Showing papers on "Inconel published in 2001"
TL;DR: Inconel 718 is one of a family of nickel-based superalloys that are used extensively for gas turbine applications requiring high temperature strength as mentioned in this paper, and it is an extremely difficult material to machine, not the least because it maintains much of its strength at elevated temperatures (∼600°C), has low thermal conductivity and is prone to work harden during cutting.
151 citations
TL;DR: In this paper, a numerical and experimental analysis of plasma enhanced machining of Inconel 718 is presented, where the results are compared with experimental results obtained with a radiation pyrometer.
Abstract: A numerical and experimental analysis of plasma enhanced machining (PEM) of Inconel 718 is presented in this paper. Surface temperatures due to plasma heating are systematically characterized through numerical modeling and experimental investigation using infrared radiation thermometry. A three-dimensional finite difference model is established to determine the temperature distribution in a cylindrical workpiece subjected to intense localized heating. The results are compared with experimental results obtained with a radiation pyrometer. A sensitivity analysis is presented to examine the effects of machining parameters on the temperature distribution. Benefits of PEM are also demonstrated through the reduction of cutting forces and improved surface roughness over a wide range of cutting conditions. In addition, improvement of productivity in machining Inconel with PEM is illustrated.
148 citations
TL;DR: Experiments were conducted with Inconel 718 at high temperatures to evaluate the rate of oxidation of the material over as wide a temperature range as possible, as well as to determine the high-temperature failure limit.
Abstract: Experiments were conducted with Inconel 718 at high temperatures to evaluate the rate of oxidation of the material over as wide a temperature range as possible, as well as to determine the high-temperature failure limit of the material. Samples of Inconel 718 were inserted into preheated furnaces at temperatures ranging from 973 to 1620 K and oxidized in air for varying periods of time. After being oxidized in air at a constant temperature for the prescribed time and then being allowed to cool, the samples were reweighed to determine their mass gain due to the uptake of oxygen. From these mass-gain measurements, it was possible to identify three regimes of oxidation for Inconel 718: a low-temperature regime in which the samples behaved as if passivated after an initial period of transient oxidation, an intermediate-temperature regime in which the rate of oxidation was limited by diffusion and exhibited a constant parabolic rate dependence, and a high-temperature regime in which material deformation and damage accompanied an accelerated oxidation rate above the parabolic regime.
99 citations
TL;DR: In this paper, the oxide phase was determined to be predominant oxide phase in the scales of these alloys, consistent with the results of a previous study using X-ray diffraction and electron probe microanalysis.
Abstract: Foil specimens of Haynes 230, Hastelloy X, Inconel 718, and Inconel 625 of 4.5 mil (∼113 μm) thickness were oxidized in wet hydrogen for several hundred hours at temperatures between 700 and 1100°C. Chromia was determined to be the predominant oxide phase in the scales of these alloys, consistent with the results of a previous study 1 of these alloys in air, as shown using X-ray diffraction and electron probe microanalysis. The oxidation kinetics of all the alloys, investigated by thermogravimetry, in a wet hydrogen atmosphere exhibited parabolic behavior. Haynes 230 and Hastelloy X exhibited the slowest oxidation kinetics of all the alloys studied. Further, the oxidation kinetics of all the alloys were faster at 800°C in a wet hydrogen atmosphere compared to oxidation in air at 800°C. However, the oxidation kinetics of these alloys in a wet hydrogen atmosphere were slower than those in air at 1100°C. The oxide scale formed in wet hydrogen exhibited a higher resistance than that formed in air. This result is attributed to the expected p-type conductivity of the oxide scales formed in both air and wet hydrogen.
78 citations
TL;DR: In this article, a plate of modified 9Cr-1Mo steel was welded with three different filler materials: standard 9Cr 1Mo, modified 9 Cr 1Mo and nickel-base alloy Inconel 182 post-weld heat treatment (PWHT) for periods of 2 and 6 hours.
