Influence of Tool Runout on Force Measurement During Internal Void Monitoring for Friction Stir Welding of 6061-T6 Aluminum

2021 ◽  
Author(s):  
Daniel Franke ◽  
Michael Zinn ◽  
Shiva Rudraraju ◽  
Frank E. Pfefferkorn
Keyword(s):  
Force Measurement ◽  
Rotational Frequency ◽  
Oscillatory Process ◽  
Rotational Axis ◽  
Monitoring Method ◽  
Friction Stir ◽  
Tool Shoulder ◽  
The Third ◽  
Process Forces ◽  
Void Interaction

Abstract The goal of this research was to examine how altering the amount of friction stir tool eccentricity while controlling the amount of slant in the tool shoulder (drivers of oscillatory process forces) effects the generation of process force transients during sub-surface void interaction. The knowledge gained will help improve the accuracy of force-based void monitoring methods that have the potential to reduce the need for post-weld inspection. Process force transients during sub-surface void formation were examined for multiple tools with varying magnitudes of kinematic runout. The eccentric motion of the tool produced oscillations in the process forces at the tools rotational frequency that became distorted when features (flats) on the tool probe interacted with voided volumes, generating an amplitude in the force signals at three times the tool rotational frequency (for three flat tools). A larger tool eccentricity generates a larger amplitude in the force signals at the tool’s rotational frequency that holds a larger potential to create a distortion during void interaction. It was determined that once void becomes large enough to produce an interaction that generates an amplitude at the third harmonic larger than 30% of the amplitude at the rotational frequency in a weld with no interaction (amplitude solely at rotational frequency), the trailing edge of the tool shoulder cannot fully consolidate the void, i.e., it will remain in the final weld. Additionally, once the void exceeds a certain size, the amplitudes of the third harmonics saturate at 70% of the amplitude at the rotational frequency during full consolidation. The interaction between the eccentric probe and sub-surface void was isolated by ensuring any geometric imperfection in the shoulder (slant) with respect to the rotational axis was removed. The results suggest that geometric imperfections (eccentricity and slant) with respect to the tool’s rotational axis must be known when developing a void monitoring method from force transients of this nature.

Influence of Tool Runout on Force Measurement during Internal Void Monitoring for Friction Stir Welding of 6061-T6 Aluminum

2021 ◽  
pp. 1-23
Author(s):  
Daniel Franke ◽  
Michael R. Zinn ◽  
Shiva Rudraraju ◽  
Frank E. Pfefferkorn
Keyword(s):  
Force Measurement ◽  
Rotational Frequency ◽  
Oscillatory Process ◽  
Rotational Axis ◽  
Monitoring Methods ◽  
Monitoring Method ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Process Forces ◽  
Void Interaction

Abstract The goal of this research is to examine how altering the amount of friction stir tool eccentricity while controlling the amount of slant in the tool shoulder (drivers of oscillatory process forces) effects the generation of process force transients during sub-surface void interaction. The knowledge gained will help improve the accuracy of force-based void monitoring methods that have the potential to reduce the need for post-weld inspection. The eccentric motion of the tool produces oscillations in the process forces at the tool's rotational frequency, which becomes distorted when features on the probe interact with voids, generating an amplitude in the force signals at three times the tool rotational frequency (for three flat tools). A larger tool eccentricity generates a larger amplitude in the force signals at the tool's rotational frequency, which has a greater potential to create a distortion during void interaction. Once a void becomes large enough to produce amplitude at the third harmonic larger than 30% of the amplitude at the rotational frequency, the trailing edge of the tool shoulder cannot fully consolidate the void. The interaction between the eccentric probe and sub-surface void is isolated by ensuring any geometric imperfection in the shoulder (slant) is removed. The results suggest that geometric imperfections (eccentricity and slant) with respect to the tool's rotational axis must be known when developing a void monitoring method from force transients of this nature.

Analysis of tool wear and deformation in friction stir welding of unequal thickness dissimilar Al alloys

2020 ◽  
pp. 146442072097176
Author(s):  
Tanveer Majeed ◽  
Yashwant Mehta ◽  
Arshad Noor Siddiquee
Keyword(s):  
Friction Stir Welding ◽  
Tool Wear ◽  
Tilt Angle ◽  
Dissimilar Materials ◽  
Welding Temperature ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Process Forces ◽  
Wide Range ◽  
Lower Tool

Friction stir welding between plates of unequal thickness, which are made from similar or dissimilar materials, finds wide range of applications in the aerospace and automotive sectors. Friction stir welding of plates made from dissimilar materials having unequal thicknesses is challenging. One of the major challenges is the control of rapid tool degradation which occurs during welding. This work reports a maiden study on tool degradation of high thickness ratio unequal thickness dissimilar material joints made between 6.3 mm thick AA2024-T3 and 2.5 mm thick AA7475-T7 plates. The degradation of friction stir welding tool made of T4 tool steel having tapered cylindrical pin and scrolled shoulder was analyzed. The geometry of tool (before and after welding) was compared; the degradation was categorized, characterized, and analyzed in the light of measured welding temperature, process forces, and process parameters. It was found that the pin undergoes significant degradation in the form of wear and deformation compared to the tool shoulder. The experimental results demonstrated that lower flow stresses caused by higher process temperature leads to lower tool wear and deformation, and vice versa. In addition to temperature and process forces, the surface tilt angle was found to significantly affect the pin deformation. The higher surface tilt angle caused an increase in tool wear and deformation.

