Superalloy C263 Research Articles

Optimizing the Electrical Discharge Machining Process Parameters of the Nimonic C263 Superalloy: A Sustainable Approach

Engineers continue to be concerned about electrical discharge-machined components’ high energy consumption, machining debris, and poor dimensional precision. The aim of this research is to propose a hybrid neuro-genetic approach to improve the machinability of the electrical discharge machining (EDM) of the Nimonic C263 superalloy. This approach focuses on reducing the energy consumption and negative environmental impacts. The material removal rate (MRR), electrode wear ratio (EWR), specific energy consumption (SEC), surface roughness (Ra), machining debris (db), and circularity (C) are examined as a function of machining parameters such as the voltage (V), pulse on time (Ton), current (I), duty factor (τ), and electrode type. By employing the VIKOR method, all the responses are transformed into a distinctive VIKOR index (VI). Neuro-genetic methods (a hybrid VIKOR-based ANN-GA) can further enhance the best possible result from the VIKOR index. During this step, the hybrid technique (VIKOR-based ANN-GA) is used to estimate an overall improvement of 9.87% in the response, and an experiment is conducted to confirm this condition of optimal machining. This work is competent enough to provide aeroengineers with an energy-efficient, satisfying workplace by lowering the machining costs and increasing productivity.

Examining the Impact of Metallurgical and Optimised Machining Parameters on Inconel 713C Superalloy Using the Taguchi Technique

Examining the Impact of Metallurgical and Optimised Machining Parameters on Inconel 713C Superalloy Using the Taguchi Technique

An investigation on the effect of heat input to wear behavior and corrosion-cavitation erosion mechanism of Hastelloy C-276 coating by cold metal transfer

Cold metal transfer (CMT) technology based on wire-arc manufacturing has attracted wide attention because of its advantages of high manufacturing efficiency, low heat input (HI) and near-net-shape. In this study, a CMT-Hastelloy C-276 superalloy surface modification coating by optimizing HI is used to solve the problem of premature failure of key over-flow components of stainless steel in marine engineering. When the HI is increased from 269 J/mm to 358 J/mm, the serious cavitation erosion (CE) damage caused by pore defects and excessive residual tensile stress due to excessive low HI of Hastelloy C-276 coating can be avoid, which is attributed to the effective Orowan strengthening and high proportion of low angle grain bounds (LAGBs: 70.2%). In addition, high contents of Cr, Mo and W elements can promote it's passivation film to maintain excellent self-healing ability during CE to provide continuous and stable protection effect (Rct = 75.68 kΩ·cm2) in the 3.5 wt% NaCl artificial seawater. Therefore, even after 10 h-CE, it still maintains the highest corrosion resistance from both of the thermodynamic (Ecorr = −193.5 ± 3.6 mV) and kinetic perspective (Icorr = 69.3 ± 3.1 μA·cm−2) and has the lowest mean depth erosion rates (MDER, 0.94 ± 0.07 μm/h). However, further increase of HI will cause coarsing of grains (89.6 ± 2.7 μm → 342.8 ± 9.7 μm), excessive precipitation of brittle Mo-rich p phase and excessive dilution of elements from the substrate, resulting in changes in the wear mechanism and deterioration of strength and corrosion resistance. Moreover, the potential of zero charge (PZC) measurements and Mott-Schottky (M-S) test confirmed the decreasing trend of the repulsive ability to Cl ions (ΔE = 0.58 V) and the increased ion doping concentration (ND = 5.94 ± 0.02 × 1022 cm−3) of the weakened n-type passivation films. The optimal combination of wear resistance, corrosion resistance and CE resistance of Hastelloy C-276 coating is obtained by regulating HI, which can lay a theoretical foundation for the related production and application of marine engineering.

Crystallographic texture and multiscale boundaries mediated creep anisotropy in additively manufactured Ni-based Hastelloy C276 superalloy

