Shoulder Diameter Research Articles

Multi-objective optimization of friction stir spot welded Al 6061-T6 incorporated with silicon carbide using hybrid Grey Rational Analysis-Taguchi technique

The present research investigation focused on multi-objective optimization of friction stir spot welding process for attaining an optimal combination of process parameters in order to obtain stronger welds. Experiments were designed using Taguchi L9 orthogonal array on process parameters such as, tool pin profile, tool shoulder diameter and shoulder plunge depth. The output quality characteristics measured were tensile-shear strength and micro-hardness. Multi-objective optimization was done using Hybrid Grey Rational Analysis-Taguchi technique. The significance of parameters was determined using Analysis of variance technique. The optimality of results was verified by confirmatory test.

Microstructural and Mechanical Properties of Dissimilar Aluminium Alloys by Friction Stir Welding

In the present study, the dissimilar aluminium alloys AA 2014-T651 and AA 7075-T651 of 16 joints was successfully joined with (four welding speeds (50, 60, 70, 80 mm/min), four rotational speeds (900, 1000, 1100, 1200 rpm), four different weld tool profiles (T1=12/4, T2=15/5, T3=16/4, T4=20/5 in D/d ratio) by friction stir welding machine. In the optical microstructure and SEM very fine equiaxed grains are formed in the stir zone. The maximum hardness value is 150 HV obtained in the weld nugget area of the specimen 2 under the conditions of 900 rpm, 70 mm/min for T3 profile. Compare to other tool profiles T3 profile attained maximum hardness value. The minimum hardness value is attained for the specimen 13 for the tool profile T1 was 103 HV compared to all tool profiles. In post weld heat treatment conditions, hardness values were decreased compare with as weld conditions due to over heating followed by ageing. The maximum joint efficiency attained is around 90 to 95% with T2 and T3 profiles at rotational speed of 1000 rpm, 1200 rpm and welding speed of 60, 70 mm/min. The T1 profile attained least joint efficiency of 69.5 % at 900 rpm, 50 mm/min, since it has very less shoulder diameter or contact area and maintain a D/d ratio is 3.

Corrosion and Tribological Characteristics of FSPed Aluminum Alloy AA5052

Friction stir processing (FSP) is a solid-state and effective process for surface modification of aluminium alloys. In this study the AA5052 alloy, widely used in marine applications, has been subjected to FSP. The FSP trials have been carried out by altering the FSP process parameters (tool rotation speed, tool traverse speed, and shoulder diameter). The friction stir processed specimens have been characterised / tested for microstructure, microhardness, sliding wear, immersion corrosion, and electrochemical corrosion. The hybrid polynomial – radial basis function-based models have been developed to determine the relationship between the process parameters and the evaluated properties. Furthermore, the optimum parameters for obtaining high hardness, wear resistance, and corrosion resistance have been determined. Microstructure evaluation in the friction stir processed specimens has shown refinement and uniform dispersion of β particles throughout the α-Al matrix. The results show that the improvement in properties is a result of the homogeneous dispersion of secondary β phase particles in the matrix. Friction stir processing of AA5052 alloy has improved hardness by ~14.5%, wear resistance by ~83%, and corrosion resistance ~87%. The optimum process window for friction stir processing of AA5052 alloy is tool rotation speed between 500 rpm and 900 rpm, tool traverse speed between 10 mm/min and 30 mm/min, and tool shoulder diameter of 18 mm and 21 mm.

Supervised and Unsupervised Machine Learning Algorithms for Forecasting the Fracture Location in Dissimilar Friction-Stir-Welded Joints

Artificial-intelligence-based algorithms are used in manufacturing to automate difficult activities and discover workflow or process patterns that had never been noticed before. Recent studies deal with the forecasting of the fracture location in dissimilar friction-stir-welded AA5754–C11000 alloys. Four types of supervised machine-learning-based classification algorithms i.e., decision tree, logistic classification, random forest, and AdaBoost were implemented. Additionally, in the present work, for the first time, a neurobiological-based unsupervised machine learning algorithm, i.e., self-organizing map (SOM) neural network, is implemented for determining the fracture location in dissimilar friction-stir-welded AA5754–C11000 alloys. Tool shoulder diameter (mm), tool rotational speed (RPM), and tool traverse speed (mm/min) are input parameters, while the fracture location, i.e., whether the specimen’s fracture is in the thermo-mechanically affected zone (TMAZ) of copper, or if it fractures in the TMAZ of aluminium. The results show that out of all implemented algorithms, the SOM algorithm is able to predict the fracture location with the highest accuracy of 96.92%.

