High-temperature Nickel Alloys Research Articles

Mechanochemical synthesis of chromium-based alloys

This paper presents a detailed study of the formation of chromium-based alloys, Cr–Ta–W + plasticizing additives (Nb and Zr) and Cr–Ta–Si, during milling of powder mixtures in a Fritsch (P-7) planetary mill under an Ar atmosphere. It is shown that, after milling for 18 h, all the components of the starting mixtures convert into a Cr-based BCC solid solution. The powders of chromium alloys obtained in this study are readily compacted by hot isostatic pressing (HIP) under conditions typical of the processing of powders of high-temperature nickel alloys. Heating of the powders and compacts leads to the decomposition of the supersaturated solid solution and the formation of two forms of the Cr2M Laves phase with cubic crystal lattices. The formation of a mixed-phase fine microstructure in the chromium alloys after HIP suggests that the materials studied here are potentially attractive as a base of next-generation chromium-based high-temperature alloys.

Influence of the composition of high-temperature nickel-alloy electrodes on the ingot composition in vacuum arc remelting

Statistical analysis of the chemical composition of high-temperature VZh159 nickel alloy in vacuum-induction melting and vacuum arc remelting yields regression equations that may be used to predict the metal composition in the ingots obtained by vacuum arc remelting as a function of the components in the consumable electrodes. The variation in oxygen, carbon, nitrogen, sulfur, and phosphorus concentrations in remelting is determined. The results are used in the design of production processes for high-temperature nickel-alloy ingots at PAO Ruspolimet.

Automated manufacture of compressor-blade tailpieces

An effective method of machining the geometrically complex surfaces of compressor blades in gas-turbine engines is considered (creep-feed grinding). This method is widely used in the machining of hard materials such as high-temperature nickel alloys and cobalt alloys employed in the manufacture of gas-turbine components.

ОСОБЕННОСТИ ЭЛЕКТРОЛИТНО-ПЛАЗМЕННОГО ТРАВЛЕНИЯ ЖАРОСТОЙКИХ ПОКРЫТИЙ С ПОВЕРХНОСТИ ДЕТАЛЕЙ ИЗ ЖАРОПРОЧНЫХ НИКЕЛЕВЫХ СПЛАВОВ

ОСОБЕННОСТИ ЭЛЕКТРОЛИТНО-ПЛАЗМЕННОГО ТРАВЛЕНИЯ ЖАРОСТОЙКИХ ПОКРЫТИЙ С ПОВЕРХНОСТИ ДЕТАЛЕЙ ИЗ ЖАРОПРОЧНЫХ НИКЕЛЕВЫХ СПЛАВОВ

Research of Solid Compound Formation during Thermal Deformation Effect on Intermetallic Ni<sub>3</sub>Al-Alloy with a Heat-Resistant Alloy EP975 and Influence on the Physical, Mechanical and Performance Properties

The work is aimed at processing highly efficient one-piece units of gas turbine aircraft engines discs with blades (blisks) to exclude heavy locking joints and to reduce the weight of the units while improving their reliability. Intermetallic γ ́+γ alloys based on γ ́-Ni3Al phase of the VKNA type selected as blade material and Ni-based high alloy EP975 selected for discs have similar initial melting temperatures (~1340оС and~1300оC, respectively). Solid state joints (SSJ) EP975 //VKNA-mono are obtained at the homologous temperatures of 0.86-0.91 Tm (K).It is shown that the most efficient method for producing solid joints between the Ni3Al based intermetallic alloys and the EP975-type high-temperature nickel alloys is a solid state pressure welding in the conditions of high-temperature superplasticity; this technique has been developed in the IMSP RAS (grant RFBR No 130812200).

Study on the high temperature deformation measurement using the mark shearing technique

The mark shearing technique has been successfully utilized for room-temperature strain measurement in solid mechanics research. However, when the method is applied to deformation measurement at high temperature, some new issues will occur. From our experience, we have found that an inevitable thermal radiation will emit from the oven in the measurement and may lead to a distortion of the measuring system. As a result, an undesired measurement error will arise; furthermore, the oxidation resistance marker is crucial to obtain an ideal result. In order to solve the abovementioned issues, the mark shearing techniques for high-temperature deformation measurement are studied in this work, and a novel method for fabricating the marker pattern is proposed, which can be utilized to fabricate a deformation carrier for high temperature on a different specimen surface. In combination with this marker with our self-developed mark shearing system, the high-temperature (1000 °C) mechanical properties of the high-temperature nickel alloy (GH4037) was measured.In order to characterize the thermal deformation caused by the oven during the high temperature experiment, the surface temperature distribution of the mark shearing system is measured by an infrared camera. On the basis of this result, the corresponding thermal deformation is analyzed by the finite element analysis (FEM) method. From the analysis result, we can conclude that the virtual strain of the system incurred by thermal radiation cannot be ignored for a long-time measurement.

