Friction Stir Welding Process Parameters Research Articles

Challenges in the detection of weld-defects in friction-stir-welding (FSW)

ABSTRACTFriction-Stir-Welding (FSW) involves many critical process variables that affect the overall quality of the weld produced; consequently, it is difficult to accurately predict the most favourable process parameters to acquire high-quality defect-free welds. Quality of an FSW joint is influenced by several crucial factors including welding process parameters, and many others. Since the new invention of FSW process, investigators have researched the influence of process parameters and pin tool profiles on microstructures and mechanical properties with a view to optimise FSW process, thereby keeping the degradation of the weld strength to a minimum. In this study weld defects in Friction-Stir (FS) welded thick (8.13 mm) aerospace grade aluminium alloy (AA 2219-T87) are correlated with weld process parameters from an assortment of a large matrix of weld schedules. In this investigation, a novel FSW process parameter window was established for the effective joining of aerospace grade aluminium which could successfully distinguish several types of weld schedules with characteristic and intrinsic weld-defects. Using experimental results obtained from various schedules, an empirical force index (Effective Force Index), which is a function of the critical weld process parameters is proposed to identify regions of weld schedules.

Effect of weld parameters on the microstructure and mechanical properties of dissimilar friction stir joints between pure copper and the aluminum alloy AA7075-T6

Abstract Friction stir welding frequently produces a superior microstructure and mechanical properties than conventional methods for welding nonferrous materials and alloys. In this study, friction stir welding was used to join sheets of the aluminum alloy AA7075 with commercially pure copper cpCu. Two rotational speeds, 660 and 920 rpm, and three welding speeds, 18, 32 and 54 mm × min−1, were studied to determine the effects of these parameters on the structure and mechanical properties of friction stir welded AA7075-cpCu. The joint performance was investigated by conducting optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), by microhardness measurements and mechanical testing (e. g. tensile tests). A maximum tensile strength of 224 MPa and percentage elongation of 2.49 were obtained when friction stir welding process parameters, namely rotational speed and welding speed, were kept at 660 rpm and 32 mm × min−1, respectively.

Prediction of Responses in FSW Processed Hybrid Composites Using Soft Computing Technique

In this research a proper step taken to predict friction stir welding process parameters for the aluminium hybrid composites. In FSW Weld quality is influenced by welding input parameters. The welding parameters taken for this work are axial load, tool profile, spindle speed and material composition. In the present work different combination of aluminium hybrid composite of 6 mm thick is attempted to weld using vertical milling machine. By taking the input parameters such as axial load, tool profile, spindle speed and material composition whereas the response of the model tensile strength and hardness is calculated. The ANN was trained with experimental data. Testing of the ANN is carried out using experimental data not used during training. The result shows the comparison of experimental values of tensile strength and hardness and predicted value using ANN. This indicates that the developed neural network can be used as alternative way for calculating mechanical properties for given process.

Effect of Friction Stir Welding Parameters on Mechanical Properties and Microstructure of AA2195 Al–Li Alloy Welds

In this paper, effect of friction stir welding process parameters on mechanical properties and microstructure of AA2195 welds were studied. Five levels of tool rotation speed from 400 to 1000 rpm and three levels of travel speed from 100 to 300 mm/min were considered. These parameters affected heat input generation in the welds, thereby influencing stir zone geometry, grain size evolution in stir zone, tensile properties and hardness of the weld. Low tool rotation speed and high travel speed resulted in finer grain size. Travel speed significantly affected the tensile properties compared to rotation speed. Processing window to achieve defect-free welds was identified, and maximum weld efficiency was obtained at 400 rpm rotation speed and 300 mm/min travel speed.

Identifying the optimal FSW process parameters for maximizing the tensile strength of friction stir welded AISI 316L butt joints

AISI 316L stainless steel sheets were friction stir welded in the butt joint configuration as per the design of experiment (DoE) developed using the response surface method; Box Benkhen design. The primary friction stir welding (FSW) process parameters; tool spindle speed, tool transverse speed, downward force and tool tilt angle were considered as factors of the experiment. A response surface (second order) regression model for the response, ultimate tensile strength (UTS) of the joints as a function of tool spindle speed, tool transverse speed, downward force and tool tilt angle was developed. Statistical tests such as ANOVA, F- ratio and values of actual and adjusted R2 were used to verify the adequacy of the developed model and the model was validated using conformity experimental trials. The analysis of the model showed that the UTS of the joint is sensitive to all the primary FSW parameters. Also, the tool spindle speed, tool traverse speed and downward force have significant interaction effect on the UTS of the joints. The non-linear optimization of the FSW process yielded 604 MPa as optimal UTS corresponding to optimal tool spindle speed of 597 rev/min, tool traverse speed of 74 mm/min, downward force of 13 kN and tool tilt of 1.5°.

