Friction Stir Welding Process Parameters Research Articles

An Experimental Test and Optimization of Friction Stir Welding Process for AA6082 By using GRA

Friction stir welding (FSW) is a type of joining process, it uses solid state welding method, also it is widely used in same type and different types of welding like Al, Mg, Cu, Ti, and their alloys. In this study, friction stir welding of two aluminum alloys AA6082 is done with many sets of tool rotation speed, feed and axial force. In this experimental work FSW process was carried out for AA 6082 and optimization of that FSW process parameters were find out for maximum tensile strength values. Taguchi’s L4 orthogonal array was utilized for three parameters – tool rotational speed (TRS), traverse speed (TS), and axial force (AXF) with two levels. Several optimization was carried out with Taguchi method of grey relational tests. During the investigation obtained highest tensile strength value fourth sample 60.887 N/mm2 and lowest hardness strength value second sample 31HRB and bead appearance found very best surface occurred fourth test plates at the same time angle distortion observed very fine in the fourth test plate. The result was calculated for both ultimate tensile strength and hardness value. The expected grey relational grade was shifted from 0.704 to 0.792, it was the highest value received throughout this experimental results. It was mentioned that the multi-responses of FSW process was improved with this method.

Experimental Analysis on Mechanical Properties of Friction Stir Welding in Dissimilar Aluminum Alloys

Friction stir welding (FSW) is an innovative solid state joining technique and has been employed in industries for joining aluminum, magnesium, zinc and copper alloys. The FSW process parameters such as tool, rotational speed, welding speed, axial force, etc play major role in deciding the weld quality. A mathematical modeling was developed based on experiments to predict the tensile strength of dissimilar FSW aluminum alloys. The maximum tensile strength of 210 MPa can be obtained at the tool rotational speed of 1100 rpm, welding speed of 35mm/min and an axial load of 7 kN is the Optimum welding parameters.

Experimental Analysis on Mechanical Properties of Friction Stir Welding in Dissimilar Aluminum Alloys

Friction stir welding (FSW) is an innovative solid state joining technique and has been employed in industries for joining aluminum, magnesium, zinc and copper alloys. The FSW process parameters such as tool, rotational speed, welding speed, axial force, etc play major role in deciding the weld quality. A mathematical modeling was developed based on experiments to predict the tensile strength of dissimilar FSW aluminum alloys. The maximum tensile strength of 210 MPa can be obtained at the tool rotational speed of 1100 rpm, welding speed of 35mm/min and an axial load of 7 kN is the Optimum welding parameters.

Effect of Pre-welding Heat Treatment on the Mechanical Properties of Friction Stir Welded Al–4 wt.%Cu Alloys

This research investigates the welding of aluminum alloy Al–4wt.%Cu using friction stir welding (FSW). Besides the traditionally studied FSW process parameters (i.e., pin rotational and transverse speeds), this work addresses the effects of two pre-welding heat treatment conditions (annealing vs. age hardening) on the resulting weld joint. A set of experiments was carried out to assess joint quality under different levels of process parameters with specimens either annealed or age hardened prior to welding. The results revealed that age-hardened specimens prior to welding possessed higher hardness, higher penetration, and less wear rate among joint zones compared to the annealed ones and base metal. Moreover, the best joint quality was found to be obtained at higher welding and rotational speed regardless of pre-welding heat treatments. Findings of interest to industry, it is economically recommended to weld these types of high-strength aerospace aluminum alloys after age hardening.

On the mechanical characteristics of friction stir welded dissimilar polymers: statistical analysis of the processing parameters and morphological investigations of the weld joint

The applications of industrial polymers have grown extensively owing to the fact of their competent performance characteristics, at par with commonly used engineering materials, as well as technological breakthroughs. Friction stir welding (FSW) of thermoplastics is a recent approach that enabled the permanent joining of similar or dissimilar polymers with desirable efficacy. The primary purpose of the present study is to investigate the effect of friction stir welding process parameters on the welding characteristics (tensile and flexural strength) of the two dissimilar thermoplastics, high-density polythene and polyamide (PA-6). Processing parameters such as the number of passes, pre-heating temperature, tool speed, feed rate, and plunge-in-time have been selected as input parameters, and their influence on the above-mentioned mechanical properties has been studied through Taguchi L-18-based design of experimentation. Further, the morphological investigations of the weld interface and the fractured joint have been studied by using scanning electron microscopy. It has been found that the tool speed has contributed 27.88% and 58.46% in tensile and flexural strength, respectively, at 95% confidence level. Overall, it has been found that the process parameters of FSW have a strong influence on the joint’s characteristics and shown importance to study for the futuristic developments in this technology.

