Showing papers on "Inconel published in 1998"
TL;DR: In this article, a general review of their material characteristics and properties together with their machinability assessment when using different cutting tools is presented, and the advantages and disadvantages of different tool materials with regard to the machining Inconel are highlighted.
536 citations
TL;DR: Inconel 718 is a nickel-base alloy that is difficult to machine, a high cutting force being generated in the machining of this advanced material is reported in this article.
107 citations
TL;DR: In this paper, single point continuous turning tests were carried out on Ti6A14V and Inconel 901 using various geometries of straight grade (K20) cemented carbide inserts using a high pressure coolant jet directed at the tip of the tool where the chip is formed.
Abstract: Single point continuous turning tests were carried out on Ti6A14V and Inconel 901 using various geometries of straight grade (K20) cemented carbide inserts using a high pressure coolant jet directed at the tip of the tool where the chip is formed. Trials were also carried out using a conventional coolant supply for comparison. The test results show that improved tool life can be achieved when machining the titanium-base alloy under the high pressure coolant jet while shorter tool life was obtained when machining the nickel-base alloy. The use of high pressure coolant supply during machining generally maintains constant cutting forces and reduces the chip-tool contact length, thus increasing stresses at the tool edge. This behavior tends to accelerate notching that is predominant when machining the Inconel 901 alloy, resulting in shorter tool life. This effect is not obvious when machining Ti6Ai4V where the tools failed mainly due to excessive flank wear. Effective chip control was achieved when m...
81 citations
01 Mar 1998
TL;DR: A series of machining experiments of Inconel 718 has been carried out using coated and uncoated carbides as discussed by the authors, where the effects of cutting variables (speed, feed and depth of cut) were described.
Abstract: A series of machining experiments of Inconel 718 has been carried out using coated and uncoated carbides. The paper describes the effects of cutting variables (speed, feed and depth of cut)...
60 citations
TL;DR: In this paper, nanocrystalline Inconel 718 and Ni powders were prepared using two approaches: methanol and cryogenic attritor milling, and they exhibited significant thermal stability against grain growth by maintaining a grain size around 100 nm following annealing at 1273 K for 60 min.
47 citations
TL;DR: In this paper, the authors used X-ray fluoroscopic imaging to detect a sharp boundary between the substrate and tool steel coatings and showed that a nominal contact pressure as high as 21.8 MPa was required to obtain an adherent coating.
Abstract: Friction surfacing was carried out with tool steel (AISI 01) and inconel 600 consumables on mild steel 1020 substrate in an argon atmosphere. Inconel bonded strongly with the substrate and there was evidence of interfacial compound formation between the substrate and coating. For tool steel coatings, a sharp boundary between the substrate and coating was observed by scanning electron microscopy. X-ray fluoroscopic imaging also revealed this boundary. Mechanical interlocking between the coating and the substrate appears to be insignificant so adhesion between the coatings and the substrate may be caused by solid-phase bonding. For friction surfacing of both tool steel and inconel, a nominal contact pressure as high as 21.8 MPa was required to obtain an adherent coating of uniform quality. © 1998 Chapman & Hall
39 citations
TL;DR: In this paper, the authors examined the strain hardening response of INCONEL 690 during tensile deformation between 200-1200°C and found that at low temperatures, up to 600°C, two stages of hardening associated with dislocation-dislocation and dislocationsolute interactions were observed.
29 citations
TL;DR: In this paper, a comprehensive investigation of the parameters affecting the extent of interface reactions during squeeze casting of composites consisting of a matrix of either pure Al or alloy AS13 reinforced with fibers of INCONEL 601 was made.
Abstract: A comprehensive investigation is made of the parameters affecting the extent of interface reactions during squeeze casting of composites consisting of a matrix of either pure Al or alloy AS13 reinforced with fibers of INCONEL 601. The process parameters are the preform thickness and temperature, the fiber volume fraction, the temperature and mass of the liquid metal, and the temperature of the die. Adjustment of these process parameters made possible the full control of reactions. It is found that reactions proceed mainly in the solid state after decomposition of the oxide barrier layer covering the fibers. A simple kinetic model is developed that enlightens the role of this barrier layer. No trace of reaction could be detected in composites processed using preoxidized preforms. Alloying Al with Si also induces a drastic reduction of reactivity. The high ductility of the composites attests to the processing quality. An original procedure is proposed for measuring the activation energy for initiation of reactions by differential thermal analysis.
