Showing papers on "Inconel published in 1996"
TL;DR: Wear surfaces of cutting tools are analyzed to study the wear mechanism of cemented carbide tools in turning in Inconel 718 superalloys as mentioned in this paper, and it is shown that during high speed turning condition (V = 35 m min−1) was caused by diffusion of elements (Ni or Fe) in workpiece into tool's binder (Co) by a grain boundary diffusion mechanism.
146 citations
TL;DR: In this paper, the authors presented an approach to optimize the surface finish in end milling Inconel 718 using uncoated carbide inserts under dry conditions using response surface contours constructed in speed feed planes by computer.
129 citations
TL;DR: In this paper, a model is presented which can predict microstructural changes of nickel base Inconel 718 during hot forming by means of semi-empirical equations to determine the necessary parameters for reliable prediction.
Abstract: Modelling and simulation of microstructural development is of increasing interest especially for the production of critical components for aeronautical applications such as turbine discs In this paper a model is presented which can predict microstructural changes of nickel base Inconel 718 during hot forming by means of semi-empirical equations To determine the necessary parameters for reliable prediction, hot compression tests were carried out in a temperature range of 950 to 1150°C for strain rates of 0·005 to 10 s−1 The measured data and the derived characteristic equations for the description of the hot deformation behaviour were incorporated into a finite element program and two industrial forging strategies for the production of turbine discs were simulated The finite element program used was extended by a module to take the velocity characteristics of a counterblow hammer into account Thus, a prediction of grain size evolution and recrystallised volume fraction during industrial hot wo
77 citations
15 Feb 1996-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, three laser surface modified samples were prepared, one by laser melting, and the other two by laser melt/particle injection processing with tungsten carbide and titanium carbide (TiC) particles, respectively.
Abstract: Seawater corrosion behavior of laser surface processed Inconel 625 alloy was investigated. Three laser surface modified samples were prepared, one by laser melting, and the other two by laser melt/particle injection processing with tungsten carbide (WC) and titanium carbide (TiC) particles, respectively. Particle injection involved embedding the carbide particles into a laser melted surface and resulted in a metal matrix-particulate composite surface layer which was both hard and wear-resistant. While Inconel 625 is a corrosion resistant alloy suitable for marine applications, and WC and TiC are generally inert to chemical attack, results from this study showed that laser surface modification produced microstructures that were susceptible to seawater corrosion to varying degrees. Nominal corrosion was observed in the dendritic structure produced by laser melting of the alloy surface. In the particle injected samples, the WC particulate phase in contact with the Inconel alloy matrix showed different kinds of attack, while the TiC particulate phase showed none. In both particle injected samples, resolidification of the Inconel alloy melt produced significant departures in composition and microstructure from those of the base alloy. Eutectic and dendritic carbides and, in WC, interphase carbides were some of the resolidification byproducts that formed in the matrix surrounding the particulate. Alloyed with solute elements from the base alloy, each product phase contributed to unique forms of corrosion. A qualitative analysis of the corrosion behavior of the injected samples showed that corrosive damage was more severe in the WC injected sample than in the TiC injected sample and in the laser melted sample. This paper describes the processing, microstructural and compositional characterization, and seawater corrosion behavior of the laser surface modified samples, and attempts to explain the observations as a consequence of the formation of galvanic cells.
65 citations
TL;DR: In this paper, high power laser welding techniques and related metallurgy have been investigated on Inconel 718 sheets, 4 mm and 8 mm of thickness, in annealed and aged states.
65 citations
01 Feb 1996
TL;DR: Most published research works on machining Inconel 718 have been mainly concerned with turning, while the milling process has received little attention due to the complexity of the process as mentioned in this paper.
Abstract: Most published research works on machining Inconel 718 have been mainly concerned with turning, while the milling process has received little attention due to the complexity of the process. In this...
41 citations
TL;DR: In this paper, a new analytical model that describes solidification of equiaxed dendrites was presented, which was incorporated into a commercial finite-element code, PROCAST.
