scholarly journals The Evolution of the Nugget Zone for Dissimilar AA6061/AA7075 Joints Fabricated via Multiple-Pass Friction Stir Welding

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1506
Author(s):  
Yu Chen ◽  
Zhihui Cai ◽  
Hua Ding ◽  
Fenghe Zhang
Keyword(s):  
Friction Stir Welding ◽  
Grain Refinement ◽  
Dissimilar Materials ◽  
Vertical Flow ◽  
Nugget Zone ◽  
Friction Stir ◽  
Single Pass ◽  
Multiple Pass ◽  
Welding Direction ◽  
Welding Technique

AA6061 and AA7075 aluminum alloys were successfully joined by using single-pass and multiple-pass friction stir welding techniques after which the effects on the nugget zone evolution from a second overlapping pass and its welding direction, were investigated. In comparison to single-pass friction stir welding, the application of a second overlapping pass prolonged the dynamic recrystallization time, and the grains of the nugget zone became finer with increased high angle grain boundaries. Moreover, reversing the welding direction of the second overlapping pass enhanced the vertical flow of materials, increasing the strain of the friction stir welding in the nugget zone. As a result, the efficiency of the grain refinement and mixture of dissimilar materials during the second overlapping pass were significantly elevated. The tensile strength of the nugget zone was improved after the second overlapping pass due to both the grain refinement and mechanical interlocking of the AA6061/AA7075 alloys. The nugget zone, which was fabricated via the multiple-pass friction stir welding technique using an opposite welding direction, exhibited a 23% increase in yield strength as compared to the sample using the single-pass friction stir welding technique.

Improving Friction Stir Welding between Copper and 304L Stainless Steel

2011 ◽  
Vol 409 ◽  
pp. 263-268 ◽  
Author(s):  
Yousef Imani ◽  
M.K. Besharati Givi ◽  
Michel Guillot
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Friction Stir Welding ◽  
Pure Copper ◽  
Dissimilar Materials ◽  
Metallographic Analysis ◽  
304L Stainless Steel ◽  
Friction Stir ◽  
Welding Direction ◽  
Fsw Experiments

As a solid-state welding technology, friction stir welding (FSW) can join dissimilar materials with good mechanical properties. In this paper, friction stir welding between 304L stainless steel and commercially pure copper plates with thicknesses of 3 mm was performed. A number of FSW experiments were carried out to obtain the optimum mechanical properties by adjusting the rotational speed to 1000 rpm and welding speed in the range of 14-112 mm/min and with an adjustable offset of the pin location with respect to the butt line. Microstructural analyses have been done to check the weld quality. Cross-sectioning of the welds for metallographic analysis in planes perpendicular to the welding direction and parallel to the weld crown was also performed. The mechanical properties of the welds were determined using a combination of conventional microhardness and tensile testing. From this investigation it is found that the offset of the pin is an essential factor in producing defect free welds in friction stir welding of copper and steel.

Study on the Flow Field of Friction Stir Welding of AZ31 Magnesium Alloy Based on the Temperature Variation

2014 ◽  
Vol 789 ◽  
pp. 282-289
Author(s):  
Ali Lu ◽  
Sheng Lu ◽  
Shu Jin Chen ◽  
Dai Li Yang
Keyword(s):  
Friction Stir Welding ◽  
Magnesium Alloy ◽  
Flow Field ◽  
Temperature Variation ◽  
Plastic Material ◽  
Dissimilar Materials ◽  
Peak Temperature ◽  
Az31 Magnesium Alloy ◽  
Friction Stir ◽  
Welding Direction

In this study, AZ31 magnesium alloy plates were butt welded by friction stir welding to investigate the flow field characterization, and temperature variation was measured. “Marker insert technology” and “stitch welding of dissimilar materials technique” were used to make the flow field visualization. The results indicated that both the temperature variation and the flow way of material are three dimensional asymmetric. In terms of temperature distribution, along the welding direction, the temperature is gradually increased during the process; along the thickness direction, the peak temperature is high in the upper part and low in the lower; perpendicular to the welding direction, the peak temperature of the advancing side is slightly higher than the retreating side. In terms of the flow field, the flow way of the material in the advancing side is different from retreating side. Material from the advancing side crosses the pin and is divided into two directions: part is dragged forward by the shoulder while part is extruded backward. However, materials in retreating side move backward only. At different depths, the flow range of plastic material is different. The closer to the bottom of the weld, the flow range of plastic material is smaller. Along the welding direction, the flow range of the plastic material changes larger from the initial stage to the end stage. On the cross section of the weld, plastic material that adjacent to the pin is squeezed down while part of the material at the bottom is forced to move upwards. The rising material converged with the downward current and formed a cycle. Considering the deformation tendency of the lapped surface, the advancing side is more intense than the retreating side.