Comparison of RSM with ANFIS in predicting tensile strength of dissimilar friction stir welded AA2024 -AA5083 aluminium alloys

Friction stir welding (FSW) is a solid-state joining technique which has been employed in aerospace, marine, and automotive industries for joining aluminum, copper, titanium and other alloys. The FSW process parameters such as welding speed, tool rotational speed, pin profile, and axial force have a main role in determining the joint quality. A comparative study was achieved between the response surface method (RSM) and the adaptive neuro-fuzzy inference system (ANFIS) to improve the mechanical properties of dissimilar friction stir welded AA2024-AA5083 aluminium alloys in terms of the ultimate tensile strength (UTS). The effects of the welding parameters on the UTS were investigated using four-factor, three-level ANFIS model. The statistical results of the ANFIS model were compared with those of RSM. The results reveal that the developed ANFIS model is more powerful than the RSM model.

Global Robust Control Model of Friction Stir Welding of Aluminum Alloy Based on Main Motor Power Output Prediction

Aiming at the softening problem of 7075 superhard aluminium welded joints such as hot cracks and gas holes in traditional fusion welding process, a dynamic robust control model based on the relationship between friction stir welding process parameters and welded joint strength is established. According to the non-linear relationship between global motion estimation and welded strength parameters, a dynamic robust control model of stirring needle motion is established, and the physical parameters such as elongation after fracture, tensile strength and hardness are calculated. A robust dynamic evolutionary optimization model of welding process parameters is established in the future to realize real-time optimization control of process parameters. On the basis of global motion control, the electric power output of the friction stir welding main motor is predicted according to the required line energy input of the stirring needle motion characteristics, and the real-time optimal control method of the motor electric power based on the expected thermal energy input of the welding process is established. A series of strength tests of welded joints based on the model show that the predicted results of the model can meet the needs of engineering and have practical value in engineering.

Optimization of Tensile and Corrosion Properties of Dissimilar Friction Stir Welded AA2024-7075 Joints

In this work, we performed some joining experiments of dissimilar aluminum alloys AA2024-T351 and AA7075-T651 using friction stir welding (FSW) technique with different process parameters (rotational speed, welding speed and plunge depth). Response surface methodology based on a central composite rotatable design was used to establish the mathematical models predicting the tensile properties and corrosion rate of dissimilar FSW joints with some high confidence level. Analysis of variance method was employed to verify the developed models. Besides, the influences of FSW process parameters on tensile and corrosion properties of joints were analyzed. In order to obtain a desirable combination property of the dissimilar FSW joints, the optimum process parameters after experimental verification were proposed as: rotational speed 1495 rev/min, welding speed 187 mm/min and plunge depth 0.03 mm. This verification illustrated that the developed models are appropriate for the modeling and optimization of process.

Optimization of Process Parameters for FSW of Al-Mg-Mn-Sc-Zr Alloy Using CCD And RSM

Abstract Al-Mg-Mn-Sc-Zr alloy plates of 5mm thick were welded successfully using Friction stir welding (FSW). Three-factor five-level central composite design was adopted for experimentation. Response surface methodology (RSM) was employed to construct a mathematical regression model. Optimization of FSW process parameters obtained by using response surface plots for maximize hardness, tensile strength, %elongation, impact strength and bending strength, the results were validated with confirmation tests at identified optimum conditions.

Process parameter optimization for FSW of AA6061/SiC/fly ash AMCs using Taguchi technique

In this research work, aluminum matrix composite (AMC) plates were welded using friction stir welding (FSW). AMCs contain AA6061 as a base metal with silicon carbide (SiC) and fly ash particles as reinforcements. The FSW process parameters considered in this work were tool rotational speed (revolutions/minute), tool traverse speed (millimeters/minute) and tool tilt angle (degrees). The Taguchi L9 orthogonal array was considered for optimizing the process parameters. Tensile strength and hardness were the two output responses obtained by analyzing joint efficiency and signal/noise ratio. An analysis of variance (Anova) study was conducted to identify the percentage contribution of each process parameter to the output responses. The Anova study concluded that among the three process parameters, tool rotational speed was the most dominant parameter in deciding the tensile strength and hardness of the FSW joints, followed by traverse speed and tool tilt angle. At the end, the results were validated by conducting additional experiments.

