Showing papers on "Inconel published in 1992"

Pitting Corrosion of Inconel 600 in Chloride and Thiosulfate Anion Solutions at Low Temperature

Abstract: Pitting corrosion of mill annealed Inconel 600 was studied in aqueous chloride and chloride-thiosulfate solutions at low temperature. Potentiodynamic and potentiostatic polarization techni...

Effect of selective oxidation of chromium on creep strength of Alloy 617

Abstract: In high temperature alloys, the selective oxidation of chromium to form a chromia scale leads to subsurface depletion of chromium in the alloy which in turn leads to the dissolution of chromium carbide in the depleted zone. The effect of this carbide depleted subsurface zone on the creep properties of Inconel Alloy 617 (Ni–22Cr–12Co–9Mo–1Al–0·08C; wt-%) has been determined. The specimens were subjected to heat treatments before creep testing to simulate long term service exposure of a thin walled heat exchanger tube operating at high temperatures. It was found, surprisingly, that in creep tests carried out at 900°C, specimens having extensive chromium depleted and carbide free subsurface zones exhibit higher creep strength than specimens thermally aged for the same durations, but having no chromium depleted zone. As chromium was removed from the matrix owing to selective oxidation, the carbon, released as the carbides in the chromium depleted zone dissolved, migrated to the centre of the specimen...

Performance of a trimetallic transition joint

Abstract: The critical part of the transition metal joint between type 304 stainless steel and 2.25Cr-1Mo steel, with an immediate piece of Alloy 800, is the Alloy 800/2.25Cr-1Mo steel joint welded with Inconel 182. The performance of this trimetallic transition joint was studied by accelerated thermal cycling of the Alloy 800/2.25Cr-1Mo steel joint after subjecting it to its optimum post-weld heat treatment. The thermal cycling test procedure employed produces accelerated failures in transition metal joints similar to those observed in steam generators of operating power plants. The changes in the ferritic steel heat-affected zone on thermal cycling were also studied. The results of this study show that there is a marked improvement in performance, with at least a four-fold improvement in the life of the transition metal joint, on using the trimetallic configuration, instead of the direct (bimetallic) configuration.

Superplastic forming of INCONEL alloy 718SPF

Abstract: Superplasticforming (SPF) has become an important manufacturing method for aerospace and fuselage components. The basic reasons for the popularity of this process are reviewed and the compatibilityoffine-grained INCONELB alloy71 8SPF@ to superplasticforming are presented in this paper. The temperature limitations of current aluminum and titanium alloys employed in SPF parts for gas turbine components have prompted the need to find a high temperature nickel-base alloy amenable to current SPF practice and equipment. An optimum temperature, the anticipated flow stresses and preferred strain rates are proposed for INCONEL alloy 718SPF and found to be completely compatible with current SPF equipment now in use by the aerospace industry and their fabricators. The wide use of INCONEL alloy 718SPF (UNS NO771 8) in aerospace applications is based on its high temperature strength and excellent fatigue resistance. These properties must be maintained in any SPF-processed component. Demonstration that these properties are maintained and even exceeded is established using data obtained from a prototype part for a candidate noise suppressor assembly. Finally the influence of INCONEL alloy 718SPF and the SPF method of processing on the design and manufacture of future gas turbine engines is considered and the advantages assessed from the aerospace manufacturers’ viewpoint. @INCONEL and 718SPF@ are trademarks of the Into family of companies.

Fatigue and creep crack growth of Alloy 800 and Alloy 617 at high temperatures

Abstract: A common evaluation is given for creep crack growth and fatigue crack growth experiments which have been performed at the companies ABB, Siemens-KWU and KFA. The materials under investigation were X10NiCrAlTi32 20 (Alloy 800) and NiCr22Col2Mo (Alloy 617). Several production lots and semi-finished materials as well as welded materials have been tested. Testing techniques differed at the different labs. In order to eliminate the influence of individual testing techniques, material from some production lots was investigated at different labs. The given data cover fatigue crack growth (the materials were tested between room temperature and 1050°C; the influence of temperature, R−ratio, and frequency was investigated) and creep crack growth (Alloy 800 was tested between 550°C and 900°C, Inconel 617 between 800°C and 1000°C; the evaluation was done on the basis of the fracture mechanics parameters K1 and C*).