23 citations
20 citations
TL;DR: In this article, the authors found that structural evolution appearing during heat treatment at 700 °C can be responsible for an increase in corrosion intensity after sensitization up to 24 hours and its subsequent decrease with growing sensitization time.
17 citations
TL;DR: The INCONEL Alloy 783 as mentioned in this paper is an oxidation resistant low coefficient of thermal expansion (low CTE) superalloy developed for gas turbine applications, which can resist both general oxidation and stress-accelerated grain boundary oxygen enhanced cracking (SAGBO).
Abstract: INCONEL{reg_sign} alloy 783 is an oxidation-resistant low coefficient of thermal expansion (low CTE) superalloy developed for gas turbine applications. Turbine efficiency can be increased through the use of low-CTE shrouds and case components that maintain tight blade tip clearances at different turbine operating temperatures. To achieve low CTE, alloys based on Ni-Fe-Co compositions require Cr content be maintained at low levels. Added Cr lowers the Curie temperature and thereby increases thermal expansion rate over a wider temperature range. The necessary lack of Cr minimizes resistance to both general oxidation and stress-accelerated grain boundary oxygen enhanced cracking (SAGBO). Increased amounts of Al in alloys strengthened by {gamma}{prime} alone also promotes SAGBO. Alloy 783 is the culmination in the development of an alloy system with very high aluminum content that, in addition to forming {gamma}{prime}, causes {beta} aluminide phase precipitation in the austenitic matrix. It was discovered that this type of structure can be processed to resist both SAGBO and general oxidation, while providing low thermal expansion and useful mechanical properties up to 700 C. The high Al content also reduces density to 5% below that of superalloys such as INCONEL alloy 718. Key aspects of the alloy development are presented, includingmore » the assessment of SAGBO resistance by evaluating elevated temperature crack growth in air. The alloy, now commercially available, has been successfully fabricated and welded into gas turbine engine components.« less
TL;DR: In this article, the surfaces of flame-sprayed Ni-Al coatings were sealed by Y2O3 film (0.5-1.5μm) derived pyrolytically from an yttrium acetate tetrahydrate-based precursor solution.
Abstract: The surfaces of flame-sprayed Ni–Al coatings deposited on to Inconel 625 substrates were sealed by Y2O3 film (0.5–1.5 μm) derived pyrolytically from an yttrium acetate tetrahydrate-based precursor solution. Y2O3-sealed Ni–Al coating specimens were placed into an automated cyclic furnace and then subjected to heating–cooling cycle tests (one cycle=12 h at 900 °C+12 h at 25 °C) to evaluate the usefulness of this coating system in preventing oxidation of the underlying Inconel. After 75 cycles, the weight gains of sealed Ni–Al coatings were ∼50% lower than those of unsealed coatings. Such effectiveness of the Y2O3 sealer in improving the efficacy of the Ni–Al protective coatings was due mainly to its reactivity with Al2O3 formed by oxidation of Al within the coatings. This selective reaction led to the formation of a crystalline YAlO3 phase. Extended oxidation resulted in the transformation of YAlO3 into the Y3Al5O12 phase as a result of a secondary reaction between YAlO3 and Al2O3. Consequently, the sealing layers consisting of Y2O3, YAlO3, and Y3Al5O12 contributed significantly to filling and eliminating inherent open spaces in the Ni–Al coatings, thereby suppressing the diffusion of oxygen through the pores. Such oxygen-impervious layers endow the Ni–Al layers with a long useful life-span as oxidation-resistant coatings for Inconel.
01 Jan 1998
TL;DR: In this article, two superalloys, namely Inconel 718 and inconel 625, with a thickness of 3mm were welded by Nd:YAG laser process, which showed no significant hardness change in the weld region.
Abstract: Superalloys, particularly highly alloyed precipitation hardenable alloys, may exhibit propensity to HAZ cracking, i.e. microfissuring caused by eutectic formation, solidification cracking and base material degradation in the HAZ region during fusion welding. The eutectic formation can be suppressed by laser beam welding process, which involves rapid cooling. Moreover, the ability of this process to join the difficult-to-weld thin section aerospace alloys with minimal component distortion due to low heat input and high reproducibility of joint quality is of prime interest. Although some success has already been reported in laser beam welding of these alloys, there is still a lack of mechanical properties data of these joints. A better understanding of the microstructure-mechanical properties relationship of laser beam welded superalloy joints will promote the application of this joining process in many structural applications including aerospace industry. In the present study, two superalloys, namely Inconel 718 (precipitation hardened) and Inconel 625 (solid solution strengthened), with a thickness of 3mm were welded by Nd:YAG laser process. Microhardness measurements were conducted to determine the hardness profiles, which showed no significant hardness change in the weld region. Transverse-tensile specimens and for fracture toughness determination standard bend specimens in the form of CT specimens were extracted from the joints. Tensile and fracture toughness tests were carried out at room temperature. All transverse tensile specimens failed in the weld zone. Joint efficiencies of 91% and 95% in terms of strength have been achieved for Inconel 625 and 718 alloys, respectively. The CTOD fracture toughness results obtained from standard fracture toughness specimens were used to explain the influence of mechanical heterogeneity of the weld region on fracture behaviour as well as to establish the toughness-microstructure relationship. This paper intends to report the partial results of a on-going Brite-Euram Project ASPOW.
