Faculty Publications

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Author: search.filters.author.Narendranath, S.Subject: search.filters.subject.Ternary alloys

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    Effect of electrode material in wire electro discharge machining characteristics of Ti50Ni50-xCux shape memory alloy
    (Elsevier Inc. usjcs@elsevier.com, 2015) Manjaiah, M.; Narendranath, S.; Basavarajappa, S.; Gaitonde, V.N.
    Abstract TiNiCu alloy belongs to new class of shape memory alloy (SMA), which exhibits superior properties like shape memory effect, super elasticity and reversible martensitic transformation phase and thus find broad applications in actuators, micro tools and stents in biomedical components. Even though, SMA demonstrates outstanding property profile, traditional machining of SMAs is fairly complex and hence non-traditional machining like wire electric discharge machining (WEDM) has been performed. Hence, there is a need to investigate the WEDM performance characteristics of shape memory alloys due to excellent property profile and potential applications. In the present investigation, various machining characteristics like material removal rate (MRR), surface roughness, surface topography and metallographic changes have been studied and the influence of wire material on TiNiCu alloy machining characteristics has also been evaluated through ANOVA. Ti50Ni50-xCux=10, 20 was prepared by vacuum arc melting process. The proposed alloy as-cast material exhibits austenite property (B2 phase) and having higher hardness when compared to TiNi alloy. The investigation on WEDM of Ti50Ni50-xCux alloy reveals that the machining parameters such as servo voltage, pulse on time and pulse off time are the most significant parameters affecting MRR as well as surface roughness using both brass and zinc coated brass wires. However, machining with zinc coated brass wire yields reduced surface roughness and better MRR and also produces less surface defects on the machined surface of Ti50Ni50-xCux alloys. © 2015 Elsevier Inc. All rights reserved.
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    ANN and RSM modeling methods for predicting material removal rate and surface roughness during WEDM of Ti50Ni40Co10 shape memory alloy
    (AMSE Press 16 Avenue Grauge Blanche Tassin-la-Demi-Lune 69160, 2017) Soni, H.; Narendranath, S.; Ramesh, M.R.
    Present study exhibits the comparison between experimental and predicted values. Where response surface method (RSM) and artificial neural network (ANN) were used as predictor for the prediction of wire electro discharge machining (WEDM) responses such as the material removal rate (MRR) and surface roughness (SR) during the machining of Ti50Ni40Co10 shape memory alloy. It has been noticed from the literature survey that pulse on time and servo voltage are most important process parameters for the machining of TiNiCo shape memory alloy, hence there are five levels of these process parameters were chosen for the present study. For the present study selected alloy has been developed through vacuum arc melting and L-25 orthogonal array has been created by using Taguchi design of experiment (DOE) for experimental plan. During the present study ANN predicted values have been found to very close to experimental values compare to RSM predicted values, hence it can be say that ANN predictor gives more accurate values compare to RSM predicted values. © 2017 AMSE Press. All rights reserved.
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    Investigation on material removal rate, surface and subsurface characteristics in wire electro discharge machining of Ti50Ni50-xCux shape memory alloy
    (SAGE Publications Ltd info@sagepub.co.uk, 2018) Manjaiah, M.; Narendranath, S.; Basavarajappa, S.; Gaitonde, V.
    TiNiCu shape memory alloys have superior properties as compared with NITINOL due to their greater ductility, reduced hysteresis temperature range, and quick actuation response. The present article investigates the surface and subsurface modifications occurring due to wire electro discharge machining of Ti50Ni50-xCux shape memory alloy. The machining experiments were performed considering the pulse on time, pulse off time, and servo voltage as the process parameters. The influence of these parameters was studied on the material removal rate, surface roughness, recast layer thickness, microhardness, and phase changes in the machined surface. Longer pulse on time causes greater discharge energy, hence leading to higher material removal rate, surface roughness, and recast layer thickness. The machined surface hardness increased up to 900 Hv, which is about 59% increase with respect to the base material for longer pulse on time due to the recast layer thickness and the formation of oxides. A phase change on the machined surface was observed to cause the shape recoverability of the alloy. The microstructure, composition through EDAX, and the phase changes of the machined surface are also discussed in the article. © 2015, © IMechE 2015.
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    Experimental Investigation on Effects of Wire Electro Discharge Machining of Ti50Ni45Co5 Shape Memory Alloys
    (Springer Netherlands rbk@louisiana.edu, 2018) Soni, H.; Narendranath, S.; Ramesh, M.R.
