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The main purpose of the present work is to study the effect of tool pin profiles on mechanical properties of welded plates made with two different aluminium alloy plates.

The welded plates were fabricated with the three different kinds of pin profiled tools such as taper cylindrical, taper threaded cylindrical and stepped cylindrical pin profiles. Tensile properties of welded plates were evaluated using tensile testing machine at room temperature. Microstructures studies were carried out using scanning electron microscope.

Tensile properties were improved with the use of taper threaded cylindrical pin tool in friction stir welding process when compared with taper cylindrical and stepped cylindrical pin tools. This is due to refinement of grains and mixing of plasticized material occurred with generation of sufficient heat with the taper threaded pin tool. Through these studies, it was confirmed that friction stir welding can be used to weld Al6061 and Al2014 aluminium alloy plates.

In the present study, the friction stir welding is performed with constant process parameters such as tool rotational speed of 900 rpm, transverse speed of 24 mm/min and tilt angle of 1°.

Aluminium alloys are widely using in automotive and aerospace industries due to holding a high strength to weight property. These aluminium alloy blanks can be developed with friction stir welding method with better properties.

Very limited work had been carried out on friction stir welding of aluminium alloys of Al 6061 and Al2014 with different tool pin profiles. Furthermore, this work analyzed with tensile properties of welded plates correlated with weld zone microstructures.

The purpose of this paper is to investigate the impact of ultrasonic vibration (UV) and tool pin profile on mechanical properties and microstructural behaviour of AA7075-T651 and AA6061-T6 joints was analysed.

The joints were fabricated using three different tool pin profiles such as cylindrical, square and triangle. For each tool pin profile, two different UV powers of 1.5 kW and 2 kW were used.

On both the advancing and retreating sides of the weld, the thermo-mechanically affected zone has the lowest microhardness. In all joints, the tensile fracture locations match to the minimum hardness values. Field emission scanning electron microscope fractography of tensile tested specimens reveals heterogeneous modes of brittle, shear and ductile fracture. Three-point bending analysis was performed to determine the ductility and soundness of the weld joint. The acoustic softening effect of UV, as well as the static and dynamic ratio of tool pin profile, plays an important role in determining the material flow and mechanical behaviour of the joint.

Dissimilar aluminium joining fascinates many applications like aircraft, aerospace, automobiles, ship building and electronics, where fusion welding is a very intricate process because of the deviation in its physical and chemical properties.

From this study investigation, it is found that the square pin profiled tool with 2 kW UV power produces metallurgical defect-free and mechanically sound weld with maximum tensile strength, hardness and bending load of 297 MPa, 151HV and 3.82 kN, respectively.

This study aims to predict the mechanical properties such as equivalent tensile strength and micro-hardness of friction-stir-welded dissimilar aluminium alloy plates AA 6063-O and AA 2014-T6, using artificial neural network (ANN).

The ANN model used for the experiment was developed through back propagation algorithm. The input parameter of the model consisted of tool rotational speed and weld-traverse speed whereas the output of the model consisted of mechanical properties (tensile strength and hardness) of the joint formed by friction-stir welding (FSW) process. The ANN was trained for 60% of the experimental data. In addition, the impact of the process parameters (tool rotational speed and weld-traverse speed) on the mechanical properties of the joint was determined by Taguchi Grey relational analysis.

Subsequently, testing and validation of the ANN were done using experimental data, which were not used for training the network. From the experiment, it was inferred that the outcomes of the ANN are in good agreement with the experimental data. The result of the analyses showed that the tool rotational speed has more impact than the weld-traverse speed.

The developed neural network can be used to predict the mechanical properties of the weld. Results indicate that the network prediction is similar to the experiment results. Overall regression value computed for training, validation and testing is greater than 0.9900 for both tensile strength and microhardness. In addition, the percentage error between experimental and predicted values was found to be minimal for the mechanical properties of the weldments. Therefore, it can be concluded that ANN is a potential tool for predicting the mechanical properties of the weld formed by FSW process. Similarly, the results of Taguchi Grey relational analysis can be used to optimize the process parameters of the weld process and it can be applied extensively to ascertain the most prominent factor. The results of which indicates that rotational speed of 1,270 rpm and traverse speed of 30 mm/min are to be the optimized process parameters. The result also shows that tool rotational speed has more impact on the mechanical properties of the weld than that of traverse speed.

The main purpose of the present work is to study the multi response optimization of dissimilar friction stir welding (FSW) process parameters using Taguchi-based grey relational analysis and desirability function approach (DFA).

The welded sheets were fabricated as per Taguchi orthogonal array design. The effects of tool rotational speed, transverse speed and tool tilt angle process parameters on ultimate tensile strength and hardness were analyzed using grey relational analysis, and DFA and optimum parameters combination was determined.

