Material Flow and the Shear Layer in the Upper Weld Zone during Friction Stir Welding of Aluminium Alloys

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.

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The Effect of Tool Pin Size and Taper Angle on the Thermal Process and Plastic Material Flow in Friction Stir Welding

10.21203/rs.3.rs-335152/v1 ◽

2021 ◽

Author(s):

Jie Chen ◽

Lei Shi ◽

Chuansong Wu ◽

Yuanning Jiang

Keyword(s):

Friction Stir Welding ◽

Shear Layer ◽

Layer Thickness ◽

Material Flow ◽

Horizontal Plane ◽

Thermal Process ◽

Plastic Material ◽

Taper Angle ◽

Friction Stir ◽

Tool Pin

Abstract Friction stir welding (FSW) tool pin, as a critical component of FSW tool, plays an important role in determining the final joint properties by affecting the heat generation, plastic material flow, welding loads and so on. However, the influence of tool pin on heat and mass transfer in FSW are not elucidated. In the present study, a validated model was adopted to quantitatively analyze the effects of pin size and taper angle on the thermal process and plastic material flow in FSW. It reveals that the torque and transverse force imposed on the pin are increased with the increase of the pin diameters (including its root diameter, its tip diameter and its size in condition of constant taper angle), while the total tool torque various a little for the tool pin diameter considered in this study. When the pin diameters increase, the viscosity of the materials near the pin is decreased, while the temperature as well as the flow velocity is increased. More plastic material near the tool could rotate around the tool with an increase of the pin diameter. The TMAZ boundary is enlarged with larger pin diameters in FSW. Particularly, the shear layer thickness of the same horizontal plane in the range of 1 mm < z < 5 mm is significantly enlarged with an increase of pin root diameters. However, the shear layer thickness of the same horizontal plane in the region of z < 5 mm is increased when using a larger pin tip diameter. In addition, maximum width of TMAZ boundary at the top surface of workpiece was not affected by pin diameters. The model is validated by experimental results. It lays solid foundation for optimizing the tool pin size and taper angle in FSW.

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Experimental Investigation of Dry and Cryogenic Friction Stir Welding of AA7075 Aluminium Alloy

Advances in Materials Science and Engineering ◽

10.1155/2021/9961590 ◽

2021 ◽

Vol 2021 ◽

pp. 1-21

Author(s):

A. Praveen Raj Navukkarasan ◽

K. Shanmuga Sundaram ◽

C. Chandrasekhara Sastry ◽

M. A. Muthu Manickam

Keyword(s):

Grain Size ◽

Friction Stir Welding ◽

Aluminium Alloy ◽

Aluminium Alloys ◽

Dry Friction ◽

Weld Zone ◽

Grain Structure ◽

Temperature Differential ◽

Friction Stir ◽

Aa 7075

An attempt has been made to investigate dry and cryogenic friction stir welding of AA 7075 aluminium alloy, which is predominantly availed in aerospace and defence component industries. These industries avail friction stir welding for joining two nonferrous materials, and minimal deviations and maximum strength are the preliminary and long time goal. A cryogenic friction stir welding setup was developed to conduct the joining of two aluminium alloy pipes. An increase of 0.76–42.93% and 3.79–31.24% in microhardness and tensile strength, respectively, is ascertained in cryogenic friction stir welding in correlation to dry friction stir welding of aluminium alloys. TOPSIS evaluation for the experimental run indicated tool profile stepped type, pipe rotation speed of 1000 rpm, welding speed of 50 mm/min, and axial force of 8 kN as close to unity ideal solution for dry and cryogenic friction stir welding of AA 7075 aluminium alloys. The friction stir-welded component under the cryogenic environment showcased drop in temperature, curtailed surface roughness, and fine grain structure owing to reduction in temperature differential occurring at the weld zone. A curtailment of 50.84% is ascertained in the roughness value for cryogenic friction stir welding in correlation to dry friction stir welding of AA 7075 alloy. A decrement of 21.68% is observed in the grain size in the cryogenic condition with correlation to the dry FSW process, indicating a drop in the coarse structure. With the curtailment of grain size and drop in temperature differential, compressive residual factor and corrosion resistance attenuated by 40.14% and 67.17% in the cryogenic FSW process in correlation to the dry FSW process, respectively.

