scholarly journals A Weighting Grade-Based Optimization Method for Determining Refill Friction Stir Spot Welding Process Parameters

2019 ◽  
Vol 28 (10) ◽  
pp. 6471-6482
Author(s):  
Rafał Kluz ◽  
Andrzej Kubit ◽  
Tomasz Trzepiecinski ◽  
Koen Faes ◽  
Wojciech Bochnowski
Keyword(s):  
Process Parameters ◽  
Rotational Speed ◽  
Spot Welding ◽  
Load Capacity ◽  
Base Material ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Welding Parameters ◽  
Tool Rotational Speed ◽  
Friction Stir

Abstract The welding process used in fabricating thin-walled structures by refill friction stir spot welding (RFSSW) should be characterized by a high strength of welds and high process repeatability which is demonstrated by a small dispersion of the load capacity of the joints. The present work is designed to optimize RFSSW process parameters for 7075-T6 Alclad aluminum alloy sheets used to fabricate aircraft structures. The optimization was performed by scalarization of the objective function using the weighting grades method. The study considers the effect of process parameters, i.e., tool plunge depth, duration of welding, tool rotational speed, on the tensile/shear strength of the joints, and dispersion of the load capacity. It was found that it was possible to choose the optimal welding parameters taking into account maximization of the load capacity and minimization of the dispersion of the joint strength via a best compromise between the tool rotational speed ensuring adequate plasticization of the base material and the duration of welding ensuring that a fine-grained joint microstructure is obtained.

scholarly journals Shoulder Related Temperature Thresholds in FSSW of Aluminium Alloys

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4375
Author(s):  
David G. Andrade ◽  
Sree Sabari ◽  
Carlos Leitão ◽  
Dulce M. Rodrigues
Keyword(s):  
Heat Generation ◽  
Process Parameters ◽  
Rotational Speed ◽  
Aluminium Alloys ◽  
Spot Welding ◽  
Base Material ◽  
Main Process ◽  
Welding Temperature ◽  
Friction Stir ◽  
Tool Diameter

Friction Stir Spot Welding (FSSW) is assumed as an environment-friendly technique, suitable for the spot welding of several materials. Nevertheless, it is consensual that the temperature control during the process is not feasible, since the exact heat generation mechanisms are still unknown. In current work, the heat generation in FSSW of aluminium alloys, was assessed by producing bead-on-plate spot welds using pinless tools. Coated and uncoated tools, with varied diameters and rotational speeds, were tested. Heat treatable (AA2017, AA6082 and AA7075) and non-heat treatable (AA5083) aluminium alloys were welded to assess any possible influence of the base material properties on heat generation. A parametric analysis enabled to establish a relationship between the process parameters and the heat generation. It was found that for rotational speeds higher than 600 rpm, the main process parameter governing the heat generation is the tool diameter. For each tool diameter, a threshold in the welding temperature was identified, which is independent of the rotational speed and of the aluminium alloy being welded. It is demonstrated that, for aluminium alloys, the temperature in FSSW may be controlled using a suitable combination of rotational speed and tool dimensions. The temperature evolution with process parameters was modelled and the model predictions were found to fit satisfactorily the experimental results.

Friction Stir Spot Welding of AZ31B Magnesium Alloy

2017 ◽  
Vol 867 ◽  
pp. 105-111
Author(s):  
S. Ramesh Babu ◽  
M. Nithin ◽  
S. Pavithran ◽  
B Parameshwaran
Keyword(s):  
Shear Strength ◽  
Magnesium Alloy ◽  
Rotational Speed ◽  
Spot Welding ◽  
Dwell Time ◽  
Friction Stir Spot Welding ◽  
Resistance Welding ◽  
Hardness Distribution ◽  
Tool Rotational Speed ◽  
Friction Stir

The Electrical Resistance Welding (ERW) of Magnesium and Aluminium is more difficult than steel because the welding machines must provide high currents and exact pressures in order to provide the heat necessary to melt the magnesium for proper fusion at the interface in order to produce a sound weld. Further, resistance welding of magnesium requires a backup plate made of steel to conduct the heat to the workpiece material. To overcome this problem, Friction Stir Spot Welding (FSSW) has been developed. In this study, the hardness distribution and the tensile shear strength of FSSW welds in the AZ31B Magnesium alloy has been investigated and it has been found that tool rotational speed and dwell time plays a major role in determining the weld strength. From the experimental study, a tool rotational speed of 1100 rpm and dwell time of 20 s produced good shear strength of 2824 N and the corresponding grain size was 4.54 μm. This result is very well supported by microstructural examinations and hardness distribution studies.