Investigation of mechanical properties of AA6082-T6/AA6063-T6 friction stir lap welds

A study is conducted to investigate the microstructure and mechanical properties of lap joints produced by friction stir welding (FSW) between 3.5 mm thick sheets of automotive aluminum alloys AA6082-T6 with AA6063-T6. The FSW tool used in this study includes a set of WiperTM scrolls on the shoulder face and a probe having right hand threads, a set of tapered flats, and a set left hand CounterFlowⓇ grooves. The FSW process parameters are first optimized through the use of Design of Experiments (DOE) methodology. Static lap-shear tests are performed on the DOE coupons to identify the optimized parameters and once an optimized set of process parameters is identified, lap joint coupons are fabricated from sheets of each alloy for further mechanical and metallurgical investigation. The study implemented post-weld material characterization tests alongside a novel real-time feedback signal monitoring method for assessing the properties of friction stir lap welds. The analysis included microstructural examination, microhardness testing, lap shear testing, and an advanced electronic non-destructive evaluation (e-NDE) technique that uses the process feedback forces to detect weld anomalies primarily in the form of voids in real time. The analysis includes microstructural examination, microhardness testing, lap shear testing, and an advanced electronic (signal/frequency analysis) non-destructive evaluation (e-NDE) technique in order to detect weld anomalies primarily in the form of voids. For comparison purposes, the specimens are tested under two different loading scenarios; loading of the advancing side, and loading of the retreating side. During FSW, the plasticized material is dragged by the tool from the retreating side of the weld to the advancing side around the rear of the tool. Each loading scenario is tested for three conditions; as-welded, naturally-aged, and post-weld heat treated. The weld produced by the optimized parameters was fully consolidated and had no volumetric defects; absence of hooking is clearly identified in the microstructural analysis of the dissimilar lap joint along with good material flow and mixing of the alloys. The ‘advancing-side-loading’ is found to perform with higher strength than the ‘retreating-side-loading,’ which is evidence that ‘retreating-side-loading’ is less favorable in the FSW lap joints produced in this study because of weaker weld strength in the retreating side. A finite element modeling procedure is utilized to examine the distribution of stresses and displacements in a shear test of a lap weld sample. This study identifies improved process parameters for friction stir welding of dissimilar aluminum alloys for enhanced performance.

Predicting tensile strength of filler added friction stir welded AA6082 and AA5052 dissimilar joint

Friction Stir Welding (FSW) process parameters and tool parameters are playing pivotal role in the weld joint characteristics. The combination is selected for the investigation of AA6082 and AA5052, which finds major application in ship structural frame and building constructions. Along with these usual parameters the composition of filler elements is considered in this work to improve the weld joint strength. The process parameters considered in this study are rotational speed, welding speed, shoulder penetration, filler holes center distance, and powder mixing ratio. The Central Composite Design (CCD), the most commonly used Response Surface Methodology (RSM) is considered to develop the prediction equation. A validation analysis is carried out and the results were compared with the relative impact of input parameters on tensile strength. The maximum tensile strength of fabricated joint was obtained with the process parameters combination of 1000 rpm rotational speed, 125 mm/min welding speed, 0.15 mm shoulder penetration, 2 mm filler holes center distance, and powder mixing ratio of 95% Mg and 5% Cr.

