Mechanical and Corrosion Behavior of Friction Stir Welded AA 6063 Alloy

Friction stir welding (FSW) is considered to be the most significant development in solid state metal joining processes. This joining technique is energy efficient, environmentally friendly, and versatile. In particular, it can be used to join high-strength aerospace aluminum alloys and other metallic alloys that are hard to weld by conventional fusion welding. The project aims to join Aluminum 6063 alloy plates by FSW and emphasize the (1) mechanisms responsible for the formation of welds without any defects, microstructural refinement, and (2) effects of FSW parameters on resultant microstructure, mechanical, and corrosion properties.

The Influence of the Mechanism of Double-Sided FSW on Microstructure and Mechanical Performance of AZ31 Alloy

In the friction stir welding (FSW) process, the final performance of weld joints is determined by microstructures influenced mainly by the heat input and mechanical deformation. In this research, the effects of FSW parameters, rotation speeds, and welding passes, on microstructure and mechanical properties of AZ31 alloy were systematically and comparatively studied. It was found that the microstructure at the joint center with multi-pass FSW could obtain a smaller average grain size compared with the single pass. The differences of the grain size were reduced significantly when the samples experienced the double-side FSW process. The mechanical performance results showed that the optimum strength (315 MPa) was achieved through the double-side FSW process with a rotation speed of 500 r/min and welding speed of 60 mm/min. The mechanism of the parameters and double-sided process on mechanical properties of the joint samples was elaborated.

Prediction of the optimal FSW process parameters for joints using machine learning techniques

In this work, a couple of dissimilar AA2024/AA7075 plates were experimentally welded for the purpose of considering the effect of friction-stir welding (FSW) parameters on mechanical properties. First, the main mechanical properties such as ultimate tensile strength (UTS) and hardness of welded joints were determined experimentally. Secondly, these data were evaluated through modeling and the optimization of the FSW process as well as an optimal parametric combination to affirm tensile strength and hardness using a support vector machine (SVM) and an artificial neural network (ANN). In this study, a new ANN model, including the Nelder-Mead algorithm, was first used and compared with the SVM model in the FSW process. It was concluded that the ANN approach works better than SVM techniques. The validity and accuracy of the proposed method were proved by simulation studies.

ANALYSIS OF TENSILE STRENGTH, CRYSTALLINITY, CRYSTALLITE SIZE, AND THERMAL STABILITY OF POLYPROPYLENE JOINED BY FRICTION STIR WELDING

This paper aims to investigate the joining of polypropylene using friction stir welding (FSW). FSW parameters were the rotation speed of 620 rpm, the travel speed of 7.3 mm/min, and 13 mm/min. The tensile test was performed using a universal testing machine, and the results of the tensile test were related to the crystallite size and degree of crystallinity. X-ray diffraction (XRD) was performed to examine the crystallite size and degree of crystallinity while thermal analysis was carried out using TGA/DSC. Besides, the effect of the degree of crystallinity on the thermal stability at the weld nugget area due to travel speed is explained in this paper. The findings showed that FSW with a travel speed of 7.3 mm/min had a higher crystallite size and degree of crystallinity than that with a travel speed of 13 mm/min, because there is a fusion of crystals and also recrystallization occurs, as an effect of the difference in the length of time exposed to heat during the FSW process. From the study results, it can be seen that the FSW with a 7.3 mm/minute travel speed has a higher crystal size and degree of crystallinity compare with the use of 13 mm/minute travel speed. The reason for that, the difference in heat exposure time during FSW affects crystal fusion and recrystallization. A sample with a travel speed of 7.3 mm/min had high tensile strength because it obtains sufficient heat for a more complete joint. In terms of thermal stability, the specimen with a lower travel speed showed a higher stability level than the specimen with a higher travel speed in that of the higher degree of crystallinity.

Optimization of FSW Process Parameters to Yield Maximum Shear Fracture Load of AA2024 Aluminum Alloy Joints

AA2024 Aluminum alloy has predominantly been used for making aircraft engine parts and frames. The normal welding process does not apply to join aluminum alloy. Because Al and its alloy have a low melting point and high thermal conductivity, which can easily lead to porosity and partially melting; as a result, Friction Stir Welding (FSW) has been employed to solve these issues. This work focused on the parameter’s optimization to the conceived maximum strength of AA2024 aluminum alloy. Four major parameters viz., tilt angle, shoulder diameter, welding speed, and rotational speed were selected. The formulation of empirical relationship was made using statistical tool design of experiment, and analysis of variance has been used to check the developed model’s adequacy. Furthermore, the response surface graphs were used to identify the maximum strength and its corresponding FSW parameters. The joint obtained the full power from the experimental results at a tilt angle of 1.5 deg., traverse speed of 15 mm/min, speed of tool 1100 rpm, and diameter of shoulder 24 mm.

Experimental and thermal investigation with optimization on friction stir welding of nylon 6A using Taguchi and microstructural analysis

Friction stir welding is an environmentally friendly process of joining due to the non-usage of flux, or any shield gas. Therefore, this article proposes an experimental and thermal investigation with optimization technique for studying the process of FSW on nylon 6A or polycaprolactam polymer composite plates. Specifically, the influence of input operating process parameters such as tool rotational speed (TRS), feed rate, and pitch values on the output response parameters like ultimate tensile strength (UTS), and hardness of welded joints is examined. In addition, L27 orthogonal array of Taguchi approach is employed for the optimization of design experiments of FSW parameters. The experimental setup is carried out with various process parameter combinations like 500, 1000, and 1500 rpm as TRS, 30, 40, and 50 mm as feed rate by varying the pitch values as 1, 2, and 3 mm. Further, the analysis of variance (ANOVA) also employed for finding the significant parameters of input process using the regression analysis equations. Finally, microstructural analysis is used to assess the mixing or dispersing uniformity of composites effectively. The experimental and optimum FSW parameters for maximum UTS are obtained at a feed rate of 30 mm/min, tool pitch of 3 mm, and the TRS of 500 rpm.