Heat Index Based Optimisation of Primary Process Parameters in Friction Stir Welding on Light Weight Materials

In friction stir welding, tool shoulder diameter and its rotational speed are the major influencing parameters than others. A simple novel correlation is proposed to select the optimum range of tool shoulder diameter with respect to the chosen rotational speed and vice versa. The conditions to apply derived correlation were defined through process heat index number as the joint efficiency in the friction stir welding depends on the effective heat supply to the volume of material deformed in the stir zone. Weld speed is the key parameter through which generated heat can be regulated towards optimum heat supply to attain defect-free weld in the stir zone. Effective heat input also has obvious effect on grain growth and corresponding property eradication in the heat affected zone. The experimental study was carried out on AA2024-T3 plates to understand the effect of process heat index on the prescribed optimum range of tool shoulder and rotational speed defined in the correlation. Eventually, a novel relationship was attained between the first order process influencing parameters to deliver maximum joint efficiency.

Сравнение результатов использования хронологического и скелетного (биологического) возрастов как группирующих факторов в межпопуляционных морфологических исследованиях детей и подростков

Introduction. In anthropological and medical practice, in most cases, the method of grouping individuals by chronological age is used in comparative age studies. A number of authors spoke about the need for a different approach to children of the same calendar age and taking into account the level of their morphophysiological development. [Deryabin, 2004]. In this paper, the comparison of age morphological characteristics in the studied groups was carried out using both chronological and biological (skeletal) ages as grouping factors. Materials and methods. Comparative studies were conducted in the combined group of Khalkha Mongols, Turkmens of G. Chardjev, Bashkirs of Beloretsky and Abzelilovsky districts and Chuvash of Yadrin district. The age range of the examined was 7-17 years. The Tanner-Whitehouse method (TW-2) was used to determine individual values of skeletal maturity. The following features were included and analyzed in the analysis: body length, body weight, leg length, shoulder and pelvic diameters, chest girth, the size of the average fat fold, the size of the epiphyses of the forearm and thigh. The body mass index, as well as the chest index and body surface area were calculated. All anthropometric studies were carried out according to a unified methodology within the framework of the standard program adopted at the Moscow State University Research Institute of Anthropology [Bunak, 1941]. Mathematical processing of the data used was carried out using computer programs "Statistica" (versions 5-10) (StatSoft, USA) and "Microsoft Excel". Results and discussion. Estimates of the temporal variability of skeletal age relative to chronological age were carried out in each of the presented groups. The changes in the rates of ontogenesis in different periods of maturation, differing in magnitude, orientation, time of onset and intensity, have been established. Sex differences were found for a number of morphological features when comparing samples by chronological and skeletal ages as grouping factors. It is shown that the main differences between the compared groups by morphological characteristics are associated with the rate of maturation of children and adolescents, as well as the presence of adaptive characteristics formed under the influence of climatic and geographical environmental factors. Conclusion. The use of biological age as a grouping factor is desirable and necessary for an adequate comparison of groups with different rates of ontogenesis and acceleration of development, changing under the influence of environmental factors.

Indentifying the effect of micro friction stir spot welding (µFSSW) parameters on weld geometry, mechanical properties, and metallography on dissimilar materials of AZ31B and AA1100

Micro-friction stir spot welding (µFSSW) is one type of welding that is suitable for joining lightweight materials. One of the challenges in joining lightweight materials with µFSSW is that the material is easily perforated, or the join is not strong enough, so it is necessary to select the right µFSSW parameters. In this article discusses about investigates the micro-Friction Stir Spot Welding (µFSSW) parameters on weld geometry, mechanical properties, and metallography on dissimilar materials of AZ31B and AA1100. The material thickness of the AZ31B and AA100 is 0.5 mm and 0.32 mm, respectively. The µFSSW tool is made of high-speed steel (HSS) with a pin diameter of 0.25 mm and a shoulder diameter of 0.5 mm. The constant process parameters of the µFSSW joint used, i. e., plunge depth, dwell time plunge rate, and high tool rotational speed of 33,000 rpm. Welding test results include weld geometry, mechanical properties, and metallography. Weld geometry testing to determine the weld nugget diameter. The mechanical properties test was shear tensile test and cross tensile test, while the metallographic test included macrostructure and microstructure observations. The results of the FSSW weld geometry show that at a dwell time of 700 milliseconds and a plunge depth of 600 microns, the weld pin diameter and weld shoulder diameter are close to the pin diameter and the diameter of the shoulder tool used. Dwell time and plunge depth has a significant effect on tensile strength. The maximum shear and cross loads achieved were 387±17 N and 29±2 N, respectively. Intermetallic compounds (IMC) are observed at the interface of the two materials, while a dwell time of 700 milliseconds give the effect of cracks on the inside of the weld