TL;DR: In this paper, the grain structures and microscopic features of a nickle-base Inconel 738LC were examined under various melting and casting conditions, and it was shown that the gain size of the γ matrix is reduced significantly by a treatment of lowing melt superheat temperature (LMST).
TL;DR: In this article, a composite made of a pure aluminium matrix reinforced with an Inconel fiber network was constructed by swaging to a true strain of 2.7 and the properties of the wires were investigated using the Clyne model and the modified shear lag model.
Abstract: This work investigates the formability of a composite made of a pure aluminium matrix reinforced with an Inconel fibre network. Composites were formed into wires by swaging, to a true strain ɛtrue = 2.7. Thermal expansion, Young's modulus and tensile properties of these wires were measured. Young's modulus of the wires is slightly larger than that of the as-cast composites, indicating that no significant porosity is present in the composite after deformation. Tensile strength and ductility are found to decrease with increasing reduction of diameter. Scanning electron microscope (SEM) observations show that fibres align during swaging and that fibre fragmentation occurs beyond a certain strain. Fibre fragments reach a critical aspect ratio of about 7 after a swaging true strain of 1.5. Qualitatively, the evolution of the properties is explained by a combination of fibre fragmentation and fibre alignment effects. Properties of the wires are discussed using the Clyne model and the Nardone and Prewo model (modified shear lag models).
01 Sep 1998
TL;DR: In this article, the authors used three-dimensional computational fluid dynamics simulations to predict temperature, velocity, and pressure distributions in the spallation Neutron Source (SNS) target, which is a high power facility for producing neutrons that utilizes flowing liquid mercury inside an austenitic stainless steel container.
Abstract: The Spallation Neutron Source (SNS) is a high power facility for producing neutrons that utilizes flowing liquid mercury inside an austenitic stainless steel container as the target for a 1.0 GeV proton beam. The energy deposited in the target is transported by two separate mercury flow streams: one to transport heat in the interior target region and one to cool the stainless steel container. Three-dimensional computational fluid dynamics simulations have been performed to predict temperature, velocity, and pressure distributions in the target. Results have generally shown that the power deposited in the bulk mercury can be effectively transported with reasonable flow rates and the bulk mercury temperature should not exceed 160{deg}C. Assuming good thermal contact, the maximum stainless steel wall temperature should be 130 {deg}C. Type 316 SS has been selected as the container material for the mercury and consequences of exposure of 316 SS to radiation, thermal shock, thermal stress, cavitation and hot, flowing mercury are all being addressed by R&D programs. In addition, corrosion studies include evaluation of Inconel 718 because it has been successfully used in previous water cooled spallation neutron systems as a window material. With type 316 SS selected to contain the mercury target of the SNS, two types of compatibility issues have been examined: LME and temperature gradient mass transfer. Studies have shown that mercury does not easily wet type 316 SS below 275{deg}C. In the LME experiments, attempts were made to promote wetting of the steel by mercury either by adding gallium to the mercury or coating the specimen with a tin-silver solder that the mercury easily wets. The latter proved more reliable in establishing wetting, but there was no evidence of LME in any of the constant extension rate tensile tests either at 23 or 100 {deg}C. Inconel 718 also showed no change in room temperature properties when tested in mercwy or mercury-gallium. However, there was evidence that the fracture was less ductile. Preliminary evaluation of mass transfer of either type 304 SS, 316 SS, and Inconel 718 in mercury or mercury-gallium at 300-3500 C (maximum temperature) did not reveal significant effects. Two 5000 h thermal convection loop tests of type 316 SS are in progress, with specimens in both hot and cold test regions, at 300 and 240{deg}C, respectively.
02 Jun 1998
TL;DR: In this article, the microstructure of commercially produced alloys 783, 718, and 909 were characterized using optical microscopy, Scanning Electron Microscopy (SEM), and Transmission Electron microscopy (TEM).