Abstract: Modified 9Cr-1Mo steel finds increasing application in power plant construction because of its excellent high-temperature properties While it has been shown to be weldable and resistant to all types of cracking in the weld metal and heat-affected zone (HAZ), the achievement of optimum weld metal properties has often caused concern The design of appropriate welding consumables is important in this regard In the present work, plates of modified 9Cr-1Mo steel were welded with three different filler materials: standard 9Cr-1Mo steel, modified 9Cr-1Mo, and nickel-base alloy Inconel 182 Post-weld heat treatment (PWHT) was carried out at 730 and 760 °C for periods of 2 and 6 h The joints were characterized in detail by metallography Hardness, tensile properties, and Charpy toughness were evaluated Among the three filler materials used, although Inconel 182 resulted in high weld metal toughness, the strength properties were too low Between modified and standard 9Cr-1Mo, the former led to superior hardness and strength in all conditions However, with modified 9Cr-1Mo, fusion zone toughness was low and an acceptable value could be obtained only after PWHT for 6 h at 760 °C The relatively poor toughness was correlated to the occurrence of local regions of untransformed ferrite in the microstructure
75 citations
TL;DR: In this article, the mutual dependences between enthalpy, electrical resistivity, temperature, and density of the alloy in the solid and liquid phase were estimated from resistivity data by the Wiedemann-Franz law.
Abstract: Wire-shaped alloy samples are resistively volume heated as part of a fast capacitor discharge circuit. Time resolved measurements with submicrosecond resolution allow the calculation of specific heat and the mutual dependences between enthalpy, electrical resistivity, temperature, and density of the alloy in the solid and liquid phase. Thermal conductivity is estimated from resistivity data by the Wiedemann-Franz law at the end of the solid phase and at the beginning of the liquid phase. These high-speed measurements are compared to results of quasistatic measurements of specific heat obtained by differential scanning calorimetry and expansion measurements by dilatometry. The results are presented and compared with results of other research groups.
75 citations
TL;DR: Inconel 718 is a material under consideration for areas in the target region of the spallation neutron source (SNS), now under construction at Oak Ridge National Laboratory (ORNL) in the US as discussed by the authors.
68 citations
TL;DR: In this article, the possibility to repair etched tubular components of nuclear power plant by Nd:YAG laser is investigated, and a structure with low restraint and equipment to realize the welding on the inner wall of sleeve are designed.
65 citations
TL;DR: In this paper, an induction brazing of Inconel 718 to InConel X-750 using Ni-7Cr-3Fe-3.2B-4.5Si (wt.-%) foil as a filler metal was conducted at the temperature range 1373-1473 K for 0-300 s in a flow argon environment.
Abstract: Induction brazing of Inconel 718 to Inconel X-750 using Ni-7Cr-3Fe-3.2B-4.5Si (wt.-%) foil as brazing filler metal was investigated in this paper. Brazing was conducted at the temperature range 1373–1473 K for 0–300 s in a flow argon environment. Both interfacial microstructures and mechanical properties of brazed joints were investigated to evaluate joint quality. The optical and scanning electron microscopic results indicate that good wetting existed between the brazing alloy and both Inconel 718 and Inconel X-750. Microstructures at joint interfaces of all samples show distinct multilayered structures that were mainly formed by isothermal solidification and following solid-state interdiffusion during joining. The diffusion of boron and silicon from brazing filler metal into base metal at the brazing temperature is the main controlling factor pertaining to the microstructural evolution of the joint interface. The element area distribution of Cr, Fe, Si, Ni and Ti was examined by energy dispersive X-ray analysis. It was found that silicon and chromium remain in the center of brazed region and form brittle eutectic phases; boron distribution is uniform across joint area as it readily diffuses from brazing filler metal into base metal. The influence of heating cycle on the microstructures of base material and holding time on the mechanical properties of brazed joint were also investigated.
64 citations
TL;DR: Inconel 690 is a nickel base alloy with a broad range of application such as nuclear reactor technology as mentioned in this paper, and a low temperature plasma assisted nitriding treatment is expected to improve the tribological properties without changing the corrosion resistance of this alloy.
Abstract: Inconel 690 is a nickel base alloy with a broad range of application such as nuclear reactor technology. A low temperature plasma assisted nitriding treatment is expected to improve the tribological properties without changing the corrosion resistance of this alloy. The nitrided case is constituted of two or three distinct layers depending on the plasma reactivity. These layers are, respectively, associated to three different metastable f.c.c. nitrogen solid solutions denoted γN1, γN2 and γN3. A parabolic rate constant and an apparent action energy are determined and compared to other values taken from the literature. Dislocation and stacking fault generated in the nitrided layer are expected to play a key role in the nitriding mechanisms of Inconel 690.
62 citations
TL;DR: In this paper, the dissimilar welding of nickel based 690 alloy and SUS 304L stainless steel using two alternative Inconel filler metals, namely, 82 (I-82) and 52 (I−52), was investigated.
