Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
8 results
Search Results
Item Microstructural characterization and hardness evaluation of friction stir welded composite AA6061-4.5Cu-5SiC (Wt.%)(Defense Scientific Information and Documentation Centre, 2013) Shettigar, A.K.; Salian, G.; Herbert, M.A.; Rao, S.Recent developments in advanced materials research have led to the emergence of new materials having features like low density, high strength to weight ratio, excellent mechanical properties, heat and corrosion resistance. In friction stir welding (FSW), a non-consumable rotating welding tool is used to generate the frictional heat and plastic deformation of the material in the welding zone, which is in the solid state. The advantages of FSW as compared to the fusion welding are high joint strength, less defect weld, uniform distribution of grain structure in the weld zone and low power consumption. AA6061 with 4.5 % weight of copper and 5 % weight of SiC composite material has been prepared to conduct experiment and carry out characterization, evaluation of the mechanical properties. Micro-structural characterization of the weld zone is carried out by scanning electron microscope (SEM). Evaluation of hardness was also carried out across the weld zone. A successful method for FSW of AA6061-4.5(wt.%) Cu-5(wt.%) SiC has been developed. © 2013, DESIDOC.Item Microstructure and hardness of friction stir welded aluminium-copper matrix-based composite reinforced with 10 wt-% SiCp(Maney Publishing, 2014) Shettigar, A.; Veeresh Nayak, C.; Herbert, M.A.; Rao, S.S.In the present work, an attempt has been made to join aluminium-copper matrix-based composite reinforced with 10 wt-% SiCp, by the friction stir welding technique, at different combinations of tool rotational speed (710, 1000 and 1400 rev mm1) and welding speed (50, 63 and 80 mm min1) using square profiled friction stir welding tool. Welding parameters play a predominant role in improving the mechanical strength by minimising the defects. A good number of defect free joints were obtained at various combinations of rotational speed and welding speed. It has been observed that, rotational speed and welding speed have strong influence on microstructure, Vickers hardness and quality of welds. © W. S. Maney &Son Ltd 2014.Item Parameter investigation and optimization of friction stir welded AA6061/TiO2 composites through TLBO(Springer Science and Business Media Deutschland GmbH, 2022) Prabhu B, S.R.; Shettigar, A.; Herbert, M.A.; Rao, S.S.This paper explicates the joining of AA 6061/TiO2 composites by the friction stir welding (FSW) process. FSW experiments were conducted as per the three factors, three-level, central composite ivy– face-centered design method. Mathematical relationships between the FSW process parameters, namely tool geometry, welding speed, and tool rotational speed, and the output responses such as hardness, yield strength, and ultimate tensile strength were established using response surface methodology. Adequacies of established models were assessed through the analysis of variance method. Further, the paper elucidates the application of the teaching–learning-based optimization (TLBO) algorithm to identify the optimal values of input variables and to obtain an FSW joint with superior mechanical properties. The optimized experimental condition obtained from the TLBO yields an FSW joint with a UTS of 174 MPa, yield strength of 120 MPa, and hardness of 126HV. The study revealed that the result of the TLBO algorithm matched the findings of the FSW experiments. © 2021, The Author(s).Item Development of machine learning regression models for the prediction of tensile strength of friction stir processed AA8090/SiC surface composites(Institute of Physics, 2024) Adiga, K.; Herbert, M.A.; Rao, S.S.; Shettigar, A.K.; Vasudeva, T.V.Friction Stir Processing is a state-of-the-art technology for microstructure refinement, material property enhancement, and fabrication of surface composites. Machine learning approaches have garnered significant interest as prospective models for modeling various production systems. The present work aims to develop four machine learning models, namely linear regression, support vector regression, artificial neural network and extreme gradient boosting to predict the influence of FSP parameters such as tool rotational speed, tool traverse speed and groove width on ultimate tensile strength of friction stir processed AA8090/SiC surface composites. These models were developed through Python programming and the original dataset was divided into 80% for the training phase and 20% for the testing phase. The performance of the models was evaluated by root mean squared error, mean absolute error and R2. Based on the results and graphical visualization, it was observed that the XGBoost model outperformed other models with high accuracy in predicting UTS of AA8090/SiC surface composites. © 2024 The Author(s). Published by IOP Publishing Ltd.Item Unidirectional flipped multiple-pass friction stir process: an innovative step in the fabrication of in situ Al-Cu composites(Springer Science and Business Media Deutschland GmbH, 2024) Bajakke, P.A.; Vinayak, V.; Jambagi, S.C.; Bhajantri, V.; Deshpande, A.S.The in situ Al-Cu composites were manufactured by powder metallurgy with state-of-the-art microwave sintering tailed by friction stir process in two different ways: unidirectional overlapped two-pass and unidirectional flipped two-pass. Novelty is claimed in the flipped process. An attempt was made to investigate the addition of copper beyond the solubility limit and the critical composition of an Al-Cu alloy (4.6 wt.