scholarly journals A Comparative Study of Tool-Pin Profile on Process Response of Friction Stir Welding of AA6082-T6 Aluminium Alloy

2017 ◽  
Vol 61 (4) ◽  
pp. 296 ◽  
Author(s):  
Kayode Oyedemi ◽  
Patrick McGrath ◽  
Hannalie Lombard ◽  
Balázs Varbai
Keyword(s):  
Friction Stir Welding ◽  
Material Flow ◽  
Dwell Time ◽  
Research Work ◽  
Welding Process ◽  
Nugget Zone ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Tool Pin ◽  
Welding Direction

This paper presents research work conducted to experimentally establish the process response of two diverse shaped tool-pin profiles for friction stir welding (FSW) AA6082-T6 aluminium. The dwell time was optimised by plunging each tool-pin into a plate sample until the spindle torque stabilised thus ensuring sufficient plasticised material in contact with tool shoulder and the tool-pins. The welds were conducted by employing the optimised dwell time, which in turn revealed a minimised process response time and distance to reach weld stability with respect to (1) the force exerted on the tool-pin in the welding direction, Fx , and (2) the spindle torque, T, during the welding process. Both Fx and T stabilised well within the set (pre-determined) ramp-up distance of 20 mm, indicating that the effective (useful) weld length is maximised. The macrographs also revealed good dynamic material flow within the nugget zone regions and more evident in the nugget zone of the flared tool.

scholarly journals Microstructural Evolutions of 2N Grade Pure Al and 4N Grade High-Purity Al during Friction Stir Welding

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3606
Author(s):  
Tomoya Nagira ◽  
Xiaochao Liu ◽  
Kohasaku Ushioda ◽  
Hidetoshi Fujii
Keyword(s):  
Friction Stir Welding ◽  
Dynamic Recrystallization ◽  
Grain Refinement ◽  
High Purity ◽  
Cube Texture ◽  
Grain Structure ◽  
Welding Temperature ◽  
Friction Stir ◽  
Continuous Dynamic Recrystallization ◽  
Dislocation Annihilation

The grain refinement mechanisms along the material flow path in pure and high-purity Al were examined, using the marker insert and tool stop action methods, during the rapid cooling friction stir welding using liquid CO2. In pure Al subjected to a low welding temperature of 0.56Tm (Tm: melting point), the resultant microstructure consisted of a mixture of equiaxed and elongated grains, including the subgrains. Discontinuous dynamic recrystallization (DDRX), continuous dynamic recrystallization (CDRX), and geometric dynamic recrystallization are the potential mechanisms of grain refinement. Increasing the welding temperature and Al purity encouraged dynamic recovery, including dislocation annihilation and rearrangement into subgrains, leading to the acceleration of CDRX and inhibition of DDRX. Both C- and B/-type shear textures were developed in microstructures consisting of equiaxed and elongated grains. In addition, DDRX via high-angle boundary bulging resulted in the development of the 45° rotated cube texture. The B/ shear texture was strengthened for the fine microstructure, where equiaxed recrystallized grains were fully developed through CDRX. In these cases, the texture is closely related to grain structure development.

scholarly journals Effect of Stirring Pin Rotation Speed on Microstructure and Mechanical Properties of 2A14-T4 Alloy T-Joints Produced by Stationary Shoulder Friction Stir Welding

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1938
Author(s):  
Haifeng Yang ◽  
Hongyun Zhao ◽  
Xinxin Xu ◽  
Li Zhou ◽  
Huihui Zhao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Rotation Speed ◽  
Weld Nugget ◽  
Al Alloy ◽  
Nugget Zone ◽  
T Joints ◽  
Friction Stir ◽  
Stationary Shoulder ◽  
Microstructure And Mechanical Properties

In this study, 2A14-T4 Al-alloy T-joints were prepared via stationary shoulder friction stir welding (SSFSW) technology where the stirring pin’s rotation speed was set as different values. In combination with the numerical simulation results, the macro-forming, microstructure, and mechanical properties of the joints under different welding conditions were analyzed. The results show that the thermal cycle curves in the SSFSW process are featured by a steep climb and slow decreasing variation trends. As the stirring pin’s rotation speed increased, the grooves on the weld surface became more obvious. The base and rib plates exhibit W- or N-shaped hardness distribution patterns. The hardness of the weld nugget zone (WNZ) was high but was lower than that of the base material. The second weld’s annealing effect contributed to the precipitation and coarsening of the precipitated phase in the first weld nugget zone (WNZ1). The hardness of the heat affect zone (HAZ) in the vicinity of the thermo-mechanically affected zone (TMAZ) dropped to the minimum. As the stirring pin's rotation speed increased, the tensile strengths of the base and rib plates first increased and then dropped. The base and rib plates exhibited ductile and brittle/ductile fracture patterns, respectively.