Abstract: The object of the present work is to research the dissimilar welding of nickel based 690 alloy and SUS 304L stainless steel using two alternative Inconel filler metals, namely, 82 (I–82) and 52 (I–52). Gas tungsten arc welding with identical parameters and procedures was used to carry out single V groove butt welding with six passes in four layers on nickel based alloy 690 and 304L stainless steel. Mechanical and corrosion resistance tests were performed. Metallographical, fractographical, and compositional analysis were used to study filler metal dissimilarities. Mechanical tests show that the I–82 weldment, owing to its denser dendrites and formation of abundant niobium enriched precipitates, has a higher strength and hardness than the I–52 weldment. Rupture occurred in the alloy 690 base metal. In comparison, the I–52 weldment, with coarse dendrites and no niobium enriched precipitates, exhibits superior corrosion resistance to the I–82 weldment but has a lower tensile strength and ruptured in ...
TL;DR: In this article, a flow reactor study was carried out to investigate the carbon deposition on nickel-, cobalt-, molybdenum-, and iron-based alloy foils during thermal stressing of a JP-8 fuel at 500 °C wall temperature and 34 atm (500 psig), for 5 h at a fuel flow rate of 4 mL/min.
Abstract: A flow reactor study was carried out to investigate the carbon deposition on nickel-, cobalt-, molybdenum-, and iron-based alloy foils during thermal stressing of a JP-8 fuel at 500 °C wall temperature and 34 atm (500 psig), for 5 h at a fuel flow rate of 4 mL/min. Temperature-programmed oxidation (TPO) analysis and SEM examination showed that the amount and the nature of the carbonaceous deposits on the foils depend strongly on the chemical composition of the foil surface. The amount of carbon deposited on metal foils decreased in the order Inconel 600 > Havar > Fecralloy > Waspaloy > Hastelloy-C > MoRe > Inconel 718. The presence of minor components, such as Ti, Al, and Nb, in the alloys appears to be responsible for reducing carbon deposition from jet fuel thermal stressing. This effect can be attributed to the formation of a passive layer on alloy surfaces that limits the access of deposit precursors to base metals, Ni, Fe, and Co, that catalyze deposit formation.
TL;DR: In this paper, materials R&D for the vessel and in-vessel components have been performed in support of ITER design, and comprised the structural mate-rials (316L(N), CuCrZr, CuAl25, Inconel 718 andTi-alloys), plasma facing materials (Be, W andCFC), joints of stainless steel (SS), betweenSS/Cu alloys, Cu alloys/Be, Cu/W and Cu/CFC, and ceramic materials, (Al
TL;DR: In this article, the authors present results of measurements of the resistance to tensile fracture at spallation in nickel, cobalt, stainless steel, AlMg6% alloy, and Inconel IN 738 LC alloy.
TL;DR: In this article, it was shown that oxygen increased the rates of crack growth in niobium-containing alloys (such as Inconel 718, Rene-95 and3750) at high temperatures by up to 4.5 orders of magnitude over those observed in an inert environment.
TL;DR: In this article, the effects of grain boundary carbides on the tensile and impact properties of Inconel 600 at 25 and −196°C were studied, and deep grain boundary cracks were observed on the fracture surfaces.
TL;DR: In this paper, a sliding wear test was performed to evaluate wear properties of Inconel 600MA and 690TT steam generator (SG) tube materials against 405 and 409 ferritic stainless steels.
TL;DR: In this paper, a newly developed ultra-high-speed grinding machine and a conventional grinding machine were used for the experiments, and the surface roughness and residual stress values of the ground super-alloys and advanced ceramics were measured using a profilometer and a residual stress analyzer, respectively.
Abstract: This paper studies grinding of Inconel 718, Hastelloy, and some advanced ceramics. A newly developed ultra-high-speed grinding machine and a conventional grinding machine were used for the experiments. The ultra-high-speed grinding machine is equipped with a specially designed and built spindle unit that can run up to 200 m sec−1 and deliver a maximum output of 12 kW. The surface roughness and residual stress values of the ground super-alloys and advanced ceramics were measured using a profilometer and a residual stress analyzer, respectively. The ground surfaces were also assessed using a scanning electron microscope. The effect of h m (undeformed chip thickness) on surface topography of the difficult-to-machine materials was also investigated. A higher grinding wheel speed produces a smaller cutting depth and undeformed chip thickness, and thus smaller grinding force, decreased residual surface stress, and better surface finish. High productivity and good surfaces with ductile streaks could be obtained ...
