Superalloy C263 Research Articles

An optimal approach for improving the machinability of Nimonic C-263 superalloy during cryogenic assisted turning

Abstract The present work proposes a combined experimental methodology and optimization strategy of the process parameters for the turning of Nimonic C-263 superalloy with a multilayer CVD coating using TiN-MT-TiCN-Al2O3 grade KCM25 inserts. Taguchi’s L-27 orthogonal array is used for the experimental design. The outcomes of machining parameters viz. cutting speed (vc), cutting feed (f), depth of cut (ap), cryogenic temperature (T) and holding time (t) are explored on the machining characteristics like surface roughness (SR), nose wear (NW), flank wear (NW) and cutting force (F). The results are further compared with the cryogenic environmental studies that have improved the tool life and led to better machinability of the alloy. The multiple responses of the cryogenic machining environment are converted into the equivalent closeness factor (CF) using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method. The TOPSIS based results are further improved using a neuro-genetic algorithm (combined ANN-GA). A confirmatory test is further carried out on the optimum machining parameters obtained by the hybrid approach (the combination of TOPSIS and ANN-GA) to validate the proposed work. It is seen that the closeness factor is improved by 6.17 %. The proposed model can be useful to select the ideal process conditions and to enhance the productivity of turning processes.

Effects of High-Temperature Aging on Precipitation and Corrosion Behavior of a Ni-Cr-Mo-Based Hastelloy C276 Superalloy

The effects of short-term aging on the precipitation and corrosion behavior of a Ni-Cr-Mo-based superalloy Hastelloy C276 were studied in this work. Aging treatments were performed at 800 °C for 1 h, 2 h, 4 h, 8 h, 12 h and 15 h. It is found that M6C carbide, which is rich in Mo and W, is prone to precipitate at grain boundary when the aging time exceeds 4 h, associated with the formation of a Mo and W depletion zone adjacent to the grain boundary. The potentiodynamic polarization curves in 3 wt.% NaCl solution show no obvious differences among the aged samples. But the surface morphologies of samples after double-loop electrochemical potentiodynamic reactivation method (DL-EPR) tests in HCl solution present typical intergranular corrosion attack. The calculated degrees of sensitization based on the DL-EPR curves increase dramatically with the increase in aging time, which is consistent with the precipitation trends. It is recommended that hot working of Hastelloy C276 superalloy should avoid high temperature exposure (e.g., at 800 °C more than 4 h) or do heat treatment again after high-temperature processing.

Performance Analysis of Untreated Tungsten Carbide Tool and Cryogenically Treated With Oil Quenched Tungsten Carbide Tool While Turning Of Inconel 713c

Inconel 713C bars are widely used in aviation industries and engineering applications. The machining of Inconel 713C superalloy is suitable for the above applications. The performance enhancement of untreated WC-Co tools and cryogenically treated with oil quenched WC-Co tools were checked and they were estimated for their properties through Vicker hardness (untreated tools 1601 HV, cryogenically treated with oil quenched tools 1881 HV) and also were administered to machining of difficult to cut material Inconel 713C superalloy under dry condition. The acquiesced cutting speed ranges from 70 to 110 m/min which shows its unique parameters of cutting speed in machining Inconel 713C with WC-Co tools. The cutting force magnitude and surface roughness were found to be lesser in cryogenically treated with oil quenched WC-Co tools than in untreated WC-Co tools. Obviously cryogenically treated WC-Co tools indicated better execution when contrasted with untreated WC-Co tools.