The microstructure and high-temperature creep mechanisms of Ni-based Hastelloy C276 superalloy fabricated using wire and arc-based directed energy deposition were investigated systematically and innovatively. The microstructural investigation revealed that the as-fabricated samples comprise γ-Ni matrix and topologically close-packed (TCP) P phase precipitates. The γ matrix subgrains and grains are spread over multiple highly textured columnar dendrites, with a majority of γ <001> crystallographic orientations closely aligned along the deposition direction. Moreover, the interdendritic regions exhibit severe Mo segregation, P phase particles, and dislocation bands. Creep tests were conducted on miniature samples under various temperature and stress conditions, loaded either in the deposition direction (DD) or travel direction (TD). DD samples exhibit lower minimum strain rates, greater strains-to-failure, and longer creep rupture lifetimes than TD samples, indicating significant creep anisotropy. Dislocation creep was identified as the primary creep mechanism for both DD and TD conditions. During creep, dynamic precipitation of TCP phases occurred in the interdendritic regions, resulting in varying creep resistance between interdendritic and dendritic core regions. Isostress and isostrain models, considering both crystallographic texture and precipitation strengthening, reasonably predicted the observed creep anisotropy during the secondary creep stage. Additionally, variations in the Schmid factor led to significant deformation incompatibility among dendrites in TD samples. Dislocation accumulation in TD sample interdendritic regions promoted new grain nucleation, triggering dynamic recrystallisation, facilitating grain boundary sliding, and accelerating tertiary creep. Furthermore, TCP phase particles in the interdendritic regions contributed to microcrack development, further accelerating creep fracture, especially in the TD condition.

Sensitivity analysis on surface topography for laser-surface-texturing of Hastelloy C-276 superalloy: studies on micro-structure morphology characterization

Sensitivity analysis on surface topography for laser-surface-texturing of Hastelloy C-276 superalloy: studies on micro-structure morphology characterization

Study on creep characteristics and the isochronous stress–strain curve of Ni-Cr-Mo superalloy

ABSTRACT C276 superalloy is considered as a potential structural material for advanced nuclear reactor with good mechanical properties and corrosion resistance. High-temperature creep behaviour of C276 alloy was investigated in the temperature range of 650°C–700°C and at stresses of 140–430 MPa. A linear relationship was fitted between stress and minimum creep rate in the logarithmic coordinate system. The rupture time is analysed for life prediction in terms of isotherm extrapolation method, Monkman–Grant relation, and Larson–Miller parameter method, respectively. The isochronous stress–strain curves as a means of representing stress–strain–time relations under creep conditions were established by the parameter method. The fracture surface morphology of ruptured specimens was characterised by a scanning electron microscope to elucidate the failure mechanism.

Low-temperature hot corrosion of arc evaporated Ti1−xAlxN on Ni-Cr-Co based superalloys

Cathodic arc evaporated Ti1−xAlxN coatings were deposited on a Nimonic c-263 superalloy and tested under low temperature hot corrosion conditions. Treated with a MgSO4/Na2SO4 salt-mixture, all samples were annealed at 700 °C in a 2800 ppm(volume) SOx-rich atmosphere for 1, 5, 15 and 30 h. A significantly reduced corrosion severity was exhibited by all Ti1−xAlxN variants over the uncoated NiCrCo alloy. A synergistic fluxing mechanism was found to be the dominant factor for the coating breakdown. Depending on the relative Al-to-Ti content on the Ti1−xAlxN sublattice, differences in the coatings’ corrosion and scaling behavior were observed.

Study on deviation distribution of Σ3 and Σ9 boundaries in Hastelloy C-276 superalloy with different hot rolling reductions

In this study, the deviation distributions of Σ3 and Σ9 grain boundaries in a Hastelloy C-276 sheet were measured using electron backscatter diffraction technology (EBSD) and the grain boundary plane orientation was analyzed using a five-parameter technique after hot rolling at 900 °C with different thickness reductions. The results show that the relative areas of Σ3 grain boundary planes reveal a strong peak at the (111) twist position, and the corresponding intensity significantly decreases as the reduction increases. The hot rolling generates dislocations, resulting in significant deviation of Σ3 grain boundary orientations and the loss of special properties. However, the Σ9 grain boundary plane distribution (GBPD) becomes more diffused with increasing deformation, and the multiples of random distribution (MRD) value is ∼2. In addition, the large deviation of the Σ9 grain boundary orientation varies across the different strain samples. In low-strain samples, the deviation of the Σ9 grain boundary orientation may be affected by the Σ3 grain boundary deviation with construction of the Σ3–Σ3–Σ9 triple junction. The deformation microstructures mainly determine the deviation of the Σ9 grain boundary orientation in high-strain samples. Moreover, the distorted grain boundaries act as potent nucleation sites of dynamic recrystallization (DRX) during the hot rolling process.