TL;DR: In this article, a refurbishment of the Inconel 617 alloy after 37,000 h of operation in the field is carried out through the heat-treatment process, and the electrochemical response of the heat treated alloy is determined through potentiodynamic testing of the surfaces.
Abstract: Inconel alloys find wide application in industry as high-temperature resistance materials. In the present study, refurbishment of the Inconel 617 alloy after 37,000 h of operation in the field is carried out through the heat-treatment process. The electrochemical response of the heat-treated alloy is determined through potentiodynamic testing of the surfaces. The heat-treatment process is carried out at 1175 °C for 1 and 2 h in an air free furnace. The corrosion rate is estimated from TAFEL and polarization measurements. The surface morphology after the electrochemical tests is studied using scanning electron microscopy (SEM), while the material characterization at the surface is carried out using energy disperse spectroscopy (EDS). It is found that the corrosion resistance improves considerably for the workpieces subjected to 1 h heat treatment. The depletion of Cr and Mo at grain boundaries results in excessive pitting in this region. Moreover, enrichment of Cr at the surface after 1 h heat treatment reduces the corrosion current.
TL;DR: In this paper, the effect of bonding time, temperature, and pressure on the joint integrity was assessed, and the results showed that partial recrystallisation occurs in joints bonded attemperatures lower than 970°C.
Abstract: Solid state diffusion bonding of Inconel 718 has been studied. Mechanical tests and metallographic examinations were used to evaluate the joint quality. The effect of bonding time, temperature, and pressure on the joint integrity was assessed. The results showed thatpartial recrystallisation occurs in joints bonded attemperatures lower than 970°C. In addition, large amounts of d phase precipitates were also found and both the ductility and the tensile strength were poor. Nevertheless, the joint strength was comparable to thatof the parent metal when bonding was carried outat temperatures greater than 970°C. When bondingwas carried out at 1000°C, a pressure of 32 MPa, and a bonding time of 30 min, the joint tensile strength obtained was 874 MPa. There was no further improvement with increasing bonding time beyond 240 min.
31 Jul 2001-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the influence of the γ′-precipitates on the Bauschinger effect in the Inconel X-750 Nickel-base superalloy has been investigated for: solution heat treated, underaged, and overaged samples.
Abstract: The influence of the γ′-precipitates on the Bauschinger effect, in the Inconel X-750 Nickel-base superalloy, has been investigated for: solution heat treated, underaged, and overaged samples. It is found that the internal stresses increase with the aging time, providing evidence on the appearance of unshearable particles in the microstructure, the results are compared with the yield stress data (del Valle, et al., Scripta Mater., 1999, 41, 237). In the overaged samples, the dependence of the internal stresses on strain behaves qualitatively in accordance with the theories of relaxed deformation in dispersion hardened metals; however, their magnitude is smaller than the predicted, producing a contribution to work hardening of about 15%.
15 Jul 2001-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In situ straining experiments in a high-voltage electron microscope (HVEM) have been performed on the oxide-dispersion strengthened (ODS) nickel-base superalloy INCONEL MA 754 at 1020 and 1065 K as discussed by the authors.
Abstract: In situ straining experiments in a high-voltage electron microscope (HVEM) have been performed on the oxide-dispersion strengthened (ODS) nickel-base superalloy INCONEL MA 754 at 1020 and 1065 K. The results can be interpreted by interfacial pinning of dislocations at the dispersoids and, in some cases, by the Orowan mechanism. In addition to the thermally activated detachment of dislocations from particles, a viscous friction mechanism possibly due to point defect diffusion in the dislocation cores and Taylor hardening contribute to the flow stress.
TL;DR: Superallo et al. as mentioned in this paper investigated the influence of precipitate distribution on the occurrence of dynamic strain aging in annealed and solution treated materials and found that serrated flow at longer aging times is attributed to solute depletion due to precipitation.
