Constant Heat Input Friction Stir Welding of Variable Thickness AZ31 Sheets Through In-Process Tool Rotation Control

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Gianluca Buffa ◽  
Davide Campanella ◽  
Archimede Forcellese ◽  
Livan Fratini ◽  
Michela Simoncini ◽  
...  
Keyword(s):  
Variable Thickness ◽  
Heat Input ◽  
Weld Line ◽  
Sheet Thickness ◽  
Strain Curve ◽  
Thickness Change ◽  
Friction Stir ◽  
Tailored Blanks ◽  
Joint Properties ◽  
Tool Rotation

Tailored blanks characterized by variable thickness were friction stir welded (FSWed) with the aim to obtain constant joint properties along the weld seam, regardless of the thickness change. To pursue this goal, the heat input was kept constant by in-process control of tool rotation. A dedicated numerical model of the process was used to determine the tool rotation values as a function of the sheet thickness. The mechanical properties and the microstructure of the FSWed joints, produced with varying process parameters, were studied. It was found that the proposed approach can produce joints with uniform properties along the weld line in terms of stress–strain curve shape, joint strength, elongation at failure, and microstructure.

Incremental Forming of Friction Stir Welded Taylored Sheets

2006 ◽  
Author(s):  
G. Ambrogio ◽  
L. Fratini ◽  
F. Micari
Keyword(s):  
Metal Forming ◽  
Cost Reduction ◽  
Large Scale ◽  
Incremental Forming ◽  
Research Work ◽  
Sheet Thickness ◽  
Friction Stir ◽  
Tailored Blanks ◽  
Metal Stamping ◽  
Light Components

In the last decade sheet metal forming market has undergone substantial mutations since the development of more efficient strategies in terms of flexibility and cost reduction is strictly due. Such requirements are not consistent with traditional metal stamping processes which are characterized by complex equipment, capital and tooling costs; thus the industrial application of such processes is economically convenient just for large scale productions. For this reason most of the research work developed in the last years has been focused on the development of new sheet forming processes able to achieve the above discussed goals. Contemporary, with particular reference to the automotive industries the requirement of light components and the engineering of the outer skin parts of the vehicles have determined the growing utilization of tailored blanks characterized by either different material or different sheet thickness. In the paper SPIF processes of FS welded aluminium blanks are investigated in order to analyse the product properties in terms of strength and formability. A proper experimental investigation has been carried out and interesting guidelines have been highlighted in the next paragraphs.

Microstructure and Mechanical Properties of Friction Stir Welded Annealed Pure Copper Joints

2013 ◽  
Vol 787 ◽  
pp. 346-351
Author(s):  
Salar Salahi ◽  
Vahid Rezazadeh ◽  
Atabak Iranizad ◽  
Ali Hosseinzadeh ◽  
Amir Safari
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Welding Speed ◽  
Heat Input ◽  
Applied Load ◽  
Rotation Speed ◽  
Pure Copper ◽  
Friction Stir ◽  
Tool Rotation Speed ◽  
Tool Rotation

As a novel technique for joining materials, friction stir welding (FSW) has significant advantages over the conventional welding methods and is widely applied for joining different materials including aluminum, magnesium and copper alloys. In this research, the mechanical and microstructural characteristics of friction stir welded annealed pure copper joints were investigated. The influence of the tool rotation speed, welding speed and applied load was studied. The friction stir welding (FSW) was conducted at welding speed ranged from 30 to 70 mm/ min, rotation speed ranged from 400 to 1200rpm and applied load ranged from 1000 to 1500 kg. After welding process, tensile and Vickers hardness tests were performed. It has been found that increasing the tool rotational speed and/or reducing the welding speed increases heat input and causes grain coarsening in stir zone. High applied load refines the microstructure of NZ and increases the hardness and tensile strength of NZ. An optimum heat input condition was found to reach the best mechanical properties of the joints. The tensile characteristics of the friction stir welded tensile samples depend significantly on the tool rotation speed ,welding speed and applied load.