Prediction of cutting forces including tool wear in high-feed turning of Nimonic® C-263 superalloy: A geometric distortion-based model

The hottest parts of aerospace components are often made of heat-resistant materials. Due to the high requirements in such parts and accelerated wear rates, machining is a challenging task. Recently, new high-feed machining strategies were launched by tool developers. The main idea is ​​using extremely low side cutting edge angles Kr so that high feeds and low chip thicknesses are both possible. These tools are supposed to be decisive for greater productivity rates. However, tool wear’s traceability is the key in order to replace them before dramatic failure. Additionally, the machining of such aggressive materials must be assisted by high pressure cooling. To reduce the environmental footprint, cryogenic techniques look promising. This work proposes a prediction cutting model for high feed turning of Nimonic© C-263 superalloy including tool wear. It allows to consider the geometric tool deterioration, which is the key mechanism in the evolution of cutting forces on this superalloy. The concept of reducing side cutting edge angle and its benefit on productivity is also explored. Besides, oil emulsion and CO2 cryogenic conditions are also compared. The wear prediction model showed good agreement with the experimental results by obtaining relative errors of less than 5 % using cutting speeds lower than 100 m/min and less than 14 % for higher speeds. The benefit of reducing the side cutting edge angle on tool life 8 (from 90° to 30°) was also demonstrated by increasing tool life x3 (from 8 to 24 min). Notches were removed. In contrast, using cryogenic conditions do not seem to be a clear advantage over this type of superalloy. Finally, optimum conditions were found: using vc = 70 m/min, f = 0.2 mm/rev and = 1 mm, good surface finish, chip control and tool life can be satisfied.

Characterization and mechanism analysis of interaction between Inconel 713C superalloy and a novel crucible-shell “integrated” mold

A novel crucible-shell “integrated” mold for rapid preparation of supercharged turbines was quantitatively characterized, and the interaction mechanism between refractory and melt was systematically analyzed. The results show that Inconel 713C superalloy is not easy to react with aluminum silicate fiber crucible, and the interaction between them is physical penetration. At the same time, the slag balls in the crucible are easy to peel off into the alloy and form inclusions. The reaction between Inconel 713C superalloy and shell surface material (ZrSiO4) can be divided into Penetration, Stalling/dissolution, Reaction and Diffusion stages. The interface reaction layer is composed of Nb2O5, Al2O3, ZrO2, Cr2O3 and TiO2. The oxide elements produced by the reaction come from the alloy and ceramic shell. Compared with the traditional preparation of turbocharger turbine under discontinuous vacuum, the use of “integrated” mold to prepare turbine under continuous vacuum environment reduces the oxygen, nitrogen and hydrogen content of castings, and the purity of Inconel 713C superalloy is higher and the preparation time is faster, which is conducive to industrial production, which can shed new lights on choosing alternative refractory material for the rapid preparation of high-purity superalloys.

Microstructural and Tribological Behavior of Pack-Borided Ni-Based Hastelloy C-276 Superalloy

Microstructural and Tribological Behavior of Pack-Borided Ni-Based Hastelloy C-276 Superalloy

Grain Boundary Engineering and Its Effect on Intergranular Corrosion Resistance of a Ni-Cr-Mo Based C276 Superalloy

A Ni-Cr-Mo-based C276 superalloy was cold rolled to 5–40% and annealed at 1050 °C for 30 min. The microstructure and grain boundary character distribution after cold rolling and annealing were characterized. Grain refinement and a certain amount of coincident-site lattice (CSL) boundaries were obtained through recrystallization. The fraction of CSL boundaries reached peak at the cold rolling of 15% and annealing at 1050 °C for 30 min, which was the critical condition for completed recrystallization. In addition, sensitization treatments and double-loop electrochemical potentiokinetic reaction (DL-EPR) tests were applied to the cold rolled and annealed samples. The samples with a high fraction of CSL boundaries showed higher intergranular corrosion resistance as compared to the ones with a low fraction of CSL boundaries. It implies that the intergranular corrosion resistance of C276 superalloy can be enhanced by optimizing the grain boundary structure through cold rolling and annealing.

Characterization of the Transient Contact Heat Transfer between C276 Superalloy and 5CrMnMo

The thermal contact conductance (TCC) between billet and tool is a key parameter to determine the contact heat transfer in the thermal processing of alloys and metals. In this work, a self-developed transient contact heat transfer detective equipment was applied to determine the TCC between C276 superalloy and die steel. The temperature variations in specified regions of specimens during transient heat transfer process were measured and the temperatures at contacted interface were programed based on the reverse heat transfer algorithm. Then the values of TCC between C276 superalloy and die steel were calculated. The TCC shows high dependency on the interface temperature, contact pressure, lubricant, and surface oxidation conditions. The increasing interface temperature difference and contact pressure enhanced the thermal contact conductance, while the surface oxidation alleviated the heat transfer capability. In addition, the addition of lubricant was also found to enhance the thermal contact conductance. The determined values are supposed to be of significant importance for processing optimization and numerical simulation.