The tensile strength and hardness values were evaluated from the welded joints. The optimum values of process parameters were estimated through grey relational analysis and DFA methods. Similar kind of optimum levels of process parameters were obtained through two optimization approaches as tool rotational speed of 1150 rpm, transverse speed of 24 mm/min and tool tilt angle of 2° are the best process parameters combination for maximizing both the tensile strength and hardness. Through these studies, it was confirmed that grey relational analysis and DFA methods can be used to find the multi response optimum values of FSW process parameters.

In the present study, the FSW is performed with L9 orthogonal array design with three process parameters such as tool rotational speed, transverse speed and tilt angle and three levels.

Aluminium alloys are widely using in automotive and aerospace industries due to holding a high strength to weight property.

Very limited work had been carried out on multi objective optimization techniques such as grey relational analysis and DFA on friction stir welded joints made with dissimilar aluminium alloys sheets.

Recently, several studies have been performed on lap welding of aluminum and copper using friction stir welding (FSW). The formation of intermetallic compounds at the weld interface hampers the weld quality. The use of an intermediate layer of a compatible material during welding reduces the formation of intermetallic compounds. The purpose of this paper is to optimize the FSW process parameters for AA6063-ETP copper weld, using a compatible zinc intermediate filler metal.

In the present study, a three-level, three-factor central composite design (CCD) has been used to determine the effect of various process parameters, namely, tool rotational speed, tool traverse speed and thickness of inter-filler zinc foil on ultimate tensile strength of the weld. A total of 60 experimental data were fitted in the CCD. The experiments were performed with tool rotational speeds of 1,000, 1,200 and 1,400 rpm each of them with tool traverse speeds of 5, 10 and 15 mm/min. A zinc inter-filler foil of 0.2 and 0.4 mm was also used. The macrograph of the weld surface under different process parameters and the tensile strength of the weld have been investigated.

The feasibility of joining 3 mm thick AA6063-ETP copper using zinc inter-filler is established. The regression analysis showed a good fit of the experimental data to the second-order polynomial model with a coefficient of determination (R²) value of 0.9759 and model F-value of 240.33. A good agreement between the prediction model and experimental findings validates the reliability of the developed model. The tool rotational speed, tool traverse speed and thickness of inter-filler zinc foil significantly affected the tensile strength of the weld. The optimal conditions found for the weld were, rotational speed of 1,212.83 rpm and traverse speed of 9.63 mm/min and zinc foil thickness is 0.157 mm; by using optimized values, ultimate tensile strength of 122.87 MPa was achieved, from the desirability function.

Aluminium and copper sheets could be joined feasibly using a zinc inter-filler. The maximum tensile strength of joints formed by inter-filler (122.87 MPa) was significantly better as compared to those without using inter-filler (83.78 MPa). The optimum process parameters to achieve maximum tensile strength were found by CCD.

The weld joint mechanical properties of friction stir welding (FSW) are majorly reliant on different input parameters of the FSW machine. The study and optmization of these parameters is uttermost requirement and aim of this study to increase the suitability of FSW in different manufacturing industries. Hence, the input parameters are optimized through different soft computing methods to increase the considered objective in this study.

In this research, ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) of FSW prepared butt joints of AA6061 and AA5083 Aluminium alloys materials are investigated as per American Society for Testing and Materials (ASTM E8-M04) standard. The FSW joints were prepared by changing the three input process parameters. To develop experimental run order design matrix, rotatable central composite design strategy was used. Furthermore, genetic algorithm (GA) in combination (Hybrid) with response surface methodology (RSM), artificial neural network (ANN), i.e. RSM-GA, ANN-GA, is exercised to optimize the considered process parameters.

The maximum value of UTS, YS and EL of test specimens on universal testing machine was measured as 264 MPa, 204 MPa and 14.41%, respectively. The most optimized results (UTS = 269.544 MPa, YS = 211.121 MPa and EL = 17.127%) are obtained with ANN-GA for the considered objectives.

The optimization of input parameters to increase the output objective values using hybrid soft computing techniques is unique in this research paper. The outcomes of this study will help the FSW using manufacturing industries to choose the best optimized parameters set for FSW prepared butt joint with improved mechanical properties.

Presently, the materials used in light combat aircraft structures are aluminium alloys and composites. These structures are joined together through riveted joints. The weight of these rivets for the entire aircraft is nearly one ton. In addition to weight, the riveted connection requires a lot of tools, equipments, fixtures and manpower, which makes it an expensive and time-consuming process. Moreover, Al alloy is also welded using tungsten inert gas (TIG) welding process by proper control of process parameters. This process has limitations such as porosity, alloy segregation and hot cracking. To overcome the above limitations, an alternative technology is required. One such technology is friction stir welding (FSW), which can be successfully applied for welding of aluminium alloy in LCA structures. Therefore, this paper aims to compare the load carrying capabilities of FSW joints with TIG welded and riveted joints.