Effect of Friction Stir Welding pin Shape on Mechanical Properties of AA6061 Alloy Weldment

2013 ◽  
Vol 465-466 ◽  
pp. 1309-1313
Author(s):  
Mohd Hasbullah Idris ◽  
Mohd Shamsul Husin
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Friction Stir Welding ◽  
Material Flow ◽  
Weld Line ◽  
Butt Joint ◽  
Hardness Distribution ◽  
Plunge Depth ◽  
Friction Stir ◽  
Joint Properties

The present study is aimed to determine the effect of friction stir welding pin; square and diamond shape on mechanical properties of butt joint AA6061 weldment. Welding was carried out at different plunge depths of 0.0, 0.2, 0.3 and 0.4 mm together with rotation and transverse speeds of 500 rpm and 40 mm/min, respectively. Material flow, tensile strength and hardness of the weldment were evaluated. The results indicated that joint properties were significantly affected by tool design. It was found that material flow was higher for diamond pin tool compared to that of square pin resulting in considerable increased in tensile strength of the joint. In addition, the highest tensile strength was obtained on the samples welded with square shape pin at 0.4 mm plunge depth whilst the lowest was by diamond shape at the plunge depth of 0.0 mm. Regardless of pin shape and plunge depth; asymmetrical hardness distribution was observed for all weldments. The highest hardness was found to be close to the weld line produced by the diamond shaped pin at 0.0 mm plunge depth.

Welding speed effect on joint properties in air and immersed friction stir welding of AA2014

2017 ◽  
Vol 231 (5) ◽  
pp. 897-909 ◽  
Author(s):  
Nilesh D Ghetiya ◽  
Kaushik M Patel
Keyword(s):  
Tensile Strength ◽  
Friction Stir Welding ◽  
Welding Speed ◽  
Heat Input ◽  
Nugget Zone ◽  
Friction Stir ◽  
Maximum Tensile Strength ◽  
Joint Properties ◽  
Welding Joints ◽  
Speed Effect

In immersed friction stir welding, the workpiece is fully immersed in the water during welding. This work illustrates the effect of welding speed on mechanical properties and microstructure. Friction stir welding joints were produced using AA2014-T6 at different welding speeds ranging from 80 to 125 mm/min with constant rotational speed of 1000 r/min in air and immersed water conditions. Results revealed that with an increase in welding speed, the tensile strength of joint increased, this is due to a reduction in heat input while using both air and immersed friction stir welding, which in turn reduces the dissolution of strengthening precipitates. Microstructure result showed that grain size decreased with an increase in welding speed due to less heat input at increased welding speed. The dissolution of strengthening precipitates weakened with an increase in welding speed in both air and immersed friction stir welding, leading to an increase in hardness value at the nugget zone. Maximum tensile strength was obtained at a welding speed of 100 mm/min in immersed friction stir welding and was around 17% higher compared with a maximum tensile strength obtained using air friction stir welding.

scholarly journals The effect of ice-sheet thickness change on the accumulation history inferred from GISP2 layer thicknesses

1995 ◽  
Vol 21 ◽  
pp. 26-32 ◽  
Author(s):  
Nadine N. Cutler ◽  
C.F. Raymond ◽  
E. D. Waddington ◽  
D.A. Meese ◽  
R.B. Alley
Keyword(s):  
Layer Thickness ◽  
Variable Thickness ◽  
Flow Model ◽  
Accumulation Rate ◽  
Ice Sheet ◽  
Sheet Thickness ◽  
Constant Thickness ◽  
Accumulation Rates ◽  
Thickness Change ◽  
Accumulation History

Net accumulation rates at the Greenland summit have been inferred using layer-thickness data from the GISP2 ice core with corrections for strain using a non-linear, one-dimensional flow model of an ice sheet. The flow model accounts for thickness changes in ice-sheet in response to mass-balance variations. The model is used to investigate how net accumulation-rate changes affect the time evolution of: (1) the ice-sheet thickness. (2) the vertical strain rate, and (3) the corresponding internal annual-layer structure. The model, parameterized to fit the present net accumulation rate and thickness of the Greenland ice-sheet summit, has a characteristic time constant for adjustment to accumulation-rate changes of about 6000a and yields an ice sheet 200-400 m thinner than its present thickness during the last glacial period. Accumulation-rate histories inferred from GISP2 layer-thickness data using both a constant- and a variable-thickness model are compared. The variable-thickness model predicts accumulation rates about 25% lower than the constant-thickness model. Our results also indicate that high-frequency changes in accumulation rates (i.e. alter the Younger Dryas event) are consistent with earlier analyses. However, sensitivity tests indicate that the accumulation-rate history cannot be precisely determined. Our analysis defines an envelope of likely accumulation histories bounded above by the accumulation history inferred by the constant-thickness model. Predictions become increasingly uncertain for old ice because of (1) intrinsic difficulties associated with this inverse problem, and (2) decreased accuracy of the data.

scholarly journals The Joint Properties of 5754 Aluminium Alloy by Friction Stir Spot Welding

