Alloy C-276 Research Articles

Investigation of Machining Characteristics and Drilling Parameters Optimization in Drilling of Nimonic C-263 Alloy

This paper contains the investigation of machining characteristics and machining parameters optimization while drilling Nimonic C263 alloy. The proposed method is designed as per Taguchi’s Design and drilling trials are conducted utilizing ALCRONA coated drills. An empirical model has been proposed for process performance prediction via RSM (Response Surface Methodology). The optimization of multi response has also been carried out depends on function of desirability approach. The optimized cutting conditions were established. Confirmation tests were conducted to confirm the modelling results.

Effect of Frequency on Microstructural and Corrosion Demeanour of Alloy C-276 Weldment

Abstract This research work describes the effect of varying frequency of pulsed current gas tungsten arc welding (PCGTAW) on alloy C-276. Investigations were carried out to evaluate the consequence of varying frequency (Hz) on the microstructural and corrosion demeanour of alloy C-276 weldment. Bead-on-weld trials was carried out by varying the frequency from 1 to 10 Hz and keeping other process parameters as constant. The microstructural property of the bead on weld is studied through optical and scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Corrosion behaviour studies were carried in synthetic seawater condition. Micro-examinationreveals the presence of equiaxed dendritic structure on all the trials of the bead on the weld. The absence of secondary phase was observed through scanning electron microscope (SEM). From the EDS analysis, the absence of micro segregation can be observed for all the weldments. Corrosion rate increase as the frequency (1 to 10 Hz) of the weldment increase. It is inferred from the results that as frequency increase from 1 to 10 Hz, refining of grain takes place with an increase in the corrosion rate

Machinability investigation on Nimonic C263 alloy in electric discharge machine

Nickel based alloys, are difficult to machine with conventional machining approach at precision level. However, these alloys can be machined up to good accuracy and preciseness with non-conventional machining process such as electrical discharge machining (EDM) process. In the present study, EDM of Nimonic C263 work piece, a nickel based super alloy, has been carried out with three tool materials viz. copper, copper-tungsten and tungsten. Box-behnken design is used to plan the experiments. Consequences of different electrode material, voltage, duration of spark and discharge current are studied on machining performance of the process viz. material removal rate (MRR) and surface roughness. The influence of parameters on each response is analyzed by means of analysis of variance (ANOVA). It is observed that discharge current, electrode material and voltage have significant effect on the performance measures. Proposed study is useful for tool engineers working on aerospace and aviation industries manufacturing various aircraft components up to desired accuracy.

Fabrication and characterization of coated Hastelloy C-276 Alloy by SDP technology

Recently, much attention has been received by ion beam assisted deposition (IBAD) technology for the preparation of second-generation high temperature coated conductors. Surface roughness (Ra) for substrate material fabricated via IBAD route is required as less than 2 nm (5 μm × 5 μm). The aim of this current study is to reduce Ra as less than 2 nm, which is 20 nm for original tapes. Solution deposition planarization (SDP) technique was utilized in order to further improve the surface quality of polished Hastelloy C-276 alloy, for which maximum Ra value is usually greater than 5nm. The processing parameters and precursors, influencing Ra, crystallinity, morphology and film thickness were systematically investigated. Precursor solutions with different concentration were prepared by utilizing yttrium acetate as solute, ethanol as solvent, di-ethanolamine and ethylene triamine as additives. The average Ra < 2 nm and maximum Ra(max) < 5 nm (5 μm × 5 μm) was obtained after the heat treatment at 530 °C. The obtained results suggested SDP technique as an effective way to resolve the problem of surface roughness.

