Clarification of material flow and defect formation during friction stir welding

Abstract Friction stir welding (FSW) is widely accepted by industry because of multiple advantages such as low-temperature process, green technology, and capable of producing good quality weld joints. Extensive research has been conducted to understand the physical process and material flow during FSW. The published works mainly discussed the effects of various process parameters on temperature distribution and microstructure formation. There are few works on the prediction of defect formation from a physics-based model. However, these models ignore chip formation or surface morphology and material loss during the FSW process. In the present work, a fully coupled 3D thermo-mechanical model is developed to predict the chip formation and surface morphology during welding. The effects of various process parameters on surface morphology are also studied using the current model. Coupled Eulerian-Lagrangian (CEL) technique is used to model the FSW process using a commercial software ABAQUS. The model is validated by comparing the results in published literature. The current model is capable of predicting the material flow out of the workpiece and thus enables the visualization of the chip formation. The developed model can extensively be used to predict the surface quality of the friction stir welded joints.

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Material flow and void defect formation in friction stir welding of aluminium alloys

Science and Technology of Welding & Joining ◽

10.1080/13621718.2018.1471844 ◽

2018 ◽

Vol 23 (8) ◽

pp. 677-686 ◽

Cited By ~ 12

Author(s):

X. H. Zeng ◽

P. Xue ◽

D. Wang ◽

D. R. Ni ◽

B. L. Xiao ◽

...

Keyword(s):

Friction Stir Welding ◽

Aluminium Alloys ◽

Material Flow ◽

Defect Formation ◽

Void Defect ◽

Friction Stir

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Flow, process forces and strains during Friction Stir Welding: A comprehensive First principle approach

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1177/0954405420970087 ◽

2020 ◽

pp. 095440542097008

Author(s):

Dhruv Bajaj ◽

Arshad Noor Siddiquee ◽

Noor Zaman Khan ◽

AK Mukhopadhyay ◽

Sohail M A Khan Mohammed ◽

...

Keyword(s):

Friction Stir Welding ◽

Shear Strain ◽

Material Flow ◽

Large Scale ◽

Defect Formation ◽

First Principle ◽

Flow Process ◽

Maximum Shear Strain ◽

Friction Stir ◽

Process Forces

Friction stir welding is recent yet spectacular process, which assumes accrescent expanse to evolve as a multi-purpose process. Its potential is greatly being tapped through large-scale experimental and computer simulation-based investigations. Several simulation and empirical models have been proposed but exact fundamental analyses on forces, material flow and strain are still absent. Complexities associated with the process are perhaps the main reason that a fundamental analysis is difficult. A comprehensive analysis of this kind is critical for understanding the evolution of microstructure, mechanical properties of joint and defect formation. This study presents an analysis of material flow, process forces and strains using first principle approach. Results have been presented as exact mathematical expressions in terms of material properties and process parameters. It was demonstrated that the material during stirring experiences direct and shear strains both when it moves from advancing side to retreating side in front of the tool and after rotation deposits behind the tool. It was also demonstrated that the strain significantly reduced from advancing to retreating side; for a typical case the shear strain greater than 10,000% prevails in advancing side and the maximum shear strain on retreating side is of the order of 6000%.

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Defect formation and material flow in Friction Stir Welding

European Journal of Mechanics - A/Solids ◽

10.1016/j.euromechsol.2019.103912 ◽

2020 ◽

Vol 80 ◽

pp. 103912

Author(s):

Narges Dialami ◽

Miguel Cervera ◽

Michele Chiumenti

Keyword(s):

Friction Stir Welding ◽

Material Flow ◽

Defect Formation ◽

Friction Stir

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Investigation of material flow and thermomechanical behavior during friction stir welding of an AZ31B alloy for threaded and unthreaded pin geometries using computational solid mechanics simulation

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406220962540 ◽

2020 ◽

pp. 095440622096254

Author(s):

RAR Giorjao ◽

EB Fonseca ◽

JA Avila ◽

EF Monlevade ◽

AP Tschiptschin

Keyword(s):

Friction Stir Welding ◽

Material Flow ◽

Solid Mechanics ◽

Defect Formation ◽

Welding Process ◽

High Sensitivity ◽

Thermomechanical Behavior ◽

Welding Parameters ◽

Arbitrary Lagrangian Eulerian ◽

Friction Stir

In the friction stir welding process, the tool role in the material flow and its thermomechanical behavior is still not entirely understood. Several modeling approaches attempted to explain the material and tool relationship, but to this date, insufficient results were provided in this matter. Regarding this issue and the urgent need for trustful friction stir welding models, a computational solid mechanic's model capable of simulating material flow and defect formation is presented. This model uses an Arbitrary Lagrangian-Eulerian code comparing a threaded and unthread pin profile. The model was able to reproduce the tool's torque, temperatures, and material flow along the entire process, including the underreported downward flow effect promoted by threaded pin's. A point tracking analysis revealed that threads increase the material velocity and strain rate to almost 30% compared to unthreaded conditions, promoting a temperature increment during the process, which improved the material flow and avoided filling defects. The presented results showed the model's capability to reproduce the defects observed in real welded joints, material thermomechanical characteristics and high sensitivity to welding parameters and tool geometries. Nevertheless, the outcomes of this work contribute to essential guidelines for future friction stir welding modeling and development, tool design, and defect prediction.

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Thermo-Mechanical Modelling of Friction Stir Welding Process

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.774-776.1155 ◽

2013 ◽

Vol 774-776 ◽

pp. 1155-1159 ◽

Cited By ~ 2

Author(s):

Xiao Cong He

Keyword(s):

Finite Element Analysis ◽

Friction Stir Welding ◽

Mechanical Behaviour ◽

Material Flow ◽

Welding Process ◽

Element Analysis ◽

Friction Stir ◽

Mechanical Modelling ◽

Major Factors ◽

Realistic Prediction

Friction stir welding (FSW) is a solid-state welding process where no gross melting of the material being welded takes place. Numerical modelling of the FSW process can provide realistic prediction of the thermo-mechanical behaviour of the process. Latest literature relating to finite element analysis (FEA) of thermo-mechanical behaviour of FSW process is reviewed in this paper. The recent development in thermo-mechanical modelling of FSW process is described with particular reference to two major factors that influence the performance of FSW joints: material flow and temperature distribution. The main thermo-mechanical modelling used in FSW process are discussed and illustrated with brief case studies from the literature.

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

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.160.313 ◽

2010 ◽

Vol 160 ◽

pp. 313-318 ◽

Cited By ~ 4

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.

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Influence of Tool Geometry and Contact Condition on Friction Stir Welding of Al-Cu Laminated Composites

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.856.16 ◽

2013 ◽

Vol 856 ◽

pp. 16-21

Author(s):

R. Beygi ◽

Mohsen Kazeminezhad ◽

A.H. Kokabi ◽

S. Mohammad Javad Alvani ◽

D. Verdera ◽

...

Keyword(s):

Friction Stir Welding ◽

Material Flow ◽

Laminated Composites ◽

Flow Behavior ◽

Tool Geometry ◽

Contact Conditions ◽

Friction Stir ◽

Tool Geometries ◽

Welding Procedure ◽

Sem Analyses

In this study friction stir welding of Al-Cu laminated composites were carried out by two different tool geometries. Welding procedure was carried out from both sides of Al and Cu. Analyzing cross section of welds showed that different contact conditions between shoulder and material, offers different material flow behavior which is dependent on the tool geometry. SEM analyses showed that mixing of materials in nugget region is more pronounced in the advancing side. Also XRD results indicated that welding from Cu side, leads to intermetallic formation in mixed regions.

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