2019 ◽  
Vol 3 (1) ◽  
pp. 8
Author(s):  
Orhan Dedeoğlu ◽  
Hande Güler Özgül
Keyword(s):  
Rotational Speed ◽  
Spot Welding ◽  
Friction Stir Spot Welding ◽  
Fracture Pattern ◽  
Single Type ◽  
Tool Geometry ◽  
Friction Stir ◽  
Joint Properties ◽  
Hardness Values ◽  
Tool Rotation

In this study, AA5754 sheet samples joined by using a friction stir spot welding method using different rotational speed parameters has been analyzed experimentally. During the experiments, rotational speed of the tool was changed while other process parameters and the tool geometry were kept constant. The effect of tool rotational speed on the hardness values, macrostructure, and tensile properties of joints has been investigated and the results of the experiments show the best tensile shear strength and hardness values are obtained for the tool rotation speed of 1850 rpm. According to the macroscopic investigation, all of the fractured samples failed by nugget pullout and the fractured samples have only a single type fracture pattern.

scholarly journals The effect of ice-sheet thickness change on the accumulation history inferred from GISP2 layer thicknesses

1995 ◽  
Vol 21 ◽  
pp. 26-32 ◽  
Author(s):  
Nadine N. Cutler ◽  
C.F. Raymond ◽  
E. D. Waddington ◽  
D.A. Meese ◽  
R.B. Alley
Keyword(s):  
Layer Thickness ◽  
Variable Thickness ◽  
Flow Model ◽  
Accumulation Rate ◽  
Ice Sheet ◽  
Sheet Thickness ◽  
Constant Thickness ◽  
Accumulation Rates ◽  
Thickness Change ◽  
Accumulation History

Net accumulation rates at the Greenland summit have been inferred using layer-thickness data from the GISP2 ice core with corrections for strain using a non-linear, one-dimensional flow model of an ice sheet. The flow model accounts for thickness changes in ice-sheet in response to mass-balance variations. The model is used to investigate how net accumulation-rate changes affect the time evolution of: (1) the ice-sheet thickness. (2) the vertical strain rate, and (3) the corresponding internal annual-layer structure. The model, parameterized to fit the present net accumulation rate and thickness of the Greenland ice-sheet summit, has a characteristic time constant for adjustment to accumulation-rate changes of about 6000a and yields an ice sheet 200-400 m thinner than its present thickness during the last glacial period.Accumulation-rate histories inferred from GISP2 layer-thickness data using both a constant- and a variable-thickness model are compared. The variable-thickness model predicts accumulation rates about 25% lower than the constant-thickness model. Our results also indicate that high-frequency changes in accumulation rates (i.e. alter the Younger Dryas event) are consistent with earlier analyses. However, sensitivity tests indicate that the accumulation-rate history cannot be precisely determined. Our analysis defines an envelope of likely accumulation histories bounded above by the accumulation history inferred by the constant-thickness model. Predictions become increasingly uncertain for old ice because of (1) intrinsic difficulties associated with this inverse problem, and (2) decreased accuracy of the data.

scholarly journals Microstructural Characteristics and Mechanical Properties of Friction Stir Spot Welded 2A12-T4 Aluminum Alloy

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Huijie Liu ◽  
Yunqiang Zhao ◽  
Xingye Su ◽  
Lilong Yu ◽  
Juncai Hou
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Fracture Mode ◽  
Heat Input ◽  
Tensile Shear ◽  
Microstructural Characteristics ◽  
Friction Stir ◽  
Welding Heat Input ◽  
Mixed Fracture ◽  
Spot Welded

2A12-T4 aluminum alloy was friction stir spot welded, and the microstructural characteristics and mechanical properties of the joints were investigated. A softened microstructural region existed in the joint, and it consisted of stir zone (SZ), thermal mechanically affected zone (TMAZ), and heat affected zone (HAZ). The minimum hardness was located in TMAZ, and the average hardness value in SZ can be improved by appropriately increasing welding heat input. The area of complete bonding region at the interface increased with increasing welding heat input because more interface metals were mixed. In a certain range of FSSW parameters, the tensile shear failure load of the joint increased with increasing rotation speed, but it decreased with increasing plunge rate or decreasing shoulder plunging depth. Two kinds of failure modes, that is, shear fracture mode and tensile-shear mixed fracture mode, can be observed in the tensile shear tests, and the joint that failed in the tensile-shear mixed fracture mode possessed a high carrying capability.

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