    TiNiCo shape memory alloy is most popular shape memory alloy for biomedical applications due to their outstanding properties such as shape memory effect, pseudoelasticity and transformation temperature. Machining of such kind of alloys is very difficult through conventional machining process is very difficult because they may affect their internal properties of these alloys. However conventional machining processes give poor surface quality during the machining hence non-conventional machining processes such as (wire electro discharge machining, water jet machining and electro discharge machining etc.) are more suitable for machining of such kind of alloy. From the literature it has been found that Wire electro discharge machining (WEDM) is more suitable non-conventional machining process for such kind of alloy. Present study exhibits the effects WEDM characteristics of Ti50Ni45Co5 shape memory alloy. L-9 orthogonal array has been created by using Taguchi as a design method for machining of selected alloy and machined surface characterization has been carried out at the optimized process parameters with respect to microstructures, surface topography, microhardness, XRD analysis and residual stresses. To find the optimum setting of the input process parameters a couple of optimization techniques are used, namely principal component analysis (PCA) and Gray relational analysis (GRA) technique. 125?s pulse on time (Ton), 35?s pulse off time (Toff) and 40V servo voltage (SV) were found as an optimal setting for the higher material removal rate (MRR) with better surface roughness (SR) in the present study. Moreover, characterization of the machined surface is performed with respect to microstructures, surface topography, microhardness analysis, XRD and residual stresses. Harder surface observed near the cutting edge and TiNio3 Tio2 and CuZn were noticed on the surface of machined component through XRD analysis. However, compressive residual stress has been noticed on the machined surface during WEDM process. © 2018, Springer Science+Business Media B.V., part of Springer Nature.
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    Impact of variation in wire electro discharge machining responses of homologous TiNiCu shape memory alloys for smart applications: An experimental investigation
    (Institute of Physics Publishing helen.craven@iop.org, 2018) Roy, A.; Narendranath, S.
    In this study, three distinct TiNiCu alloys were processed using wire electro discharge machining. These alloys are potential materials for smart applications owing to their fast actuation response resulting from suitable martensitic transformation temperatures. Due to differences in their physical property (thermal conductivity in this case), these alloys exhibit variation in machining response during wire electro discharge machining. Based on wire electro discharge machining responses of these alloys, order of thermal conductivity of these alloys are concluded in this study. This investigation aims at addressing the variation in terms of kerf width, recast layer thickness and machined surface microhardness to form the basis for production of intricate components. Ti50Ni40Cu10 alloy exhibited diverging machining response compared to its counterparts. Influential parameter for a given machining response changes depending on thermal property of the workpiece which makes it vital to investigate and choose the parameters in a more sensible manner while machining such materials. It was found that kerf width decreases with increasing servo voltage whereas recast layer thickness (mostly influenced by pulse off duration) increases with increasing pulse off duration. Microhardness of the machined surface (mostly influenced by pulse on duration) increases at higher discharge energy levels owing to presence of oxides formed during spark erosion process. Microhardness of Ti40Ni50Cu10 was found to be high (approximately 560 Hv) compared to its counterparts which was due to presence of Ni rich and ?-CuTi precipitates which also affected its phase transformation temperatures. © 2018 IOP Publishing Ltd.
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    Effects of Wire Electro-Discharge Machining Process Parameters on the Machined Surface of Ti 50 Ni 49 Co 1 Shape Memory Alloy
    (Springer Netherlands rbk@louisiana.edu, 2019) Soni, H.; Narendranath, S.; Ramesh, M.R.
    Wire electro-discharge machining is one of the advanced machining processes which can machine all conductive materials without changing their internal properties. Pulse on time and servo voltage are the most influential process parameters of wire electro-discharge machining. In the present study, attempts have been made to study the effects of these process parameters on the machined surface of Ti 50 Ni 49 Co 1 shape memory alloy by adopting a two process parameters experimental design approach. Cutting speed and surface roughness were considered as output parameters; surface crack density, microhardness and XRD analysis were carried out at the higher and lower values of these parameters. Higher surface crack density has been found at high values of cutting speed (125 ?s pulse on time and 20 V servo voltage) while it is lower at the lower value of cutting speed (105 ?s pulse on time and 60 V servo voltage). Moreover, a harder surface was found near the machined surface. By XRD analysis it was found that the crystal size of the WED machined surface was reduced at high T on and lower SV. © 2018, Springer Science+Business Media B.V., part of Springer Nature.
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    Effect of Annealing and Aging Treatment on Pitting Corrosion Resistance of Fine-Grained Mg-8%Al-0.5%Zn Alloy
    (Springer, 2019) Naik, G.M.; Narendranath, S.; Satheesh Kumar, S.S.; Sahu, S.
