused by the excellent creep deformation property due to the oxide dispersion.

Heat treating method for improving corrosion resistance of solid-solution strengthened ni base alloy

Abstract: PURPOSE:To provide the heat treating method for improving the corrosion resistance of a solid-soln. strengthened Ni base alloy for a nuclear reactor for solving the serious problem of the corrosive damage of 'Inconel(R)' 600 used for a structure in a BWR(boiling water reactor) caused by the sensitization of material in a reactor water environment of BWR. CONSTITUTION:This method is characterized in that in heat treatment in the final stage, for obtaining high corrosion resistance and good mechanical properties of a solid solution strengthened Ni base alloy, setting its heating temp. to 1000 to 1100 deg.C, allowing >=60% of the C content therein to enter into solid solution, regulating the grain size to fine one of >=4 grain size number and thereafter executing rapid cooling from the heating temp. to 300 deg.C at >=200 deg.C/sec cooling rate.

Diffusion bonding of Inconel 600 to Alumina

Abstract: Solid-state bonding experiments, between Alumina and Inconel 600 without interlayers, are carried out at temperatures ranging from 1100°C to 1300°C under Argon at a pressure of 100 MPa for 30 min. to 120 min. using the hot-isostatic pressing (H.I.P.) technique. Optimal bonding conditions are assessed by shear testing at room temperature. Strengths up to about 70 MPa are obtained with fracture primarily occuring within the Alumina.

Study on Transient Liquid Insert Metal Diffusion Bonding of Ni-base Superalloys(Part 6). Newly Development in Transient Liquid Insert Metal Diffusion Bonding Using Alloying Powder.

Abstract: This study developed the new Transient Liquid Insert Metal Diffusion Bonding (TLIM-bonding) technique using alloying powder whose chemical compositions were similar to those of base metal. The base metals used were commercial Ni-base superalloys such as MM007, MarM247 and Inconel 713C alloys. They were bonded with both a Ni-15%Cr-4%B amorphous insert metal and IN100 alloying powder sheet with the thickness of about 250 μm.In the case of a MM007 alloy, the times required for completion of isothermal solidification and sequent homogenizing process were about 0.6 ks and 86.4 ks at 1423 K, respectively using this technique even with the bonding clearance of about 100 μm. The former time was about 1/80 and the latter time was about 1/30 compare to the times obtained by a conventional TLIM bonding. The short period during homogenizing process may be due to element diffusion from alloying powder to base metal by three-dimensional diffusion process.The tensile strength of MM007, MarM247 and Inconel 713C joints at 1255 K were almost equal to those of each base metal, respectively.From the experimental results, it should be useful to insert alloying powder to a wide bonding clearance joint during TLIM-bonding in fabrication

Potentiostatic pulse technique to determine the efficiency of hydrogen absorption by alloys

Abstract: A potentiostatic pulse technique was used to determine the efficiency of hydrogen entry and trapping in two precipitation-hardened (Inconel 718 and Incoloy 925) and two work-hardened (Inconel 625 and Hastelloy C-276) nickel-base alloys in an acetate buffer (1 M acetic acid/1 M sodium acetate) containing 15 p.p.m. As2O3. The data were examined as a function of charging time and overpotential. The trapping efficiency increases with charging time (f c) and is linearly dependent on (t c)1/2 for sufficiently short times. The range of linearity is determined by the apparent trapping constant for the alloy. The entry efficiency is independent of charging time but it can vary with overpotential depending on the value of the charge transfer coefficient (α) for the hydrogen evolution reaction. In the case of Inconel 718 and Hastelloy C-276, the value of α was 1.4, which is consistent with a mechanism for hydrogen evolution involving fast discharge followed by slow electrochemical desorption.

The Diffusion Bonding of Engineering Ceramics to Nickel Based Superalloys by Hot Isostatic Pressing (Hipping)

Abstract: This present work is investigating the HIP diffusion bonding of NITRASIL Si3N4 and REFEL SiC ceramics to the nickel-based superalloys INCOLOY 909 and INCONEL 718.

Interaction of tin telluride and cesium hydroxide with reactor materials in steam

Abstract: Two laboratory tests were designed to study the behavior of SnTe and CsOH in steam at {approximately}1230 K with the reactor materials Inconel 600, 304 stainless steel, silver and nickel, a nonoxidizing constituent of Inconels and steels in reactor accident environments. Thermochemical calculations examined the sensitivity of species in the H-O-Cs-Te-Sn system to temperature, to hydrogen and SnTe concentrations and to total system pressure. Test results indicate that should SnTe be formed from fission product tellurium and the tin in zircaloy cladding, it may not remain stable in steam in the presence of unoxidized (or lightly oxidized) metals. Calculations show a small amount of SnTe, in equilibrium with steam, decomposes to primarily Te and SnO. It is felt that these decomposition producets react with the reactor materials since Sn and Te are seen to be deposited separately and not as SnTe. The deposition velocity for SnO vapor in the system was estimated to be 0.57 m/s. The response of CsOH in the system was similar to behavior observed previously: some cesium combined with silicon found in Inconel and stainless steel oxides. At lower temperatures ({le}940 K) CsOH corroded Inconel, stainless steel and nickel providing enhanced surface area for additional trappingmore » of species. There was no experimental evidence for the formation of cesium telluride; vapor equilibrium calculations did not predict formation either. 33 refs., 29 figs, 7 tabs.« less

Welding wire consisting of nickel-base alloy

Abstract: PURPOSE:To maintain the characteristics of an inconel material to be used for a superconducting rotor, etc., by constituting the welding wire of a nickel based alloy made of a compsn. contg. specific weight % of C, Si, Mn, P, S, Ni, Cr, Mo, Nb, Ti, and B. CONSTITUTION:The welding wire is constituted of the nickel-based alloy. The nickel-based alloy is made of the compsn. contg., by weight %, <=0.25% C, <=0.3% Si, <=5.5% Mn, 45 to 55% Ni, 10 to 30% Cr, 3.4 to 6.0% Mo, 2 to 4.5% Nb, 1.5 to 2% Ti, and <=0.001% B. Welding procedures are executed without generating weld crack in this way.

Control rod for nuclear reactor

Abstract: PURPOSE:To eliminate an anisotropy by arranging or dispersing neutron absorbing materials made of a hafnium or a hafnium alloy in a base phase constituent material, and concurrently to enable a mechanical strength of the materials to be improved and to make them be of long-life by making them be of multiply constituted material. CONSTITUTION:A hafnium or a hafnium alloy 1 is dispersed at random in a Ni radical alloy 2 of a stainless steel or an Inconel or the like, which is a base phase constituent material of a control rod. As for the manufacturing methods, one is performed by casting in which, utilizing a characteristic that a melting temperature of the Ni radical alloy 2 of a stainless steel or an Inconel or the like is lower than that of the hafnium or the hafnium alloy 1, the hafnium or the hafnium alloy 1 is dispersed in the Ni radical alloy 2 of a stainless steel or an Inconel or the like, can be selected. As another manufacturing method, a powder metallurgy manufacturing method, in which the hafnium or the hafnium alloy 1, and the Ni radical alloy 2 of a stainless steel or an Inconel or the like are pulverized and then sintered, is also feasible.