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Item Process parameter optimization for ultimate tensile strength of friction stir welded joint of Al-10Mg-8Ce-3.5Si aluminium alloy plates using Taguchi technique(Elsevier Ltd, 2022) D’Souza, A.D.; Rao, S.S.; Herbert, M.A.The Friction stir welding (FSW) process has become a popular method of joining metals, due to its clean and efficient nature of producing welds. The input process parameters: the tool rotation speed, tool feed and tool pin shape are the deciding parameters for an optimum output quality characteristic, the Ultimate tensile stress (UTS) of the weld joint. Here in this research, the Taguchi full factorial design technique is discussed for maximizing the UTS of the weld joint formed in Al-10Mg-8Ce-3.5Si aluminium alloy plates. The ANOVA of means and Signal to Noise ratios for UTS was used to assess the influence of each of the input process parameters on output UTS. The main effect plots of the ANOVA results demonstrated that, the tool rotation speed at level 2 or 1000 rpm, the tool feed at level 3 or 20 mm/min and tool pin shape at level 1 or triangular cross section, gave the optimum results for output UTS. The ANOVA for UTS also showed the percentage contribution of input process parameters; the shape of tool pin as 60.06%, the tool feed as 15.42% and shape of tool pin as 2.41%. The UTS value predicted by the Taguchi analysis was at 108.47 MPa which was in good agreement with the experimentally obtained value of 106.84 MPa. A nonlinear regression equation was developed by correlating the input process parameters, which could be used to predict the optimum UTS results. © 2022 Elsevier Ltd. All rights reserved.Item A comprehensive review of friction stir techniques in structural materials and alloys: challenges and trends(Elsevier Editora Ltda, 2022) Prabhakar, D.A.P.; Shettigar, A.; Herbert, M.A.; Gowdru Chandrashekarappa, M.; Pimenov, D.Y.; Giasin, K.; Prakash, C.Friction-stir techniques are the potential alternative to fusion-based systems for processing and welding metallic alloys and other materials. This review explores the advantages, applications, limitations, and future directions of seven friction-based techniques namely, Additive Friction Stir Deposition (AFSD), Friction Stir Additive Manufacturing (FSAM), Friction Stir Welding (FSW), Friction Stir Processing (FSP), Friction Surfacing (FS), Friction Stir Spot Welding (FSSW), and Friction Stir Lap Welding (FSLW). The basic underlying principle of these processes uses friction as a thermal energy source to weld/process/deposit materials. The common control parameters of all friction stir processing techniques are axial force, rotational speed, and weld or traverse speed. In addition, tool profiles and tool dimensions are known to influence the weld quality. The tool's rotational speed and axial force generate friction between the workpiece and tool material interface, which could plasticize the material. The additive powder bed friction stir process (APBFSP) is another new solid-state manufacturing technique that focus on fabricating the polymer matrix nanocomposites (PNC). In this, a hollow tool like AFSD and the fundamental principle of FSP are combined. The said parameters affect the quantity of material getting deposited/welded. However, weld speed/traverse speed alters the weld quality, and higher traverse speed results in porosity and voids in the welded/deposited/processed region. The only difference between AFSD and other friction stir techniques (FSTs) is that in the AFSD technique, the hollow rotating tool comprises two protrusions with different tool profiles (cylindrical, threaded cylindrical, and tapered cylindrical, square) used. Threaded cylindrical profile and tool steel as the tool material is the most commonly employed in FSTs. Apart from that, tungsten carbide is preferred for hard materials. The working principles and process parameters of FSTs that affect the part quality are discussed in detail. The above review gives the reader an understanding of the domain of FSTs that can be researched further. A summary of some of the potential research works with objectives, process parameters, and outcomes is highlighted. This will