scholarly journals Study on residual stresses caused by underwater friction stir welding: FE modeling and ultrasonic measurement

2018 ◽  
Vol 233 (1) ◽  
pp. 118-137
Author(s):  
Solaleh Salimi ◽  
Pouya Bahemmat ◽  
Mohammad Haghpanahi
Keyword(s):  
Residual Stress ◽  
Friction Stir Welding ◽  
Residual Stresses ◽  
Ultrasonic Method ◽  
Stress Fields ◽  
Optimum Process ◽  
Friction Stir ◽  
Mechanical Deformations ◽  
Underwater Friction Stir Welding ◽  
Precipitation Phenomena

Predicting residual stresses arising from the thermal and mechanical loading history during engineering processes including welding would be a viable tool to reach the optimum process parameters. In the present article, an elasto-thermo-visco-plastic model has been employed to estimate the residual stress caused by the underwater friction stir welding, which are resulted by large thermo-mechanical deformations on one hand and rapid cooling arising from the enormous non-uniform boiling heat convention of water on the other hand. Finally, the numerical results are compared with experimental data acquired by the ultrasonic method to evaluate the accuracy of the simulation process. Regarding the low temperature during underwater friction stir welding, the employed constitutive equations result in acceptable residual stress fields, while for in-air case, the amount of error increases significantly due to experience of high temperatures and intensification in hardening precipitation phenomena.

Process - Property Correlation of Friction Stir Welding of Marine Grade Aluminium Alloy 5083 Using Finite Element Analysis

2021 ◽  
Vol 163 (A2) ◽  
Author(s):  
M Sahu ◽  
A Paul ◽  
S Ganguly
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Finite Element ◽  
Friction Stir Welding ◽  
Residual Stresses ◽  
Process Variables ◽  
Friction Stir ◽  
Stress Region ◽  
Longitudinal Residual Stress ◽  
Process Property

In this article, a 3D finite element based thermo-mechanical model for friction stir welding (FSW) of a marine-grade aluminium alloy 5083 is proposed. The model demonstrates the thermal evaluation and the distribution of residual stresses and strains under the variation of process variables. The temperature profile of the weld joint during the FSW process and the mechanical properties of the joints are also experimentally evaluated. The necessary calibration of the model for the correct implementation of the thermal loading, mechanical loading, and boundary conditions was performed using the experimental results. The model simulation and experimental results are analyses in view of the process-property correlation study. The residual stress was evaluated along, and across the weld, centreline referred as longitudinal and transverse residual stresses, respectively. The magnitude of longitudinal residual stress is noted 60-80% higher than that of the transverse direction. The longitudinal residual stress generated a tensile oval shaped stress region around the tool shoulder confined to a maximum distance of about 25mm from the axis of the tool along the weld line. It encompasses the weld-nugget to thermo-mechanically affected zone (TMAZ), while the parent metal region is mostly experiences the compressive residual stresses. However, the transverse residual stress region appears like wing shaped region spread out in both the advancing and retreating side of the weld and occupying approximately double the area as compared to the longitudinal residual stresses. Overall, the study revealed a corelation between the FSW process variables such as welding speed and the tool rotational speed with the residual stress and the mechanical properties of the joint.

Analysis on the Residual Stresses in the Aluminum Alloy Friction Stir Welded Joints

2011 ◽  
Vol 291-294 ◽  
pp. 958-963
Author(s):  
Li Jie Cao
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Residual Stresses ◽  
Simulation Analysis ◽  
Engineering Application ◽  
Stress Fields ◽  
Weld Strength ◽  
Technological Parameters ◽  
Friction Stir ◽  
Wide Range

The residual stress fields can have strong influences on the integrity and performance of friction stir welded aluminum alloy structure, comprehensive insight into the residual stress distribution is the key to the Friction stir welding (FSW) engineering application for a wide range of materials and thicknesses improving the weld strength and fatigue life. In this paper, the current state of the residual stresses in the FSW aluminum alloy joints is reviewed, The focus is on recent advances of experimental research, the results of numerical simulation analysis, and the effects of the technological parameters(welding speed, rotational speed, shoulder geometry et al.) on residual stress fields was evaluated. In the end, The controlling technique of residual stresses from published literatures is summarized.