Hot deformation behavior of C276 superalloy in shifted strain rate compression: Experiments and cellular automaton modelling

Plastic deformation is always inhomogeneous and complicated during hot processing of the superalloy component, making it hard to accurately predict the flow behavior and microstructure evolutions which may deviate greatly from those results obtained during traditional compression tests with a constant strain rate. The hot deformation behavior of a Ni-Cr-Mo based superalloy C276 in shifted strain rate conditions was investigated and a comparison with the constant strain rate compressions was conducted. The flow stress was found to immediately change after varying the strain rate. The strain rate sensitivity (m), which is the exponent of stress change against the strain rate, was calculated to about 0.16–0.24 for C276 superalloy at 1323 K with strain rate in the range of 0.001–1 s−1. The strain rate variation affected the microstructure evolution greatly, leading to different dynamic recrystallization (DRX) tendencies from the compressions with a constant strain rate. Shifting the strain rate from high value to low value resulted into a higher extent of DRX in comparison with the reverse process. A cellular automaton (CA) model, considering the evolutions of dislocation density, recrystallization nucleation and grain growth in deformation procedure, was developed to simulate the microstructure evolution and stress response in shifted strain rate compressions. The successful predictions by the CA model showed a good potential application of this approach in understanding the DRX behavior in non-constant hot processing of C276 superalloy.

Comparative analysis of indirect, direct and hybrid cryogenic machining of Nimonic C-263 superalloy

Nickel based superalloys finds extensive usage in manufacturing of intricate part shapes in gas turbine, aircraft, submarine, and chemical industries owing their excellent mechanical property and heat resistant abilities. However, machining of such difficult-to-machine alloys up to the desired accuracy and preciseness is a complex task owing to a rapid tool wear and failure. In view of this, present work proposes an experimental investigation and optimization of process parameters of the cryogenic assisted turning process during machining of Nimonic C-263 superalloy with a multilayer CVD insert. Taguchi’s L-27 orthogonal array is used plan the experiments. Effects of input parameters viz. cutting speed (V), cutting feed (F), depth of cut (D) are studied on responses viz. surface roughness (SR), nose wear (NW) and cutting forces (CF) under indirect, direct and hybrid cryogenic (indirect+direct) machining environment. A scanning electron microscope (SEM) analysis is carried out to explore the post- machining outcomes on the performance measures. The multiple responses are converted in to single response and ranked according to Taguchi based grey relational analysis (TGRA). Feed rate (F) is found to be the most influential parameter from the analysis of variance (ANOVA) of grey relational grade (GRG). Further, the means of GRG for each level of process parameters are used to improve the optimal process parameters. Finally, a confirmative experiment is performed on the optimum machining conditions to validate the optimization study results. It is seen that the value of GRG is improved by 9.34% when compared to the previous best result. The proposed work can be beneficial to choose ideal process conditions to enhance the performance of turning operation.

Reductions of Intergranular Corrosion Resistance and Wear Resistance in a Ni-Cr-Mo-Based Superalloy by Aging-Treatment-Induced Precipitation

Ni-Cr-Mo-based superalloy is widely used as a key component in many critical environments. To ensure that the manufacturing process does not impact the long-term service performance of these components, the aging precipitation behavior at different temperatures and its effect on intergranular corrosion (IGC) resistance and wear resistance of a Ni-Cr-Mo-based C276 superalloy were investigated. The equilibrium phase diagram was calculated first using thermodynamic software to confirm the potential phases. Carbides of M6C were found to be formed at grain boundaries after aging at 800–850 °C for short-term treatment. The other two phases (μ phase and P phase) indicated in the phase diagram were not observed for the samples after aging treatment up to 15 h. Furthermore, double loop electrochemical potentiokinetic reactivation (DL-EPR) tests were conducted to examine the IGC resistance. The degree of sensitization increased with the aging time and severe corrosion was found to occur at grain boundaries. For the first time, the influence of aging treatment on the wear behavior of this superalloy has been specifically studied. Concerning the hot processing of Ni-Cr-Mo-based C276 superalloy, these results indicate the importance of avoiding high-temperature heat treatment for long periods.

Tensile Strength of Interpulse Gas Tungsten Arc Welded Butt Joints of Nimonic Super Alloy C263

Nimonic C263 a nickel base super-alloy is generally used in the major components particularly in various structural and hottest sections of the gas turbine engine mainly in the combustor, exhaust sections including blades, discs, liners, and casings, etc. The interpulse gas tungsten constricted welding process is a modified controlled heat input arc welding technique. In this experiment response surface, rotatable central composite experimental design is methodically implemented for the evaluation of the impact of the key factors (i.e. interpulse current, weld current, weld speed and background current) on the tensile strength of butt-welded joints. The welded coupons are tested for tensile tests and obtained a maximum of 1152MPa. The outcome of this experimental examination and thorough optimization will be useful in choosing the most appropriate and suitable welding ranges of the above-mentioned factors for interpulse gas tungsten constricted arc welding of Nimonic superalloy C263 for automotive and aerospace applications.