Optimization of high-speed turning parameters for Inconel 713C based on Taguchi grey relational analysis

In this work, a propelled dynamic approach, Taguchi grey relational analysis has been employed to estimate the impact of untreated and cryogenically treated and oil-quenched WC-Co tools in high-speed turning of Inconel 713C alloy on cutting force and surface roughness. Taguchi grey relational analysis is executed to maximize the high-speed turning of Inconel 713C alloy taking into account various operating parameters (cutting speed, feed rate, and depth of cut). The L27 orthogonal array has been utilized to determine the signal-to-noise ratio. Analysis of variance was performed to recognize the large number of components influencing surface roughness. The numerical examination showed that feed rate, with percentages as high as 95%, had the most predominant impact on machining performance, followed by cutting speed for untreated and treated WC-Co tools.

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.

Comparison of the Phase Stability and Corrosion Resistance of the Ni-Based Alloys C-4 and C-276

A one-to-one correspondence is developed between the phase stability and corrosion resistance of the commercial (Ni-Cr-Mo)-based alloys C-276 and C-4. Alloy C-4 is shown to outperform alloy C-276 in acidic oxidizing media and approaches its resistance in acidic reducing media. Both alloys are found to have similar resistance to chloride-induced stress corrosion cracking in the annealed condition with short-range order. The aqueous corrosion resistance of both alloys is found to be improved by long-range order; however, they become highly susceptible to chloride-induced stress corrosion cracking. Alloy C-4 is distinguished by being stable toward precipitation of detrimental intermetallic compounds. However, alloy C-276 is shown to be prone to precipitation of mu phase which degrades its resistance to aqueous corrosion and chloride-induced stress corrosion cracking. It is concluded that the chemical composition of alloy C-4 is tailored to make it more versatile than alloy C-276 in acidic oxidizing media and the results are found to be consistent with the concept of atomic percent factor of each alloy.

Influence of filler material composition on the microstructural evolution, mechanical properties and corrosion behaviour of nickel-based super alloy C-276

The microstructural evolution, mechanical properties and corrosion resistance of nickel-based-Super Alloy C-276 joints were examined in the current investigation. Four different filler materials (ERNiCrMo-4, ERNiCrMo-10, ERNiCrMo-3 and ERNiCr-3) in combination with pulsed current gas tungsten arc welding were used to join 6 mm thick sheets of Alloy C-276. The better understanding of evolution of microstructures and their subsequent effect on the properties would be beneficial for employing such joints in practical applications. The microstructural analysis showed transition in the solidified structure for different filler materials. Furthermore, SEM-EDS analysis clearly revealed the precipitation of Mo or Nb-rich precipitates in the welds (or close to fusion boundary) for all the weldments. This situation caused a reduction in the mechanical properties and the initiation of corrosion pits (or cracking) during modified Huey test. However, the segregation of TCP phases (P or μ) was found to be in a lesser amount in the ERNiCrMo-4 weld followed by ERNiCrMo-10 weld (which needs further investigation) and hence resulted in a better mechanical properties and superior corrosion resistance as compared to the weld fabricated using ERNiCr-3 filler material. Therefore, the authors recommend the use of ERNiCrMo-4 filler material for joining of Alloy C-276 (followed by ERNiCrMo-10 filler material) in corrosive industrial applications.

High Temperature Isothermal Oxidation Behavior of Superheater Materials

Abstract During combustion of biomass, alkali chloride-rich ash deposits condense on the surface of superheater tubes, thereby induce corrosion. A well-developed protective oxide layer formed from pre-oxidation treatment is an environmental friendly and cost effective technique for corrosion protection of superheater materials at high temperature in alkali salt environment. The ability of the pre-oxidized layer to protect the alloys depend on the properties such as porosity, thickness, continuity and composition of the layer. The characteristics of the oxide layer could be controlled by proper understanding on the oxidation behaviour of the materials. The main objective of this work is to obtain information on the oxidation behaviour of Hastelloy C22 (C22) and 304 Stainless Steel (304SS) at high temperature environment, hence to justify the suitability of these alloys to be subjected for pre-oxidation treatment. Oxidation of C22 and 304SS was conducted at temperature 900 °C and 1000 °C for 24 hours by thermogravimetric analysis (TGA). The oxide morphology and elemental analysis were characterized using Field Emission Scanning Electron Microscope (FESEM) equipped with Energy Dispersive X-ray Spectroscopy (EDX). The phases of the oxidation products were determined using X-ray diffraction analysis (XRD). The weight change of 304SS is higher as compared to C22 which indicates higher oxidation rate for 304SS. However, the oxide layer formed on Hastelloy C22 is more protective compared to the oxidation products of 304SS. The finding justifies the high potential of C22 alloy to be subjected for pre-oxidation treatment before used as superheater materials for biomass industry.

