Effects of various tool pin profiles on mechanical and metallurgical properties of friction stir welded joints of cryorolled AA2219 aluminium alloy

2018 ◽  
Vol 115 (2) ◽  
pp. 212
Author(s):  
Karupannan Kamal Babu ◽  
Kavan Panneerselvam ◽  
Paulraj Sathiya ◽  
Abdul Haq Noorul Haq ◽  
Srinivasan Sundarrajan ◽  
...  
Keyword(s):  
Weld Joint ◽  
Material Flow ◽  
Weld Zone ◽  
Mechanical Analysis ◽  
Grain Structure ◽  
Friction Stir ◽  
Precipitate Dissolution ◽  
Fine Grain ◽  
Mechanical Tensile ◽  
Tool Pin

Friction stir welding (FSW) process was conducted on cryorolled (CR) AA2219 plate using different tool pin profiles such as cylindrical pin, threaded cylindrical pin, square pin and hexagonal pin profiles. The FSW was carried out with pairs of 6 mm thick CR aluminium plates with different tool pin profiles. The different tool pin profile weld portions' behaviors like mechanical (tensile strength, impact and hardness) and metallurgical characteristics were analyzed. The results of the mechanical analysis revealed that the joint made by the hexagonal pin tool had good strength compared to other pin profiles. This was due to the pulsating action and material flow of the tool resulting in dynamic recrystallization in the weld zone. This was confirmed by the ultra fine grain structure formation in Weld Nugget (WN) of hexagonal pin tool joint with a higher percentage of precipitate dissolution. The fractograph of the hexagonal tool pin weld portion confirmed the finer dimple structure morphology without having any interior defect compared to other tool pin profiles. The lowest weld joint strength was obtained from cylindrical pin profile weld joint due to insufficient material flow during welding. The Transmission Electron Microscope and EDX analysis showed the dissolution of the metastable θ″, θ′ (Al2Cu) partial precipitates in the WN and proved the influence of metastable precipitates on enhancement of mechanical behavior of weld. The XRD results also confirmed the Al2Cu precipitation dissolution in the weld zone.

Effect of Weld Zone Shape on Microstructure and Tensile Properties in Friction Stir Welding Process

2020 ◽  
Vol 978 ◽  
pp. 84-90
Author(s):  
Prashant Prakash ◽  
Ravi Shankar Anand ◽  
Sanjay Kumar Jha
Keyword(s):  
Friction Stir Welding ◽  
Ductile Fracture ◽  
Tensile Properties ◽  
Fracture Mode ◽  
Weld Joint ◽  
Testing Machine ◽  
Weld Zone ◽  
Experimental Result ◽  
Friction Stir ◽  
Tool Pin

This article presents the effect of weld zone shapes on microstructure and tensile properties of weld joints in friction stir welding. Experiments are conducted using four different tool pin profiles that are cylindrical, conical, cylindrical-conical and stepped-conical for analysing the weld zone shape. The weld zone shape properties are defined by characteristic length. Grain size and mode of fracture surface behavior are analysed by optical microscope and scanning microscope respectively and tensile strength is measured by universal testing machine. It is also observed that the weld zone shape of all pin profile tool is vase shape. In which, cylindrical, conical and cylindrical-conical pin profile tools produce basin dominant vase shape and stepped-conical pin profile tool produces cylinder dominant vase shape. The experimental result shows that the weld joint fabricated by stepped-conical pin profile tool produces the smallest grain, good ductile fracture mode and highest tensile properties as compared to other pin profile tool. This analysis shows that cylinder dominant vase shape produces high tensile properties and enhance ductile fracture mode in the weld joint.

scholarly journals Influence of Tool Pin Profile on Mechanical Properties and Microstructure of Friction Stir Welded Aluminium AA7075 Alloy