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On use of weld zone temperatures for online monitoring of weld quality in friction stir welding of naturally aged aluminium alloys

Materials & Design (1980-2015) ◽

10.1016/j.matdes.2013.06.014 ◽

2013 ◽

Vol 52 ◽

pp. 730-739 ◽

Cited By ~ 19

Author(s):

Murshid Imam ◽

Kajal Biswas ◽

Vikranth Racherla

Keyword(s):

Friction Stir Welding ◽

Aluminium Alloys ◽

Online Monitoring ◽

Weld Zone ◽

Weld Quality ◽

Friction Stir

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Metallurgical Nature at the Interface between Tool Shoulder and Workpiece during Friction Stir Welding

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.29-30.43 ◽

2007 ◽

Vol 29-30 ◽

pp. 43-46

Author(s):

Zhan W. Chen ◽

Timotius Pasang ◽

Q. Yin ◽

R. Peris

Keyword(s):

Friction Stir Welding ◽

Aluminium Alloys ◽

Material Flow ◽

Intermetallic Layer ◽

Contact Condition ◽

Sliding Contact ◽

Metallographic Examination ◽

Friction Stir ◽

Tool Shoulder ◽

Fsw Experiments

Knowledge on the contact condition at the tool/workpiece interface is essential for understanding many aspects of FSW. In the present study, FSW experiments were conducted using aluminium alloys followed by metallographic examination focusing on the tool shoulder-workpiece interface region. It was observed that an interfacial intermetallic layer and hence metallurgical sticking/soldering readily formed. Temperature measurements have suggested the presence of interface liquid, hence suggesting a mechanical sliding contact condition dominant. This has been supported by the observation on material flow within the shear layer.

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Material flow in Friction Stir Welding

Microscopy and Microanalysis ◽

10.1017/s1431927608089472 ◽

2008 ◽

Vol 14 (S3) ◽

pp. 87-90 ◽

Cited By ~ 6

Author(s):

C. Leitão ◽

R.M. Leal ◽

D.M. Rodrigues ◽

P. Vilaça ◽

A. Loureiro

Keyword(s):

Plastic Deformation ◽

Friction Stir Welding ◽

Automotive Industry ◽

Aluminium Alloys ◽

Material Flow ◽

Dissimilar Materials ◽

Tool Geometry ◽

X Ray ◽

Friction Stir ◽

Solid State Joining

Friction stir welding (FSW) is a solid-state joining technique initially developed for aluminium alloys. The heat generated by a rotating tool softens the material in the vicinity of the tool. The material undergoes intense plastic deformation following quite complex paths around the tool, depending on the tool geometry, process parameters and material to be welded. The comprehension of the material flow is essential to prevent voids and other internal defects which may form during welding. Several techniques have been used for tracking material flow during FSW such as metallography, the use of a marker material as a tracer or the flow visualization by FSW of dissimilar materials or even the X-ray and computer tomography. Some of these techniques are useless in the analysis of welds in homogenous materials or welds between materials of the same group. The aim of this investigation is tracking the material flow in FSW between 1mm thick sheets in aluminium alloys AA 5182-H111 and AA 6016-T4, currently used in automotive industry.

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Mathematical Modelling of Material Flow during Friction Stir Welding of Aluminium Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1146.115 ◽

2018 ◽

Vol 1146 ◽

pp. 115-120

Author(s):

Cosmin Ighisan ◽

Bogdan Radu ◽

Cristian Ciucă

Keyword(s):

Mathematical Model ◽

Friction Stir Welding ◽

Aluminium Alloys ◽

Material Flow ◽

Good Precision ◽

Two Dimensional ◽

Element Analysis ◽

Friction Stir ◽

The Mathematical Model ◽

Distribution Field

The paper presents the results of a mathematical model of the material flow during Friction Stir Welding (FSW) of aluminium alloys using a Finite Element Analysis. The authors presented their work on a two-dimensional visco-plastic model, using User Define Functions (UDF) in a commercial CFD code (FLUENT). The model developed was validated by microstructural investigations on experimental FSW joints and by a comparative analysis of temperature distribution field of the experimental FSW joint and numerical simulated model. The results confirmed that the mathematical model describes with a good precision the material flow and temperature field during FSW process.