provide the readers with an overview of the work carried out by researchers across the globe. Finally, the potential research gaps for future directions to be explored soon across the globe are outlined. © 2022 The Author(s).Item Assessment of influence of process parameters on properties of friction stir welded Al-Ce-Si-Mg aluminium alloy(Institute of Physics Publishing helen.craven@iop.org, 2019) D’Souza, A.D.; Rao, S.S.; Herbert, M.A.The research on friction stir welding is mainly focused on welding of aluminium alloys. The material of interest in this research is an aluminium alloy known as Al-Ce-Si-Mg aluminium alloy. The FSW of this alloy finds applications in aerospace industry like joining of aircraft structure parts such as fuselage, cladding and engine components and in automotive industry for welding of parts of body structure and engine. The quality of the weld produced by FSW such as macrostructure defects, average grain size, ultimate tensile stress and weld zone hardness etc are dependent on input parameters like tool revolution, tool feed rate and tool pin profile. The weld defects like tunnel hole, worm hole and pin holes were not predominant in the tool revolution range of 800 to 1200 rpm and tool feed rate range of 10 to 20 mm min-1. The maximum ultimate stress was found to be lesser in the low and high tool revolution and tool feed rates compared to the medium speeds. The maximum value of UTS noted was 102.55 MPa for the weld at a tool revolution of 800 rpm and tool feed rate of 20 mm min-1 with a triangular pin profile tool, giving a joint efficiency of 67%. The Vickers hardness values were less at lower and higher speed ranges of tool revolution and tool feed rates for all the tool pin profiles used. The maximum value of Vickers hardness was noted for a tool revolution of 1000 rpm and tool feed rate of 20 mm min-1 with a triangular pin profile tool. The lowest grain size was observed for the tool revolution of 1000 rpm and tool feed rate of 20 mm min-1 with a triangular pin profile tool, indicating the inverse relation between hardness and grain size. In all the experiments it was observed that the triangular pin profile tool gives the best results at medium tool revolution and tool feed rate ranges. © 2019 IOP Publishing Ltd.Item Evaluation of Microstructure, Hardness and Mechanical Properties of Friction Stir Welded Al–Ce–Si–Mg Aluminium Alloy(Korean Institute of Metals and Materials, 2020) D’Souza, A.D.; Rao, S.S.; Herbert, M.A.Abstract: A vast majority of the research on friction stir welding(FSW) is mainly focused on welding of aluminium alloys. The research studies in this paper are based on one such alloy known as Al–Ce–Si–Mg aluminium alloy, of which, the microstructure and other mechanical properties of the friction stir welded joints are yet to be studied. The plates of Al–Ce–Si–Mg aluminium alloy were friction stir welded using a non consumable, rotating tool with triangular profile pin and circular shoulder, with different combinations of tool rotation speeds and weld speeds. The microstructure, hardness and mechanical properties of the weld were analyzed. The microstructure of the weld zones revealed that, the average grain size at the bottom of the Nugget Zone (NZ) is 5 ± 0.12 ?m and gradually increases to 15 ± 0.23 ?m at the top of the NZ. In the TMAZ the grain size is 20 ± 0.14 ?m and is bigger compared to the NZ. In the HAZ, the grain size is around 37 ± 0.21 ?m and is bigger than that in the TMAZ. The maximum Vickers hardness value at the NZ center is 231.9 ± 2 Hv, and uniformly reduces to 100 ± 2.4 Hv in the TMAZ and 65 ± 1.3 Hv in the HAZ and then increases to 98 ± 1 Hv in the base material (BM). The maximum ultimate tensile strength (UTS) of FSW joint was found to be around 102.55 ± 3 MPa with elongation at fracture of 2.5%. The BM UTS was 154 ± 4.5 MPa. For a tool rotation speed of 800RPM and a weld speed of 20 mm/min a maximum joint efficiency of 67%. was obtained. Hence these were chosen as the optimum process parameters to join the alloy Al–Ce–Si–Mg by FSW. Graphic Abstract: [Figure not available: see fulltext.] © 2019, The Korean Institute of Metals and Materials.Item 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.