Surface modification technique to enhance metallurgical and mechanical properties of alloy C-276 weldment by laser shock peening without coating

Microsegregation of alloying elements is prone to hot cracking in the weldment of alloy C-276. The formation of topologically close packed phases P and µ is largely responsible for the hot cracking. The present study articulates the effect of laser shock peening (LSP) to improve the metallurgical and mechanical properties of the weld joint. The weld joint was fabricated by pulsed current gas tungsten arc welding (PCGTAW) using an ERNiCrMo-3 filler wire. LSP without coating was carried out on the cap surface of the weldment. Microstructural studies were carried out to compare the as-welded and laser-peened microstructure on the fusion zone. The results show that a fine equiaxed dendritic structure was observed in both conditions. EDS analysis was carried out to evaluate the microsegregation of alloying elements. EDS analysis indicates that there are no secondary intermetallic phases. X-ray diffraction analysis was carried out to evaluate the phase change and crystallite size in the as-welded and laser shock peened fusion zone. The result shows 48.99% reduction in crystallite size after LSP. Hardness and tensile strength results indicate there is a consequential increase in laser shock peened specimen compared with as-welded specimen.

Continuous electropolishing technique for long-length Hastelloy C-276 tape

Preparation of the second-generation high-temperature superconducting tape by ion beam-assisted deposition (IBAD) requires a flat metal substrate. In this work, the electrochemical polishing of long-length Hastelloy C-276 alloy was studied, and its process parameters, characterized roughness and other properties were investigated. A 10-meter-long Hastelloy C-276 alloy was prepared by electrochemical polishing. The following optimized processing parameters are obtained: temperature of 45 °C, current density of 0.439 A·cm−2 and polishing time of 60 s. The average roughness value (Ra) of the surface is less than 5 nm (5 μm × 5 μm), which was characterized by atomic force microscopy. This value satisfies the requirements for the further preparation of transition-layer pair by the IBAD technology route.

Relationships Between the Σ9 and Σ27 Boundaries and the Connectivity of Random Boundary in Hastelloy C-276 Alloy

Hastelloy C-276 was subjected to 10% deformation and annealed at 1100 °C for different time. The fractions of Σ3n (n=1, 2, 3) boundaries and the connectivity of random boundary networks were characterized by electron back-scatter diffraction (EBSD). The results show that the Σ3 boundary fraction is hardly increased during the annealing period. Instead, the fractions of Σ9 and Σ27 boundaries have a dramatic change with annealing time, whose peaks are arisen after annealing for 15 min. Meanwhile, the corresponding connectivity of random boundary network is effectively disrupted. This can be attributed to the incoherent Σ3 boundary producing more Σ9 and Σ27 boundaries and incorporating those boundaries into the random boundary networks. Actually, the connectivity of random boundary networks can be definitely identified by Σ(9+27)/Σ3 radio.

Significant impact of yttrium microaddition on high temperature tensile properties of Inconel 713C superalloy

High temperature tensile properties of Inconel 713C without and with Yttrium microaddition have been investigated. Yttrium addition affected the solidification structure with promotion of equiaxed grain formation in the center of mold. Ultimate tensile strength increased from approximately 892 to 1006 MPa while the elongation increased from approximately 13% to 21% by 0.05 mass% Yttrium addition. 0.05 mass% Yttrium addition in Inconel 713C alloy showed optimum high temperature tensile property.