Effect of Friction Stir Welding Process Parameters with Interlayer Strip on Microstructural Characterization and Mechanical Properties

Process parameters of friction stir welding (FSW) with different values of interlayer strip widths have become a very vital research area to reinforce the weak part of the nugget zone in welded joints. So, the objective of this work is to study the effect of different process parameters of FSW such as the tool rotational speed (R), travel velocity (υ) and inclination angle (Θ) with different values of interlayer strip widths (W) of compensation material on microstructural characterization and mechanical properties. Optical microscope, scanning electron microscope, energy-dispersive x-ray spectroscopy and x-ray diffraction techniques were used to characterize the microstructural changes after FSW process. Microhardness and tensile tests were also used to characterize the mechanical properties of the produced joints. The results of mechanical properties of FSW process parameters with different values of interlayer strip width showed that when the tool rotational speed is increased till 2000 rpm, the tensile strength has been increased till 321 MPa, while the reduction in tool traverse speed till 20 mm/min led to an increase in the tensile strength till 239 MPa. Moreover, the best inclination angle was 2.5°. The microstructure observations revealed that the use of process parameters of FSW at 2000 rpm rotational speed, 20 mm/min traverse velocity and 2.5° inclination angle with different values of interlayer strip width showed excellent connections of reinforcement clusters of AA7075 compensation material between the matrices of AA2024 base metals.

Multiresponse optimization of friction stir welding process parameters by an integrated WPCA-ANN-PSO approach

Majority of conventional optimization techniques found in the literature deals with single response optimization problems. However, real life industrial processes are having multiple responses, which are conflicting with each other i.e, if we try to optimize one response we may have to compromise with the other. An attempt to optimize all the responses simultaneously to get all response in their acceptable range is called as Multiresponse Optimization (MRO) problem. This paper proposes an integrated WPCA-ANN-PSO approach to perform MRO of Friction Stir Welding (FSW) processes. It is a three stage process, in the first stage the multiple responses are converted into a single multiperformance index (MPI) using Taguchi-Weighted Principal Component Analysis (WPCA) approach. In the second stage an Artificial Neural Network (ANN) model is developed which is capable of predicting MPI for given set of control factors. Finally, in the third stage Particle Swarm Optimization (PSO) algorithm is used to search the global optimal solution using the developed ANN model. Further, to demonstrate the effectiveness of the proposed approach a case study on MRO of FSW process was carried-out to join two plates of AA2024-T4 aluminum using tool of HS steel of grade 304. The control factors considered were D/d ratio, tool rotation speed (TRS) and weld speed (WS). The responses considered were ultimate tensile strength (UTS) and hardness of the joint. The experiments were planned as per Taguchi orthogonal array L8. By WPCA approach the optimal parameters were found to be D/d ratio of 3, TRS of 670 rpm and WS of 17. This solution was further improved by WPCA-ANN-PSO approach and validated by confirmation experiments successfully.

Fundamentals and review on material science, control theory and parametric inter-dependencies during friction stir welding of aluminium metal matrix composites

Purpose The purpose of this study is to present a comprehensive review of the fundamental concepts and terminologies pertaining to different types of aluminium metal matrix composites, their joining techniques and challenges, friction stir welding (FSW) process, post-welding characterizations and basic control theory of FSW, followed by the discussions on the research reports in these areas. Design/methodology/approach Joining of aluminium metal matrix composites (Al-MMC) poses many challenges. These materials have their demanding applications in versatile domains, and hence it is essential to understand their weldability and material characteristics. FSW is a feasible choice for joining of Al-MMC over the fusion welding because of the formation of narrow heat affected zone and minimizing the formation of intermetallic compounds at weld interface. The goal in FSW is to generate enough thermal energy by friction between the workpiece and rotating tool. Heat energy is generated by mechanical interaction because of the difference in velocity between the workpiece and rotating tool. In the present work, a detailed survey is done on the above topics and an organised conceptual context is presented. A complete discussion on significance of FSW process parameters, control schemes, parameter optimization and weld quality monitoring are presented, along with the analysis on relation between the interdependent parameters. Findings Results from the study present the research gaps in the FSW studies for joining of the aluminium-based metal matrix composites, and they highlight further scope of studies pertaining to this domain. Originality/value It is observed that the survey done on FSW of Al-MMCs and their control theory give an insight into the fundamental concepts pertaining to this research area to enhance interdisciplinary technology exploration.