Effect of Dwell Time on Fracture Load of Friction Stir Spot Welded Dissimilar Metal Joints

The dissimilar materials joining in heavy structural fabrication industries is tedious work for welding and design engineers, since the weld region’s criticality is encountered by hot cracking and its associated problems. Moreover, dissimilar materials are joined by mechanical locking such as rivets, bolt and nuts, and screws. Nowadays, the fasteners are eliminated by friction stir welding (FSW). The friction stir spot welding (FSSW) is a variant of FSW; it can be avoided by seam welding. Hence, in this investigation, FSSW is used for joining AA6061 aluminum alloy with mild steel using tool rotation speed, plunge depth and rate, and shoulder to pin diameter ratio. The experimental method observed that the joint fabricated with a rotational speed of 1000 rpm, plunge rate of 5 mm/min, plunge depth of 6 mm/min, and shoulder diameter to pin diameter ration of 3.0 yielded highest fracture load The optimum heat input could obtain the improvement in FSSW joint strength. Recrystallized grains and favorable intermetallic compound formation are the primary factors for sound welding.

Evaluating interlayer gaps in friction stir spot welds for rapid tooling applications

Potential for a rapid hybrid additive/subtractive manufacturing technique capable of generating large aluminum components with deep geometrical features exists if, for example, layers of aluminum plates can be deposited and held in place using friction stir welding followed by machining. However, when plates of aluminum are friction stir spot welded together, adjacent material can deform causing a gap between layers. This research investigates how friction stir tool geometry affects the formation of interlayer gaps and the lap shear strength of the weld. For this purpose, residual stresses and microhardness were measured to characterize the weld formation process. While friction stir welding of 6061 aluminum bar stock was carried out on a machining center with three different pin diameters (5.7, 6.4, 7.0 mm) and two pin lengths (8.9, 10.2 mm). In general, outcomes of the research show that lap shear strength trends upward with increasing pin diameter but does not show a strong relation to the pin length. Interlayer gap size increases with pin length, but does not show a clear trend with pin diameter. Compressive residual stresses were observed on the weld shoulder with no significant variations occurring among the studied stir tool geometries. No significant change was measured in microhardness values when the pin length or shoulder diameter were changed, suggesting that the increase in lap shear strength is due to a change in weld cross-section instead of a material property change. This research will guide friction stir tool geometry selection for this hybrid manufacturing process and can be applied more broadly to any application where material deformation around a weld is undesirable.

Process factors optimisation for friction stir process of ZK 60 magnesium alloy employing Box Behnken approach

ABSTRACT A clear understanding of heat transmission and material course during the friction stir processed (FSP) ZK60 magnesium alloy (Mg) can help eliminate flaws like cracks, voids, and flash. It enhanced the mechanical properties of the FSP of ZK60 Mg alloy. It is mainly controlled by process parameters like axial force, plunge depth, tilt angle, shoulder diameter, traverse speed, and rotational speed. Our investigation focuses on the influence of advanced factors such as tool tilt angle (TTA-deg), rotational tool speed (TRS-rpm), and tool traverse speed (TTS-mm/min), with the aid of the design of experiment technique by Box Behnken method to enhance the hardness. It is necessary to develop finite element models to support experimental results. And is further preceded by transient temperature dispersion throughout FSPed ZK60 Mg alloy fabricated through the Finite Element process. The temperature fields determined numerically engage well by trial data and the highest temperature throughout the FSPed at the stir zone. The temperature distribution is simulated by TRS and TTS in which higher temperature is relative to TRS and indirectly close to TTS. From the model, the highest temperature was determined to be 462°C, which is particularly fewer than the plate’s melting temperature.