Consumable selection for pulsed current gas tungsten arc welded bimetallic joints between Super C-276 alloy and Ti -stabilized Grade 321

The present work investigates the influence of filler materials composition on the bimetallic joints between nickel based Super C-276 alloy and Ti-stabilized Grade 321 using multi-pass pulsed current gas tungsten arc welding process. The analysis was carried out to determine the correlationship between the morphology of the weld metals and the resultant mechanical properties and corrosion resistance. Four different filler materials including ERNiCrMo-4, ERNiCrMo-3, ERNiCr-3 and ER347 were employed. The microstructural analysis revealed fully austenitic structure along with variation in the dendritic morphology from cellular/columnar to an equiaxed structure near weld center line for different filler materials. SEM-EDS point analysis results displayed the existence of white particles (both Mo and Nb-rich) in the weld as well as at the weld boundaries occupying the interdendritic regions on account of their low solubility in the matrix. Compositional analysis revealed that the ERNiCr-3 weld had greater degree of Nb-rich precipitation occurred along the migrated grain boundaries which causes cracking in the weld during modified Huey test. Mechanical test results indicates that amongst all dissimilar weldments, welds fabricated by employing ERNiCrMo-4 and ERNiCrMo-3 showed the optimum properties. In conclusion, for the dissimilar joining of Super C-276 alloy and Ti stabilized Grade 321, ERNiCrMo-4 filler material (followed by ERNiCrMo-3) offers superior properties compared to other filler materials employed.

Investigation on Microstructure and Mechanical Properties of ATIG welded alloy C-276 with Fe2O3 flux

Alloy C-276 susceptible to hot cracking. The microsegregation occurs during solidification is the largely responsible for the hot cracking in the alloy. The present study investigates the microstructure and mechanical properties of alloy C-276 weld joint fabricated by ATIG welding technique. The macro examination was carried out assess the defects in the weld joints. Optical and scanning electron microscope examination was carried out to see the structural changes in the fusion zone. The tensile test was performed to evaluate the strength of the weld joints. The results show the defect free welding was achieved in the established process parameters. The macrograph shows the full depth of penetration was obtained in the single pass by the effect of Marangoni convection. Energy Dispersive X-ray spectroscopy (EDS) analysis illustrates the absence of microsegregation in the interdendritic zone. The tensile test shows the improved mechanical properties compared to the base metal.

Investigation on Microstructure, Micro segregation and Mechanical Properties of ATIG welded Alloy C-276

This research article reports the activated flux tungsten inert gas (ATIG) welding of alloy C-276. Microstructures of the welded joint were studied using optical and scanning electron microscope. Energy-dispersive X-ray spectroscopy (EDS) analysis showed that segregation of Mo and W lead to the formation of the secondary phases. The microstructure results show that fine cellular structure was observed in the fusion zone. Studies using scanning electron microscopy revealed the formation of secondary phases in the grain boundaries. Strength and ductility of the welded joint was evaluated using tensile test. It was inferred that the joint strength was almost matching to the strength of the base metal. It was deduced that the formation of the secondary phases had reduced the ductility and toughness of the weld joint.

Optimization of process parameters in Electrical Discharge Machining of Haste Alloy C276 using Taguchi’s method

Nickel based superalloys are most commonly used materialin various engineering applications such as gas turbines, nuclear reactors and aerospace industries. The nickel based superalloys are very hard to machine materials with the use of conventional machining methods. Electrical Discharge Machining (EDM) is an appropriate unconventional material removal process used for machining such kind of difficult to machine materials. This present investigation details the determination of optimum process parameter to attain the better machining performance in EDM of Haste alloy C276. The experimental combinations are planned and analyzed by Taguchi’s design of experiments approach. The influence of process variables such as current, pulse on and pulse off time were investigated to control the various desired performance measures such as Material removal rate, surface roughness and overcut. Analysis of variance (ANOVA) a statistical analysis tool has been applied to ascertain the significance of the input process variables on electrical discharge machining of Haste alloy C276. The statistical results confirmed that the current is the most influencing process variable on material removal rate, surface roughness and overcut. Multiple regression models have been developed to correlate the relationship among the independent and dependent variables in electrical discharge machining of Haste Alloy C276.