FSW joints and TIG welded joints were fabricated using optimized process parameters, followed by riveted joints using standard shop floor practice in the butt and lap joint configurations.

The load-carrying capabilities of FSW joints are superior than those of other joints. FSW joints exhibited 75 per cent higher load-carrying capability compared to the riveted joints and TIG-welded joints.

From this investigation, it is inferred that the FSW joint is suitable for the replacement of riveted joints in LCA and TIG-welded joints.

Friction stir butt joints exhibited 75 per cent higher load-carrying capability than riveted butt joints. Friction stir welded lap joints showed 70 per cent higher load-carrying capability than the riveted lap joints. Friction stir butt joints yielded 41 per cent higher breaking load capabilities than the TIG-welded butt joints. Moreover, Friction stir lap weld joints have 57 per cent more load-carrying capabilities than the TIG-welded lap joints.

Friction stir welding (FSW) and underwater friction stir welding (UWFSW) of aluminium alloy 2024-T351 was carried out, with a chosen set of parameters, namely, rotational speed of 450 rpm, 560 rpm and 710 rpm, welding speed of 25 mm/min, 40 mm/min and 63 mm/min and tool tilt angle of 0º, 1° and 2º. This study aims to understand the correlation between temperatures and weld parameters, finite element simulation was carried out using Abaqus®.

Comparative analysis of the mechanical properties of the samples welded with FSW and UWFSW was carried out and correlated with that of the microstructures. Microhardness survey was also conducted across the weldments to support the findings.

Samples welded with higher rotational speed and low traverse speed favoured good quality, defect-free welds with enhanced material flow. Underwater welded samples resulted in improved mechanical properties than that of the samples welded with conventional FSW. Higher cooling rates resulted in finer grains in all UWFSW samples than that of conventional FSW samples, which, in turn, also reflected in the microhardness survey done across the weldments. Among the chosen window of the parameter, samples welded with 710 rpm, 25 mm/min and 2° had shown improvement in mechanical properties.

This work was carried out in a milling machine, which limits the rotational speed which could be used. Optimistically, this limitation also paves way for using the commonly available milling to be used for FSW.

This original research study shall open opportunities to enable FSW and UWFSW to be done on similar/dissimilar joints of varying composition. Additionally, this research study throws enough light on the age – hardenable aluminium alloy being welded in a commonly available milling machine.

Dissimilar materials found applications in the structural fields to withstand the different types of loads and provide multi-facet properties to the final structure. Aluminum alloy materials are mostly used in aerospace and marine industries to provide better strength and safeguard the material from severe environmental conditions. The purpose of this study is to develop new material with superior strength to challenge the severe environmental conditions.

In the present investigation, friction stir welding (FSW) dissimilar joints were prepared from AA6061 and AA5083 aluminum alloys, and the weld nugget (WN) was reinforced with hard reinforcement particles such as La₂O₃ and CeO₂. The tribological and mechanical properties of the prepared materials were tested to analyze the suitability of material in the aerospace and marine environmental conditions.

The results showed that the AA6061–AA5083/La₂O₃ material exhibited better mechanical and tribological characteristics. The FSW dissimilar AA6061–AA5083/La₂O₃ material exhibited lower wear rate of 7.37 × 10⁻³ mm3/m and minimum friction coefficient of 0.31 compared to all other materials owing to the reinforcing effect of La₂O₃ particles and the fine grains formed by FSW process at WN region. Further, FSW dissimilar AA6061–AA5083/La₂O₃ material displayed a maximum tensile strength and hardness of 378 MPa and 118 HV, respectively, among all the other materials tested.

This work is original and novel in the field of materials science engineering focusing on tribological characteristics of friction stir welded dissimilar aluminum alloys by the reinforcing effect of hard particles such as La₂O₃ and CeO₂.

This paper aims to predict the performance of friction stir welded AA8090 joint.

In the present study, Al-Li AA8090 plates are butt joined using friction stir welding (FSW). The experiments are designed and optimized using a Taguchi-orthogonal array. The experiments are conducted at three different process parameters, i.e. tool rotational speed (TRS), tool transverse speed (TTS) and dwell time (DT). The ultimate tensile strength (UTS) and microhardness (MH) are considered as response parameters. In addition, a statistical tool (ANOVA) is used to check the adequacy of experiment results.

The maximum UTS of 220 MPa is obtained at a TRS of 1,400 rpm, tool TTS of 40 mm/min and DT of 15 s. The maximum microhardness is obtained for 1,400 rpm, 25 mm/min and 8 s, i.e. 108.6 HV. The microstructural showed that the minimum grain is observed at the nugget zone. Fractography analysis revealed the ductile behaviour of fractured surfaces.

From the reported literature, it has been observed that very limited work is reported on the FSW of AA8090 alloy. Further, the thermal behaviour of welded joint is also observed in this experimental work.