Nimonic C-263 Research Articles

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.

Experimental analysis of process parameters in drilling nimonic C263 alloy under nano fluid mixed MQL environment

Nimonic C263 is a super alloy and it is difficult to cut. As this alloy possess high proportion of chromium, cobalt, and molybdenum, which fortify the material by solution hardening, which inhibits the dislocation movement, resulting in higher plastic deformation. In this research, an attempt has been made to model, analysis and investigate the machining characteristics such as thrust force, temperature at drill cutting edge, flank wear and surface finish during drilling of this alloy using silver nano fluid mixed Minimum Quantity Lubrication (MQL) environment. Residual stress at various combinations of process parameters was also observed and discussed. RSM based empirical models of the process parameters and optimization of multi response was developed. Thrust force, Temperature at drill cutting edge, surface roughness and tool wear affected by feed rate (percentage of contribution-60%), spindle speed (percentage of contribution-88.63%), spindle speed (percentage of contribution-71.42%) and feed rate (percentage of contribution-67.76%) respectively followed by other parameters.

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.

Optimization of Cutting Parameters Based on Surface Roughness and Cutting Force During End Milling of Nimonic C-263 Alloy

The surface integrity of machined surfaces greatly influences the functional properties of the components such as fatigue life, etc. Nickel-based superalloy such as Nimonic C-263 is termed as difficult to machine material due to its unique properties as well as high strength at elevated temperatures. This study intends to optimize the cutting parameters (cutting speed, feed, depth of cut) during the end milling of Nimonic C-263 and the machining has been carried out using solid tungsten carbide tool coated with TiAlN and Vertical Machining Center. Experimentation is carried out using Taguchi L9 orthogonal array technique and based on signal to noise ratio data, optimum machining parameters were achieved for preferred observable characteristics such as cutting force and surface roughness. Additionally, Multi-purpose optimization (Grey analysis) of the observable characteristics was conducted to predict the optimum machining parameters combination which offers better producible surface finish and lowest cutting force requirement. Further, the analysis of variance (ANOVA) reveals that the feed rate is the farthest influencing factor followed by the depth of cut, cutting speed, and the variations in cutting force and surface roughness are confirmed through chip morphology using Scanning electron microscopy.

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.

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.

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.

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.

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).

Heat-affected zone crack healing in IN939 repaired joints using hot isostatic pressing

Simulation defects in IN 939 superalloy were repaired by gas tungsten arc welding (GTAW) using Nimonic C263 as filler metal. The microstructures and chemical compositions of fusion zone under the condition of as-welded and post-weld heat treatment (PWHT) were investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron probe X-ray microanalysis (EPMA). Moreover, the liquation cracking and strain age cracking in heat-affected zone (HAZ) were characterized as well. Post-weld hot isostatic pressing (HIP) was also applied to heal the HAZ cracks. The results show that elements segregation at as-welded joints could be significantly reduced by PWHT. HAZ cracks consisted of liquation cracking and strain age cracking. The liquation cracking was shorter than the strain age cracking. HIP is an effective way to heal the cracks in the repaired joints especially for liquation cracking. Though the strain age cracking can be healed by HIP, the healed trace concentrated with Al, Ti, B, and Zr elements can still be detected. Post-weld HIP is a necessary process to obtain crack-free joints.

Analysis of multipoint cutting tool temperature using FEM and CFD

Nimonic C-263 is a British nickel–chromium–cobalt–molybdenum alloy specially meant to be used in high-temperature and high-strength applications. Consequently, it produces high thermo-mechanical loads on the machining tool when machined. As a result, excessive heat is generated during dry drilling, between Nimonic C-263 and tungsten carbide tool coated with Alcorna, which in turn reduces the durability of the tool. In order to determine the temperature distribution of the tool, the coupling of finite element machining simulations along with computational fluid dynamics simulations is performed. The temperature distribution of the tool under dry condition is simulated via the DEFORM 3D software and the Altair AcuSolve software. Further investigation under cooling condition is performed using Altair AcuSolve software. The mass flow rate of the coolants is kept constant when the temperature distribution is obtained during the CFD analysis under cooling condition. Silver nano coolant has high heat reduction compared to other coolants and is found to generate 34% less heat than dry condition.