Abstract: Recently developed INCONEL® alloy 783 (nominal composition of Ni-34Co-26Fe-5.4Al-3Nb-3Cr) is precipitation strengthened by Ni3Al-type Gamma Prime and NiAl-type Beta Phases. Due to its low co-efficient of thermal expansion (CTE), high strength, and good oxidation resistance alloy 783 has been specified for use in aircraft gas turbine components such as rings, casings, shrouds, and seals and has been considered for use in a number of other critical industrial turbine components.In this study, commercially produced alloys 783, 718, and 909 were annealed and aged following recommended heat treatments. The materials were then isothermally exposed at 1100°F (593°C) for times up to 10,000 hours. At 1000 hour intervals, specimens of these alloys were removed from the furnace and subjected to room temperature tensile (RTT) and high temperature tensile (HTT) testing at 1200°F (649°C). The microstructure of as-produced and exposed materials was characterized using optical microscopy, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). Variation in tensile properties with isothermal exposure time was correlated with the microstructure.Copyright © 1998 by ASME
TL;DR: In this paper, annealing at 500°C developed a coalescent microstructure of coarse particles consisting of amorphous yttrium carbonate as the major component and crystalline Y2O3 as the minor one.
Abstract: “Sol paint” that yields yttrium-based compounds was prepared by mixing four chemical ingredients, yttrium acetate tetrahydrate precursor, diethanolamine, isopropyl alcohol, and hydrochloric acid, and then applied as oxidation/corrosion resistant coatings for Inconel 625 substrates. Annealing the coatings at 500°C developed a coalescent microstructure of coarse particles consisting of amorphous yttrium carbonate as the major component and crystalline yttrium oxide (Y2O3) as the minor one. At 700°C, the yttrium carbonate was transformed into Y2O3 by decarbonation. Increasing the annealing temperature to 900°C led to the formation of the YCrO3 phase yielded by interaction between Y2O3 and the Cr2O3 which had arisen from the oxidation of the underlying Inconel; the YCrO3 phase created a particle coating with a densified microstructure. There were two key factors in mitigating the degree of oxidation of Inconel at 900°C in air: (1) an uptake of oxygen by Y2O3 in the coatings, and (2) a densified coating layer that suppresses the diffusion and permeation of oxygen through it. Furthermore, inhibiting the rate of NaCl-caused corrosion was not only due to the excellent coverage of particle coatings over the entire surfaces of the substrates, but also may be associated with a good adherence of the coatings to the substrates.
TL;DR: Inconel-600 (Ni-Cr-Fe alloy) was modified by repetitive potential cycling in 1M NaOH solution, which induced the growth of a hydrous oxide film, following the same mechanism as previously reported for pure nickel in alkaline solution under similar experimental conditions as discussed by the authors.
Abstract: In this study, Inconel-600 (Ni–Cr–Fe alloy) was modified by repetitive potential cycling in 1M NaOH solution. This procedure induced the growth of a hydrous oxide film, following the same mechanism as previously reported for pure nickel in alkaline solution under similar experimental conditions. The electrode, modified by 30 repetitive potential cycles, exhibited about one order of magnitude lower current density in both the active and passive ranges of the anodic polarization curve. Selective dissolution of nickel and iron in acid solution was determined by rotating ring–disc electrode measurements. This process resulted in chromium enrichment as shown by use of X-ray electron spectroscopy. The proposed model for the enhanced stability of the modified electrode agrees with the percolation model of passivity of stainless steels and Fe–Cr alloys.
TL;DR: The Trans-Varestraint test was conducted in order to examine the solidification cracking susceptibility of Inconel 706 as a function of Ni content in base metal.
Abstract: Ni-base superalloy Inconel 706 which was developed from Inconel 718 has an economical advantage to save the major element Ni content less than Inconel 718. This alloy has such high strength, ductility and resistance against high temperature oxidation as equivalent to those of Inconel 718, but have a slight higher susceptibility to hot cracking. However the hot cracking susceptibility of Inconel 706 has not been investigated in detail.The Trans-Varestraint test was conducted in order to examine the solidification cracking susceptibility of Inconel 706 as a function of Ni content in base metal. Three kinds of Ni-base alloys with three different levels of Ni content were used.Typical dendrite structure was observed in the fractured surface of the specimen of Trans-Varestraint tested. Quantitative analysis of crack revealed that the solidification crack length and the temperature range in which hot cracking occurred (brittle temperature range, BTR) decreased with the increase of Ni content. Calculation of liquidus and solidus temperature of alloys by thermo-calc data indicated that the solidification temperature range also decreases with increase of Ni content.On the basis of these results, it was deduced that the improvement of the solidification cracking susceptibility with Ni content was attributed to the decrease of the solidification temperature range of alloys.