Abstract: In Part I of the article, a new analytical model that describes solidification of equiaxed dendrites was presented. In this part of the article, the model is used to simulate the solidification of INCONEL 718 superalloy castings. The model was incorporated into a commercial finite-element code, PROCAST. A special procedure called microlatent heat method (MLHM) was used for coupling between macroscopic heat flow and microscopic growth kinetics. A criterion for time-stepping selection in microscopic modeling has been derived in conjunction with MLHM. Reductions in computational (CPU) time up to 90 pct over the classic latent heat method were found by adopting this coupling. Validation of the model was performed against experimental data for an INCONEL 718 superalloy casting. In the present calculations, the model for globulitic dendrite was used. The evolution of fraction of solid calculated with the present model was compared with Scheil’s model and experiments. An important feature in solidification of INCONEL 718 is the detrimental Laves phase. Laves phase content is directly related to the intensity of microsegregation of niobium, which is very sensitive to the evolution of the fraction of solid. It was found that there is a critical cooling rate at which the amount of Laves phase is maximum. The critical cooling rate is not a function of material parameters (diffusivity, partition coefficient,etc.). It depends only on the grain size and solidification time. The predictions generated with the present model are shown to agree very well with experiments.
37 citations
TL;DR: In this article, the effects of heat treatment on fatigue crack growth rates (FCGRs) of Inconel 690 and inconel 600 have been investigated in terms of carbide morphology and grain size.
36 citations
TL;DR: In this paper, a mathematical model for average tangential cutting force in end milling Inconel 718 using uncoated carbide inserts under dry conditions has been developed in terms of cutting speed and axial depth of cut.
33 citations
Patent•
22 Jul 1996TL;DR: In this article, a cap-like reservoir defining system is proposed to increase the lifetime of cutting tools by allowing user adjustable location of application of cutting tool lifetime increasing cryogenic cooling to a workpiece contacting edge of a cutting tool.
Abstract: Disclosed is a cap-like reservoir defining system which allows user adjustable location of application of cutting tool lifetime increasing cryogenic cooling to a workpiece contacting edge of a cutting tool, in a workpiece machining system. The present invention method of use finds application in the machining of materials such as ceramics, heat resistant materials, titanium, inconel alloys, and super alloys.
32 citations
Journal Article•
TL;DR: In this article, the friction and wear properties of several nickel-based alloys (Rene'41, Inconel X-750, INCONEL 713C), iron based alloys and a ceramic (Al2O3) were tested in an induction-heated high temperature pin-on-disk tribometer.
Abstract: The friction and wear behavior of unlubricated metal/metal sliding couples was investigated to screen potential candidates for high temperature foil bearings. The tribo-tests were run in an induction-heated high temperature pin-on-disk tribometer in an air atmosphere at a load of 4.9 N and at a sliding velocity of 1 m/s. The friction and wear properties of several nickel based alloys (Rene'41, Inconel X-750, Inconel 713C), iron based alloys (MA956 and Inconel 909) and a ceramic (Al2O3) were tested at 25, 500, and 800 C. In general, at elevated temperatures the alloys oxidized and formed a tenacious and lubricous oxide surface film or layer. At 800 C, Inconel X-750 versus Rene'41 had the lowest friction coefficient (0.27) and at 500 C, Inconel X-750 versus Inconel 909 the lowest pin wear (2.84 x 10(exp -6)cu mm/N-m). Gouging and severe wear of the softer material occurred whenever a significant difference in hardness existed between the pin and disk specimens.
TL;DR: In this article, surface features of superalloys roughened by a pure high-pressure waterjet in preparation for thermal spraying have been investigated using interferometric profilometry.
Abstract: Surface features of superalloys roughened by a pure high-pressure waterjet in preparation for thermal spraying have been investigated using interferometric profilometry. Waterjet roughening was performed on Inconel 718 and Mar-M 509, and the surface morphology resulting from this process was compared to conventional grit blasting. Results confirm earlier reports showing that waterjet roughening yields a unique surface structure having some advantages over grit blast roughening. The surface structure of waterjet roughened superalloys is shown to have a high degree of microroughness and a high negative skewness of the surface height distribution. Tensile bond strength of an MCrAlY coating is shown to be enhanced by waterjet roughening of the superalloy substrate. Bond testing of the plasma sprayed MCrAlY on waterjet surfaces showed consistent high strength bonding regardless of coating thickness or superalloy type.