Effect of Temperature on Tensile flow behaviour of Nimonic C-263 alloy

Tensile properties, deformation and flow behaviour of Ni base superalloy, Nimonic C-263, was studied at modified solutionizing and aging condition, in the temperature range of 25-650 oC and at a strain rate of 1.3×10-3S-1. The presence of Dynamic strain aging (DSA) behaviour was observed at a wide temperature regime of 200 oC to 600 oC. Also an anomalous variation in tensile properties was observed in the temperature ranges between 400 oC to 650 oC. The yield strength (Y.S) was decreased slightly with temperature up to 300 oC and from there, there is a peak in YS at 400 oC with minimum(%) of elongation and strain hardening rate is maximum at 400 oC. An attempt has been done in this paper, to Co-relate the mechanical properties and flow behaviour of the alloy with microstructral studies and flow equations at different temperatures. It is observed that Ludwigson equation provides the best fit at high temperature, at 650 oC, compared to Hollomon and Ludwik equations.

A study on die sinking EDM of Nimonic C-263 super alloy : an intelligent approach to predict the process parameters using ANN

In current study, machining characteristics of Nimonic C-263 are analysed by TAGUCHI and modelled using Artificial Neural Networks (ANN). The response parameters under consideration are Material Erosion Rate (MER), Electrode Wear Rate (EWR), Surface Roughness (SR) and Dimensional Overcut (DOC). A regression mathematical model is also developed to verify the capabilities of ANN. The modelling of ANN includes identifying appropriate combination of hidden layers and number of neurons in each hidden layer. Study on machining characteristics revealed, peak current as the most influential process parameters affecting all the responses; followed by Pulse on-time. A contrary effect is observed for Pulse off-time. A rare process parameter named flushing pressure showed negligible influence on responses. Among various ANN architectures, 6-6 architecture is noted to possess phenomenal prediction accuracy of 99.71% compared to 93.55% of regression analysis.

Comparative evaluation of machinability characteristics of Nimonic C-263 using CVD and PVD coated tools

Machining of Nimonic C-263 has always been a challenging task owing to its hot strength, low thermal conductivity, tendency to work harden and affinity towards tool materials. Although coated tools have been used to overcome some of these challenges, selection of coated tool with appropriate deposition technique is of immense significance. The current study attempts to comparatively evaluate various performance measures in machining of Nimonic C-263 such as surface roughness, cutting force, cutting temperature, chip characteristics, and tool wear with particular emphasis on different modes of tool failure for commercially available inserts with multi-component coating deposited using chemical vapour deposition (CVD) and physical vapour deposition (PVD) techniques. Influence of cutting speed (Vc) and machining duration (t) has also been investigated using both coated tools. The study demonstrated remarkable decrease in surface roughness (74.3%), cutting force (6.3%), temperature (13.4%) and chip reduction coefficient (22%) with PVD coated tool consisting of alternate layers of TiN and TiAlN over its CVD coated counterpart with TiCN/Al2O3 coating in bilayer configuration. Severe plastic deformation and chipping of cutting edge and nose, abrasive nose and flank wear along with formation of built-up-layer (BUL) were identified as possible mechanisms of tool failure. PVD coated tool successfully restricted different modes of tool wear for the entire range of cutting speed. Superior performance can be attributed to the hardness and wear resistance properties, thermal stability due to presence of TiAlN phase and excellent toughness owing to PVD technique and multilayer architecture.

Experimental assessment on performance of TiN/TiCN/Al<SUB align="right">2O<SUB align="right">3/ZrCN coated tool during dry machining of Nimonic C-263

Nimonic C-263 is one of most important grades of nickel-based superalloys particularly used in hot section of gas turbines, aerospace, power generators and heat exchangers. It belongs to the class of difficult-to-cut materials because of its unique properties such as high hardness, fatigue strength, low thermal conductivity, high chemical affinity and tensile strength along with resistance to corrosion and oxidation. Machinability can be improved with proper selection of cutting tool and cutting parameters. The present paper deals with comparative analysis of tool wear and chip characteristics when machining Nimonic C-263 with uncoated and multilayer coated carbide inserts. Dry turning operation was carried out at two different cutting speeds (Vc) of 51 m/min and 84 m/min with a constant feed (f) of 0.2 mm/rev and depth of cut (ap) of 1 mm. Chip reduction coefficient (ζ), tool wear, surface roughness and cutting temperature were observed during dry machining of Nimonic C-263. While surface finish could not be improved, remarkable reduction in cutting temperature, chip reduction co-efficient and tool wear was noted for the multi-layer coated insert under different cutting condition.