Investigations on the Microstructure, Microsegregation and Hardness Properties of Bead on Plasma Arc Welded C-276 Alloy

The present study investigates the microstructure, microsegregation, and microhardness of alloy C-276 plates by a bead on trials of plasma arc welding (PAW). The bead – on welds were carried out by autogenous plasma welding using melt in mode technique. Microstructural characterization studies were performed using optical and scanning electron microscopy (SEM) techniques. The studies showed the presence of close networks of fine equiaxed dendrite structures while employing lower heat inputs. Whereas the increasing heat energy input demonstrates the occurrence of columnar dendrite structures. SEM/EDAX analysis demonstrates the presence of secondary phases of P and µ in the fusion zone. Energy Dispersive X-Ray Analysis (EDAX) analysis was performed to infer the microsegregation of alloying elements. Microhardness study was carried out to evaluate the hardness of the weld zones in different heat input. The hardness test revealed that on increasing the heat input, the hardness values were impoverished.

The effect of aging on the serrated yielding and intermediate temperature embrittlement of nickel-base C-276 alloy

The influence of aging on serrated yielding and intermediate temperature embrittlement (ITE) of nickel-based C-276 alloy has been investigated by microstructural characterization and tensile tests at temperatures ranging from 300 to 950°C with strain rate of 3 × 10–4s–1. The precipitated phases in the C-276 alloy aged at 870°C for various times were identified as μ phase and M6C. Tensile ductilities obtained at 700°C were found to increase with extending aging time until 12h, and thereafter, it remained almost unaffected by the aging time. Serrated flow was noticed for all temperatures for the solutionized alloy, and the alloy presented the typical ITE. Aging the solutionized alloy at 870°C/36h resulted in a disappearance of serrated yielding in the temperature range of 600–750°C, which is most possibly attributed to the very weak interaction between Mo atoms and mobile dislocation as a result of precipitation. Although aging for 36h at 870°C decreased the tensile ductilities of this alloy below 600°C, the aged alloy showed the absence of ITE and higher yield strength in comparison with solutionized alloy. The tensile ductilities in the aged alloy were insignificantly affected by increasing the temperature until 700°C, beyond which the tensile ductilities were found to increase drastically with temperature.

Properties of the Inconel 713 Alloy Within the High Temperature Brittleness Range

Abstract Nickel-based alloys are widely used in industries such as the aircraft industry, chemicals, power generation, and others. Their stable mechanical properties in combination with high resistance to aggressive environments at high temperatures make these materials suitable for the production of components of devices and machines intended for operation in extremely difficult conditions, e.g. in aircraft engines. This paper presents the results of thermal and mechanical tests performed on precision castings made of the Inconel 713C alloy and intended for use in the production of low pressure turbine blades. The tests enabled the determination of the nil strength temperature (NST), the nil ductility temperature (NDT), and the ductility recovery temperature (DRT) of the material tested. Based on the values obtained, the high temperature brittleness range (HTBR) and the hot cracking resistance index were determined. Metallographic examinations were conducted in order to describe the cracking mechanisms. It was found that the main cracking mechanism was the partial melting of grains and subsequently the rupture of a thin liquid film along crystal boundaries as a result of deformation during crystallisation. Another cracking mechanism identified was the DDC (Ductility Dip Cracking) mechanism. The results obtained provide a basis for improving precision casting processes for aircraft components and constitute guidelines for designers, engineers, and casting technologists.