Implementation of hybrid RSM-GA optimization techniques in underwater friction stir welding

Standard friction stir welding process parameters have a considerable impact on the quality of functional parts produced by underwater friction stir welding (UWFSW) with additive water. Hybrid statistical techniques may be used to optimize operating parameters in order to improve the aim function. The tensile strength (UTS)of parts fabricated with UWFSW by Al 6063 material in accordance with ASTMD638-14 tests is investigated in this study. In the construction of test specimens, three parameters were varied: rotational speed from 1000 to 1800 rpm, travel speed from 4 to 10 mm/s, and shoulder diameter from 10 to 20 mm. The response surface methodology (RSM) based central composite design (CCD) matrix for the parametric combination was constructed using a second-order polynomial fitting model. The maximum UTS of testing samples on the 201T universal testing machine (UTM) was 208.27 MPa. These process parameters are also optimized using hybrid optimization approaches such as response surface methodology- genetic algorithm (RSM-GA). RSM-GA had the highest precision of 98.99 percent, which resulted in optimal characteristics such as rotating speed 1800 rpm, travelling speed 4 mm/s, and shoulder diameter 15 mm, which resulted in a maximum tensile strength of 199.0212 MPa.

Optimization of friction stir welding AA6082-T6 parameters using analysis of variance and grey relational analysis

Friction stir welding (FSW) is a solid-state welding process, which has a significant role in solid-state welding processes for nonferrous alloys. Conventional arc welding processes for aluminum alloys such as metal inert gas (MIG) and tungsten inert gas (TIG) are replaced by FSW. The effect of FSW parameters such as rotational and traverse speeds, tool geometry, plunge depth, tilt angle, etc., on weld quality were considered in several optimization studies. Hence, the effect of fixture position is included in this study. Multi-criteria decision-making (MDCM) techniques such as grey relational analysis (GRA) were used to determine the optimal condition among experimental runs designed by response surface methodology (RSM). The Taguchi method was widely applied with MCDM techniques. Therefore, the experiments were conducted according to response surface methodology. Input parameters were (14, 16 and 18) mm for shoulder diameter (SD), (0.0, 0.2 and 0.4) mm for plunge depth (PD), and (30, 60 and 90) mm for fixture position (FP), which is the distance between fixture bolts used to fix the welded plate. The results obtained by GRA were similar to the ANOVA optimizer, and the optimum process conditions are shoulder diameter of 14 mm, plunge depth of 0.2 mm, and fixture position of 60 mm.

알루미늄 3003 합금의 마찰교반접합특성에 용접조건의 영향

Two-way factorial design method was applied to evaluate the joint strength of friction stir welded aluminum 3003 alloy in this study. The welding factors and levels were the tool rotation speeds of 1,300, 1,800, 2,300, and 2,800 rpm and the tool travel speeds of 150, 250, 350, and 450 mm/min under the shoulder diameter of 18 mm and pin diameter of 4 mm. The uniaxial tension tests were carried out for varience analysis of tensile strength of welded part, and micro-structure observations were also performed with hardness measurements at welded part. From the results, the variance analysis revealed that the contributions of welding factors on the tensile strength of the weld part were the rotation speed of 67.9% and the travel speed of 31.8%. The optimum condition for FSW was predicted the welding speed of 450 mm/min and rotating speed of 1,300 rpm, and the presumption range of tensile strength at optimal condition of reliability 95% was estimated to 135.53 ± 1.11 MPa. In addition, the lower the rotation speed and the higher the travel speed, the higher the tensile strength. Finally the hardness and grain size of optimal condition was higher and finer than that of lowest condition at weld part.

Influence of process parameters on mechanical and microstructural properties of friction stir welded AA5052

ABSTRACT The current research work explores the process parameters namely tool shoulder diameter, tool pin design, tool rotational and welding speed and its influence on mechanical and metallurgical qualities of aerospace-grade 5052 aluminium alloy. The research observation shows that the intermediate extent of process parameters indicates enhanced mechanical qualities compared to the lower and higher regimes. When considering different individual tool pin profiles, square pin (SQ) tool geometry yields the highest ultimate tensile strength in comparison with threaded cylindrical, tapered cylindrical and straight cylindrical tools. A set of the best combination of process parameters with 24 mm shoulder diameter SQ pin tool geometry at tool rotational speed of 1000 rev/min along with the welding speed of 40 mm/min produced defect-free joint with excellent mechanical characteristics with an ultimate tensile strength of 92% compared to the base metal. Microstructural analysis of the best welded specimen (considering the above parameters) revealed 81% finer grain compared to base material that leads to enhanced mechanical attributes. Fractography detects ductile fracture of the welded specimen. The effects of individual process parameters on grain size, micro-hardness, flexural strength, bending angle and percentage of elongation of each sample are represented in this research article.