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Joining of AA2014 and AA5059 dissimilar aluminium alloys by Friction Stir Welding

Journal of Achievements of Materials and Manufacturing Engineering ◽

10.5604/01.3001.0013.7945 ◽

2019 ◽

Vol 1 (97) ◽

pp. 15-20

Author(s):

A.A. Saleh

Keyword(s):

Mechanical Properties ◽

Friction Stir Welding ◽

Aluminium Alloys ◽

Weld Zone ◽

Friction Stir ◽

Fine Grain ◽

Base Materials ◽

Microstructure And Mechanical Properties ◽

Metal Research ◽

Weld Area

Purpose: This work aims to investigate the microstructure and mechanical properties achieved by FSW of butt joints, namely of dissimilar sheets namely of 2014-T3 to 5059-H11 Al alloys by bonding the two materials perpendicular to their rolling directions. Design/methodology/approach: AA 2014T3 and AA 5059H11 were two dissimilar aluminium alloys friction stir welded. The joint has been examined in terms of hardness, microstructure, and mechanical properties. The microstructure of the weld area was characterized by using optical microscopy. Seven diverse regions of the microstructure in the joint can be illustrious. Findings: It has been noticed that a structure of fine grain is formed in the nugget region as a consequence of recrystallization. The thermos mechanically affected and heat affected zones of aluminium alloy 2014 are characterized by the lowest hardness values in spite of there are a general hardness decrease through the weld zone compared to both base metals. The ultimate tensile strength values of the dissimilar joint were found to be varying between 54% to 66% those of the base metal. Research limitations/implications: The t joining in FSW takes place with the base materials remnant in the solid state, which gives a considerable possibility to produce joints between the alleged difficult-to-weld heat treatable aluminium alloys. Originality/value: The outcomes display that friction stir welding can be effectively applied for the joining of dissimilar aluminium alloys.

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Effect of friction stir welding tool profiles on mechanical properties of dissimilar welded aluminum alloy plates

International Journal of Structural Integrity ◽

10.1108/ijsi-10-2020-0097 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Bhanodaya Kiran Babu Nadikudi

Keyword(s):

Mechanical Properties ◽

Friction Stir Welding ◽

Aluminium Alloy ◽

Tensile Properties ◽

Aluminium Alloys ◽

Testing Machine ◽

Weld Zone ◽

Content Type ◽

Friction Stir ◽

Tool Pin

PurposeThe main purpose of the present work is to study the effect of tool pin profiles on mechanical properties of welded plates made with two different aluminium alloy plates.Design/methodology/approachThe welded plates were fabricated with the three different kinds of pin profiled tools such as taper cylindrical, taper threaded cylindrical and stepped cylindrical pin profiles. Tensile properties of welded plates were evaluated using tensile testing machine at room temperature. Microstructures studies were carried out using scanning electron microscope.FindingsTensile properties were improved with the use of taper threaded cylindrical pin tool in friction stir welding process when compared with taper cylindrical and stepped cylindrical pin tools. This is due to refinement of grains and mixing of plasticized material occurred with generation of sufficient heat with the taper threaded pin tool. Through these studies, it was confirmed that friction stir welding can be used to weld Al6061 and Al2014 aluminium alloy plates.Research limitations/implicationsIn the present study, the friction stir welding is performed with constant process parameters such as tool rotational speed of 900 rpm, transverse speed of 24 mm/min and tilt angle of 1°.Practical implicationsAluminium alloys are widely using in automotive and aerospace industries due to holding a high strength to weight property. These aluminium alloy blanks can be developed with friction stir welding method with better properties.Originality/valueVery limited work had been carried out on friction stir welding of aluminium alloys of Al 6061 and Al2014 with different tool pin profiles. Furthermore, this work analyzed with tensile properties of welded plates correlated with weld zone microstructures.

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