Processing parameters optimization to produce nanocomposite using friction stir welding

This paper deals with the fabrication of particulate metal-matrix nanocomposites (PMNCs) reinforced with Al2O3 nanoparticles via friction stir welding (FSW) process. The reinforcement particles (RPs) are incorporated inside the base matrix on abutting edges under different FSW process parameters to achieve maximum joint efficiency. The effect of different parameters namely tool rotational speed, transverse speed, and volume fraction of Al2O3 nanoparticles as input parameters on the ultimate tensile strength (UTS) of the produced nanocomposites has been investigated using the Taguchi methodology. Analysis of variance was employed to obtain the significance of independent variables on overall quality characteristics of friction stir welded nanocomposites. The multi-response optimized variables were found as: tool rotational speed = 2000rpm, transverse speed = 70 mm min−1 and volume fraction of Al2O3 nanoparticles = 0.30%. Based on the optimized parameters, the maximum ultimate tensile strength of the produced PMNCs was 218 MPa. The optimum results obtained using Taguchi method has been validated by conducting confirmation experiments. Macro and microstructural characterization of the produced nanocomposites using scanning electron microscopes revealed that the increase in the amount of heat due to tool stirring action as well as the addition of Al2O3 nanoparticles in the nugget zone leads to improve the interfacial bonding between the reinforcement particles and the base metal matrix and in turn produce the fine PMNCs.

Optimal FSW Process Parameters to Improve the Strength of Dissimilar AA6061-T6 to Cu Welds with Zn Interlayer

Dissimilar welding of Al-Cu has many potential applications in electric power, electronic and piping industries due to high corrosion resistance, heat and conducting properties. Weld joints through friction stir welding (FSW) process are free from melting- and solidification-related defects. Compared to the recently used Box–Behnken design of response surface methodology, a simple and reliable modified Taguchi design of experiments is utilized for the dissimilar welding of AA6061-T6 to Cu with Zn interlayer to obtain the optimal FSW process parameters and the expected range of strength properties. Empirical relation for the tensile strength is developed in terms of FSW process parameters (viz., tool rotation speed, tool travel speed and tool pin offset) and validated through test results. Most of the test data are within the expected range.

Studies on the effect of welding parameters for friction stir welded AA6082 reinforced with Aluminium Oxide

Abstract Friction Stir Welding (FSW) is a relatively new process which has proved to be a much more viable joining process for all Aluminium Alloys than earlier techniques, such as Metal Inert Gas, Tungsten Inert Gas, Laser Welding and Resistance Welding. Friction Stir Welding is the fastest evolving joining technology and the principal prospective technique for implementing integral fuselage structure in aircraft manufacturing. Friction Stir Welding is a solid-state joining process that uses a non-consumable tool to join two facing work pieces without melting the work piece material. The main objective of the work is to study the effect of mechanical properties like Hardness, Tensile strength along with Microstructure by varying the tool rotational speed of 500 rpm, 710 rpm, 1000 rpm and 1400 rpm during the Friction Stir Welding of Aluminium Alloy 6082 with different reinforcement percentages of 5%, 10% and 15% of Aluminium Oxide (Al2O3). FSW process parameters were optimized using the ANOVA method and Response Surface Methodology to determine the optimum values of Tensile strength of the joints.

Investigation of Heat-Assisted Dissimilar Friction Stir Welding of AA7075-T6 Aluminum and AZ31B Magnesium Alloys