Study on the effect of the welding environment on the dynamic recrystallization phenomenon and residual stresses during the friction stir welding process of aluminum alloy

2021 ◽  
pp. 146442072110251
Author(s):  
Mahmoud Abbasi ◽  
Amin Abdollahzadeh ◽  
Behrouz Bagheri ◽  
Ahmad Ostovari Moghaddam ◽  
Farzaneh Sharifi ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Residual Stresses ◽  
Welding Process ◽  
Friction Stir ◽  
Friction Stir Welding Process ◽  
Underwater Friction Stir Welding ◽  
Processed Sample ◽  
Vibration Welding ◽  
Strength And Ductility

Various methods have been proposed to modify the friction stir welding. Friction stir vibration welding and underwater friction stir welding are two variants of this technique. In friction stir vibration welding, the adjoining workpieces are vibrated normal to the joint line while friction stir welding is carried out, while in underwater friction stir welding the friction stir welding process is performed underwater. The effects of these modified versions of friction stir welding on the microstructure and mechanical characteristics of AA6061-T6 aluminum alloy welded joints are analyzed and compared with the joints fabricated by conventional friction stir welding. The results indicate that grain size decreases from about 57 μm for friction stir welding to around 34 μm for friction stir vibration welding and about 23 μm for underwater friction stir welding. The results also confirm the evolution of Mg2Si precipitates during all processes. Friction stir vibration welding and underwater friction stir welding processes can effectively decrease the size and interparticle distance of precipitates. The strength and ductility of underwater friction stir welding and friction stir vibration welding processed samples are higher than those of the friction stir welding processed sample, and the highest strength and ductility are obtained for underwater friction stir welding processed samples. The underwater friction stir welding and friction stir vibration welding processed samples exhibit about 25% and 10% higher tensile strength compared to the friction stir welding processed sample, respectively. The results also indicate that higher compressive residual stresses are developed as underwater friction stir welding and friction stir vibration welding are applied.

Evaluation of 7050 Aluminum Plates Joined by Friction Stir Welding Using Acoustoelastic

2017 ◽  
Author(s):  
Shirley Alexandra García Ruano ◽  
Felipe Bertelli ◽  
Auteliano Antunes dos Santos
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Residual Stresses ◽  
Ultrasonic Method ◽  
Welding Process ◽  
Longitudinal Direction ◽  
Structural Components ◽  
Friction Stir ◽  
Low Weight ◽  
Aluminum Plates

The 7050-T7451 aluminum alloy has been widely used in the aerospace industry. Due to its chemical composition, this alloy has high levels of mechanical properties that allow the production of low-weight aircraft structural components. However, these alloys are thermally treatable and are not able to bear manufacturing processes involving heat. Because of the importance of their applications, studies based on the development of solid state welding process would be desirable aiming to find an alternative to generate welded joints for this kind of components. In this work, an investigation concerning the behavior of the 7050-T7451 aluminum alloy during Friction Stir Welding (FSW) was carried out. The profile of longitudinal residual stresses of plates welded by the FSW process was obtained using the ultrasonic method through critically refracted longitudinal waves (LCR). Two different frequencies were employed, 3.5 MHz and 5 MHz. The measurements were performed in the longitudinal direction of the welded joint at different distances from the center line of the weld. The magnitude and distribution of residual stresses found with this method are consistent with literature review, reaching 150MPa on the center of the weld.