Abstract: The influence of precipitate distribution on the occurrence of dynamic strain aging has been investigated in Inconel 718. In process annealed and solution treated materials, serrated yielding has been observed in the temperature range 400 K 900 K. Three different types of serrations, identified as A, B and C serrations were observed depending upon the temperature, strain rate, and test mode (i.e., tension or compression). Types A and B serrations were observed in the lower temperature range of 400K -750K while type C serrations were observed in the temperature range -750 K 900 K. An average activation energy, calculated using five different analysis techniques, of 117 k 29 kJ/mol was determined for types A and B serrated flow while the average activation energy ranged from 185 + 42 kJ/mol to 206 f 39 kJ/mol for type C serrated flow. Annealing the solution treated materials at 1033 K18 hours resulted in a contraction of the regime associated with serrated flow and in a change in serration type from types A and B to type C. Continued annealing for 110 hours results in a complete disappearance of serrated yielding. Comparison of the results with literature data suggest that the rate controlling mechanisms for dynamic strain aging are the migration of interstitial solutes for type A and B serrations and the migration of substitutional solutes for type C serrations. The disappearance of serrated flow at longer aging times is attributed to solute depletion due to precipitation. Superallo) s 715. 625. 706 and Various Derivatives Edited b>. E . A Loria TMS (The llinrrnls. bI~:till~ & Materials Society). 2001
TL;DR: In this article, the potential of this process for the production of jet engine disks from the direct aged nickel base alloy IN718 was evaluated on industrial equipment, and the results of these analyses clearly demonstrate that direct aged turbine disks is possible on ;I screw press.
Abstract: SCIXL~' press forging experiments on industrial equipment are carried out in order to evaluate the potential of this process for the production of jet engine disks from the direct aged nickel base alloy IN718. Metallography, electron microscopy and elevated temperature tensile tests are pell'ormed to analyse and quantify the strength improvements due to direct aging. The results of these analyses clearly demonstrate that the production of direct aged IN718 turbine disks is possible on ;I screw press.
TL;DR: In this article, the authors investigated the wear behavior of the contact between Zircaloy-4 tube and Inconel 600, which are used as the fuel rod cladding and grid, respectively, in PWR nuclear power plants.
Abstract: The fretting wear behavior of the contact between Zircaloy-4 tube and Inconel 600, which are used as the fuel rod cladding and grid, respectively, in PWR nuclear power plants was investigated in air. In this study, number of cycles, slip amplitude and normal load were selected as the main factors of fretting wear. The results indicated that wear increased with load, slip amplitude and number of cycles but was affected mainly by the slip amplitude. SEM micrographs revealed the characteristics of fretting wear features on the surface of the specimens such as stick, partial slip and gross slip which depended on the slip amplitude. It was found that fretting wear was caused by the crack generation along the stick-slip boundaries due to the accumulation of plastic flow at small slip amplitudes and by abrasive wear in the entire contact area at high slip amplitudes.
TL;DR: In this article, the corrosion properties of Inconel 617 alloy, after 37,000h of operation as a transition piece in the gas turbine engine, are examined using an Nd-:YAG pulsed laser.
TL;DR: Loria et al. as discussed by the authors presented the creep crack growth data of Inconel 706-MST between 600°C and 700°C in order to assess the materials suitability for ultra high temperature steam turbine applicat~ons.
Abstract: Creep crack growth data of Inconel 706-MST between 600°C and 700°C are presented i n order to assess the materials suitability for ultra high temperature steam turbine applicat~ons. Hereby, "MST" stands for a heat treatment modification proposed earlier by the authors. It is demonstrated that the creep crack growth resistance can be raised to the level of more creep ductile materials such as Waspaloy and Inconel 617 and that the benefit relative to conventional heat treatment cycles is particularly pronounced at 700°C. The results are interpreted in terms of the precipitation sequence during thermal exposure. Siipcrallo! s 718. 625. 706 and Various Derimtivcs t;tlitc.d b ~ . t :l. Loria T M S (Thc hlineruls. hletals & blatzrials Socirty). 2001
TL;DR: In this paper, the electrochemical and mechanical responses of Inconel 617 alloy over 30,000 hours of operation as a transition-piece in agas turbine engine are examined, and the heat treatment process at two different temperature levels is applied when refurbishing the alloy microstructure.
Abstract: Inconel 617 alloy is widely used in industry due to its superior high temperature properties. After long periods of operation, the alloy microstructure changes. One of the methods to regain the alloy microstructure is heat treatment at elevated temperatures. In the present study, electrochemical and mechanical responses of Inconel 617 alloy over 30,000 hours of operation as a transition‐piece in agas turbine engine are examined. The heat treatment process at two different temperature levels is applied when refurbishing the alloy microstructure. The electrochemical tests are conducted to investigate the corrosion response of the alloy before and after the heat treatment process. Fatigue and tensile tests are carried out for the workpieces subjected to the electrochemical tests. SEM is introduced to examine the fractured surfaces.