Experimental investigation of Hastelloy C-276 using abrasive waterjet milling

Abrasive waterjet milling (AWJ Milling) is a machining method as it can be used to quickly process a wide range of industrial materials without adversely affecting their properties. The viability of using AWJ milling to machine Hastelloy C-276 Ni-Mo-Cr super alloy was investigated here in detail for the first time. Experiments were performed by varying AWJ milling process parameters, including the water jet pressure, standoff distance, traverse speed, and abrasive flow rate using the Taguchi orthogonal array. A desirability function analysis was applied to identify the optimum AWJ milling conditions for maximizing material removal rate and minimizing surface roughness. The surface morphology of the super alloy samples was studied to determine the material removal mechanism under the optimal milling conditions. In addition, a semi-empirical model was developed to predict the surface roughness of Hastelloy C-276 processed using AWJ milling. These findings are expected to promote the wider use of AWJ milling for machining of Hastelloy C-276 super alloy, which could improve the processing efficiency and quality of parts for chemical and nuclear industries, among others.

Effect of cooling rate on macro- and microstructure of thin-walled nickel superalloy precision castings

The macro- and microstructure of nickel superalloys castings, especially thin-walled ones, have a large influence on their mechanical properties. Better understanding of the macro- and microstructure response to casting conditions will enable the optimization of technological and mechanical properties of the alloy. Presented research results refer to different diameter cylindrical specimens of Inconel 713C superalloy cast under various conditions to impose different cooling rates. The function model for correlation between secondary dendrite arm spacing (SDAS) and cooling rate was proposed. Statistical analysis of the influence of the main casting process parameters on the SDAS and cooling rate on grains morphology was performed. It was found that casting diameter had a biggest impact on the SDAS while mold temperature and thermal insulation had less influence on the alloy microstructure. Quantitative microstructural analysis results indicated also the effect of cooling rate on grain size.

Effect of different parameters on surface roughness and material removal rate in abrasive water jet cutting of Nimonic C263

Abrasive water jet cutting is the recent non-conventional and useful processes because of its characteristic advantages. The influence of jet pressure, standoff distance and cutting Speed on surface roughness, material removal rate during abrasive waterjet cutting of Nimonic C263 super alloy has been analyzed in this paper. The roughness of the surface was evaluated in four phases along the width to know the distinct texture of the surface. The rate of material removal was also measured during experiment. The experimental results showed that the roughness of the bottom surface was extremely affected by standoff distance and pressure of jet. The rate of material removal was also noticed to be dependent upon the cutting parameters.

Cellular automaton modeling of dynamic recrystallization of Ni–Cr–Mo-based C276 superalloy during hot compression

Abstract

Effect of laser surface texturing on wear resistance of nickel based superalloy

PurposeThis paper aims to investigate the effect of laser surface texturing (LST) on the wear behavior of C-263 nickel-based superalloy and to identify the optimum wear operating condition.Design/methodology/approachC-263 nickel-based superalloy was selected as substrate material and pico-second Nd-YAG laser was used to fabricate the waviness groove texture on their surface. Wear experiments were designed based on Box-Bhenken design with three factors of sliding velocity, sliding distance and applied load. Wear experiments were performed using pin on disc tribometer. Morphologies of textures and worn-out surfaces were evaluated by scanning electron microscopy and energy dispersive spectroscopy. Surface topographies and surface roughness of the textures were evaluated by weight light interferometry. The response surface methodology was adopted to identify the optimum wear operating condition and ANOVA to identify the significant factors.FindingsLST improves the wear resistance of C-263 nickel-based superalloy by appeoximately 82 per cent. Higher wear rate occurs at maximum values of all operating conditions, and applied load affects the coefficient of friction. Applied load significantly affects the wear rate of un-textured specimen. The interaction of sliding velocity and applied load also affects the wear rate of textured specimens. The optimum parameters to get minimum wear rate for un-textured specimens are 1.5 m/s sliding velocity, 725 m sliding distance and 31 N of applied load. For textured specimens, the optimum values are 1.5 m/s sliding distance, 500 m sliding distance and 40 N of the applied load.Originality/valueLiterature on laser texturing on nickel-based superalloy is very scarce. Specifically, the effect of laser texturing on wear behavior of the nickel-based superalloy C-263 alloy is not yet reported.