Friction stir welds of aluminium alloy pipes: an investigation of defects and mechanical properties

ABSTRACT With the elimination of solidification defects, friction stir welding becomes the most effective process for joining flat and curved surfaces. Tool geometry (tool pin profile, shoulder diameter) and tool rotation speed mainly contribute to the overall weld quality. The study evaluates the simultaneous effect of tool geometry, rotational speed, base offset and double pass Friction Stir Welding (DP-FSW) on the defect formation and the mechanical properties. Micro-structure and macro-structure have been analysed for weld strength and hardness characterisation, and found, at high tool rotation speed maximum hardness is achieved in the Stir Zone (SZ). A small tunnel present near the middle proved to be more detrimental than the large one at the bottom. Grain refinement in the SZ was 87.2% while augmentation in hardness was 21.3 HV. Maximum tensile strength of approximately 103% with decent bead profile is obtained, using taper cylindrical tool at 710 rpm with 14 mm shoulder diameter. Fractography of the fractured surface revealed a pure ductile failure. It has been discovered that with base offset the strength of the weld is increased. However, reduction of 4.8% was obtained with DP-FSW. Better weld profile gives better strength. With DP-FSW, a significant improvement in bead surface is obtained.

Influence of process parameters on mechanical and microstructural properties of friction stir welded AA5052

ABSTRACT The current research work explores the process parameters, namely, tool shoulder diameter, tool pin design, tool rotational as well as welding speed and its influence on mechanical and metallurgical qualities of aerospace grade 5052 aluminium alloy. The research observation shows the intermediate extent of process parameters indicates enhanced mechanical qualities compared to the lower and higher regimes. With considering different individual tools pin profiles, square pin (SQ) tool geometry yields the highest ultimate tensile strength in comparison with threaded cylindrical, tapered cylindrical, and straight cylindrical tool. A set of the best combination of process parameters with 24 mm shoulder diameter, SQ pin tool geometry at tool rotational speed of 1000 rev/min along with the welding speed of 40 mm/min, produced defect-free joint with excellent mechanical characteristics with an ultimate tensile strength of 92% compared to the base metal. Microstructural analysis of the best welded specimen (considering the above parameters) revealed 81% finer grain compared to base material that leads to enhanced mechanical attributes. Fractography detects ductile fracture of the welded specimen. The effect of individual process parameters on grain size, micro-hardness, flexural strength, bending angle and percentage of elongation of each sample are represented in this research article.

Friction Stir Welding of Aluminum 7075 Alloys

Abstract: Friction Stir Welding (FSW) is a solid-state welding method which was developed by The Welding Institute and patented in 1999. The process is solid state and relies on local forging of weld region to perform weld. New welding schedules are being continuously developed for materials that are traditionally difficult to join by fusion welding methods (e.g., TIG/MIG). These experiments are performed to find out the best possible parameters to smoothly weld the aluminium 7075 alloys. By using Taguchi robust design of experiment, we selected 3 parameters namely rotation speed and transverse speed and tool shoulder diameter against the optimization function of ultimate tensile strength. The tilt angle and the plunge depth are kept constant. The variation of tensile strength is mainly due to the change in tool shoulder diameter then with welding speed and then with rotation speed. The heat generated is modelled on ANSYS software by inserting the rotation speed, coefficient of friction , material properties , radius of pin etc. The model is validated by conducting the experiment through thermocouples. The model predicted a temperature of about 410 degrees Celsius and the experimental value is 380 degrees Celsius, showing that the welding temperature is about 80% of heat generation. The Taguchi experiment consist of 4 experiments with a range of rotation speeds of 900 and 1120 respectively and a welding speed of 64mm/min and 100 mm/min respectively. The tool shoulder diameter is kept 14mm and 17mm. the welds are cut in transverse direction in order to obtain the UTS test coupon. The best possible combination is found using Taguchi Analysis. This thesis is a collection of data and response variables that correctly informs at what conditions we should weld 7075 alloy. Appropriate SN ratio is calculated and high is the best is considered as our objective function is tensile strength. Some additional tests are also performed namely hardness and microstructure and heat generation in order to identify the behaviors of aluminium alloy. Hardness and heat generated are dependent on the tool shoulder diameter then on the welding speed. This conclusion is derived from Taguchi analysis. This study is useful for the selection of parameters for the further welding operations. However, a change in plunge depth can also be taken into consideration for future scope. As tunneling defect was observed in some runs thus plunge depth has to be varied. Also, the number of experiments can be increased in order to get more refined parameters. Also, the making of base material can also be taken into consideration because of the zinc precipitate distribution. Casted AA7075 has different properties, rolled AA 7075 can have different.