%). The overlapped process enforced higher temperature, cumulative strain, and strain rate. Since Al and Cu are high-stacking fault energy metals, both dynamic recrystallization and dynamic recovery occurred and resulted in grain refinement and higher fractions of Al2Cu. The self-hard and brittle nature of Cu and Al2Cu improved strength (Al-3wt.%Cu, 231.23 MPa), hardness (Al-6wt.%Cu, 82.5 HV), and deteriorated ductility (Al-7wt.%Cu, 5.2%). The formed Al2Cu at the interface were surrounded by Al particles and formed passive films Al2O3 and Cu2O enhanced corrosion resistance (Al-5wt.%Cu, 0.00717191 mpy). The process densely compacted the material, minimized porosity, decreased dislocation density, and increased strain aided in better electrical conductivity (Al-5wt.%Cu, 145.92%IACS). The flipped process circumvented excessive heating and embrittlement of the material thereby improving strength without loss of ductility (Al-7wt.%Cu, 235.85 MPa and 25.53%). Al-3wt.%Cu with minimum corrosion current (5.681 µA/cm2) exhibited maximum resistance to corrosion (0.169852 mpy). The highest electrical conductivity was noticed for (Al-5wt.%Cu, 104.17%IACS). © The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature 2024.Item Comparative analysis of flipped and overlapped microwave sintered plus friction stir processed in-situ Al-Cu composites(Springer Nature, 2024) Vinayak, V.R.; Bajakke, P.A.; Jambagi, S.C.; Bhajantri, V.; Deshpande, A.S.The in-situ Al-Cu composites were fabricated with Cu content more than the solubility limit (5.65%) and the critical composition of an Al-Cu alloy (4.6%). A powder metallurgy route with state-of-the-art microwave sintering and friction stir process with overlapped and flipped conditions was attempted. The overlapped friction stir resulted in a minimum area of nugget region, unidirectional material mixing, high heat input in successive passes, and brittleness in the material. This accounted for the material to exhibit high strength with low ductility. Whereas flipped friction stir leads to a maximum area of stir zone, bidirectional material mixing, and similar thermal cycles in individual passes and avoids excessive heating. This facilitated the material to possess maximum strength by retaining ductility. The newly developed in-situ Al-Cu composite material (with Cu wt% in ranges of 8–12) possesses equivalent strength, ductility, electrical conductivity, and rate of corrosion compared to copper. Notably, these attributes, combined with its cost-effectiveness, position this material as a promising alternative to copper conductors in electrical applications. From the present investigation, it is strongly recommended to choose a flipped friction stir for better properties. © Qatar University and Springer Nature Switzerland AG 2024.Item Influence of weld parameters on the tribocorrosion behaviour of friction stir welded AA5052 in the marine environment(Elsevier Ltd, 2025) Anantharam, G.S.; Bhole, K.B.; Kuriachen, B.; Arya, S.B.The study involves tribocorrosive investigation of FSW-AA5052 formed at tool-speeds of 800, 1000, and 1200 rpm and welding-speeds of 60, 80, and 100 mm/min, for which Pin-on-disc tests in conjunction with open-circuit-potential and potentiodynamic-polarization techniques were utilised. For microstructures EBSD, Optical images and XRD were taken. Results revealed that cast (?1.212 V; 332.43 ?m/year), 800 rpm (?1.213 V; 433.51 ?m/year) and 1000 rpm (-1.236 V; 227.45?m/year) welded samples showed better performance than all the 1200 rpm welded samples. Frictional characteristics of 800 rpm (CoF-1.28) and 1000 rpm (CoF-1.32) samples were better than other samples due to uniform and stable passivation. Elemental analysis showed Oxides and Chlorides of Al and Mg formed over the worn surfaces. © 2025 Elsevier LtdItem Investigation of the effect of process parameters on the mechanical properties of friction stir additive manufactured (FSAM) AA8090 alloy(Elsevier B.V., 2025) D A P, P.; Shettigar, A.K.; Herbert, M.A.; Korgal, A.; Adiga, K.Friction Stir Additive Manufacturing (FSAM), an emerging technique, falls under the category of sheet lamination additive manufacturing. It employs a layer-by-layer fabrication where all the plates should be flat and of the same size. This process was developed to fabricate near-net-shaped components and refined microstructures. FSAM has been extensively used in the fabrication of aluminum alloys for aerospace applications. In this work, FSAM has been carried out for AA8090 aluminum alloy. AA8090 is the second-generation Al-Li alloy with 2.3 % Li, lightweight, 10 % lower density and 11 % higher modulus than the existing commercial 2014 and 2024 Al alloy. The experiments were carried out at rotational speed (1000 – 2000 rpm), traverse speed (45–55 mm/min) and 1° constant tilt angle. The macrostructure and microstructure analysis were carried out. This was followed by microhardness and tensile test analysis. The microhardness was carried out at nine points on each layer and tensile specimen was made according to ASTM E8 standard. The maximum reduction in grain size, which is 62 %, maximum hardness value 113 HV and maximum tensile value 346.8 MPa were observed at 2000 rpm. The size of the grains decreased from the top layer into the bottom layers. The maximum hardness for all the experiments was observed in the re-stir zone of the specimens. It was concluded that with increase in process parameters, better mechanical and microstructural properties can be achieved. The fractography analysis showed the presence of dimples and tear ridges indicating a ductile fracture. © © 2025. Published by Elsevier B.V.