Influence of Heating Friction Stir Spot Welding Process Parameters on Steel Aluminum Forming Quality

2018 ◽  
Vol 917 ◽  
pp. 246-251
Author(s):  
Kai Xu ◽  
Shu Quan Zhang
Keyword(s):  
Spot Welding ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Joint Line ◽  
Welding Parameters ◽  
Forming Quality ◽  
Rotating Speed ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Welding Pressure

A lap welding experiment of DP590 steel and 6061 aluminum plate is carried out by using Heating Friction Stir Spot Welding (HFSSW) to study the influence of welding parameters on the forming quality. The results show that a lap joint with better forming can be obtained for the dissimilar metal of steel and aluminum. Under the condition that the rotating speed of the stirring tool is 1000r/min, the penetration depth, 0.2mm, the dwell time, 90s, the welding pressure, 0.2Mp, and the flow rate of cooling air, 20L/min, the forming quality of the surface of the joint line is good & bright, and the exit hole is also smaller. The mechanism of heat production is revealed in the following: the main heat is produced by the friction between the stirring tool shoulder and the welded part & between the probe and the welded part as well as by the latent heat resulted from the plastic deformation of the material in joint line during welding.

Effect of Welding Parameters on Temperature Distribution During Friction Stir Spot Welding of Commercial Pure Copper Lap Joint

2018 ◽  
Author(s):  
Ahmed Mahgoub ◽  
Abdelaziz Bazoune ◽  
Fadi Al-Badour ◽  
Necar Merah ◽  
Abdelrahman Shuaib
Keyword(s):  
Rotational Speed ◽  
Spot Welding ◽  
Dwell Time ◽  
Pure Copper ◽  
Friction Stir Spot Welding ◽  
Temperature History ◽  
Welding Parameters ◽  
Deformation Model ◽  
Friction Stir ◽  
Good Agreement

In this paper, a Coupled Eulerian Lagrangian (CEL) finite element model (FEM) was developed to simulate the friction stir spot welding (FSSW) of commercial pure copper. Through simulations results, the paper presents and discusses the effect of FSSW process parameters; namely rotational speed, plunging rate and dwell time, on the developed temperatures and their distribution within the workpiece as well as material flow and deformation. Model validation showed a good agreement between predicted temperature history and the experiment one, with a maximum error of 6%. Furthermore, the predicted formation of flash was also found in good agreement with the experiment with an error of only 7%. Simulation results predicted peak temperature and plastic strain among all studied welding conditions were 920 K and 3.5 respectively at 1200 rpm rotational speed, 20 mm/min plunging rate and 4 seconds dwell time, which is approximately 70% of the melting point of pure copper.

Simulative Model for the Evaluation of Thermo-Mechanical Effects in Friction Stir Spot Welding (FSSW) of Aluminum Sheets

2014 ◽  
Vol 622-623 ◽  
pp. 557-566
Author(s):  
G. D’Urso ◽  
Claudio Giardini
Keyword(s):  
Process Parameters ◽  
Spot Welding ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Lap Joints ◽  
Local Pressure ◽  
Friction Stir ◽  
Welding Forces ◽  
Set Up ◽  
Simulative Model

A study was performed to evaluate how the Friction Stir Spot Welding process parameters affect both the thermal distribution in the welding region and the welding forces. An experimental campaign was performed by means of a CNC machine tool and FSSW lap joints on AA6060-T6 aluminum alloy plates having a thickness of 2+2 mm were executed. Five thermocouples were inserted into the samples at a specific distance from the specimen center. A set of tests was carried out by varying the process parameters, namely rotational speed, axial feed rate, plunging depth and dwell time. Axial welding forces were also measured during the execution of the experiments by means of a piezoelectric load cell. The experimental data collected were used to set up and to validate a simulative model of the process. In particular, a 2D FEM model was set up using the commercial code Deform 2D. A 2-dimensional FEM code was preferred in order to guarantee a very simple and practical model able to achieve results in a very short time. Since it is not possible to simulate the rotation of the tool in a 2D configuration, a specific external routine for the calculation of the developed thermal energy due to the friction between tool and workpiece was set up and implemented into the code starting from the local pressure distribution along the contact area.