Sustainable Electrical Discharge Machining of Nimonic C263 Superalloy

Nimonic C263, a nickel-based superalloy, finds extensive application in manufacturing of complex parts in gas turbine, aircraft and automotive industries exclusively for exhaust sections. Machining of the alloy through traditional approach is a difficult task owing to its poor thermal conductivity, work hardening and high strength properties. However, the superalloy can be machined up to desired accuracy by non-traditional machining processes like electrical discharge machining (EDM). Yet again, machining of these difficult-to-machine materials not only consumes a significant amount of energy, but also produces unpleasant noise, hindering the sustainable aspect of the process. To meet the requisite of sustainable EDM and explore the machinability, an experimental investigation is proposed in this work, when Nimonic C263 superalloy is machined with three different electrodes, viz. copper, tungsten, and copper–tungsten. Outcomes of important process parameters, viz. voltage (U), discharge current (I), pulse-on-time (Ton), duty factor (τ), and electrode material, are studied on the responses, viz. specific energy consumption, machining noise (N), material removal rate, electrode wear rate, surface roughness (Ra) and radial overcut (C). Analysis of variance is conducted to analyse the influence of each parameter on the responses. A scanning electron microscope investigation is carried out to analyse the pre-machining and post-machining scenarios on the machined surface. The multiple responses are converted into single response by calculating the net outranking flow by application of preference ranking organization method for enrichment evaluation (PROMETHEE) approach. The PROMITHEE-based results are further improved by using a hybrid cuckoo search algorithm (combined PROMITHEE-based cuckoo search). A confirmative test is further conducted on the optimum machining conditions obtained by the hybrid approach (combination of PROMITHEE and cuckoo search) indicating an overall improvement of 6.02% for the responses, validating the proposed work.

Modelling and Simulation of Machining Attributes in dry Turning of Aircraft Materials Nimonic C263 using CBN

In the current scenario, machinability of the super alloys is of greater importance in an aircraft turbine engine and land-based turbine applications owing to its superior properties. However, the machinability of these alloys is found to be poor owing to its inherent properties. Hence, a predictive model has been developed based on DEFORM 3D to forecast the machining attributes such as cutting force and insert's cutting edge temperature in turning of Nimonic C263 super alloy. The dry turning trials on Nimonic C263 material were carried out based on L27 orthogonal array using CBN insert. Linear regression models were developed to predict the machining attributes. Further, multi response optimization was carried out based on desirability approach for optimizing the machining attributes. The validation test was carried out for optimal parameter values such as cutting speed: 117 m/min, feed rate: 0.055 mm/rev and depth of cut: 0.25 mm. The minimum cutting force of 304N and insert's cutting edge temperature of 468 °C were obtained at optimum level of parameters.The predicted values by FEA and linear regression model were compared with experimental results and found to be closer with minimum percentage error.The minimum percentage error obtained by FEA and linear regression model for the machining attributes (cutting force, temperature) as compared with experimental values were (0.32%, 0.23%) and (2.34%, 1.63%) respectively.

The effects of thermal exposure on the high temperature behaviour of a Laser Powder Bed Fused nickel based superalloy C263

Additive manufacturing (AM) processes are currently being investigated to determine their suitability for wider adoption in the aero engine industry where material consistency and structural integrity are essential. A key driver is the ability of AM to produce near net-shape components and complex geometries, reducing material wastage and traditional processing stages. However, one major limitation remains in the anisotropic structures due to the complex thermal history of the process. Previous studies have employed heat treatment schedules attempting to alleviate such behaviour, although little research is currently available that explores microstructural evolution of AM alloys at in-service temperature conditions. In this research, the effects of thermal exposure on microstructure and mechanical behaviour of Laser Powder Bed Fused (LPBF) C263 is evaluated and assessed against a Cast equivalent. Results show that when exposing Cast and LPBF C263 samples to service temperatures for an extended period of time, the materials experience microstructural and chemical alterations directly controlling the mechanical response. The thermal exposure programme has demonstrated that with the precipitation of carbide phases in the exposed LPBF variant, grain boundary morphologies are highly comparable to the wrought equivalent of the same alloy.