scholarly journals Analogue Modelling of Flow Patterns in Bobbin Friction Stir Welding by the Dark-Field/Bright-Field Illumination Method

2020 ◽  
Vol 20 (1) ◽  
pp. 56-70 ◽  
Author(s):  
A. Tamadon ◽  
D. J. Pons ◽  
D. Clucas
Keyword(s):  
Friction Stir Welding ◽  
Weld Zone ◽  
Welding Process ◽  
Internal Flow ◽  
Flow Patterns ◽  
Dark Field ◽  
Bright Field ◽  
Analogue Model ◽  
Friction Stir ◽  
Flow Features

AbstractThe flow-inducing effect of the bobbin-tool features (tri-flat pin and scrolled shoulder) were replicated by a simple analogue model for aluminium welds by layered plasticine samples. Flow patterns of the weld zone were clarified by a typical stereomicroscopy instrument assisted by dark-field/bright-field illumination. The effects of the pin features, specifically threads and flats in centre of bond zone and scrolled shoulder in sides of stirred zone, were identified. This study shows that internal flow features for BFSW welds is transferable from the friction stir welding process to the functional metal forming processes such where the shearing can extensively affect the microstructure. The similarity between the flow pattern of the provided aluminium samples and the plasticine analogue can validate the accuracy of the flow model presented in this work.

scholarly journals Internal Material Flow Layers in AA6082-T6 Butt-Joints during Bobbin Friction Stir Welding

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1059 ◽  
Author(s):  
Tamadon ◽  
Pons ◽  
Clucas ◽  
Sued
Keyword(s):  
Friction Stir Welding ◽  
Grain Boundaries ◽  
Material Flow ◽  
Internal Flow ◽  
High Density ◽  
Butt Joints ◽  
Friction Stir ◽  
Discontinuous Flow ◽  
Flow Features ◽  
Oxidation Layers

Bobbin friction stir welding with a double-sided tool configuration produces a symmetrical solid-state joint. However, control of the process parameters to achieve defect-free welds is difficult. The internal flow features of the AA6082-T6 butt-joints in bobbin friction stir welding were evaluated using a set of developed reagents and optical microscopy. The key findings are that the dark curved patterns (conventionally called 'flow-arms'), are actually oxidation layers at the advancing side, and at the retreating side are elongated grains with a high-density of accumulation of sub-grain boundaries due to dynamic recrystallization. A model of discontinuous flow within the weld is proposed, based on the microscopic observations. It is inferred that the internal flow is characterized by packets of material ('flow patches') being transported around the pin. At the retreating side they experience high localized shearing at their mutual boundaries, as evidenced in high density of sub-grain boundaries. Flow patches at the advancing side are stacked on each other and exposed to oxidization.

scholarly journals The Preliminary Exploration of Micro-Friction Stir Welding Process and Material Flow of Copper and Brass Ultra-Thin Sheets

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2401
Author(s):  
Changqing Zhang ◽  
Zhuo Qin ◽  
Chen Rong ◽  
Wenchen Shi ◽  
Shuwen Wang
Keyword(s):  
Friction Stir Welding ◽  
Flow Behavior ◽  
Pure Copper ◽  
Weld Zone ◽  
Metal Flow ◽  
Welding Process ◽  
Process Conditions ◽  
Friction Stir ◽  
Plastic Metal ◽  
Tool Pin

In the friction stir welding (FSW) of ultra-thin dissimilar metal sheets, different physical material properties, the reduction of plastic metal in the weld zone, and insufficient plastic metal flow lead to poor weld seam shapes and joint qualities. Therefore, it is necessary to study the flow behavior during the FSW of ultrathin sheets. In this study, micro friction stir welding (μFSW) was conducted and analyzed for the butt welding of 0.6-mm-thick ultrathin brass (H62-H) and pure copper (T2-Y) sheets. By analyzing the electric signals of the temperature and force during the welding process, testing the mechanical properties, and analyzing the metallography of the joint, the influences of the process parameters on the metal flow behavior during μFSW were studied. In the proper process conditions, the material preferentially migrated and concentric vortex flow occurred in the vicinity of the shoulder and tool pin action areas. The copper was pushed from the retreating side (RS) to the advancing side (AS) of the weld, allowing it to flow more fully. A mixture of both materials formed at the bottom of the weld nugget, and less migration occurred in the heat-affected zone of the AS at this time. The highest tensile strength can reach 194 MPa, accounting for 82.6% of the copper. The presence of brittle phases Cu5Zn8, AgZn3 and AgZn caused the hardness to fluctuate slightly.

scholarly journals Temperature Based Optimization of Friction Stir Welding of AA 6061 Using GRA Synchronous With Taguchi Method

2021 ◽  
Author(s):  
Eyob Messele ◽  
Assefa Asmare Tsegaw
Keyword(s):  
Friction Stir Welding ◽  
Base Metal ◽  
Weld Zone ◽  
Welding Process ◽  
Quality Characteristic ◽  
Heat Transfer Analysis ◽  
Al Alloy ◽  
Welding Temperature ◽  
Friction Stir ◽  
Tool Pin