This study investigates the successful joining methods of dissimilar metals of AZ31B Mg and AA7075-T6 Al alloys. The specimens were joined by using open-flame heating system and investigated the effect of the friction stir welding (FSW) process parameters on the welding quality, transverse rupture strength (TRS), tensile strength, microhardness, and microstructure of the resulting specimens. The welding experiments were conducted based on the Taguchi mixed-orthogonal-array for tests, L16 (42 × 22), at a constant spindle speed of 500 rpm using a K10 grade carbide mixing tool with two different tilt angles (0° and 3°), and two tool tip geometries (square and triangle). The specimens were successfully welded, and the test results revealed that the welding temperatures and forces had the strongest effect on the welding quality. The achieved maximum tensile strength and TRS were approximately 122.1 MPa and 712.1 MPa, respectively, at a tool travel speed of 20 mm/min, tool offset value of 0.75 mm, tool tilt angle of 3°, and using a triangle tool tip. The microstructural analysis indicated that a dynamically recrystallized and grain refinement structure formed in the welded zone depending on the temperature and on the excessive deformation. The increase in the microhardness values depends on the intermetallic compounds ratio and fine-grained structure in the welded zone.

A simulation-based study on the effect of underwater friction stir welding process parameters using different evolutionary optimization algorithms

This paper investigates the effect of underwater friction stir welding process parameters on the mechanical properties of the aluminum alloy 6082-T6 joint and further simulates this process using various evolutionary optimization algorithms. Three independent underwater friction stir welding process parameters, i.e. shoulder diameter (in mm) at two levels, rotational speed (in r/min) at three levels, and traverse speed (in mm/min) also at three levels, were varied according to the Taguchi’s L18 standard orthogonal array. The effect of variations in these parameters, on the ultimate tensile strength (in MPa), percentage elongation (in %), and impact strength (in J) of the welded joint was experimentally measured and recorded. In order to simulate this underwater friction stir welding process, three evolutionary optimization algorithms, i.e. particle swarm optimization, firefly optimization, and non-dominated sorting established on the genetic algorithm (NSGA-II), were employed. In these simulations, an artificial neural network with two layers, resembling a non-linear function, was employed as the cost function to predict the values of the response variables, i.e. ultimate tensile strength, elongation, and impact strength, which were experimentally measured earlier. In these simulations, several experiments were conducted using different randomly selected data set and subsequently, the accuracy of each individual simulation was compared. Results revealed that the firefly optimization-based simulation performed the best with least mean squared error while predicting the response variable values, as compared to the particle swarm optimization and the NSGA-II. The minimum value of the mean squared error for the firefly optimization-based simulation was observed to be as low as 0.009%, 0.004%, and 0.017% for ultimate tensile strength, elongation and impact strength, respectively. Furthermore, it was also observed that the computational time for the firefly optimization-based simulation was significantly lower than that of both particle swarm optimization and NSGA-II-based simulations.

Process parameter optimization and characterization of friction stir welded advancing side AA6082-T6 with retreating side AA7075-T651

The significant effects of process parameters on the mechanical and metallurgical properties of dissimilar friction stir welding of AA6082 and AA7075 is studied. A Taguchi orthogonal array design of experiments employed for the optimization of the friction stir welding process parameters to achieve maximum tensile strength. This present investigation has indicated that providing the tool to be tilted to 1⁰ and 2⁰ angle showing good mechanical properties while 0° of lower strength with worm defect. The joint strength was analyzed using ANOVA to emphasis the weld strength. Microhardness survey was also carried out for the understanding of the distribution of hardness across different zones of the weld. The process parameters were correlating with the joint strength by microstructural studies.

Microstructural Development and Mechanical Properties of Friction Stir Welded Ferritic Stainless Steel AISI 409

This work investigates the effect of friction stir welding process parameters (rotation rate and traverse speed) on the microstructural evolution of friction stir welded (FSWed) ferritic stainless steel (FSS) AISI 409. Optical microscope, scanning electron microscope and electron backscattering diffraction are used to quantitatively assess the development in grain structure and texture. The microstructural development suggested that thermo-mechanical deformation occurs in the stir zone within the austenite/ferrite phase region, ultimately transforming upon cooling into bainitic/ferritic microstructure. The fraction and size of the bainitic/ferritic grains are found to vary through the thickness of the joints. High fractions of coarse ferritic grains are found near the top of the stir zone, and low fraction of fine ferritic grains is found near the bottom of the stir zone. This bainitic/ferritic grain structure resulted in an increase in the hardness of the stir zone by about 74% relative to the base material. The tensile strength of the FSWed FSS joints is almost at the same level of the base material with reduction in the ductility as a result of the increased hardness of the weld zone.