High-efficiency rotary dressing method for cubic boron nitride wheels

The paper addresses kinematics of the rotary method whereby a grinding wheel is dressed by a rotating diamond cup wheel. Through the example of grinding high-temperature nickel and titanium alloys and high-alloy steels using highly porous vitrified cubic boron nitride wheels, the authors have demonstrated the advantages of the proposed dressing method over that with a single-point diamond dresser.

Influence of the cutting speed on chip formation in turning high-temperature chromium and nickel alloys

Chip formation in the turning of high-temperature chromium and nickel alloys is investigated as a function of the cutting speed and the structure and properties of the machined alloys, whose variation on heating is taken into account.

Sustainable machining of high temperature Nickel alloy – Inconel 718: part 2 – chip breakability and optimization

Abstract Global competition, stricter environmental legislation and demands for fulfilling sustainability initiatives, are increasing the pressure on the manufacturing industry, to develop and implement in their production alternative sustainable machining processes. This work focuses on sustainability evaluation and comparison in machining of high-temperature Nickel-based alloy (Inconel 718). Four sustainable machining alternatives (dry, near-dry (MQL), cryogenic and cryo-lubrication (cryogenic + near-dry)) to conventional machining, are evaluated based on the performance models from the Part 1 of the paper and used in the optimization procedure for determining the overall optimum machining conditions. As chip breakability is important machining characteristic, performance-based models of sustainable machining processes, developed in Part 1, are upgraded in this Part 2 of the paper with an additional model for chip breakability. Updated models are used as inputs to the optimization procedure developed, based on the combined overall desirability function. Genetic algorithms (GA) are used to evaluate and optimize the machining process for each cooling/lubrication (C/L) application. Results of the work show that machining performance optimization, when including beside machining parameters also the sustainable alternative cooling/lubrication conditions, can provide further improvement of the processes through tool-life, machined surface quality, chip breakability, productivity and nevertheless power consumption.

NIPPON/SUMITOMO HR11N

Abstract Sumitomo HR11N is a high temperature nickel alloy with a high chromium content to provide excellent corrosion and oxidation resistance. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming and joining. Filing Code: Ni-718. Producer or source: Sumitomo Metal USA Corporation.

Nickel-rhenium compound sheds light on the potency of rhenium as a strengthener in high-temperature nickel alloys

For many decades, it has been known that rhenium imparts a tremendous resistance to creep to the nickel-based high-temperature alloys colloquially known as superalloys. This effect is so pronounced that is has been dubbed ``the rhenium effect.'' Its origins are ill-understood, even though it is so critical to the performance of these high-temperature alloys. In this paper we show that the currently known phase diagram is inaccurate, and neglects a stoichiometric compound at 20 at.% Re $(\text{Ni}{}_{\mathbf{4}}\text{Re})$. The presence of this precipitate at low temperatures and the short-range ordering of Re in fcc-Ni observed at higher temperatures have important ramifications for the Ni-based superalloys. The $\text{Ni}{}_{\mathbf{4}}\text{Re}$ compound is shown to be stable by quantum mechanical high-throughput calculations at 0 K. Monte Carlo simulations show that it is thermally persistent up to $\ensuremath{\approx}930$ K when considering configurational entropy. The existence of this compound is investigated using extended x-ray absorption fine spectroscopy on a $\text{Ni}{}_{96.62}\text{Re}{}_{3.38}$ alloy.

NIPPON/SUMITOMO HR6W

Abstract Sumitomo HR6W is a high temperature nickel alloy with higher elevated temperature strength and better structural stability than conventional 310. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming. Filing Code: Ni-717. Producer or source: Sumitomo Metal USA Corporation.

Sustainable machining of high temperature Nickel alloy – Inconel 718: part 1 – predictive performance models

This two-part paper presents the results from modeling and optimization of alternative sustainable machining processes of Inconel 718. Nickel and Titanium, as representatives of high temperature alloys, with their specific thermo-mechanical properties, pose significant difficulties in machining. The high temperature and the consequent work hardening of these materials during the machining processes adversely affect cutting forces, tool-wear, surface integrity and chip breakability. This first part (Part 1) of the paper presents the experimental study of sustainable high performance machining of Inconel 718 with the development of performance-based predictive models for dry, near-dry (MQL), cryogenic and cryo-lubrication (cryogenic + near-dry) machining processes using response surface methodology (RSM). The robustness of these models was verified using the ANOVA. Cutting forces, surface roughness and tool-wear were measured, analyzed and modeled. The results show that the cooling/lubrication condition has an influence on machining performance and that optimum machining conditions have to be determined, at which an improved overall machining performance can be achieved, while sustainability directions are followed in terms of reducing cutting forces/power consumption, the prolonging of tool-life, and increasing productivity. The models developed in the first part of the paper are used for process evaluation and optimization in the second part, to determine optimum machining conditions for an overall process performance improvement.

Aluminide Protective Coatings Obtained by Slurry Method

The slurry aluminide coatings are produced on the three kind of substrates: hightemperature creep resistant cast steel, titanium alloy and nickel alloy. The slurry as active mixture containing aluminium and silicon powders, an activator and an inorganic binder. The coating were obtained by annealed in air atmosphere. The structure of these coatings is two zonal and depend on the type of substrate and technological parameters of producing.