Towards Tool Path Numerical Simulation in Modified Friction Stir Spot Welding Processes

2009 ◽  
Vol 83-86 ◽  
pp. 1220-1227
Author(s):  
Gianluca Buffa ◽  
Livan Fratini
Keyword(s):  
Spot Welding ◽  
Tool Path ◽  
Base Material ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Lap Joints ◽  
Hollomon Parameter ◽  
Friction Stir ◽  
Strain And Strain Rate ◽  
Welding Processes

Spot welding can be considered a very common joining technique in automotive and transportation industries as it permits to obtain effective lap-joints with short process times and what is more it is easily developed through robots and automated systems. Recently the Friction Stir Spot Welding (FSSW) process has been proposed as a natural evolution of the already known Friction Stir Welding (FSW) process, allowing to obtain sound spot joints that do not suffer from the insurgence of typical welding defects due to the fusion of the base material. In the paper, a modified Friction Stir Spot Welding (FSSW) process, with a spiral circular movement given to the tool after the sinking stage, is proposed. A continuum based numerical model for Friction Stir Spot Welding process is developed, that is 2D Lagrangian implicit, coupled, rigid-viscoplastic. This model is used to investigate the distribution of the main field variables, namely temperature, strain and strain rate, as well as the Zener-Hollomon parameter which, in turn, strongly affects the Continuous Dynamic Recrystallization (CDRX) process that takes place in the weld nugget. Numerical and experimental results are presented showing the effects of the process parameters on the joint performances and the mechanical effectiveness of the modified process.

scholarly journals Optimization of Process Parameters for Friction Stir Welding of Dissimilar Aluminium Alloy AA6061 to AA5183 using TOPSIS Technique

2019 ◽  
Vol 8 (9S3) ◽  
pp. 1315-1319
Keyword(s):  
Friction Stir Welding ◽  
Aluminium Alloy ◽  
Rotational Speed ◽  
Transverse Velocity ◽  
Welding Process ◽  
Fusion Welding ◽  
Welding Parameters ◽  
Optimum Process ◽  
Tool Rotational Speed ◽  
Friction Stir

Friction stir welding has proven to be the most promising solid state joining process. It can be used to get high weldability in joining of high strength aerospace aluminium alloys and other metallic alloys which used to be low with traditional fusion welding process. This paper emphasises on finding the optimum process parameter for friction stir welding of dissimilar aluminium alloy AA6061 to AA5183 using multi criteria decision making method (MCDM). Friction stir welding was done at different tool rotational speed and transverse velocity and mechanical properties such as tensile strength, percentage elongation and hardness were studied for each weld specimen. Finally optimization was done using TOPSIS (Techniqueof Ordered Preference by Similarity to Ideal Solution). The result revealed that the tool rotational speed of 1200 rpm and welding speed of 80mm/min are the optimum welding parameters.

Effect of Welding Conditions on Sheets’ Interface Properties in Friction Stir Spot Welding of Copper

2019 ◽  
Author(s):  
Ahmed Mahgoub ◽  
Neçar Merah ◽  
Abdelaziz Bazoune
Keyword(s):  
Surface Morphology ◽  
Rotational Speed ◽  
Spot Welding ◽  
Dwell Time ◽  
Friction Stir Spot Welding ◽  
Tensile Failure ◽  
Welding Parameters ◽  
Welding Condition ◽  
Friction Stir ◽  
Joint Fracture

Abstract Friction Stir Spot Welding (FSSW) is a solid-state joining technique widely applied to high conductive metals. In this paper, the effects of FSSW parameters, namely, rotational speed (N), plunging rate (V) and dwell time (DT) on the joint fracture mode and fractured surface morphology were investigated using scanning electron microscopy (SEM). The effect of the abovementioned welding parameters on the microhardness profile along the sheets’ interface was also investigated to gain insight into the strength of the joint and the width of the bonding ligament. Two conditions were considered for each parameter 1200 rpm and 900 rpm for N, 60 mm/min and 20 mm/min for V, 4 and 2 seconds for DT. The welding condition 1200 rpm rotational speed, 20 mm/min plunging rate and 2 seconds dwell time showed a wider bonding ligament, relatively higher elongation, higher tensile failure load, and greater microhardness on the sheets’ interface. Dimple surface morphology (DSM) with regular dimples along the stir zone was also observed at the abovementioned set of process parameters.

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