01 Dec 1998
TL;DR: In this article, the effects of the variation of neutron energy spectrum on induced radioactivity have been investigated at TFTR in a mixed D-T and D-D neutron field over the past three years, and the results of these measurements offer an invaluable opportunity for benchmarking of three-dimensional calculations of fusion neutron transport and activation for application to the design and regulatory licensing of large complex fusion reactors such as ITER.
Journal Article•
TL;DR: In this article, the mass percentage of δ phase in Inconel 718 cold rolled to different reductions and then treated at different temperatures for different times were measured by X-ray diffraction, and the effect of cold rolling on the kinetics of ǫ phase precipitation was investigated.
Abstract: The mass percentages of δ phase in Inconel 718 cold rolled to different reductionsand then treated at different temperatures for different times were measured by X-ray diffraction,and the effect of cold rolling on the kinetics of δ phase precipitation was investigated. Therelationship between the mass percentage of δ phase and annealing time follows the Avramiequation. At 960℃, cold rolling has a little effect on the time exponent (n) and the rate constantof δ phase (α). Below 910 ℃, as cold rolling reduction and annealing temperature increases, theValue of n decreases, whereas the value of or increases. The relationship between the rate constantof δ phase and temperature follows Arrhenius equation. As cold roiling reduction increases,the apparent activation energy of δ precipitation decreases. Cold rolling promotes the γ\" → δtransformation. According to the kinetics of δ precipitation, the precipitation-temperature-time(PTT) curves of δphase were given.It has been found that the C curve shifts left as cold rolling reduction increases.
Journal Article•
TL;DR: In this article, the authors presented the prediction of dynamic recrystallization behavior during hot forging of Inconel 718 and another experiment of pancake forging was also carried out.
Abstract: This paper presents the prediction of dynamic recrystallization behavior during hot forging of Inconel 718. Another experiment of pancake forging was also carried out to examine the recrystallization ration dynamically recrystallizaed grain size, and grain growth in the forging. In experiments cylindrical billets were forged by two operations with variations of forging temperature, reduction ration of deformation. and preheating process at each forging step. Also the finite element program, developed here for the prediction using the metallurgical models was used for the analysis of to Inconel 718 upsetting and the results were compared with experimental ones.
TL;DR: In this article, the effect of temperature and strain rate of hot compression on the microstructure and secondary recrystallization of primary rolled INCONEL alloy MA 754 plate is investigated.
02 Jun 1998
TL;DR: Inconel 718 alloy is used extensively in aerogas turbines and this alloy is most difficult to machine and highly prone to dimensional instability after machining as mentioned in this paper, such detrimental phenomenon poses enormous problem in engine assembly and affect structural integrity.
Abstract: Inconel 718 alloy is used extensively in aerogas turbines and this alloy is most difficult to machine and highly prone to dimensional instability after machining. Such detrimental phenomenon poses enormous problem in engine assembly and affect structural integrity. This paper highlights the systematic research work undertaken to study the plastic deformation characteristics of Inconel 718, effect of process variables on machined surface, subsurface and dimensional instability. Also illustrated the technique developed for simultaneous optimization of several process variables such as cutting speed, feed, depth of cut, rake angle and tool nose radius, to control the residual stresses and dimensional instability, within the acceptable tolerance band of the component. Prediction equations were developed for residual stress, dimensional instability, tool life, surface finish and material removal rate. Predicted data were validated experimentally. This paper also presents the qualitative and quantitative data on dimensional instability with specific case studies of jet engine components and clearly illustrates the approach followed to develop technique to control such detrimental effect.Copyright © 1998 by ASME
01 Mar 1998
TL;DR: In this paper, a NASA/MFSC study was conducted to quantify the damping in CMC's as compared to a typical super-alloy, Inconel 718.
Abstract: The scientific community has felt that ceramic matrix composite (CMC) materials possess more material damping than the superalloys used in the production of rocket engine turbomachinery turbine-end components. The purpose of this NASA/MFSC study is to quantify the damping in CMC's as compared to a typical super-alloy, Inconel 718. It was observed through testing of beam coupons and disk specimens that the CMC's do indeed possess more material damping than the baselined alloy Inconel 718.