Analysis of process parameters effects on underwater friction stir welding of aluminum alloy 6082-T6

In friction stir welding of heat treatable aluminum alloys, the thermal cycles developed during the joining process result in softening of the joints which adversely affect their mechanical properties. Underwater friction stir welding can be a process of choice to overcome this problem due to low peak temperature and short dwell time involved during the process. Consequently, this article presents a study pertaining to the underwater friction stir welding of aluminum alloy 6082-T6 with an aim to develop a mathematical model to optimize the underwater friction stir welding process parameters for obtaining maximum tensile strength. The results of the study reveal that the tool shoulder diameter (d), tool rotational speed (ω), welding speed (v), and second-order term of rotational speed, that is, ω2, significantly affect the tensile strength of the joint. The maximum tensile strength of 241 MPa which is indeed 79% of the base metal strength and 10.7% higher than that of conventional (air) friction stir welding joint was achieved at an optimal setting of the underwater friction stir welding parameters, that is, tool rotational speed of 900 r/min, the welding speed of 80 mm/min, and a tool shoulder of 17 mm. The article also presents the results of temperature variation, the macrostructural and microstructural investigations, microhardness, and fractography of the joint obtained at the optimal setting for underwater friction stir welded (UFSWed) joint.

Influence of rotation speed and axial force on the friction stir welding of AISI 410S ferritic stainless steel

The Friction Stir Welding process parameters were varied to provide a combination of an acceptable surface finish, absence of cracks, and full tool penetration. Two levels of rotation speed and axial forces from 10 to 30 kN were applied, whilst keeping the welding speed constant at 1 mm/s. One of the defects analyzed was the production of flashes. This can occur due to an increase in axial force and because of the instability in its applications, which implies directly on the formation of volumetric defects along the stir zone. FSW joints without root flaws can be achieved through a correct balance between the axial force and rotation speed, which also allows a greater immersion of the tool probe in the joint. Both rotation speeds using an axial force of around 20 kN proved to be good welding parameters for the FSW process. The welding of the AISI 410S steel (under these conditions) resulted in joints without internal defects and with a good surface finish.

Multi Objective Process Parameters Optimization of Friction Stir Welding using NSGA – II

Age hardenable aluminum alloys such as AA2024 and AA6061 are extensively usd in automotive, aircraft and marine industries because of its high strength to weight ratio and good ductility. When compared to fusion welding techniques Friction Stir Welding (FSW) is a promising technique to improve the quality of the weld joint. FSW process parameters such as tool rotational speed (N), welding speed (F), axial load (P) and tool pin profiles (Cylindrical, Square and Taper) have crucial effects on the mechanical properties of FS welded joints significantly. The mathematical model was developed for the responses namely Ultimate Tensile Strength (UTS) and Tensile Elongation (TE) using Response Surface Method (RSM) and the developed mathematical model was effectively utilized to optimize the FS welded process parameters using non-dominated sorting genetic algorithm-II (NSGA-II). The maximized tensile properties of FS welded age hardenable aluminum alloys were obtained nearly 143.3 N/mm2 with its corresponding tensile elongation of 12.53%. It is concluded that, the NSGA - II is very useful in optimizing the process parameters of FS Welding and improving the quality of the weld joint.

Multi response Optimization of Friction stir welding process parameters in dissimilar alloys using Grey relational analysis

A multi response optimization of friction stir welding parameters in dissimilar alloys using Taguchi based Grey relational analysis was studied in this investigation. The dissimilar nonferrous AA8011-H24 aluminium alloys and Ti3Al2.5V titanium alloys were friction stir welded under different process parameters, viz., rotational speed, tool pin profiles and welding speed on tensile strength, tensile elongation and joint efficiency have been optimized by applying multi response analysis. The grey relational grade is attained which correlates between the friction stir welding parameters and responses and the optimum level of welding parameters have been determined by grey analysis. The rotational speed is the most significant contributing parameter to decide the good quality of the welded joints followed welding speed and the tool pin profiles was found using analysis of variance. The confirmation test results showed that the grey relational grade was improved 0.059 with the predicted responses at the optimal conditions.

EFFECT OF FRICTION STIR WELDING PARAMETERS ON MICROSTRUCTURAL CHARACTERISTICS AND CORROSION BEHAVIOR OF AA7020-O BASED ON TAGUCHI DOE APPROACH

In the present study, Taguchi approach for experiment design was utilized, through an orthogonal array of L9 (33), to investigate the effect of friction stir welding (FSW) process parameters, and post weld heat treatment (PWHT) on the microstructural characteristics and corrosion behavior of the nugget zone (NZ) of the FS welded joints and the base metal (BM) samples of AA7020-O. Microstructural characteristics were investigated through grains size (GS) and aspect ratio (AR) of α-Al grains. Corrosion behavior was studied by potentiodynamic polarization test and static immersion in 3.5 % NaCl solution at room temperature. Results of analysis of variance (ANOVA) revealed that, the GS at center of the NZ is directly statistically significant affected by increasing the tool rotational speed and by changing the PWHT state from the as weld (AW) state to T4 or T6 tempers, while, the AS is directly statistically significant affected by increasing the tool rotational speed, and, it is inversely statistically significant affected by increasing the welding speed. Moreover, the corrosion rate (CR) is found to be directly statistically significant affected by changing the PWHT state from the AW state to T4 or T6 tempers, while, it is inversely statistically significant affected by increasing the tool rotational speed. Nevertheless, As compared to BM samples, FSW has highly decreased the CR in the NZ, for T4 and T6 tempers, while it is of comparable values in AW state. The percentage contribution (PC) of each factor is also determined. Key words: FSW, Processing Parameters, PWHT, Taguchi, Microstructure, Corrosion Behavior, Potentiodynamic Polarization, Corrosion Rate.