A Thermo-Fluid Analysis of the Friction Stir Welding Process

2007 ◽  
Vol 539-543 ◽  
pp. 3832-3837 ◽  
Author(s):  
D. Jacquin ◽  
Christophe Desrayaud ◽  
Frank Montheillet
Keyword(s):  
Friction Stir Welding ◽  
Bulk Material ◽  
Welding Process ◽  
Vertical Motion ◽  
Velocity Fields ◽  
Fluid Simulation ◽  
Metal Sheet ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Fluid Analysis

The thermo-mechanical simulation of Friction Stir Welding focuses the interest of the welding scientific and technical community. However, literature reporting material flow modeling is rather poor. The present work is based on the model developed by Heurtier [2004] and aims at improving this thermo-fluid simulation developed by means of fluid mechanics numerical and analytical velocity fields combined together. These various velocity fields are investigated separately and especially according to the power dissipated during the flow. Boundary conditions are considered through a new approach based on the kinematic analysis of the thread of the pin. An equilibrium is established between the vertical motion of the bulk material dragged in the depth of the metal sheet, and its partial circulation around the pin. The analyses of the obtained velocity fields enable the understanding of the welded zone asymmetry and highlights the bulk material mixing between the welded coupons in the depth of the sheet. A regression is performed on the relative sliding velocity of the aluminium according to the surface of the tool: shoulder and pin. Two dimension flow lines in the depth of the metal sheet are then obtained and successfully compared with the results obtained by Colegrove (2004) [1].

Microstructure Development in Copper Welded by the FSW-Process

2003 ◽  
Vol 807 ◽  
Author(s):  
Therese Källgren ◽  
Rolf Sandström
Keyword(s):  
Welding Process ◽  
Mechanical Deformation ◽  
Microstructure Development ◽  
Friction Stir ◽  
Friction Heat ◽  
The Third ◽  
Lower Temperature ◽  
Weld Root ◽  
Nuclear Fuel Waste ◽  
Joining Process

ABSTRACTTo ensure safe storage of nuclear fuel waste, copper canisters are proposed as corrosion barrier. One alternative for sealing the copper canisters is Friction Stir Welding (FSW). During the joining process friction heat and mechanical deformation appear between the rotating tool and the material being welded. Liquid metal will not form, since this is a solid state welding process. Three distinct microstructural zones are developed namely the nugget, the thermo-mechanically affected zone (TMAZ) and heat-affected zone (HAZ). The nugget is in the centre of the weld, where the pin is located and where severe plastic deformation occurs that leads to recrystallisation. Surrounding the nugget, the TMAZ is only partially recrystallised, due to lower temperature increase and deformation compared to the nugget. The third zone, HAZ, surrounds the TMAZ. The initial nugget can have a classic round aluminium nugget image, when the welding conditions are cold, but the steady state nugget, is wider near the shoulder and shorter in the weld root.

Effect of plasma preheating on weld quality and tool life during friction stir welding of DH36 steel

2021 ◽  
pp. 095440542199013
Author(s):  
Avinish Tiwari ◽  
Pardeep Pankaj ◽  
Saurav Suman ◽  
Piyush Singh ◽  
Pankaj Biswas ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Tool Life ◽  
Force Measurement ◽  
Deep Understanding ◽  
High Strength ◽  
Microstructural Characterization ◽  
Stir Zone ◽  
Friction Stir ◽  
Allotriomorphic Ferrite ◽  
Fsw Parameters

Friction stir welding (FSW) of high strength materials is challenging due to high tool cost and low tool life. To address this issue, the present investigation deals with an alternative of plasma-assisted friction stir welding (PFSW) of DH36 steel with WC-10%Co tool. Plasma preheating current (13 A, 15 A, and 17 A) was varied by keeping other FSW parameters as constant. During the FSW and PFSW process, force measurement and thermal history aided in a deep understanding of the process, tool degradation mechanisms, accompanied by the mechanical and microstructural characterization of the welded joints. The stir zone hardness was increased from 140 HV0.5 to about 267 HV0.5. The yield and tensile strength of weld increased from 385 MPa and 514 MPa to about 391 MPa and 539 MPa, respectively. Weld joint elongation (%) was increased from ~10% of weld 1 to ~13.89% of weld 4. During PFSW, the process temperature was increased, the cooling rate was lowered, and the weld bead was widened. The results also revealed that the plasma-assisted weld resulted in polygonal ([Formula: see text]) and allotriomorphic ferrite as the major constituents in the stir zone. Pearlite dissolution and spheroidization were observed in the ICHAZ and SCHAZ, respectively. Additionally, the plasma preheating reduced the tungsten tool’s wear by 58% compared to FSW.