Mechanical properties and residual stresses of 5083 to AM60B dissimilar friction stir welding with different process parameters

In this paper, friction stir welding process parameters (material position, rotation rate, traverse speed, tool offset) were prepared to study theirs influences on microstructure, mechanical properties and residual stresses of friction stir welded joints of 5083 Al alloy to AM60B cast Mg alloy. Sound friction stir welded joints were obtained with intermediate rotation rate of tool (1000 rpm) and proper traverse speed (50–150 mm/min) when 5083 Al alloy was on advancing side, no tool offset, and the highest tensile strength (170 MPa) of the joints could reach up to 75% of that of the AM60B cast Mg alloy base material. The intermetallic compounds (IMCs) consisted of Al3Mg2 and Mg17Al12 were observed in the severe intercalated zone. Fracture which was featured by the cleavage feature always occurred near the joint interface because of the brittle IMCs, which indicated the typical brittle fracture. The residual stresses across the welds were distributed asymmetrically and tensile residual stresses on the advancing side were higher than that on the retreating side due to the higher heat input on the advancing side.

Multi-response optimization of friction stir welding process parameters for dissimilar joining of Al6101 to pure copper using standard deviation based TOPSIS method

Friction stir welding is a new and effective solid-state welding process for joining dissimilar materials such as aluminum (Al) and copper (Cu). Joint quality of the friction stir welded materials gets influenced by the welding strategy and different friction stir welding process parameters, i.e. rotational speed, welding speed, tool design, tool pin offset, and tilt angle. In this paper, the effect of combination of different friction stir welding process parameters during joining of Al-6101 and pure copper is studied using Taguchi L18 orthogonal array. Four friction stir welding process parameters, i.e. shoulder diameter (A), pin offset (B), welding speed (C), and rotational speed (D) each at three levels except shoulder diameter, which is at two levels are selected. The effect of different combinations of these parameters on ultimate tensile strength and micro-hardness of the joints is investigated. Subsequently, single response optimization for ultimate tensile strength and micro-hardness and multi-response optimization of ultimate tensile strength and micro-hardness taken together is carried out to obtain the optimal combination of the friction stir welding process parameters. Taguchi method is used for single response optimization, whereas Taguchi-based TOPSIS method is employed for multi-response optimization. For single optimization, the optimum combination of the friction stir welding parameters yielding maximum strength and micro-hardness are A1B1C2D2 and A2B1C2D3, respectively. The optimum combination of the process parameters for multi-response optimization is A2B1C2D2. From the results of the study for single- and multi-response optimization, it is revealed that the rotational speed is the most significant process parameter affecting the tensile strength and micro-hardness of the joints followed by the welding speed. Further, the macro/microstructure and micro-hardness profile of the joint obtained at the optimal combination of the multi-response optimization are given and discussed for better understanding of material mixing and joining.

Microstructure and micro-hardness analysis of friction stir welded bi-layered laminated aluminum sheets

Friction Stir Welding (FSW) is an economical and environment friendly solid-state welding technique. Properties such as high specific strength, low crack propagation rate and high resistance to impact and fatigue loadings enhance the use of aluminum laminates in the modern aircraft and automotive industry. In this study, FSW process was employed for butt joining of bi-layered Al-1350 laminated sheet. Preliminary experimentation, microhardness and microstructure evolution of the FSWed laminates were examined. The microscopic investigations revealed that the FSW process parameters greatly affect the dissolution of strengthening particles, material mixing and formation of defects. The Scanning Electron Microscopy (SEM) revealed that increasing in the tool rotation rate led to increase in the grain size and the size of second phase particles. However, with increasing tool traverse speed a very small rise in the grain size was observed. The increase in the density of second phase particles promoted a small rise in the hardness. Moreover, the microhardness of bi-layered aluminum weldments decreased with increase in grain size hence, following the Hall–Petch relationship. A comparative analysis of FSW of multilayered and monolithic sheet was also performed. Finally, a set of best suited parameters was suggested for the welding of bi-layered laminated sheets of aluminum.