Influence of Melt-Pouring Temperature and Composition of Primary Coating of Shell Mold on Tensile Strength and Creep Resistance of Ni-Based Superalloy

Eight investment castings of Inconel 713C superalloy were fabricated, varying in the melt-pouring temperature, from 1400 to 1520 °C, and CoAl2O4 inoculant content, 0 or 5 wt.%, in the primary coat. Their influence on grain size on tensile and creep properties was investigated. The best combination of yield stress (815 MPa) and elongation (A4 = 7.65%) at ambient temperature was obtained in surface-modified castings poured from 1520 °C. The longest time to rupture was for the unmodified castings (76.8 h) poured from 1520 °C, while for the modified variant, the time to rupture was lower around, 7.4 h, which was still a satisfactory value. During tensile testing, microcracks were formed in large eutectic γ′, carbides and borides, due to the accumulation of stress at interfaces with the matrix. During creep, N-type rafting of γ′ precipitates and phase transformation MC + γ → γ′ + M23C6 took place.

Experimental investigation on wire electric discharge machining (WEDM) of Nimonic C-263 superalloy

ABSTRACTNimonic C-263 superalloy offers a wide range of outstanding properties, namely, high-temperature resistance, high specific strength, high thermal fatigue, and hot corrosion resistance. The concern of the present study is mainly focused on the effect of wire electrical discharge machining (WEDM) process parameters namely, spark energy, spark frequency, and peak current on surface roughness, average cutting rate, and surface integrity aspects of Nimonic C-263 superalloy by using one-parameter-at-a-time (OPAT) approach. Surface roughness and average cutting rate were showing the increasing trend with the spark energy and peak current and reverse trend with the spark frequency. Surface integrity aspects of Nimonic C-263 such as surface topography, surface morphology, recast layer thickness, elemental composition, and phase analysis have been also considered in this study. Scanning electron microscope (SEM) micrograph of the machined surface shows the presence of micro-voids, discharge craters, micro-globules, and droplets of molten material. A recast layer of minimum thickness, with less transfer of foreign atoms (Mo, C, and O) from dielectric fluid and molybdenum wire, has been formed at lower spark energy compared to higher spark energy. The various compounds of Ni, Fe, Al, and Ti such as Fe1.2Ni0.8, Fe1.5Ni0.5, Co0.06Fe0.94, and Alo.29Ni0.27Ti0.44 were formed on the machined surface identified through analysis of XRD peaks.

Characterization of Static Recrystallization of a Ni-Cr-Mo-Based C276 Superalloy in Two-Stage Isothermal Compression

In order to clarify the microstructure evolution characteristics during holding period after slight degree of deformation for a Ni-Cr-Mo-based C276 superalloy, two-stage isothermal compression tests have been performed at the temperature range of 1000-1150 °C and the strain rate range of 0.1-5 s−1. The stress–strain curves and microstructure observation infer that both static recovery (SRV) and static recrystallization (SRX) took place during the holding period when the specimens were deformed at 1100-1150 °C and only SRV occurred in the specimens that deformed at the temperatures lower than 1100 °C. The softening effects increase with the increasing temperature and deformation degree, while the influence of strain rate seems less pronounced because of the limited stored energy resulted from the small deformation. The grain boundary characteristics, analyzed using electron backscatter diffraction technique, indicate that high densities of twins and $$\varSigma 3$$ grain boundaries form associated with the nucleation and growth of SRX grains. Finally, the recrystallization during and after deformation, i.e., dynamic recrystallization, SRX and metadynamic recrystallization, was discussed concurrently.