Experimental investigation on impact energy of friction stir welded aluminum and copper dissimilar joint using full factorial method

This research work carried out friction stir welding (FSW) of dissimilar aluminum AA3003-H12 and copper C12200-H01, with wide application in the refrigeration and heat exchanger industry. The main aim of this study is to investigate the influence of process parameters, i.e. pin type (PT), weld speed (WS), rotational speed (RPM), and shoulder diameter (SD) on impact energy (IE) of Al-Cu welded joint. The experimental study used the full factorial method with mixed levels of process parameters. Analysis of Variance (ANOVA) determines the significance of process parameters on impact energy. The results of the analysis of variance (ANOVA) shows that rotational speed (RPM) is the most influential process parameter contributing to the impact energy (IE) of dissimilar Al-Cu weld joint. The response optimizer tool in Minitab 18 software gives optimum weld conditions of process parameters for better weld performance. The FSW experiment with a tapered pin, weld speed of 16 mm/min, rotational speed of 1120 rpm, and shoulder diameter of 22.5 mm obtained the maximum impact energy value of 6.5367 J. The fine-grain recrystallization formed intermetallic compounds in the stir zone (SZ). These intermetallic compounds give a maximum microhardness of 382.24 Hv (0.1). The microstructure analysis of the stir zone (SZ) shows an equiaxed grain structure on the Cu side, while the Al side shows a fine recrystallized grain structure.

Experimental Investigation of Peak Temperature and Microhardness in Friction Stir Processing of AA6082 T6 using Taguchi GRA

Friction stir processing demonstrated tremendous potential for improving mechanical properties and its success relies on the optimal level of process parameters that result in a flawless stir zone. The present study is an experimental investigation of performance characteristics peak temperature and microhardness on FSPed AA6082-T6. The experiments are designed using the Taguchi L16 orthogonal array by considering four different levels of rotational speed, traverse speed, shoulder diameter, and tilt angle. The grey relational analysis is used for multiple responses to optimise the FSP process parameters and analysis of variance is utilised to establish the relevance of parameters for these responses. According to the findings, the shoulder diameter and traverse speed are the most important determinants for peak temperature and microhardness. It is observed from the experimental analysis that the main reasons for defect formation are either excessive or inadequate heat generation. The multi-response optimal condition is attained at a rotating speed of 1400 rpm, transverse speed of 112 mm/min, shoulder diameter of 25 mm, and tilt angle of 1º.

Numerical modelling of friction stir welding of pipes: Effect of tool shoulder on mechanical property and metallurgical characterization

One of the challenges during FSW of pipe is establishing sufficient contact between the tool shoulder and the pipes to be welded. With improper contact, the torque requirement increases, which thereby increases the power consumption. The present work focuses on the demonstration of a 3D thermo-mechanical model showing the influence of tool shoulder diameter on temperature rise, plastic strain development, spindle torque, material flow occurrence, and power consumption. The model showed a good correlation with experimentally observed temperature and maximum spindle torque for different rotational speeds. It was observed from the developed model that, an increase in the shoulder diameter increases the contact area and spread of maximum temperature resulting in a wider HAZ zone. Hence, optimization of the tool shoulder diameter was necessary, and it has been addressed considering its effect on contact area, heat generation, material flow, and spindle torque. The material flow behaviour has also been studied, and it was found that a larger shoulder diameter does not produce sufficient material stirring. The welded sample has been investigated by tensile strength and microstructure analysis. The optimum tool shoulder diameter of 16 mm resulted in joint strength efficiency of 90%.