2020 ◽  
Vol 6 (10) ◽  
pp. 7-11
Author(s):  
G.Venkateswarlu
Keyword(s):  
Mechanical Properties ◽  
Traverse Speed ◽  
Grain Structure ◽  
Tool Rotational Speed ◽  
Friction Stir ◽  
Fine Grain ◽  
Shoulder Diameter ◽  
Aa 7075 ◽  
7075 Alloy ◽  
Tool Pin

The present investigation describes the effect of different tool pin profiles on microstructure and mechanical properties of friction stir welded aluminium AA-7075 alloy. The tool pin profiles namely taper cylindrical threaded (TT), cylindrical (CT), square (SQ), triangular (TR), pentagonal (PT), hexagonal (HX) with constant shoulder diameter have been selected to make joints. The friction stir welding was done at constant tool rotational speed and traverse speed. From this study, it is noted that the weld joints prepared using taper cylindrical threaded pin profile exhibited good mechanical properties when compared to other pin profiles. It is due to more surface contact of tool pin and production of equiaxed fine grain structure in the weld region.

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.

Grain Structure Formation Ahead of Tool during Friction Stir Welding of AZ31 Magnesium Alloy

2010 ◽  
Vol 160 ◽  
pp. 313-318 ◽  
Author(s):  
Uceu Suhuddin ◽  
Sergey Mironov ◽  
H. Takahashi ◽  
Yutaka S. Sato ◽  
Hiroyuki Kokawa ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Magnesium Alloy ◽  
Structure Formation ◽  
Material Flow ◽  
Boundary Migration ◽  
Deformation Mode ◽  
Grain Structure ◽  
Az31 Magnesium Alloy ◽  
Structure Evolution ◽  
Friction Stir

The “stop-action” technique was employed to study grain structure evolution during friction-stir welding of AZ31 magnesium alloy. The grain structure formation was found to be mainly governed by the combination of the continuous and discontinuous recrystallization but also involved geometric effect of strain and local grain boundary migration. Orientation measurements showed that the deformation mode was very close to the simple shear associated with the rotating pin and material flow arose mainly from basal slip.

scholarly journals Influence of Mx-Trivex, A-Skew, Three Flat Threaded and Concave Shouldered Mx-Triflute Tool Pin Profiles on Tensile Properties and Fractural Behaviour of Aa 6082-T6 Weldments During Friction Stir Welding

2020 ◽  
Vol 9 (4) ◽  
pp. 1376-1384
Keyword(s):  
Friction Stir Welding ◽  
Tensile Test ◽  
Weld Zone ◽  
Base Material ◽  
Traverse Speed ◽  
Friction Stir ◽  
Tool Pin ◽  
Solid State Joining ◽  
Joining Process ◽  
Brass Wire

Friction Stir Welding (FSW) is a topical and propitious solid-state joining process producing economical and strengthened joints of age-hardened and heat-treatable Aluminium Alloy AA 6082-T6. Mechanical and fractural behaviour of weldments were investigated in order to find crack initiation and necking on the weld zone thereby perceiving the complete behaviour of fracture occurred near the weld zone. Weldments are fabricated by employing four tool pin profiles namely MX-TRIVEX, A-SKEW, Three flat threaded and Concave shouldered MX-TRIFLUTE tools at various rotational speeds 1000 rpm, 1200 rpm and 1400 rpm at single traverse speed 25 mm/min. EXCETEX-EX-40 CNC wire cut EDM with 0.25 mm brass wire diameter has been employed to perform the extraction of tensile test specimens from the weldments according to ASTM E8M-04 standard. Tensile test was performed on elctromechanically servo controlled TUE-C-200 (UTM machine) according to ASTM B557-16 standards Maximum Ultimate Tensile Strength (UTS) of 172.33 MPa (55.5% of base material) and 0.2% Yield Stress (YS) of 134.10 MPa (51.5% of base material) were obtained by using A-SKEW at 1400 rpm, 25 mm/min and maximum % Elongation (%El) of 11.33 (113.3% of base material) was obtained at MX-TRIVEX at 1000 rpm, 25 mm/min. Minimum UTS of 131.16 MPa (42.30% of base material) and 0.2% YS of 105.207 MPa (40.46% of base material )were obtained by using Concave shouldered MX-TRIFLUTE at 1400 rpm, 25 mm/min. Minimum % El of 5.42 ( 54.2% of base material) was obtained by using A-SKEW at 1000 rpm, 25 mm/min.