TL;DR: In this paper, the role of P and S in nickel base superalloys was investigated, where nine experimental heats were melted on the base of conventional Inconel 718 chemical composition with variation of P (from 10 to 130 ppm) and S (from 15 to 175 ppm) respectively.
Abstract: Phosphorus and sulfur are generally regarded as the most common impurities and detrimental elements in nickelbase superalloys. For further understanding the role of P and S in Inconel 718 nine experimental heats were melted on the base of conventional Inconel 718 chemical composition with variation of P (from 10 to 130 ppm) and S (from 15 to 175 ppm) respectively. Phosphorus and sulfur both have almost no influence on strengths and ductilities at room temperature tensile test, Phosphorus also has no effect on the yield and ultimate strengths and elongation at 650°C tensile test, However, sulfur has an obviously decreasing effect on 650°C tensile elongation but no effect on yield and ultimate strengths. Sulfur has a remarkable detrimental effect on stress rupture life and especially on ductility loss at 650°C. However, phosphorus is in total difference to sulfur effect, generally can increase stress rupture life and ductility both. Microstructure observation on grain structure, S-phase and strengthening phase y” and y’ can not reveal the effect of P and S on the morphology and amount of precipitates. Fractography analyses show different patterns of stress rupture specimens with the variation of P and S contents. Experimental results lead us to consider the segregation behaviors of P and S at grain boundaries, however the effect of P and S should be different.
30 Nov 1996-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, a 2.5 kW CO2 laser was used to reduce the hardness of the Ni-base superalloy in a tensile test under a 29.4 MPa hydrogen atmosphere at room temperature.
Abstract: A Ni-base superalloy, INCONEL 718, has a high sensitivity to hydrogen embrittlement. Hydrogen induced cracking tends to occur at the surface of the stress concentrated regions. Reducing the hardness of such surface regions locally is known to be effective in preventing such cracking. To this end, in the present work, a laser surface solutionizing has been applied to INCONEL 718 using a 2.5 kW CO2 laser. The surface solutionized zones up to approximately 1 mm in depth, where age precipitates of γ and γ′' were dissolved in the matrix; could be obtained without melting the treated zones by optimizing the laser conditions. While the base metal has a hardness of approximately 450 Hv, the hardness of the laser solutionized zones was reduced to below 250 Hv. The ductility of the surface solutionized specimen was almost twice that of the base metal in a tensile test under a 29.4 MPa hydrogen atmosphere at room temperature with hydrogen pre-charging. Thus, the laser surface softening is effective in reducing the sensitivity of INCONEL 718 to hydrogen embrittlement.
TL;DR: In this article, an x-ray diffraction and temperature dependent magnetic measurements have been carried out in INCONEL 718 superalloy before and after high temperature aging treatments (INCONEL is a trademark of the INCO family of companies).
Abstract: X-ray diffraction and temperature dependent (5 K–380 K) magnetic measurements have been carried out in INCONEL 718 superalloy before and after high temperature aging treatments (INCONEL is a trademark of the INCO family of companies) The nominal composition of this alloy is Ni (525%), Cr (190%), Fe (185%), Nb (51%), Mo (30%), Ti (09%), Al (05%), Cu (015%), and C (008%), and it yields an x-ray diffraction pattern consisting of a fcc phase with α = 35987 (3) A and an orthorhombic phase associated with δ-Ni3Nb It is concluded that the fcc pattern is due to both the γ austenitic phase and γ′ Ni3(Al, Ti) phase of alloy 718 The standard annealing and aging treatment carried out in air at temperatures between 621 and 982 °C produces surface oxides (Cr, Fe)2O3 and FeNbO4 (which are easily removed by etching and polishing) and contracts the lattice Magnetic measurements show a distinct phase transition at Tc = 14 K, which has been attributed to the γ′-Ni3(Al, Ti) phase by the process of elimination and by observing that it has most of the characteristics of the weak itinerant ferromagnet Ni745Al255 This transition may have some effects on the cryogenic applications of this alloy
TL;DR: In this paper, the effect of gamma prime depletion in the near-surface region on the creep behavior of the nickel base superalloy was investigated, and it was shown that the gamma prime degradation in the air-exposed specimens caused a weakening effect, leading to enhanced creep rate.