Modeling and Optimization of Machining Nimonic C-263 Superalloy using Multicut Strategy in WEDM

In recent years, wire-electrical discharge machining (WEDM) has gained popularity in the industry due to its capability to generate complicated shapes in exotic materials, irrespective of their hardness. Conventional machining of Nimonic C-263 superalloy is an extremely difficult and costly process due to its high hardness and tool wear rate. The present research work investigates the influence of the WEDM process parameters on different performance measures during machining of Nimonic C-263 superalloy. A mathematical model for all four important performance measures, namely, cutting rate, surface roughness, spark gap, and wire wear ratio, was developed and the responses were used for studying the interrelationship between performance measures and process parameters. The optimal settings of operating conditions were predicted using desirability function. The effectiveness of multicut strategy was also investigated in the article.

Evaluation of Kerosene Fuelled Scramjet Combustor using a Combination of Cooled and Uncooled Struts

The scramjet combustor a vital component of scramjet engine has been designed by employing fuel injection struts. Several experimental studies have been carried out to evaluate the propulsive performance and structural integrity of the in-stream fuel injection struts in the connect-pipe test facility. As the mission objective of hypersonic demonstrator is to flight test the scramjet engine for 20 s duration, in-stream fuel injection struts which are designed as heat sink devices encounter hostile flow field conditions especially in terms of high thermal and high convective loads in the scramjet combustor. To circumvent these adverse conditions, materials like Niobium C-103 and W-Ni-Fe alloys have been used for the construction of struts and a number of tests have been carried out to evaluate the survivability of the in-stream fuel injection struts in the scramjet combustor. The results thus obtained show that the erosion of leading edges of the Stage-II fuel injection struts in the initial phase and subsequently puncturing of the fuel injection manifold after 10-12 s of the test are noticed, while the other stages of the struts are found to be intact. This deteriorating leading edges of Stage-II struts with respect to time, affect the overall propulsive performance of the combustor. To mitigate this situation, Stage-II struts have been designed as cooled structure and other Stages of struts are designed as un-cooled structure. Material of construction of struts used is Nimonic C-263 alloy. This paper highlights the results of the static test of the scramjet combustor, which has been carried out at a combustor entry Mach number of 2.0, total temperature of 2000 K, with an overall kerosene fuel equivalence ratio of 1.0 and for the supersonic combustion duration of 20 s. Low back pressure has been created at the exit of the scramjet combustor using ejector system to avoid flow separation.Visual inspection of the fuel injection struts after the test revealed that all the Struts are found to be thermo-structurally safe in the combustor environment except for minor erosion of the leading edges of the struts. Stage-II struts made of two-passage cooled configuration are found to be thermo-structurally safe. Although other stages of struts used in the test are of un-cooled configuration, they too are found to be safe and intact. This demonstrates the fact that they experience thermally benign flow conditions compared to Stage-II struts in the scramjet combustor. Defence Science Journal, 2014, 64(1), DOI:http://dx.doi.org/10.14429/dsj.64.2733

Microstructure stability: Optimisation of 263 Ni-based superalloy

To reduce CO 2 emissions on coal-fired power plant, A-ultra supercritical (A-USC) power plant whose steam conditions exceed 700 °C are being developed. At these elevated temperatures, the use of Ni-base superalloys becomes necessary. In this context and within the European project NextGenPower, focus is made on commercial Nimonic C-263 as a candidate material for turbine rotors. Nimonic C-263 is known to have low sensitivity to segregation, high workability and high weldability which are major properties for the manufacture of large shafts. Long-term creep strength is also required for this application and unfortunately Nimonic C-263 shows η-phase precipitation after long-time exposure between 700 °C–900 °C which is detrimental for long-term creep properties. The composition of Nimonic C-263 was thus optimised to overcome the formation of η-phase. Trial tests were made in order to study the effect of hardening contribution elements on microstructural and mechanical properties. Then, a 500 mm diameter forged rotor was made from optimised 263 alloy and shows promising properties.

Theoretical predictions and experimental validations on machining the Nimonic C-263 super alloy

The current paper presents the simulated 3D Finite Element Model (FEM) and experimental validation while turning the Nimonic C-263 super alloy using a cemented carbide cutting tool. FEM machining simulations was carried out using a Lagrangian finite element based machining model to predict the tangential cutting force, temperature distribution at tool tip and the effective stress and strain. All simulations were performed according to the cutting conditions designed, using the orthogonal array. The work piece was considered as perfectly plastic and its shape was taken as a curved model. An experimental validation of the cutting process was conducted in order to verify the simulated results of tangential cutting force and temperature at tool tip and the comparison shows that the percentage error 6% was observed and the shear friction factor 0.6 indicates good agreement between the simulated results and the experiment results. As the cutting speed is increased from 22m/min to 54m/min at higher feed rate, a larger strain to an extent of up to 6.55mm/mm, a maximum value of 810MPa stress and higher temperature localization to an extent of 620°C at tool tip were observed.