Faculty Publications
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Item Influence of Chloride Content and Exposure Time on Corrosion Behavior of AZ80 Wrought Mg Alloy(Springer Nature, 2020) Gote, G.D.; Naik, G.M.; Narendranath, S.This study aims to investigate the corrosion behavior of wrought AZ80 magnesium alloys in different chloride ion concentrations and exposure time. During the study, the effect of exposure time and chloride content on the corrosion resistance of AZ80 wrought Mg alloy has been studied with 2, 3.5, and 5 wt% NaCl aqueous solution for 12 h and 24 h exposure time. Charge transfer resistance for each sample was established using the Nyquist plot and corrosion rate obtained from polarization curve by adopting Tafel extrapolation method. Corrosion morphology was examined using scanning electron microscopy and XRD. The study revealed that corrosion product layer formed at initial stage was observed unstable after short exposure time which results in decrease in corrosion resistance at initial stage. An increase of chloride content in aqueous environment reduces the corrosion resistance of AZ80 wrought Mg alloy. © 2020, Springer Nature Singapore Pte Ltd.Item Development and Surface Engineering of TiNi Shape Memory Alloy(Springer Science and Business Media B.V., 2020) Soni, H.; Narendranath, S.; Mashninini, P.M.; Roy, A.; Sebin Binoy, T.; Jyothi, K.; Rojina, J.; Krishnan, A.Shape memory alloys are currently replacing many conventional materials due to their various useful properties. Besides shape recovery above austenitic temperature and pseudo-elasticity, high strength and good corrosion properties are one of the many mentionable properties of these alloys. Due to their intriguing properties, aerospace, biomedical and automotive industries are leading the research frontier for these smart materials. This chapter presents the results of an experimental investigation conducted on development of Ti rich shape memory alloy by arc melting and hot rolling, and its surface study when machined by wire-EDM. The developed and machined specimens of TiNi alloys were also tested. Tensile study of the specimens showed that material rigidity has decreased due to intensive rolling process. Scan electron microscopic analysis of the fractured surface confirmed that the mode of failure of the rolled specimen was ductile in nature. Characteristic properties like necking, dimple formation, cracks which are related to ductile failure of metallic materials are clearly visible in the SEM micrographs. Micro hardness test revealed that micro hardness of the rolled specimens are much higher than as cast TiNi alloy and less along the edge of the fracture surface compared to bulk rolled material. © 2020, Springer Nature Switzerland AG.Item Effect of process parameters on centrifugally cast Al-Si FGM(Minerals, Metals and Materials Society 184 Thorn Hill Road Warrendale PA 15086, 2013) Kiran Aithal, K.; Desai, V.; Narendranath, S.; Mukunda, P.G.Functionally Graded Materials (FGM) are such kind of materials wherein the properties and structure are varied from one end of the cast to the other intentionally. Centrifuge technique has been used in this study to produce Al-Si FGMs. Several process parameters determine the microstructure and the distribution of phases in the FG casting. These parameters include the size and initial concentration of alloying element, the centrifugal force, solidification rate, cooling rate. In this work an attempt has been made to produce FGMs using three different process variables such as mold temperature, melt temperature and mold rotational speed, their effect on the structure and properties. For this study Al-17wt%Si is used. From the results it is seen that for a particular melt and mold temperatures by increasing the mold rotation speed enhances the segregation of the Si particles at the one end of the casting. Similarly increasing mold or melt temperature only, increases the segregation.Item Effect of thermal treatment on the wear behavior of lean duplex stainless steel and super duplex stainless steels(Institution of Engineering and Technology journals@theiet.org, 2013) Naveen Kumar, R.; Davangeri, M.B.; Joshi, A.G.; Narendranath, S.; Kadoli, R.The duplex stainless steel (DSS) is a two phase microstructure of about equal proportion of austenite (chromium- nickel) and ferrite (chromium). Austenite is ductile in nature and ferrite is brittle in nature, this combination provides an excellent mechanical properties (hardness, impact toughness etc) and corrosion resistance [1]. This paper deals with the