Molten nitrate salts at 600 and 680 °C: Thermophysical property changes and corrosion of high-temperature nickel alloys

This paper examines the effects of long-term, high-temperature corrosion processes on materials used in concentrated solar power tower systems. More specifically, the heat transfer fluid and the containment metal are examined at operating temperatures of 600 and 680°C. A 60/40% NaNO3/KNO3 mixture of molten salt and nickel-based alloys HA230 and In625 were tested for up to 4000h at the given temperatures. HA230 and In625 alloys showed metal losses of 688 and 594μm/year, respectively, after 1000h at 680°C. The solar salt used in this study showed significant decreases (as much as 60°C) in melting point. Further experiments showed that the primary reason for the decrease in melting point is due to high nitrite concentrations in the molten salt. However, other thermophysical properties of aged solar salt appear to change little during high-temperature corrosion tests.

Fatigue life of deposited repair welds on single-crystal high-temperature nickel alloy under cyclic oxidation

In modern gas-turbine units increase of gas working temperature leads to shortening of blade service life. For this reason their repair becomes a priority. Retailoring of single-crystal blade tip by hardfacing is a rather complicated task. In order to select suitable filler material, thermal cycling tests of samples of deposited welds on CMSX-4 alloy with a single-crystal structure have been performed. Evolution of the structure under the conditions of high-temperature cyclic oxidation is considered. Selection of filler material, which ensures high temperature resistance and stability of weld metal structure, was optimized. These requirements are satisfied by Co—Ni-based material, which was earlier tried out and proved to be very good in complex technology of repair of a blade from ZMI-3U alloy. The technology includes airfoil tip retailoring by hardfacing with subsequent deposition on the item surface of a high-temperature metal coating by electron beam deposition to ensure the required service properties of the item. 18 Ref., 4 Tables, 10 Figures.

Machinability of high-temperature nickel and chromium alloys

Research centers on the machinability (resistance to cutting) of high-temperature nickel and chromium alloys when using a tool based on various replaceable sandwich inserts, with and without a coating. Inserts of small-grain hard alloys with multilayer nanocomposite coatings prove most effective.

High-temperature corrosive damage to superalloys during operation of blades of gas-turbine engines and power plants

The role of liquid nickel-sulfide eutectic in the mechanism of corrosive damage is determined by investigations of products of high-temperature oxidation and corrosion of superalloys with the use of scanning-electron microscopy and X-ray spectroscopic and X-ray structural analyses. It is found that the sulfide corrosion rate is controlled by the process of the dilution of the high-temperature nickel alloy within the liquid nickel-sulfide eutectic, diffusion of alloying constituents of the alloy in the liquid phase, and their subsequent oxidation.

Thermodynamics of Advanced Alloys Modification by Exogenous Nanophases

The thermodynamic analysis of a ceramic compound solubility was carried out for ceramic compounds which may be used for dispersion hardening of advanced nickel alloys. The thermodynamic description of stability conditions was completed for a disperse heterophase systems consists of metal melt – nanosize phases (NSP). For a thermodynamic criterion (К) of stability was selected the specific variation of a free energy of the process of a disperse system degradation (referred to change of unit of a surface phases contact). The analysis was executed in view of formation of thick and thin elastic wetting films and takes in account a disjoining pressure. The above definition of new thermodynamically rigorous criterions becomes physically real, if the isotherm of a disjoining pressure is measured. The derived criterions are simplified in the Young approximation. In this case the criterion are expressed through measurable interfacial performances - interfacial tension and wetting angles. The application of a stability condition gives a simple outcome: aggregation of NSP does not happen at a wetting angles ≤ 600. On a basis of own experimental data the evaluations are carried out for possibility of using of some compounds as exogenous modifiers of a nickel alloys. The example of dispersion hardening of high-temperature strength nickel alloy and improving its heat resisting properties is reduced.

Application of Nanophases Stability Thermodynamics to Advanced Alloys

The thermodynamic analysis of stability conditions was carried out for disperse heterophase systems obtained by a method of NSP put in metal melts for high-temperature strength of the nickel alloys. For a thermodynamic criterion (К) of stability was selected the specific variation of a free energy of the process of a disperse system degradation (referred to unit of a surface phases contact change). The analysis was carried out in view of formation of thick and thin elastic wetting films and takes in account a disjoining pressure. Obtained new thermodynamically rigorous criterions can be used, if the isotherm of a disjoining pressure is measured. The derived criterions are simplified in the Young approximation. In this case the criterion are expressed through measurable interfacial performances - interfacial tension and wetting angles. The application of a stability condition gives a simple outcome: aggregation of NSP does not happen at a wetting angles ≤ 750. On a basis of own experimental data the evaluations are carried out for possibility of using of some compounds as exogenous modifiers of a nickel alloys. The example of dispersion hardening of high-temperature strength nickel alloy is reduced.