Influence of composition and processing parameters on mechanical properties and erosion response of Ni–TiB2 coatings

Abstract: Sputtered Ni–TiB2 coatings have been shown to protect Ti–6Al–4V and Inconel 718 substrates from solid particle erosion. However, before new erosion resistant coatings can be efficiently designed, it is essential that the role of mechanical properties in determining erosion resistance be fully understood. In this investigation, nanoindentation techniques were used to quantify the effects of substrate preparation, coating composition, and sputtering process parameters on the elastic moduli and indentation hardness of thin coatings deposited on Ti–6Al–4V and Inconel 718 substrates. The influence of these parameters on coating adhesion was determined using a conventional scratch test. Elastic moduli, indentation hardnesses, and coating adhesion were correlated with erosion behaviour. The erosion resistance of the coatings that exhibited microscopic ductility is dependent on the nodule diameter and coating properties such as hardness, elastic modulus, and fracture toughness.MST/1697

An analysis of the creep embrittlement of Inconel alloy X-750 due to its prior exposure to reduced air pressure at 1150°C

Abstract: Inconel alloy X-750 test pieces exposed to a reduced air pressure at 1150°C for various times exhibited significant embrittlement during subsequent creep tests in air at 700°C. This embrittlement was characterized by a systematic reduction in time and strain to fracture and an acceleration of the minimum creep rate with increasing time of prior exposure. Earlier work has shown that the near-surface environmental damage in the form of heavily cavitated boundaries and γ-free zones are responsible for this form of embrittlement. The purpose of this investigation is to provide a comprehensive analysis of the effect of the above two forms of damage on the time and strain to fracture and the minimum creep rate. Towards this end, a three-zone creep fracture model has been developed to explain the experimental results.

Compatibility of inconel 617 R alloy with LIF-MGF 2 -kf thermal energy storage salts and vacuum at high temperature

Abstract: Thermal energy storage capsules made of Inconel 617 alloy were filled with high- purity LiF- MgF2- KF salts and thermally cycled at 983 ± 100 K in vacuum for up to 5 years. The containment life performance characteristics with fluoride salts and in vacuum were examined. Metallographic study indicated that the inside surfaces of the post- test containers had a corrosion damage of 100 um in depth after 5 years of thermal cycling. The outer surface showed a vaporization damage of 120 μm after the same period. After 5 years of thermal cycling, the aluminum concentration at the capsule interior surface was reduced to 0.424 wt% from a nominal concentration of 1.34 wt% and chromium was reduced to 18.7 wt% from a nominal concentration of 21.8 wt%. A more significant depletion of aluminum and chromium was observed at the outer surfaces. Atomic absorption spectroscopy (AAS) and differential thermal analysis (DTA) were used to reveal the alloying element dissolution and the changes in melting temperature and heat of fusion of fluoride salts during thermal cycling. A modified diffusion equation for a one-dimensional semi-infinite bar was applied to the depletion of aluminum on the interior surfaces of the containers. Good agreement was obtained between the analysis and the measured concentration profiles.

Stress corrosion cracking of pressurizer instrumentation nozzles in the French 1300 MWe units