The Influence of Friction Stir Welding Process Idealization on Residual Stress and Distortion Predictions for Future Airframe Assembly Simulations

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
R. W. McCune ◽  
A. Murphy ◽  
M. Price ◽  
J. Butterfield
Keyword(s):  
Residual Stress ◽  
Friction Stir Welding ◽  
Residual Stresses ◽  
Welding Process ◽  
Structural Components ◽  
Friction Stir ◽  
Friction Stir Welding Process ◽  
Computationally Expensive ◽  
Forging Force ◽  
Process Speed

The ability to accurately predict residual stresses and resultant distortions is a key product from process assembly simulations. Assembly processes necessarily consider large structural components potentially making simulations computationally expensive. The objective herein is to develop greater understanding of the influence of friction stir welding process idealization on the prediction of residual stress and distortion and thus determine the minimum required modeling fidelity for future airframe assembly simulations. The combined computational and experimental results highlight the importance of accurately representing the welding forging force and process speed. In addition, the results emphasize that increased CPU simulation times are associated with representing the tool torque, while there is potentially only local increase in prediction fidelity.

Integrated Design and Numerical Simulation of Stiffened Panels Including Friction Stir Welding Effects

2013 ◽  
Vol 554-557 ◽  
pp. 2237-2242 ◽  
Author(s):  
Rui Miguel Ferreira Paulo ◽  
Pierpaolo Carlone ◽  
Robertt A.F. Valente ◽  
Filipe Teixeira-Dias ◽  
Gaetano S. Palazzo
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Friction Stir Welding ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Ultimate Load ◽  
Simulation Models ◽  
Residual Stress Distribution ◽  
Stiffened Panels ◽  
Friction Stir

Stiffened panels are usually the basic structural building blocks of airplanes, vessels and other structures with high requirements of strength-to-weight ratio. They typically consist of a plate with equally spaced longitudinal stiffeners on one side, often with intermediate transverse stiffeners. Large aeronautical and naval parts are primarily designed based on their longitudinal compressive strength. The structural stability of such thin-walled structures, when subjected to compressive loads, is highly dependent on the buckling strength of the structure as a whole and of each structural member. In the present work, a number of modelling and numerical calculations, based on the Finite Element Method (FEM), is carried out in order to predict the ultimate load level when stiffened panels are subjected to compressive solicitations. The simulation models account not only for the elasto-plastic nonlinear behaviour, but also for the residual stresses, material properties modifications and geometrical distortions that arise from Friction Stir Welding (FSW) operations. To construct the model considering residual stresses, their distribution in FSW butt joints are obtained by means of a numerical-experimental procedure, namely the contour method, which allows for the evaluation of the normal residual stress distribution on a specimen section. FSW samples have been sectioned orthogonally to the welding line by wire electrical discharge machining (WEDM). Displacements of the relaxed surfaces are then recorded using a Coordinate Measuring Machine and processed in a MATLAB environment. Finally, the residual stress distribution is evaluated by means of an elastic FE model of the cut sample, using the measured and digitalized out-of-plane displacements as input nodal boundary conditions. With these considerations, the main goal of the present work will then be related to the evaluation of the effect of FSW operations, in the ultimate load of stiffened panels with complex cross-section shapes, by means of realist numerical simulation models.

A new method for measurement the residual stresses in friction stir welding

2021 ◽  
Vol 112 (2) ◽  
pp. 63-69
Author(s):  
M.J. Jweeg ◽  
Z.Kh. Hamdan ◽  
A.H. Majeed ◽  
K.K. Resan ◽  
M. Al-Waily
Keyword(s):  
Residual Stress ◽  
Friction Stir Welding ◽  
Stress Concentration ◽  
Residual Stresses ◽  
Tensile Testing ◽  
Low Cost ◽  
New Method ◽  
Ray Method ◽  
X Ray ◽  
Friction Stir