scholarly journals Texture Evolution in AA6082-T6 BFSW Welds: Optical Microscopy and EBSD Characterisation

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3215 ◽  
Author(s):  
Abbas Tamadon ◽  
Dirk J. Pons ◽  
Don Clucas ◽  
Kamil Sued
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Optical Microscopy ◽  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
Grain Structure ◽  
Friction Stir ◽  
Fine Grain ◽  
Grain Structures ◽  
Dynamic Recrystallisation

One of the difficulties with bobbin friction stir welding (BFSW) has been the visualisation of microstructure, particularly grain boundaries, and this is especially problematic for materials with fine grain structure, such as AA6082-T6 aluminium as here. Welds of this material were examined using optical microscopy (OM) and electron backscatter diffraction (EBSD). Results show that the grain structures that form depend on a complex set of factors. The motion of the pin and shoulder features transports material around the weld, which induces shear. The shear deformation around the pin is non-uniform with a thermal and strain gradient across the weld, and hence the dynamic recrystallisation (DRX) processes are also variable, giving a range of observed polycrystalline and grain boundary structures. Partial DRX was observed at both hourglass boundaries, and full DRX at mid-stirring zone. The grain boundary mapping showed the formation of low-angle grain boundaries (LAGBs) at regions of high shear as a consequence of thermomechanical nature of the process.

The Influence of Cu/Ti Overlapping Region Microstructures on the Mechanical Tensile Properties of the Joint via Friction Stir Lap Welding

2017 ◽  
Vol 1142 ◽  
pp. 260-264 ◽  
Author(s):  
Bo Li ◽  
Yi Fu Shen ◽  
Lei Yao
Keyword(s):  
Tensile Properties ◽  
Travel Speed ◽  
Lap Joints ◽  
Friction Stir Lap Welding ◽  
Friction Stir ◽  
Lap Welding ◽  
Mechanical Tensile ◽  
Tool Pin ◽  
Solid State Joining ◽  
Locking Effect

The investigation on friction stir lap welding (FSLW) of dissimilar Cu and Ti is reported in this research, aiming to achieve a reliable solid-state joining and effectively control the intermetellic (IMC) formation at the lapping Cu/Ti dissimilar welded interfaces. Following the previous process optimization of the FSLW tool rotation speed and downward plunge value of the tool pin into the lower Ti sheet, the tool travel speed was further tailored for a defect-free joint. No significant Ti-Cu IMC was founded in the generated joints. After the analyses of tensile properties of the FSLW joints, the so-called mechanical locking effect of the Cu/Ti alternate band structure was further elucidated. The composite-like structure played a so-called mechanical locking effect on the Cu/Ti lap joints. The fracture resistant strength of the joint reached 95% of that of the used parent copper.

scholarly journals Material Flow Visualization of Dissimilar Friction STIR Welding Process Using Nano-Computed Tomography

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Xun Liu ◽  
Sheng Zhao ◽  
Kai Chen ◽  
Jun Ni
Keyword(s):  
Computed Tomography ◽  
Friction Stir Welding ◽  
Heat Input ◽  
Material Flow ◽  
Volume Fraction ◽  
Weld Zone ◽  
Process Conditions ◽  
Rotating Speed ◽  
Friction Stir ◽  
Small Tool