study of dry sliding wear of Lean duplex stainless steel (AISI 304) and super duplex stainless steel (AISI 310) as a function of heat treatment conditions. The wear test specimens were heat treated at 850°C and followed by oil quenching. These wear tests are carried out using pin on disk technique at; (i) constant sliding velocity and different sliding distances, (ii) constant sliding distance and different sliding velocity and (iii) varying load and the weight loss methodology is used to calculate the wear volume. Results related to the AISI 304 wear showed that the hardness introduced due to the presence of sigma phase plays an important role on wear behavior for this type of steel.Item State-of-the-art finite element modeling of rotorcraft main rotor blade root end for bird strike damage analysis(Soc. for the Advancement of Material and Process Engineering bookorders@sampe.org, 2016) Vijaya Kumar, R.V.; Naik, D.C.; Kadoli, R.; Narendranath, S.This paper demonstrates the state-of-the-art composite modeling methodology to investigate the bird strike phenomenon using available numerical bird models through experimental tests and simulation tools. The present work is based on the application of non-linear explicit finite element analysis to simulate the response of rotorcraft main rotor blade root end under high velocity impact load. The damage behavior of blade under soft body impact depends upon bird size, blade size, blade span wise location of impact and bird orientation with respect to hitting location, blade rotational speed and rotorcraft cruise speed. Bird model is considered as hydrodynamic with length to diameter ratio of 2. A bird strike event is characterized by loads of high intensity and short duration. A transient explicit non-linear finite element based impact analysis using Autodyn has been carried out to predict bird strike resistance to withstand 1.0 kg bird at critical flight condition. Numerical analysis indicates that blades do not tear which agrees well with the physical test conducted. © 2016 by Hindunstan Aeronautics Limited. Published by the Society for the Advancement of Material and Process Engineering with permission.Item Effect of process parameters on centrifugally cast Al-Si FGM(Springer International Publishing, 2016) Kiran Aithal, A.S.; Desai, V.; Narendranath, S.; Mukunda, P.G.Functionally Graded Materials (FGM) are such kind of materials wherein the properties and structure are varied from one end of the cast to the other intentionally. Centrifuge technique has been used in this study to produce Al-Si FGMs. Several process parameters determine the microstructure and the distribution of phases in the FG casting. These parameters include the size and initial concentration of alloying element, the centrifugal force, solidification rate, cooling rate. In this work an attempt has been made to produce FGMs using three different process variables such as mold temperature, melt temperature and mold rotational speed, their effect on the structure and properties. For this study Al-17wt%Si is used. From the results it is seen that for a particular melt and mold temperatures by increasing the mold rotation speed enhances the segregation of the Si particles at the one end of the casting. Similarly increasing mold or melt temperature only, increases the segregation. © The Minerals, Metals & Materials Society 2016.Item Effect of Sigma (σ) phase on Mechanical and Dry sliding wear(Elsevier Ltd, 2017) Davanageri, M.; Narendranath, S.; Kadoli, R.In this paper, the wear behaviour of heat treated (oil and water quenched) super duplex stainless steel (SDSS) AISI 2507 was studied using dry sliding wear test rig. Initially as received materials was solution treated at 1050°C for duration of 2 h to achieve a balanced austenite (γ) and ferrite (δ) microstructure. The effect of different heat treatment techniques on microstructure and wear behaviour was studied by heat treating specimen at 850°C for duration of 1 h and was followed by oil and water quenching. The microstructure and crystal structure were studied through scanning electron microscope (SEM) and X-ray diffraction. The sliding wear test was employed with variation in load and speed at constant sliding distance. The results reveal that wear rate increased with increase in wear parameters. The oil quenched exhibited better wear resistance than water quenched and solution treated specimen. The worn surface morphology were analysed through SEM micrographs. © 2017 Elsevier Ltd.Item Optimization of Parameters Influencing Tensile Strength of Inconel-625 Welded