Abstract: The 1300 MWE French PWR pressurizers are equipped with nozzles through which instruments penetrate the pressure vessel. The nozzles are made from forged and bored bars of Inconel 600 mechanically expanded in the pressurizer wall. They are then manually welded with Inconel 182 coated electrodes to the internal stainless steel cladding of the pressuriser. To understand the origin of leaks occurring early in life and to assess the extent of the problem we undertook an analysis of the fabrication conditions. Field investigations were carried out by dye penetrant testing on the nozzle bore. Cracks have been found on 35 percent of the 119 tested penetrations. Destructive examination performed on 3 nozzles showed that the circumferential cracks did not go through the wall thickness. Laboratory investigations of the nozzle pulled from Nogent 1 confirmed that the crack morphology corresponded to that of primary water stress corrosion cracking. No correlation has been found between microstructure of the different heats of Alloy 600 and cracking. Nozzle mock-ups investigations allowed residual stress measurements by X-ray diffraction. Stress corrosion cracking tests, showed that only longitudinal cracks can be through-wall while both longitudinal and circumferential cracks are initiated on the internal surface. As a result, Electricitemore » De France decided to replace the Inconel 600 nozzles by stainless steel ones with austenitic st. st. weld. Furthermore, a full inventory of the Alloy 600 parts contained in the primary circuit has been performed. For each localized parts an assessment of the risk of stress corrosion cracking is under progress by studying material structures, stress level, operating conditions and safety point of view.« less

Heat pipe fatigue test specimen: Metallurgical evaluation

Abstract: An innovative creep/fatigue test was run to simulate the temperature, mechanical load, and sodium corrosion conditions expected in a heat pipe designed to supply thermal energy to a Stirling cycle power converter. A sodium-charged Inconel 718 heat pipe with a Nickel 200 screen wick was operated for 1090 hr at temperatures between 950 K (1250 F) and 1050 K (1430 F) while being subjected to creep and fatigue loads in a servo-hydraulic testing machine. After testing, the heat pipe was sectioned and examined using optical microscopy, scanning electron microscopy, and electron microprobe analysis with wavelength dispersive x-ray spectroscopy. The analysis concentrated on evaluating topographic, microstructural, and chemical changes in the sodium exposed surfaces of the heat pipe wall and wick. Surface changes in the evaporator, condenser, and adiabatic sections of the heat pipe were examined in an effort to correlate the changes with the expected sodium environment in the heat pipe. This report describes the setup, operating conditions, and analytical results of the sodium heat pipe fatigue test.

The influence of composition and processing parameters on the mechanical properties and erosion response of Ni + TiB2 coatings

Abstract: Sputtered Ni + TiB2 coatings have been shown to protect Inconel* 718 and Ti-6A1-4V substrates from solid particle erosion. However, before new erosion-resistant coatings can be efficiently designed, it is essential that the role of mechanical properties in determining erosion resistance be fully understood. In this investigation, nanoindentation techniques were used to quantify the effects of substrate preparation, coating composition, and sputtering process parameters on the elastic moduli and indentation hardness of thin coatings deposited on Ti-6A1-4V and Inconel 718 substrates. The influence of these parameters on coating adhesion was determined using a conventional scratch test. Elastic moduli, indentation hardnesses, and coating adhesion were correlated with erosion behavior. The erosion resistance of those coatings that exhibited microscopic ductility is dependent on the nodule diameter and coating properties such as hardness, elastic modulus, and fracture toughness.

Metallurgical response of nickel base superalloys to laser machining

Abstract: Most nickel based superalloys are found to be non-weldable. Only with using extreme precautions and advanced welding processes are some nickel based superalloys weldable with fusion processes. Fusion welds may experience hot cracking (cracking during solidification), intergranular cracking (cracking during cooling) or post weld heat treat cracking (cracking initiated by phase transformation stresses and thermal stresses during heat treating).Laser machining is currently being used in advanced automated balancing systems. The laser ablates metal from the balance land in precise target locations and amounts at surface speeds as high as 30,000 in/min. Laser machining is a fusion process where the metal is heated through the liquid state to the vapor/plasma state. Metal that is not vaporized or removed during the liquid state resolidifies and becomes a recast layer. The solidification process of this recast layer is similar to that of the fusion welding process except that the amount of liquid metal is much smaller, normally 10 to 100 microns thick. The cooling rates are very fast because of the heat sink provided by the much greater size of the parent metal compared to the amount of recast layer.This paper presents the results of an investigation into the metallurgical reactions found in the laser machined residual surface. The effects on alloys Inconel 718, Waspaloy, and IN713 will be discussed. The role of carbides will be examined in the laser machining process. Appropriate microstructures and elemental maps of cross sections through the recast layer will be presented.Most nickel based superalloys are found to be non-weldable. Only with using extreme precautions and advanced welding processes are some nickel based superalloys weldable with fusion processes. Fusion welds may experience hot cracking (cracking during solidification), intergranular cracking (cracking during cooling) or post weld heat treat cracking (cracking initiated by phase transformation stresses and thermal stresses during heat treating).Laser machining is currently being used in advanced automated balancing systems. The laser ablates metal from the balance land in precise target locations and amounts at surface speeds as high as 30,000 in/min. Laser machining is a fusion process where the metal is heated through the liquid state to the vapor/plasma state. Metal that is not vaporized or removed during the liquid state resolidifies and becomes a recast layer. The solidification process of this recast layer is similar to that of the fusion welding process except that the amount of liquid metal is much s...

