Heat transfer and metal flow behavior of AA7075 high-strength aluminum alloy in a new current-induced friction stir welding with a multi-physics field model based on the inverse method and parameter scanning batch processing technique

In friction stir welding (FSW), many defects (such as kissing bond, incomplete penetration, and weak connection) easily occur at the root of the welded joint. Based on the Levy–Mises yield criterion of the Zener–Hollomon thermoplastic constitutive equation, a 3D thermal–mechanical coupled finite element model was established. The material flow behavior and the stress field at the root area of a 6 mm thick 2024-T3 aluminum alloy FSW joint were studied. The influence of pin length on the root flaw was investigated, and the formation mechanism of the “S line” defects and non-penetration defects were revealed. The research results showed that the “S line” defect forms near the bottom surface of the pin owing to the insufficiently mixed material from the advancing side (AS) and retreating side (RS) near the weld center. The non-penetration defect forms near the bottom surface of the workpiece owing to the insufficient driving force to make the material flow through the weld center. With the continual increase of pin length, the size of the “S line” defect and non-penetration defect reduces, and finally, the defect-free welded joint can be obtained with an optimized suitable length of the pin in this case.

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On the problem of tool destruction when obtaining fixed joints of thick-walled aluminum alloy blanks by friction welding with mixing

Metal Working and Material Science ◽

10.17212/1994-6309-2021-23.3-72-83 ◽

2021 ◽

Vol 23 (3) ◽

pp. 72-83

Author(s):

Kirill Kalashnikov ◽

◽

Andrey Chumaevskii ◽

Tatiana Kalashnikova ◽

Aleksey Ivanov ◽

...

Keyword(s):

Aluminum Alloy ◽

Friction Stir Welding ◽

Friction Welding ◽

Welding Process ◽

High Strength ◽

Heterogeneous Structure ◽

Adhesive Interaction ◽

Friction Stir ◽

Tool Shoulder ◽

Electric Erosion

Introduction. Among the technologies for manufacturing rocket and aircraft bodies, marine vessels, and vehicles, currently, more and more attention is paid to the technology of friction stir welding (FSW). First of all, the use of this technology is necessary where it is required to produce fixed joints of high-strength aluminum alloys. In this case, special attention should be paid to welding thick-walled blanks, as fixed joints with a thickness of 30.0 mm or more are the target products in the rocket-space and aviation industries. At the same time, it is most prone to the formation of defects due to uneven heat distribution throughout the height of the blank. It can lead to a violation of the adhesive interaction between the weld metal and the tool and can even lead to a destruction of the welding tool. The purpose of this work is to reveal regularities of welding tool destruction depending on parameters of friction stir welding process of aluminum alloy AA5056 fixed joints with a thickness of 35.0 mm. Following research methods were used in the work: the obtaining of fixed joints was carried out by friction welding with mixing, the production of samples for research was carried out by electric erosion cutting, the study of samples was carried out using optical metallography methods. Results and discussion. As a result of performed studies, it is revealed that samples of aluminum alloy with a thickness of 35.0 mm have a heterogeneous structure through the height of weld. There are the tool shoulder effect zone and the pin effect zone, in which certain whirling of weld material caused by the presence of grooves on tool surface is distinctly distinguished. It is shown that the zone of shoulders effect is the most exposed to the formation of tunnel-type defects because of low loading force and high welding speeds. It is revealed that tool destruction occurs tangentially to the surface of the tool grooves due to the high tool load and high welding speeds.