Experimental Investigation and Optimization on Friction Stir Welding of Nylon 6A Using Taguchi and ANOVA with Microstructural Analysis

Friction stir welding is an environmentally friendly process of joining due to the nonusage of flux, or any shield gas, and it does not produce any harmful gases when compared to the joining process of fusion. Therefore, this article proposes an experimental investigation and optimization technique for studying the process of FSW on nylon 6A or polycaprolactam polymer composite plates. Specifically, the influence of input operating process parameters such as tool rotational speed (TRS), feed rate, and pitch values on the output response parameters like ultimate tensile strength (UTS) and hardness of welded joints is examined. In addition, L27 orthogonal array of Taguchi approach is employed for the optimization of design experiments of FSW parameters. The experimental setup is carried out with various process parameter combinations like 500 rpm, 1000 rpm, and 1500 rpm as TRS, and 30 mm, 40 mm, and 50 mm as feed rate by varying the pitch values as 1 mm, 2 mm, and 3 mm. Further, the analysis of variance (ANOVA) is also employed for finding the significant parameters of input process using the regression analysis equations. Finally, microstructural analysis is used to assess the mixing or dispersing uniformity of composites effectively.

Correlative Analysis Between Tensile Properties and Tool Rotational Speeds of Friction Stir Welded Similar Aluminium Alloy Joints

Friction stir welding (FSW) is considered as the new joining technique which does not involve fumes like any traditional joining techniques. The attainment of good weld depends on proper combination of FSW parameters, and this combination varies with the materials that are being welded. The tool rotational speed is known as the most critical parameter towards the generation of heat required to produce the weld in friction stir welding. This parameter plays an important role in restructuring the stir zone. The variation of this parameter may yield certain results which are dependent on the type of materials being welded. This paper reports on the impact of the rotational speed variation on the tensile properties of AA6082-T6 joints. The rotational speed was varied while keeping all the other welding parameters constant. The analysis was performed comparatively on the specimens that were sampled from different locations of the joint. The joints produced through the rotational speed of 600 rpm showed good tensile properties compared to joints produced through other rotational speeds.

The Influence of Tool Shape and Process Parameters on the Mechanical Properties of AW-3004 Aluminium Alloy Friction Stir Welded Joints

The purpose of the following study was to compare the effect of the shape of a tool on the joint and to obtain the values of Friction Stir Welding (FSW) parameters that provide the best possible joint quality. The material used was an aluminium alloy, EN AW-3004 (AlMn1Mg1). To the authors’ best knowledge, no investigations of this alloy during FSW have been presented earlier. Five butt joints were made with a self-developed, cylindrical, and tapered threaded tool with a rotational speed of 475 rpm. In order to compare the welding parameters, two more joints with a rotational speed of 475 rpm and seven joints with a welding speed of 300 mm/min with the use of a cylindrical threaded pin were performed. This involved a visual inspection as well as a tensile strength test of the welded joints. It was observed that the value of the material outflow for the joints made with the cylindrical threaded pin was higher than it was for the joints made with the tapered threaded pin. However, welding defects in the form of voids appeared in the joints made with the tapered threaded tool. The use of the cylindrical tool resulted in higher values for about 37% of mechanical properties compared with the highest result for the tapered threaded joint. As far as the parameters were concerned, it was concluded that most of the specimens were properly joined for a rotational speed of 475 rpm. In the joints made with a welding speed of 300 mm/min, the material was not stirred properly. The best joint quality was given for a rotational speed of 475 rpm as well as a variety of welding speed values between 150 and 475 mm/min.

Experimental Investigation of Friction stir Welding Using Hybrid Alloys

Friction stir welding is an emerging solid state joining process which is used to join metals and alloys having low weldability. In this research work experimental analysis has been performed on FSW for AA 6061 and MgZ31B A. Effect of FSW parameters like tool rpm, tool transverse speed and tool pin profile are investigated. A vertical milling head is used to produce FSW joints. Hot work tool steel (H13) is used as a tool material and total 3 number of tools are manufactured namely as cylindrical pin, tapered pin and square pin. Tool transverse feed of 10, 15 and 20 mm/min and tool rotational speed of 800, 1000 and 1200 rpm are taken for the study. A full factorial method is used for three numbers of parameters and their three levels and total 27 numbers of experiments are conducted keeping all other parameters constant. As a response weld tensile strength of joints are tested according to ASME-IX. Response surface method (RSM) and Analysis of variance (ANOVA) is adopted for the statistical analysis. Chi square method is used for the validation purpose and a strong match has been found between predicted and actual value of weld tensile strength of joints. As a conclusion it has been derived that feed of 15 mm/min, tool rotational speed of 1200 rpm and tapered pin profile gives better weld strength for the given experimental conditions. Furthermore research can be carried out on Bobbin type tool, numerical analysis and multi pass of FSW tool.