Temperature Transition and Deformation Process of Inconel 718 During Radial Forging.

Abstract: The radial forging machine SX 55 produced by GFM was installed in Sibukawa Plant, Daido Steel Co., Ltd. in 1986. The main purpose of this machine is to process the heat resistant materials in a fewer heats.A numerical model can be used to simulate different conditions under which the process is to operate. A decision can then made on the most suitable set of conditions.A thermal-mechanical coupled finite element method was applied using a elastoplastic material model to calculate the temperature transition of Inconel 718 deformed with 4 hammers from ingot to billet during several passes.The calculated results indicate that heat-rise caused by the penetration of stresses leads to the critical temperature for cracking due to low ductility in the case of high feeding speed and they are in good accordance with the results of forging trials.A suitable operating schedule obtained by calculations shows the possibilities of controlling the micro-structure of billet during radial forging process.

Brazeability of Nickel Base Brazing Foil on a Nickel Base Alloy and a Mild Steel.

Abstract: Recently, ductile nickel base brazing foil has been prepared by a rapid solidification technology. So that it seemed that the brazing, which used the ductile nickel base brazing foil, is more effective method for joining having a large joining area than the brazing which used the powder form nickel base brazing filler metal. Therefore it has seemed that the brazing, which used the nickel base brazing foil, has been effective method for producing of the clad materials.In this study, the clad material which have been brazed the nickel base heat resistant alloy; Inconel 600 on the mild steel; SM400B has been tried producing by the brazing using the four types of nickel base brazing foils. The brazeability was estimated by the mechanical properties, microstructures and the distributions of the elements which were investigated with a SEM and a EPMA examination.The sound joint was obtained for all of brazing conditions in this study. The shear strength of the specimen was increased by increasing brazing time and temperature. About 310 MPa was obtained as the maximum shear strength for every brazing foil. The shear strength was influenced by the cross-sectional microstructures at the brazed joint. According to the cross-sectional microstructures and the elemental distributions, when the eutectic structure concentrating Cr and B was formed in the brazed joint, the shear strength was increased by decreasing this eutectic structure.

Influence of composition and processing parameters on mechanical properties and erosion response of Ni−TiB2 coatings

Abstract: Sputtered Ni-TiB 2 coatings have been shown to protect Ti-6Al-4V and Inconel 718 substrates from solid particle erosion. However, before new erosion resistant coatings can be efficiently designed, it is essential that the role of mechanical properties in determining erosion resistance be fully understood. In this investigation, nanoindentation techniques were used to quantify the effects of substrate preparation, coating composition, and sputtering process parameters on the elastic moduli and indentation hardness of thin coatings deposited on Ti-6Al-4V and Inconel 718 substrates