Abstract One of the recent novel joining mechanisms in the solid-state-welding process is Friction Stir Welding (FSW). The process is extensively used in joining similar and dissimilar materials as well. This research studied and found the optimum process parameters of FSW based on the temperature simulation results on a 5 mm 6061 Al alloy sheet with a butt joint configuration. Steady-state heat transfer analysis was performed using a transient thermal workbench to predict and identify the optimum parameters grounded on the simulation welding temperature result. The parameters are optimized using the hybrid Taguchi L9 orthogonal array and Grey relation analysis method with a larger is better quality characteristic. Mechanical properties of the weld joints' such as hardness and tensile strength, were studied at an ambient temperature. The result revealed that a higher rotational speed with a minimum traverse speed and taper threaded tool pin impart the optimum parameter settings. Analysis of variance (ANOVA) was carried out also to determine the effects of each process parameter. At a 95 % confidence interval, rotational and traverse speeds show significant characteristics. The joint efficiency reached 92.25% of the base metal at a maximum welding temperature. Additionally, the microstructure of the stir weld zone of the specimen was studied as well. Metallographic Characterization carried out using Scanning Electron Microscope (SEM) revealed the microstructure of the samples after the weld did not show any significant change with the base metal. Furthermore, this study scheme can be extended to thick non-ferrous, ferrous, and metal-based composite materials, too.

Robustness of 802.15 Wireless Interface for Real-Time Thermal Feedback Control of the Friction Stir Welding Process

2015 ◽  
Author(s):  
Grant H. Kruger ◽  
Scott F. Miller ◽  
Albert J. Shih ◽  
Theo I. van Niekerk
Keyword(s):  
Control System ◽  
Friction Stir Welding ◽  
Feedback Control ◽  
Frictional Heating ◽  
Weld Zone ◽  
Welding Process ◽  
Signal Strength ◽  
Friction Stir ◽  
Communication Latency ◽  
Wireless Interface

Friction Stir Welding (FSW) is a modern, solid-state joining processes, involving frictional heating and mechanical forging. High quality joints can be created using a control system that compensates for external disturbances by regulating the state of the weld zone (WZ) surrounding the tool. However, in this situation direct monitoring is complex since the rotating tool is embedded in plasticized material. This research discusses the development of a Bluetooth-based Wireless Rotating Process Monitoring (WRPM) system to overcome limitations in inductive/capacitive telemetry systems. Communication channel performance was assessed to determine the suitability of Bluetooth for use in the feedback control loop for in-process FSW WZ temperature control. Peak round-trip communications latencies of 300–650 ms for 20–200 byte payloads were observed. Additionally, electrical noise from the machine tool reduced the receive signal strength measured on the Bluetooth module. The bit error rate (BER) also increased from 0 to 0.001 % as spindle speed increased from 0 to 1400 rpm. Due to the communication latency, the signal strength and BER effects were not observed to affect throughput. The results support the use of the WRPM system for feedback control of FSW. However, deterministic communication latency must be achieved to enable the design of a stable control system.

Friction Stir Welding of 6061-T6 Aluminum Alloy

2012 ◽  
Vol 501 ◽  
pp. 145-149
Author(s):  
Indra Putra Almanar ◽  
Mohd Haslam Hanapi ◽  
Abu Seman Anasyida ◽  
Zuhailawati Hussain
Keyword(s):  
Grain Size ◽  
Friction Stir Welding ◽  
Rotational Speed ◽  
Weld Zone ◽  
Welding Process ◽  
Heat Affect Zone ◽  
Filler Materials ◽  
Processing Parameter ◽  
Nugget Zone ◽  
Friction Stir

Friction stir welding (FSW) is a new and promising welding process which can produce low cost and high quality joints of heat-treatable aluminum alloys. This is because it does not require the consumable filler materials and can eliminate some welding defects such as crack and porosity. The main objective of the present work was to evaluate the processing parameter of friction stir welding (FSW) process for 6061-T6 alloy and to determine the properties of the obtained joints. Experiments have been conducted by varying the friction stir welding processing parameter ; tool rotational speed, in rpm (410, 865, 1140) and feed rate, in mm/min (22, 32, 45). The shoulder diameter of the tool for FSW was 18 mm. Microstructure, microhardness and tensile properties were investigated in this studied. The results showed that there was a variation of grain size in each weld zone which depends on the material and process parameters of FSW in the joint itself. The coarsest grain size was observed in the heat affect zone (HAZ), followed by the Thermo Mechanically Affected Zone (TMAZ) and the nugget zone. The highest hardness was reported on the nugget zone and maximum tensile strength was obtained on the sample with processing parameter 865 rpm rotational speed.

scholarly journals Effects of the FSW Parameters on Microstructure and Electrical Properties in Al 6061-T6- Cu C11000 Plate Joints