    In order to study the influence of plastic deformation, annealing and aging treatment on pitting corrosion, the AZ80Mg alloy was subjected to equal-channel angular pressing (ECAP) by route R at 325°C for up to 4 ECAP passes (P) and annealing conditions of 523 K, 623 K and 723 K followed by aging treatment at 6 h and 12 h. A microhardness and corrosion study was accomplished and microstructural evolution was recorded using optical microscopy (OM), scanning electron microscopy and electron backscatter diffraction (EBSD). OM and EBSD analysis showed that a fine-grain microstructure with average grain sizes of 32.87 µm and 6.35 µm was achieved after 2P and 4P of ECAP, respectively. During annealing and aging treatment, the fine-grain Mg alloy revealed that the maximum microhardness and improved corrosion resistance were observed mainly due to redistribution of ?-secondary phases. Specifically, 12 h aged specimens at 523 K represented maximum microhardnesses of about 85 Hv and 87 Hv for ECAP-2P and -4P, respectively. Also, 12 h aging at 723 K appeared preferable for accomplishing enhanced corrosion properties. © 2019, The Minerals, Metals & Materials Society.
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    Effect of peak current and peak voltage on machined surface morphology during WEDM of TiNiCu shape memory alloys
    (Korean Society of Mechanical Engineers, 2020) Roy, A.; Narendranath, S.; Pramanik, A.
    This study considers the effect of wire electro discharge machining (WEDM) parameter peak current (Ip) and pulse peak voltage (Vp) on the machined surface morphology of TiNiCu shape memory alloys. Various defects of machined surfaces were identified and correlated with parameter values and measured average surface roughness (Ra) and average surface depth (Rz). It was found that the nature of the machined surface is highly influenced by the nature of sparking, which is dictated by levels of peak current and peak voltage used during machining. Distinctions between machining parameters resulting in “rough-cut” and “trim-cut” machining are reported along with deviations in output responses, which counters the trend reported in the literature. © 2020, The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature.
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    Recast Layer Formation during Wire Electrical Discharge Machining of Titanium (Ti-Al6-V4) Alloy
    (Springer, 2021) Pramanik, A.; Basak, A.K.; Prakash, C.; Shankar, S.; Sharma, S.; Narendranath, S.
    Titanium alloys, in particularly Ti-6Al-4V alloy is used enormously in many high-tech sectors specially in aerospace industries due to its superior properties. Machining process (for example wire electrical discharge machining) to reshape this alloy affects the integrity of the newly generated surfaces. This experimental study has identified three affected layers using scanning electron microscopy on the cross section of the machined titanium (Ti-6Al-4V) alloy surface generated from wire electrical discharge machining (WEDM). This study also explained the formation mechanism of those three layers as no detail investigation is available in this area so far. It was found that the top flaky layers are formed due to the highest cooling rate at the outermost surface, which is induced due to the low thermal conductivity of the titanium alloy as well as the quenching effect because of the existence of dielectric. The recast layer is formed at a cooling rate lower than that at the outer surface, where the melted material is resolidified very quickly without having any grain boundaries. The heat-affected zone appears at a slightly different color, which does not melt but experience heat treatment during the machining process. © 2021, ASM International.
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    Theoretical evolution of thermal behaviour of Ti-6Al-4V subjected to selective laser melting: A powder free approach
    (Elsevier GmbH, 2023) Dutta, J.; Bhanja, D.; Narendranath, S.
    Additive manufacturing (AM) processes are considered to be the pillar of the next industrial revolution due to their inherent qualities such as design flexibility, the ability to produce complex parts and prototypes, lower cost due to the reduced requirement of materials and curtailed lead time for manufacturing. Selective laser melting (SLM) is one of the most popular metallic AM technologies since it enables accurate control over part dimensions and fabrication of high resolution features. This research paper is aimed to develop an exact analytical model of three-dimensional thermal response captured in SLM of Ti based alloy (Ti-6Al-4V). A physical model has been proposed to predict the temperature profile during the metal additive manufacturing process with consideration of the effect of thermal history developed during moving laser heat source interaction. The corresponding mathematical solution is developed by employing an amalgamation of ‘Duhamel's theorem’ and ‘Finite Integral Transform method’. The parametric laser-substrate interaction phenomenon is the prime deciding factor for the successful accomplishment of the manufacturing process. This research paper theoretically investigates the thermal characteristics (peak temperature, temperature distribution curvature, pulse time, optical penetration depth, time of laser exposure, laser absorption radius, and so on) by employing Fourier's heat conduction model with a moving laser heat source. The theoretical estimation has been validated by the existing mathematical as well as experimental research outcomes. Present work might be an asset for deciding the design of process variables and protocols in terms of laser based additive manufacturing specifically the selective laser melting process. © 2022 Elsevier GmbH