Abstract: Specimens of a nickel base superalloy were exposed to air at 1423 K to study the effect of gamma prime depletion in the near-surface region on the creep behaviour of the alloy. The results showed that the gamma prime depletion in the air-exposed specimens caused a weakening effect, leading to enhanced creep rate. Kachanov’s damage parameterf was determined and was found to be 0·5 indicating that the near-surface region, comprising of surface oxide, grain boundary oxide and gamma prime depleted region, carried a small fraction of the applied stress. It is further shown that the damaging effect is more pronounced in thinner specimens.
TL;DR: In this article, the effects of the infrared joining time on the joint and base material microstructures, elemental distribution within the micro-structures and the resulting joint shear strength were investigated.
TL;DR: In this article, the effect of various coatings of 3 μm thickness on the mechanical property of alumina after heat treatment at 1000 °C for 30 min under 10−6 torr vacuum was evaluated in terms of modulus of rupture (MOR) using a Weibull plot.
Abstract: Alumina with a sputter-deposited metal film was diffusion bonded to Inconel 600. A higher bonding strength and lower joining temperature were obtained with titanium coating compared to that for the non-coated sample. The improved joining behaviour was attributed to an enhanced interface reaction and reduction in the thermal stress. Also, the effect of various coatings of 3 μm thickness on the mechanical property of alumina after heat treatment at 1000 °C for 30 min under 10−6 torr vacuum was evaluated in terms of modulus of rupture (MOR) using a Weibull plot. While the Cu coating did not change MOR strength of alumina, the reactive Ti and Zr metal coatings caused a noticeable reduction in averaged MOR strength. The effect of co-sputtering of Ti-Cu, and bilayer coatings of Cu/Ti and Ti/Cu was also investigated.
TL;DR: In this article, the effect of lead on the oxide layers forming on Inconel 600 and Incoloy 800 tested in the laboratory in various aggressive lead-containing environments was investigated.
TL;DR: In this paper, the electrochemical behavior of Inconel 625 and Monel 400 alloys has been investigated in Dead Sea water and 0·5M K2SO4 solution using the impedance technique at several anodic potentials.
Abstract: The electrochemical behaviour of Inconel 625 and Monel 400 alloys has been investigated in Dead Sea water and 0·5M K2SO4 solution using the impedance technique at several anodic potentials. In Dead Sea water, the Monel alloy is active at anodic potentials ≥ –100 m V; owing to pitting corrosion, while the Inconel alloy is passive up to 300 mV: Above this potential, destruction of the passive layer takes place leading to the formation of two maxima in the phase angle curves, indicating that two different oxide layers are present on the surface of the alloy. The radii of the pores formed at the surface of both alloys were calculated using the Kugel diffusion impedance element. In 0·5M K2SO4 both the Inconel and Monel alloys are passive, up to 500 and 600 mV respectively. Above these potentials both alloys became active. The passivity of the Inconel alloy is explained by the formation of chromium and silicon oxides.
TL;DR: Aluminized diffusion coatings were obtained on an Inconel 738 specimen at 800-1000 °C using a preheated AlCl3 + H2 gas mixture with a 03 s holding time as mentioned in this paper.
Abstract: Aluminized diffusion coatings were obtained on an Inconel 738 specimen at 800–1000 °C using a preheated AlCl3 + H2 gas mixture with a 03 s holding time It was found that the pre-heating treatment was very effective for a high deposition rate of the aluminide coatings The thickness of the aluminide coatings was 15-47 times higher than that without pre-heating
TL;DR: In this article, the welding of Inconel Superailoy using high power CO2 and Nd YAG lasers is described for the manufacturing of aeroengine and power plant components, and the metallurgy related to the NbC and the Delta phase at grain boundaries, consequent to the typical 10 000 K/s rapid cooling of the fusion zone, has been investigated using the scanning and transmission electron microscopes.