Optimization of Melt Zone Area for Electron Beam Welded Hastelloy C-276 Sheet and Study of Corrosion Resistance of the Optimized Melt Zone in 3.5 wt% NaCl Aqueous Solution

Hastelloy C-276 superalloy has a wide range of applications including petroleum and petrochemical industries. Since welding forms an essential fabrication method for joining different structures in these industries, selection of suitable welding parameters is a prime concern that is yet to be addressed for Hastelloy C-276. In the present study, optimization of process parameters for electron beam welding of 2.6-mm-thick Hastelloy C-276 sheet has been carried out to obtain weld bead having through-penetration and minimum weld (or melt) zone cross-sectional area. A simple optimization technique is employed in the present study to solve the multi-objective minimization problem. After carrying out the full factorial experiment using selected process parameters, various geometric elements of the weld bead are identified as the output responses. The regression equation is developed for each geometric element from the experimental data. The desired value of a geometric element is specified as a constraint for the corresponding regression equation. A number of regression equations (considering all the geometric elements) are solved in parallel to obtain an optimized set of process parameters, followed by a confirmation test. Further, the optimized melt zone is subjected to cyclic potentiodynamic polarization test to study its susceptibility to localized corrosion. It is observed that polarization curve characteristics of base metal and optimized melt zone are not significantly different; however, the repassivation potential of the melt zone is less than that of the base metal. A flowchart showing the layout of the employed optimization technique followed by corrosion test is attached.

Small punch fatigue testing of a nickel superalloy

Miniaturised mechanical test approaches, specifically small punch testing, are now widely recognised as a means of obtaining useful mechanical properties to characterise the creep, tensile and fracture characteristics of numerous material systems from a range of industrial applications. Limited success has been found in replicating fatigue properties through the use of a small punch disc. This paper will discuss the ongoing research and progress in developing a novel small punch fatigue testing facility at the Institute of Structural Materials at Swansea University. Experiments have been performed on the nickel superalloy C263 at ambient room temperature, investigating three different alloy variants; two orientations produced through additive manufacturing and the cast equivalent. Fractographic analysis has been completed to interpret the complex damage mechanisms in the test method along with the differences in performance amongst the alloy variants.

Effects of heat treatment on microstructure and creep properties of a laser powder bed fused nickel superalloy

Nickel-based superalloy C263 has been consolidated with Laser Powder Bed Fusion (LPBF) with two perpendicular build orientations and exposed to either of two heat treatment programmes. This study analyses the effects of build orientation and heat treatment on the resulting microstructures produced in LPBF C263 variants, evaluated against a cast equivalent. Results show that although a strongly anisotropic microstructure was present in standard heat-treated (HT1) LPBF material, this was eradicated following an alternate heat treatment regime (HT2) through recrystallisation, aided by high local strain. Subsequently, their mechanical properties have been assessed by means of the Small Punch (SP) creep test. A contrasting presence of Σ3 formations was observed between the two LPBF heat treatment programmes with the resulting random grain boundary network (RGBN) revealing shorter potential intergranular crack paths in the HT2 material, although grain boundary carbides were found to be the dominant strengthening mechanism for improved creep resistance. Adapted Wilshire equations have been implemented to predict the long-term creep lives of the C263 variants and their apparent activation energies have been determined.

Analysis of Hole Taper, Recast Layer and Heat Affected zone in pulsed O2 and N2 laser drilling of Difficult-to-cut alloy Nimonic C-263

The quality and performance of the drilled component is of prime importance in the development of aero-engine components and are directly related to the quality of HAZ, Recast Layer and Hole taper. In order to maintain and/or improve the reliability of aerospace components, it is first essential to be aware of the possible damages that can be imparted to a material when it is drilled. Therefore, an attempt has been taken to investigate the effect of laser drilling parameters such as Gas Type: O2, N2; Power: 3200Watts, 3900Watts and Pressure: 4 bars, 5 bars, while laser drilling the Nimonic C-263 super alloy. Laser drilling trails have been conducted with different combinations of drilling parameters. The quality of the drilled holes such as Hole Tapper, HAZ and Recast Layer were evaluated quantitatively and analyzed through scanning electron microscope (SEM).