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 21
Author(s):  
Daniel García-Navarro ◽  
Juan Carlos Ortiz-Cuellar ◽  
Jesús Salvador Galindo-Valdés ◽  
Josué Gómez-Casas ◽  
Carlos Rodrigo Muñiz-Valdez ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Friction Stir Welding ◽  
Electrical Properties ◽  
Weld Zone ◽  
Welding Process ◽  
Dissimilar Materials ◽  
Traverse Speed ◽  
Friction Stir ◽  
Fsw Parameters ◽  
Pure Cu

Friction Stir Welding (FSW) is a feasible welding process to join dissimilar materials due to its solid-state nature. In this study the FSW of 6061-T6 aluminum with pure Cu plates was performed with the objective of evaluating the effects of the FSW parameters on the microstructure and electrical properties. The processing parameters (rotational and traverse speeds) were established to reduce the common defects in the friction-stir welding process. Therefore, the obtained results validated the better mechanical properties and a smaller increase of the electrical resistivity. The rotational speeds used were of 1000, 1150, and 1300 rpm, and the traverse speeds of 20, 40, and 60 mm/min, with the purpose of varying the heat input of the process. The microstructural characterization revealed the presence of a mixture of aluminum and copper into the weld zone, along with copper particles and the formation of intermetallic compounds. It was found that the electrical resistivity of the joints ranged from 0.029 to 0.036 μΩ. The highest electrical resistivity values were obtained at the lowest traverse speed (20 mm/min) and the lowest resistivity values were obtained at highest traverse speed (60 mm/min).

scholarly journals Study the effect of welding pass number on the mechanical and metallurgical properties of Aluminum type Al 1050 H14 produced by friction stir welding

2021 ◽  
Vol 28 (4) ◽  
pp. 1-13
Author(s):  
Najeeb Salman Abtan ◽  
Jawdat Ali Yagoob ◽  
Ayshan Mohammed Shukri
Keyword(s):  
Tensile Strength ◽  
Friction Stir Welding ◽  
Base Metal ◽  
Weld Zone ◽  
Welding Process ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Mechanical Mixing ◽  
Butt Welding ◽  
Friction Stir

Friction Stir Welding (FSW) is a solid-state welding technique with non-fusible rotary welds. Heat is generated by the friction produced between the weld tool and the two opposite surfaces of the two welded parts and the tool works on mechanical mixing with the presence of heat, pressure, and heat generated, reaching approximately (80-90%) of the melting point of the metal to be welded. In this study, Al 1050 H14 aluminum with a thickness of (6mm) was used for the purpose of welding it by means of the friction stir welding process in a butt welding method to obtain similar welding joints. A set with a square stitching tool Made of alloy steel was used by using a milling machine, with fixed (rotational speed of 1008 rpm and linear velocity of 40mm / min), an inclination angle of (2o), and counterclockwise rotation. The efficiency of welded joints was evaluated through static mechanical tests. Tensile tests, microscopic hardness, and visual examination. The results for all welds showed that the mixing zone (NZ) consists of fine grains of equal axes compared to the base metal. When welding on one side and in one path, the microstructure of HAZ was similar to the base metal. TAMZ was a transition region between HAZ and NZ. As for welding on one side, with two paths and three paths, the structure turned into a fine crystalline structure. By increasing the number of paths per side, the welding efficiency of the welded sample increased as the best efficiency was from one side and three paths (76.215%). Through the results, the tensile strength increases with the increase in the number of paths, as the best tensile strength was obtained when conducting the welding process from one side and by three paths, which is (93.653 MPa). It is equivalent to 76.21% of the tensile strength of the base metal. The hardness value in the weld zone (NZ) is higher than the other two zones (HAZ, TMAZ) due to the occurrence of dynamic recrystallization, which results in very fine and equiaxial crystals, but the hardness value in the weld zone remains less than the hardness value of the base metal.

Effects of bottom plate in friction stir welding of AA6061-T6

2020 ◽  
Vol 118 (1) ◽  
pp. 108
Author(s):  
M.A. Vinayagamoorthi ◽  
M. Prince ◽  
S. Balasubramanian
Keyword(s):  
Mechanical Properties ◽  
Axial Load ◽  
Weld Zone ◽  
Welding Process ◽  
Bottom Plate ◽  
Welding Parameters ◽  
Nugget Zone ◽  
Friction Stir ◽  
Weld Joints ◽  
Fine Grain

The effects of 40 mm width bottom plates on the microstructural modifications and the mechanical properties of a 6 mm thick FSW AA6061-T6 joint have been investigated. The bottom plates are placed partially at the weld zone to absorb and dissipate heat during the welding process. An axial load of 5 to 7 kN, a rotational speed of 500 rpm, and a welding speed of 50 mm/min are employed as welding parameters. The size of the nugget zone (NZ) and heat-affected zone (HAZ) in the weld joints obtained from AISI 1040 steel bottom plate is more significant than that of weld joints obtained using copper bottom plate due to lower thermal conductivity of steel. Also, the weld joints obtained using copper bottom plate have fine grain microstructure due to the dynamic recrystallization. The friction stir welded joints obtained with copper bottom plate have exhibited higher ductility of 8.9% and higher tensile strength of 172 MPa as compared to the joints obtained using a steel bottom plate.

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