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The Backing Bar Role in Heat Transfer on Aluminium Alloys Friction Stir Welding

Materials Science Forum ◽

10.4028/www.scientific.net/msf.636-637.459 ◽

2010 ◽

Vol 636-637 ◽

pp. 459-464 ◽

Cited By ~ 14

Author(s):

M.J.C. Rosales ◽

N.G. Alcantara ◽

Jorge Santos ◽

R. Zettler

Keyword(s):

Heat Transfer ◽

Friction Stir Welding ◽

Aluminium Alloys ◽

High Strength Steels ◽

High Strength ◽

Advanced Materials ◽

Mechanical Degradation ◽

Great Effort ◽

Friction Stir ◽

Advanced High Strength Steels

Although new structural and advanced materials have been used in the automotive and aircraft industries, especially lightweight alloys and advanced high strength steels, the successful introduction of such materials depends on the availability of proven joining technologies that can provide high quality and performance joints. Solid-state joining techniques such as Friction Stir Welding (FSW) are a natural choice since their welds are produced at low temperatures, so the low heat input provides limited, slight distortion, microstructural and mechanical degradation. Great effort has currently been devoted to the joining of Al-Cu-Mg and the Al-Mg-Si alloys because of their high strength, improved formability, and application in airframe structures. FSW is a continuous, hot shear, autogenous process involving a non-consumable and rotating tool plunged between two abutting workpieces. The backing bar plays an important role in heat transfer from stir zone (SZ), which can influence the weld microstructure as well as the consolidation of material in the root of the join. This study aims at investigating issues concerning heat generation, within the SZ of friction stir welded aircraft aluminium alloys.

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Sensitivity analysis of the residual stress state in friction stir welding of high strength aluminum alloy

Materials Testing ◽

10.3139/120.110809 ◽

2016 ◽

Vol 58 (1) ◽

pp. 20-26 ◽

Cited By ~ 2

Author(s):

Marcel Bachmann ◽

Michael Rethmeier ◽

Chuan Song Wu

Keyword(s):

Residual Stress ◽

Sensitivity Analysis ◽

Aluminum Alloy ◽

Friction Stir Welding ◽

Stress State ◽

High Strength ◽

Friction Stir ◽

High Strength Aluminum Alloy ◽

Residual Stress State

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

Materials ◽

10.3390/ma13102401 ◽

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.

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Abnormal fracture of 7085 high strength aluminum alloy thick plate joint via friction stir welding

Journal of Materials Research and Technology ◽

10.1016/j.jmrt.2019.09.077 ◽

2019 ◽

Vol 8 (6) ◽

pp. 6029-6040 ◽

Cited By ~ 15

Author(s):

W.F. Xu ◽

X.K. Wu ◽

J. Ma ◽

H.J. Lu ◽

Y.X. Luo

Keyword(s):

Aluminum Alloy ◽

Friction Stir Welding ◽

Thick Plate ◽

High Strength ◽

Friction Stir ◽

High Strength Aluminum Alloy

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Experimental Investigation on Joining Dissimilar Aluminum Alloy 6061 to TRIP 780/800 Steel Through Friction Stir Welding

Journal of Engineering Materials and Technology ◽

10.1115/1.4030480 ◽

2015 ◽

Vol 137 (4) ◽

Cited By ~ 5

Author(s):

Xun Liu ◽

Shuhuai Lan ◽

Jun Ni

Keyword(s):

Aluminum Alloy ◽

Friction Stir Welding ◽

Cross Sections ◽

Failure Modes ◽

High Strength ◽

Tensile Tests ◽

Weld Strength ◽

Friction Stir ◽

Aluminum Alloy 6061 ◽

Alloy 6061

Friction stir welding (FSW) technique has been successfully applied to butt joining of aluminum alloy 6061-T6 to one type of advanced high strength steel (AHSS), transformation induced plasticity (TRIP) 780/800 with the highest weld strength reaching 85% of the base aluminum alloy. Mechanical welding forces and temperature were measured under various sets of process parameters and their relationships were investigated, which also helped explain the observed macrostructure of the weld cross section. Compared with FSW of similar aluminum alloys, only one peak of axial force occurred during the plunge stage. Three failure modes were identified during tensile tests of weld specimens, which were further analyzed based on the microstructure of joint cross sections. Intermetallic compound (IMC) layer with appropriate thickness and morphology was shown to be beneficial for enhancing the strength of Al–Fe interface.

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