In this study, the friction stir welding (FSW) of aluminum alloy 6061-T6511 to TRIP 780 steel is analyzed under various process conditions. Two FSW tools with different sizes are used. To understand the underlying joining mechanisms and material flow behavior, nano-computed tomography (nano-CT) is applied for a 3D visualization of material distribution in the weld. With insufficient heat input, steel fragments are generally scattered in the weld zone in large pieces. This is observed in a combined condition of big tool, small tool offset, and low rotating speed or a small tool with low rotating speed. Higher heat input improves the material flowability and generates a continuous strip of steel. The remaining steel fragments are much finer. When the volume fraction of steel involved in the stirring nugget is small, this steel strip can be in a flat shape near the bottom, which generally corresponds to a better joint quality and the joint would fracture in the base aluminum side. Otherwise, a hook structure is formed and reduces the joint strength. The joint would fail with a combined brittle behavior on the steel hook and a ductile behavior in the surrounding aluminum matrix.

Spiral Friction Stir Processing (SFSP) for the Extrusion of Lightweight Alloy Tubes

2012 ◽  
Author(s):  
Fadi Abu-Farha
Keyword(s):  
Friction Stir Processing ◽  
Special Form ◽  
Bulk Material ◽  
Processing Technique ◽  
Grain Structure ◽  
The Novel ◽  
Friction Stir ◽  
Fine Grain ◽  
Processed Material ◽  
Novel Concept

While friction stir processing (FSP) has been used to refine the grain structure in sheet metals, this work explores the potentials of refining the grain structure of bulk material using the friction stirring phenomenon via the novel concept of spiral friction stir processing (SFSP). With this concept, the rotating stirring tool is plunged into the material, rather than being traversed across it as in FSP; this imposes severe plastic deformation on the material while pushing it radially outwards in complex spiral paths. By confining the material within a closed cylindrical die, the processed material is microstructurally-refined while forming a tube via a special form of SFSP called “friction stir back extrusion” (FSBE). The hypothesised concept was investigated using samples from the AA6063-T52 aluminium alloy and the AZ31B-F magnesium alloy. The preliminary results presented here demonstrate the viability of SFSP, and the special form of FSBE, in producing tubular samples that are structurally sound, with no signs of voids or internal channels. Optical microscopy was performed at key locations within selected tube specimens, and the obtained micrographs clearly show the presence of a stir zone with a fine grain structure; grain size measurements demonstrate the effectiveness of the processing technique in refining the microstructure of the starting material.

Numerical Study of the Tool Rake Angle Effect on the Material Flow in Friction Stir Welding Process

2007 ◽  
Author(s):  
Hosein Atharifar ◽  
Radovan Kovacevic
Keyword(s):  
Friction Stir Welding ◽  
Material Flow ◽  
Numerical Study ◽  
Welding Process ◽  
Rake Angle ◽  
Heat Transfer Analysis ◽  
Tool Geometry ◽  
Friction Stir ◽  
Tool Pin ◽  
Welding Processes

Minimizing consumed energy in friction stir welding (FSW) is one of the prominent considerations in the process development. Modifications of the FSW tool geometry might be categorized as the initial attempt to achieve a minimum FSW effort. Advanced tool pin and shoulder features as well as a low-conductive backing plate, high-conductive FSW tools equipped with cooling fins, and single or multi-step welding processes are all carried out to achieve a flawless weld with reduced welding effort. The outcomes of these attempts are considerable, primarily when the tool pin traditional designs are replaced with threaded, Trifiute or Trivex geometries. Nevertheless, the problem remains as to how an inclined tool affects the material flow characteristics and the loads applied to the tool. It is experimentally proven that a positive rake angle facilitates the traverse motion of the FSW tool; however, few computational evidences were provided. In this study, numerical material flow and heat transfer analysis are carried out for the presumed tool rake angle ranging from −4° to 4°. Afterwards, the effects of the tool rake angle to the dynamic pressure distribution, strain-rates, and velocity profiles are numerically computed. Furthermore, coefficients of drag, lift, and side force and moment applied to the tool from the visco-plastic material region are computed for each of the tool rake angles. Eventually, this paper confirms that the rake angle dramatically affects the magnitude of the loads applied to the FSW tool, and the developed advanced numerical model might be used to find optimum tool rake angle for other aluminum alloys.

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