Effect of Friction Stir Welding and Friction Stir Processing Parameters on The Efficiency of Joints

Friction Stir Welding is one of the most practical welding process at the solid state. Friction Stir Processing is used to enhance the microstructure of FSW welded zone. The present study investigates the effect of welding parameters on the tensile properties of FSW and FSP joining 3 mm AA 5083 - H111 aluminum alloy by means of stress – strain curve with a uniaxial tensile test and by comparing the efficiency between FSW , FSP and base metal .The experiments were conducted with 1000,1500 and 2000 rpm rotation speeds ,and 20,40 and 60 mm/min travel speed. The best result of the welding joint was shown at the 20 mm/min feed speed and 1500 rpm rotational speed for FSW, and 40 mm/min feed speed and 1500 rpm rotation speed for FSP. The efficiency of ultimate tensile strength reaches to 92% for FSW and 94% for FSP.

Influence of tool geometry and processing parameters on welding defects and mechanical properties for friction stir welding of 6061 Aluminium alloy

Friction stir welding (FSW) is a form of solid state welding process for joining metals, alloys, and selective composites. Over the years, FSW development has provided an improved way of producing welding joints, and consequently got accepted in numerous industries such as aerospace, automotive, rail and marine etc. In FSW, the base metal properties control the material’s plastic flow under the influence of a rotating tool whereas, the process and tool parameters play a vital role in the quality of weld. In the current investigation, an array of square butt joints of 6061 Aluminum alloy was to be welded under varying FSW process and tool geometry related parameters, after which the resulting weld was evaluated for the corresponding mechanical properties and welding defects. The study incorporates FSW process and tool parameters such as welding speed, pin height and pin thread pitch as input parameters. However, the weld quality related defects and mechanical properties were treated as output parameters. The experimentation paves way to investigate the correlation between the inputs and the outputs. The correlation between inputs and outputs were used as tool to predict the optimized FSW process and tool parameters for a desired weld output of the base metals under investigation. The study also provides reflection on the effect of said parameters on a welding defect such as wormhole.

Analysing the strength of friction stir welded dissimilar aluminium alloys using Sugeno Fuzzy model

Friction stir welding (FSW) is a promising solid state joining technique for aluminium alloys. In this study, FSW trials were conducted on two dissimilar plates of aluminium alloy AA2024 and AA7075 by varying the tool rotation speed (TRS) and welding speed (WS). Tensile strength (TS) of the joints were measured and a Sugeno – Fuzzy model was developed to interconnect the FSW process parameters with the tensile strength. From the developed model, it was observed that the optimum heat generation at WS of 15 mm.min-1 and TRS of 1050 rpm resulted in dynamic recovery and dynamic recrystallization of the material. This refined the grains in the FSW zone and resulted in peak tensile strength among the tested specimens. Crest parabolic trend was observed in tensile strength with variation of TRS from 900 rpm to 1200 rpm and TTS from 10 mm.min-1 to 20 mm.min-1.

Optimization of Process Parameters for Al6061-Al7075 alloys in Friction Stir Welding using Taguchi’s Technique

Welding is one of the main fabrication method used to join alloy materials. Friction Stir Welding (FSW) is an emerging solid state joining process which is based on frictional heat generated through contact between a non-consumable rotating tool and the work piece. This paper focuses on optimization of process parameters in FSW of Al6061-Al7075using Taguchi method of experimental design. The process parameters such as rotational speed, welding speed, and number of passes were consideredto determine the optimum process parameters with reference to Ultimate Tensile Strength (UTS) and hardness of the weld joint. L9 orthogonal array of Taguchi technique was used for experimental trials. The optimum process parameters have been identified to achieve maximum ultimate tensile strength and hardness. Significant process parameters were identified from the analysis of variance (ANOVA).

Prediction of optimum welding parameters for FSW of aluminium alloys AA6063 and A319 using RSM and ANN

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 conducted using central composite circumscribed design and is compared using ANN methodology to predict the tensile strength of dissimilar FSW aluminum alloys. It was found the error rate predicted the regression ANN was smaller than predicted by the other ANN methods.