Recovery of Mo by liquid-liquid extraction from synthetic leaching solution of spent Inconel 713C super alloy and preparation of Mo compounds

Recovery of Mo by liquid-liquid extraction from synthetic leaching solution of spent Inconel 713C super alloy and preparation of Mo compounds

Microstructural characterization of Inconel 713C superalloy after creep testing

Microstructural characterization of Inconel 713C superalloy after creep testing

TOPSIS based parametric optimization of laser micro-drilling of TBC coated nickel based superalloy

The technique for order of preference by similarity ideal solution (TOPSIS) approach was used for optimizing the process parameters of laser micro-drilling of nickel superalloy C263 with Thermal Barrier Coating (TBC). Plasma spraying was used to deposit the TBC and a pico-second Nd:YAG pulsed laser was used to drill the specimens. Drilling angle, laser scan speed and number of passes were considered as input parameters. Based on the machining conditions, Taguchi L8 orthogonal array was used for conducting the experimental runs. The surface roughness and surface crack density (SCD) were considered as the output measures. The surface roughness was measured using 3D White Light Interferometer (WLI) and the crack density was measured using Scanning Electron Microscope (SEM). The optimized result achieved from this approach suggests reduced surface roughness and surface crack density. The holes drilled at an inclination angle of 45°, laser scan speed of 3 mm/s and 400 number of passes found to be optimum. From the Analysis of variance (ANOVA), inclination angle and number of passes were identified as the major influencing parameter. The optimized parameter combination exhibited a 19% improvement in surface finish and 12% reduction in SCD.

Laser Surface Texturing of Nickel Superalloy to Improve Adhesion Bond Strength of Thermal Barrier Coating

Laser surface texturing was adopted as a strategy to improve the adhesion bond strength of thermal barrier coating generally used in aero turbine components. A picosecond Q-switched Nd: YAG laser operated at 532 nm wavelength was used to perform laser surface texturing. Two different types of texture namely, oriented square pattern having 250 µm width and 250 µm pitch and trapezoidal pattern having 150 µm width and 250 µm pitch were textured on nickel superalloy C-263 surface prior to air plasma spraying of NiCrAlY bond coat. The microstructure and surface morphology of these patterns were characterized by Optical Microscope (OM) and White Light Interferometer (WLI). The presence of pre-defined texture in the laser ablated region and greater surface contact enhanced the mechanical interlocking with the bond coat. The generation of grooves increased the surface roughness of textured substrate 6 times greater than grit blasting. Further, the trapezoidal pattern exhibited higher surface roughness due to greater laser ablated area. The adherence was tested by adhesion bond strength test which showed 35 MPa and 37 MPa adhesive strength for oriented square and trapezoidal pattern, respectively. The fractal analysis showed that the textured substrate failed predominantly by cohesion.

Investigation of the Heat Treatment Effect on Microstructures and Phases of Inconel 713C Superalloy

The application of Inconel 713C is very vast in different industries such as in automobiles, aircrafts, boilers and turbines. In this paper, Inconel 713C specimens were solutionized at 1000 and 1200 °C for 1 hours in order to study changes in phases and the structure of alloy to modify the γ' phase. The optical and the scanning electron microscopy were used to investigate the structure and the energy dispersive spectroscopic (EDS) and the X-ray diffraction (XRD) were applied to identify the composition and phase changes. Results showed that the solutioning heat treatment at 1000 °C for 1 hour caused to participate Cr23C6, but when the temperature of heat treatment increased to 1200°C, chromium carbides solutionized in the γ matrix. Besides, by applying the heat treatment at temperature of 1000 °C, the γ' phase dissolved in (200) and (220) plane and this phase in the plane of (111) had the best stability. However the (220) plane of γ' phase was stable thermodynamically for the specimen without the heat treatment. Phases of Ni5Al3 and Al0.42Ni0.58 were observed at the temperatures of 1000 and 1200 °C, respectively. In addition, as the heat treatment temperature increased from 1000 to 1200 °C the new phase of AlNi3C0.5 solutionized in the γ matrix.