10 Jun 1996
TL;DR: INCONEL® alloy 783 is an oxidation resistant low coefficient of thermal expansion (low CTE) superalloy developed for gas turbine applications as discussed by the authors, which has been successfully fabricated and welded into gas turbine engine components.
Abstract: INCONEL® 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 γ’ 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 γ′, causes β 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, including 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.© 1996 ASME
TL;DR: In this article, a pre-heated AlCl 3 + H 2 gas mixture was used for the formation of AlCl, and the weight gain and thickness of the aluminide diffusion layers were 50% and 65% higher than those obtained without preheating.
Abstract: Aluminide diffusion coatings were obtained on an Inconel 738 specimen at 1000 °C using a pre-heated AlCl 3 + H 2 gas mixture. It was found that the pre-heating treatment was effective for the formation of AlCl, and the weight gain and thickness of the aluminide diffusion layers were 50%–65% higher than those obtained without pre-heating.
Patent•
05 Dec 1996TL;DR: In this paper, the strength and wear resistance of a steel component is improved by adhering to it a material of higher strength compatible metal alloy, such as Inconel (RTM) 725, which may be deposited by welding, plasma spraying, dip coating or electroplating.
Abstract: The strength and wear resistance of a steel component is improved by adhering to it a material of higher strength compatible metal alloy. Preferably the higher strength material comprises a precipitation or age hardenable alloy such as Inconel (RTM) 725, which may be deposited by welding, plasma spraying, dip coating or electroplating. The component may then be subjected to a heat treatment regime which simultaneously softens the heat affected zone and hardens the higher strength material.
TL;DR: In this paper, a published creep-fatigue life prediction model is modified in this paper and assessed with data on Inconel 718 under different test conditions, it has been shown that the method developed within the viscosity concepts correlates the low-cycle fatigue data well.
Abstract: A published creep-fatigue life prediction model is modified in this paper and assessed with data on Inconel 718 under different test conditions. It has been shown that the method developed within the viscosity concepts correlates the low-cycle fatigue data well. This paper reports the modification over the previous model.
TL;DR: In this article, optical and transmission electron microscopy were used to characterize the microstructure of the composites and to determine the nature of the fiber/matrix reaction in the composite.
Abstract: Composites of INCONEL 718 alloy reinforced with either single-crystal (SAPHIKON) or polycrys-talline (Du Pont's FP) A12O3 fiber were fabricated by pressure casting. Optical and transmission electron microscopy were used to characterize the microstructure of the composites and to determine the nature of the fiber/matrix reaction. The widely dispersed fibers in the SAPHIKON-fiber-reinforced composite had no influence on the solidification of the matrix. Six phases, γ-Ni3Al, γ'-Ni3Nb, δ-Ni3Nb, TiC, NbC, and Laves, were present in the matrix of the composite. The last three phases were formed during solidification and the others precipitated during subsequent cooling. The high density of fibers in the FP-fiber-reinforced composite led to a more uniform microstructure within the matrix. Only three phases,γ″-Ni3Nb, NbC, and Laves, were identified. Diffusion of Ti into the A12O3 fiber resulted in preferential grain growth in the FP fiber in areas adjacent to the fiber/matrix interface. The fiber/matrix bond strength in shear in the SAPHIKON-fiber-reinforced composite was in excess of 150 MPa.
TL;DR: In this article, the authors report on work undertaken to optimize the cutting conditions for high speed steel circular saw blades machining materials from three of the principal categories of nickel based alloy.
Abstract: Nickel based alloys are machined by methods similar to those used to cut ferrous materials, however there are additional process requirements due to the poor machinability of these alloys. The current paper reports on work undertaken to optimize the cutting conditions for high speed steel circular saw blades machining materials from three of the principal categories of nickel based alloy.