scholarly journals 3D-Printed Tool Shoulder Design for the Analogue Modelling of Bobbin Friction Stir Weld Joint Quality

2021 ◽  
Vol 21 (1) ◽  
pp. 27-42
Author(s):  
A. Tamadon ◽  
D. J. Pons ◽  
K. Chakradhar ◽  
J. Kamboj ◽  
D. Clucas
Keyword(s):  
Friction Stir Welding ◽  
Cross Sections ◽  
Weld Joint ◽  
Flow Patterns ◽  
Friction Stir Weld ◽  
Butt Weld ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Analogue Modelling ◽  
3D Printed

Abstract A variety of tool shoulder designs comprising three families i.e. blade, spiral and circular shaped scrolls, were produced to improve the material flow and restrictions to avoid the tunnel void. The bobbin tools were manufactured by 3D printing additive manufacturing technology using solid filament. The butt weld joint was produced by each tool using plasticine as the workpiece material. The apparent surface features and bi-colour cross-sections provided a physical flow comparison among the shoulder designs. For the bobbin friction stir welding (BFSW), the tool shoulder with a three-spiral design produced the most stability with the best combination of the flow patterns on surface and cross-sections. The circular family tools showed a suitable intermixing on the surface pattern, while the blade scrolls showed better flow features within the cross-sections. The flow-driven effect of the shoulder features of the bobbin-tool design (inscribed grooves) was replicated by the 3D-printed tools and the analogue modelling of the weld samples. Similar flow patterns were achieved by dissimilar aluminium-copper weld, validating the accuracy of the analogue plasticine for the flow visualization of the bobbin friction stir welding.

Effects of Tool Pin Profile and Tool Shoulder Diameter on the Tensile Behaviour of Friction Stir Welded Joints of Aluminium Alloys

2014 ◽  
Vol 984-985 ◽  
pp. 586-591 ◽  
Author(s):  
R. Ashok Kumar ◽  
M.R. Thansekhar
Keyword(s):  
Friction Stir Welding ◽  
Aluminium Alloy ◽  
Tensile Properties ◽  
Welded Joints ◽  
Tensile Behaviour ◽  
Light Weight ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Shoulder Diameter ◽  
Weight Structures

— For fabricating light weight structures, it requires high strength-to weight ratio. AA6061 aluminium alloy is widely used in the fabrication of light weight structures. A356 aluminium alloy has wide spread application in aerospace industries. Friction stir welding is solid state joining process which is conducting for joining similar and dissimilar materials. The friction stir welding parameters play an important role for deciding the strength of welded joints. In this investigation, A356 and AA6061 alloys were friction stir welded by varying triangular, square, hexagonal pin profiles of tool keeping the remaining parameters same and AA6061 alloys were friction stir welded by varying tool shoulder diameter as 12mm,15mm,18mm without changing other parameters. Tensile properties of each joint have been analyzed microscopically. From the experimental results, it is observed that hexagonal pin profiled tool and 15mm shoulder diameter tool provides higher tensile properties when compared to other tools.

An Inexpensive, Portable Machine to Facilitate Testing and Characterization of the Friction Stir Blind Riveting Process

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
A Zachary Trimble ◽  
Brennan Yammamoto ◽  
Jingjing Li
Keyword(s):  
Complete Characterization ◽  
Rotational Axis ◽  
Functional Requirements ◽  
X Ray ◽  
Friction Stir ◽  
Trade Offs ◽  
X Ray Imaging ◽  
Test Parameters ◽  
Riveting Process

The expanding use of materials that are difficult to join with traditional techniques drives an urgent need, in a wide array of industries, to develop and characterize production capable joining processes. Friction stir blind riveting (FSBR) is such a process. However, full adoption of FSBR requires more complete characterization of the process. The relatively inexpensive, portable FSBR machine discussed here facilitates in situ X-ray imaging of the FSBR process, which will enhance the ability of researchers to understand and improve the FSBR process. Real-time, unobstructed, angular X-ray access drives the functional requirements and design considerations of the machine. The acute angular access provided by the machine necessitates tradeoffs in stiffness and Abbe errors. An error budget quantifies the effect of the various trade-offs on likely sensitive directions and relationships. Additionally, the machine motivates more test parameters important to machine designers (e.g., parallelism and runout) that have not yet been explored in the literature. Ultimately, a machine has been developed, which has a single rotational axis that translates parallel to the rotational axis, can be built for under $12,000, has a mass of less than 110 kg, measures 915 mm × 254 mm × 624 mm, has a rotational speed range of 400–8000 RPM, has a feed rate range of 0.1–200 mm/min, can be installed on most test benches, has total rivet runout of 0.1 mm, has plunge and rotational axis parallelism of less than 0.1 deg, and has a plunge axis repeatability of better than 2  μ m over a 10 mm range.

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

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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