Microstructure and precipitation effects in Inconel alloy 600

Abstract: The main objectives of the project were to investigate the interactions of carbon, titanium and aluminium contents, grain size and cold working, with precipitation reactions which occur during heat treatments similar to those experienced as a consequence of commercial PWR Steam Generator (SG) tube processing In order to carry out this investigation commercial material was supplemented by a range of experimental casts The selected casts allowed the investigation of the following compositional variables: (i) the effect of C in alloys free from Ti or Al, (ii) the effect of C in alloys containing both Ti and Al, and (iii) the effect of T! in alloys containing constant C and Al contents As a result of the experimental programme considerable progress has been made in clarifying the complex structure-property relationships which occur in Alloy 600 The microstructures observed have been characterised and understood in terms of thermal and mechanical treatments Studies involving analysis of the mechanical properties, have led to a clear understanding of the effects of grain size, precipitate type and distribution and residual cold work on mechanical behaviour It has been shown that the activation energy for normal grain growth increases with increasing carbon and titanium contents Explanations of the mechanical properties have been discussed in terms of grain size, dislocation hardening and solid solution hardening and it has been possible to understand the overall material properties with respect to these The kinetics of precipitation have been studied in depth, since it is the precipitation of chromium carbide which ultimately results in the principle mode of material degradation, namely, intergranular corrosion A range of carbide precipitation 'C-curves' have been established and related to thermal and mechanical processing Accelerated corrosion testing has provided an insight into the relationship between precipitation and structure on the stability of material in potentially corrosive environments

Atlas of Formability: INCONEL 718

Abstract: : In this investigation, flow behavior of Inconel 718 alloy was studied by conducting compression tests over a wide range of temperatures and strain rates. Constitutive relations were determined from the flow behavior, and a dynamic material modeling was conducted on this alloy. Thus, the optimum processing condition in terms of temperature and strain rate was identified. Microstructural changes during high temperature deformation were also characterized.

Corrosion Resistance of INCONEL Alloy 617 in Simulated Gas Turbine Environments

Abstract: It is known that the efficiency of a gas turbine engine can be improved substantially by increasing the operating temperature. However, increasing the temperature puts a tremendous demand on the performance of materials of construction such as the combustion chamber, transition ducts etc. The material has to be resistant to long-term isothermal and cyclic oxidation conditions. In addition, the thermal stability of the alloy is of utmost importance. INCONEL® alloy 617 is a solid solution, nickel - chromium - cobalt - molybdenum alloy with an exceptional combination of high-temperature strength and oxidation and carburization resistance. In this paper, the performance of alloy 617 in isothermal and cyclic oxidation, carburization and burner rig oxidation/sulfidation environments will be presented. In addition some mechanical properties data will be included to show the stability of the alloy after exposure to high temperatures for extended periods of time. For comparison the data obtained on such alloys as INCO® alloy HX and Haynes® alloys 188 and 230 will also be reported.Copyright © 1992 by ASME

Effect of thermomechanical processing on the properties of rene'220w

Abstract: A thermomechanical processing approach using sheet rolling practice was developed for Rene'220W alloy which exhibits an attractive balance of tensile, creep, rupture, and crack growth properties. Rene'220W is a Ni-Cr-Co superalloy which is structurally similar to Inconel 718. The primary difference in chemistry between Rene'220W and Inconel 718 is the substitution of cobalt for iron. In Rene'220W, alloy strengthening occurs through precipitation of gamma double prime and gamma prime. Precipitation of delta phase will also occur when processing the material below the delta solvus temperature of approximately 1080°C. Results of this study indicate that the crack growth and creep/rupture behaviors are sensitive to the specific thermomechanical processing path. The range in hold time crack growth rates obtained at 650°C was greater than 10X. The preferred processing approach produced a warm-worked, directional microstructure wjlth few, if any, recrystallized grains, and with creep and rupture properties about 27°C better and hold time crack growth behavior far superior to fine grain Inconel 718. The goal was to obtain equivalent tensile properties and 27°C higher creep/rupture properties than fine grain Inconel 718 without a degradation in hold time crack growth resistance. This processing approach, while feasible in sheet form, may be dl.fficult to transition to a production process for thick sections.

Creep-fatigue damage evaluation of inconel 738lc superalloy

Abstract: Creep-fatigue damage was evaluated by replication, X–ray, hardness and UT under uniaxial and multiaxial stress states. Crack monitoring was the most reliable method of detecting creep–fatigue damage of Inconel 738LC superalloy.