Purpose: The residual stresses in different welding methods are fundemental problems to consider. Friction stir welding is one of a solid state joining process, it is economical in that it permits joining together different materials, the specimens in this method (FSW) have excellent properties of mechanical as proven by tensile, flextural and fatigue tests, also it is environmentally friendly process minimizes consumption of energy and generate no gasses or smoke. In friction stir welding , there are two kinds of generated residual stresses: tensile stress and compressive stress. So, this study measuring the residual stresses by using a new method for measuring residual stresses depends on tensile testing and stress concentration factor, this method is a simple, fast and low cost, also it is not need special device. Design/methodology/approach: In previous studies, several techniques were used to predict the value of residual stress and its location, such as destructive, semi-destructive, and non-destructive methods. In this study, a simple, new, and inexpensive way was used based on the tensile test and stress concentration of the friction stir welding (FSW). Findings: By comparing the results obtained with the previous studies using the X-ray method, with the current research, it was found that the results are good in detecting the location and value of the residual stress of friction stir welding. The value of discrepancy of the residual stress in the results between those obtained by the previous method and the current method was about 3 MPa. Research limitations/implications: There are many rotational and linear feeding speeds used in this type of welding. This research used two plates from 6061 AA with 3mm thickness, 100 mm width, and 200 mm length. The rotational speed used in friction stir welding was 1400 rpm, and the feeding speed was 40 mm/min. Practical implications: The residual stress obtained with the new method is 6.2 MPa, and this result approximates other known methods such as the X-ray method in previus studies. Originality/value: Using a new simple method for measuring residual stresses of friction stir welding depends on stress concentration factor and tensile testing. This method is fast and low cost , also it is not need specialized device, compared to other methods such as x-ray or hole drilling methods.

scholarly journals Effect of Shot Peening on Redistribution of Residual Stress Field in Friction Stir Welding of 2219 Aluminum Alloy

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3169 ◽  
Author(s):  
Lin Nie ◽  
Yunxin Wu ◽  
Hai Gong ◽  
Dan Chen ◽  
Xudong Guo
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Stress Field ◽  
Shot Peening ◽  
Welding Residual Stress ◽  
Stress Fields ◽  
Residual Stress Field ◽  
Friction Stir ◽  
2219 Aluminum Alloy

Welding is one of the essential stages in the manufacturing process of mechanical structures. Friction stir welding structure of aluminum alloy has been used as a primary supporting member in aerospace equipment. However, friction stir welding inevitably generates residual stress that promotes the initiation and propagation of cracks, threatening the performance of the welded structure. Shot peening can effectively change the distribution of residual stress and improve the fatigue properties of materials. In this paper, friction stir welding and shot peening are performed on 2219 aluminum alloy plates. The residual stress fields induced by friction stir welding and shot peening are measured by using the X-ray diffraction method and incremental center hole drilling method, and the distribution characteristics of residual stress fields are analyzed. The effect of the pellet diameters and pellet materials used in shot peening on the redistribution of welding residual stress field are investigated. The pellet diameter used in the experiment is in the range of 0.6–1.2 mm, and the pellet material includes glass, steel, and corundum. This study provides guidance for the application of shot peening in friction stir welding structure of 2219 aluminum alloy.

Effect of friction stir welding parameters on the residual stress distribution of Al-2024-T6 alloy

2021 ◽  
Vol 15 (1) ◽  
pp. 7684-7694
Author(s):  
Majid Farhang ◽  
Omid Sam-Daliri ◽  
Mohammadreza Farahani ◽  
Azadeh Vatani
Keyword(s):  
Residual Stress ◽  
Friction Stir Welding ◽  
Residual Stresses ◽  
Rotational Speed ◽  
Welding Parameters ◽  
Tool Rotational Speed ◽  
High Rotational Speed ◽  
Friction Stir ◽  
Longitudinal Residual Stress ◽  
Al 2024

The objective of this study was to investigate the influences of the main parameters of friction stir welding (FSW) on the residual stresses remained in the FSW of Al 2024-T6. The main parameters were tool rotational speed and tool transverse speed. The effect of these parameters on the residual stresses was studied in both finite element simulation and hole drilling strain gauge measurement. The results showed a good agreement between the numerical results and the experimental outcomes. The change in transverse speed from 25 to 31.5 mm/min resulted in increase of longitudinal residual stresses in welding centerline in which the longitudinal residual stress was increased at the tool rotational speed of 1120 rpm and 1600 rpm about 12.5% and 2.67%, respectively. The results showed that at the low rotational speed, the strain rate had the most effect on the residual stresses whereas at the high rotational speed, some residual stress was released due to the generated heat in the weld zone.

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