Joints Developed Through Microwave Hybrid Heating(Elsevier Ltd, 2018) Badiger, R.I.; Narendranath, S.; Srinath, M.S.Processing of bulk metals through microwave energy in recent years is finding widespread applications and is being prominently accepted by the manufacturing industries. Present work, investigates the effect of process parameters on the tensile strength of Inconel-625welded joints produced through microwave hybrid heating using design of experiments. Experiments were carried out by using Taguchi's L16 factorial design of experiment method. Input parameters chosen were separator type; susceptor type and filler powder size. The output response chosen was ultimate tensile strength. Optimization of the process parameters is done through Taguchi method and percentage influence of each process parameter on the strength of weld is determined using ANOVA method. Combination of parameters with graphite separator, SiCsusceptor and finer filler powder yields optimum result. © 2017 Elsevier Ltd.Item Fault Diagnosis of Face Milling Tool using Decision Tree and Sound Signal(Elsevier Ltd, 2018) Madhusudana, C.K.; Kumar, K.; Narendranath, S.The monitoring of machining process can improve the quality of product and economy of production. The monitoring system helps to recognize and monitor the surface roughness, dimensional tolerance and tool condition. In this way, the condition monitoring system provides precise dimensional products, high productivity and enhanced machine tool life. This paper presents the classification of healthy and faulty conditions of the face milling tool using Decision tree (J48 algorithm) technique through machine learning approach. The sound signals of the face milling tool under healthy and faulty conditions are acquired. A set of discrete wavelet features are extracted from the sound signals using discrete wavelet transform (DWT) method. Decision tree technique is used to select prominent features out of all extracted features. The selected features are fed to the same algorithm for classification. Output of the algorithm is used to study and categorize the tool conditions. The decision tree model has provided a good classification accuracy of about 81% for the given sound signals and can be considered for fault diagnosis/condition monitoring. From the experimental results, it is suggested that the proposed method which comprises of decision tree and DWT techniques with sound signals can be recommended for the applications of fault diagnosis of the face milling tool. © 2017 Elsevier Ltd. All rights reserved.Item Experimental investigation and optimization of WEDM process parameters for Ti50Ni48Co2 shape memory alloy(Elsevier Ltd, 2018) Reddy, D.; Soni, H.; Narendranath, S.Shape Memory Alloys (SMAs) are known for their unique properties such shape memory effect and superelasticity along with biocompatibility, good ductility, corrosion and wear resistance and better fatigue strength. NiTi alloys are the most important Shape Memory alloys, which are immensely used in various fields of science. The machining of these difficult to cut alloys by conventional machining processes poses various difficulties and brings about changes in the properties of material. Hence, varieties of non-conventional machining techniques have been employed. Wire Electric Discharge machining is one of these non-conventional machining processes, which is used for machining of all conductive materials and intricate shapes. In the present study, the Wire EDM characteristics of Ti50Ni48Co2 have been studied. The effect of various process parameters such as Pulse on time, Pulse off Time and Servo Voltage on the machining characteristics such as Material removal rate (MRR) and Surface Roughness (SR) have been investigated. The experiments were designed as per Taguchi L9 Orthogonal Array. The input parameters are also optimized using Multi-objective Grey Relational Analysis (GRA) in order to maximize MRR and minimize SR simultaneously. Pulse on Time (Ton) =125μs, Pulse off Time (Toff) =35μs and Servo Voltage (SV) =40V were found as a best combination of process parameters for machining of Ti50Ni48Co2 alloy to achieve the higher MRR with better surface roughness. The characterization of the machined surface has been carried out with respect to microstructure, recast layer thickness and microhardness at the optimized process parameters. Micro cracks, micro globules were noticed on the machined surface and harder surface has been found near the machined surface during the microhardness analysis. © 2018 Elsevier Ltd. All rights reserved.