Effect of Porosity Content on the Weldability of Powder Metal Parts Produced by Friction Stir Welding

2007 ◽  
Vol 534-536 ◽  
pp. 789-792 ◽  
Author(s):  
Adem Kurt ◽  
Ilyas Uygur ◽  
Hakan Ates
Keyword(s):  
Friction Stir Welding ◽  
Powder Metal ◽  
Aluminum Powders ◽  
Friction Stir ◽  
Metal Parts ◽  
Constant Friction ◽  
Sintered Powder ◽  
Hardness Values ◽  
Welding Technique ◽  
Traveling Speed

Friction stir welding technique (FSW) has many advantages in terms of tool design, rotational speed and traveling speed, and can be adjusted in a precise manner. It enables heat input into the system to be controlled. In this study, Aluminum powders were compacted at 350,400 and 450 MPa pressure and sintered at 450 oC temperature for 30 minutes in Ar atmosphere. Sintered powder metal parts were joined to each other by FSW at the speed of 1800 rpm and traveling welding speed 200 mm/min under a constant friction force. The results show that the amount of porosity affects the weldability of powder metallurgy (P/M) parts. Furthermore, the porosity and microstructural evolution of the Aluminum also affected the hardness values of the tested materials.

Microstructure and Mechanical Properties at the Unsteady Areas of Non-Linear Friction Stir Welding

2007 ◽  
Vol 561-565 ◽  
pp. 1059-1062 ◽  
Author(s):  
H. Takahara ◽  
Masato Tsujikawa ◽  
Sung Wook Chung ◽  
Y. Okawa ◽  
Kenji Higashi
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Welding Parameter ◽  
Butt Joints ◽  
Friction Stir ◽  
Non Linear ◽  
Linear Friction ◽  
Fsw Parameters ◽  
Five Axis ◽  
Welding Direction

The influence of tool control in non-linear friction stir welding (FSW) on mechanical properties of joints was investigated. FSW is widely applied to linear joints. It is impossible for five axis FSW machines, however, to keep all the FSW parameters in optimum conditions at non-linear welding. Non-linear FSW joints should be made by compromise with the order of priority for FSW parameters. The tensile test results of butt joints with rectangular change in welding direction on plate plane (L-shaped butt joints) with various welding parameter change. It was found that turn to the retreating side is encouraged when welding direction change. And the method of zero inclination tool angle is effective at non-linear and plane welding.

Influence of Friction Stir Welding Process on the Weld Formation and Tensile Strength of Titanium and Aluminum Dissimilar Alloys Welded Joint

2011 ◽  
Vol 189-193 ◽  
pp. 3266-3269 ◽  
Author(s):  
Yu Hua Chen ◽  
Peng Wei ◽  
Quan Ni ◽  
Li Ming Ke
Keyword(s):  
Tensile Strength ◽  
Friction Stir Welding ◽  
Cross Section ◽  
Welded Joint ◽  
Welding Process ◽  
Dissimilar Materials ◽  
Influence Of Process Parameters ◽  
Friction Stir ◽  
Dissimilar Alloys ◽  
Titanium Aluminum

Titanium alloy TC1 and Aluminum alloy LF6 were jointed by friction stir welding (FSW), and the influence of process parameters on formation of weld surface, cross-section morphology and tensile strength were studied. The results show that, Titanium and Aluminum dissimilar alloy is difficult to be joined by FSW, and some defects such as cracks and grooves are easy to occur. When the rotational speed of stir head(n) is 750r/min and 950r/min, the welding speed(v) is 118mm/min or 150mm/min, a good formation of weld surface can be obtained, but the bonding of titanium/aluminum interface in the cross-section of weld joint is bad when n is 750r/min which results in a low strength joint. When n is 950r/min and v is 118mm/min，the strength of the FSW joint of Titanium/Aluminum dissimilar materials is 131MPa which is the highest．

Numerical Simulation of Plunge Force During the Plunge Phase of Friction Stir Welding and Ultrasonic Assisted FSW

2008 ◽  
Author(s):  
Kwanghyun Park ◽  
Bongsuk Kim ◽  
Jun Ni
Keyword(s):  
Numerical Simulation ◽  
Friction Stir Welding ◽  
High Frequency ◽  
Hybrid Welding ◽  
Ultrasonic Vibrations ◽  
Welding Quality ◽  
Friction Stir ◽  
Ultrasonic Assisted ◽  
Welding Force ◽  
Welding Technique

Ultrasonic assisted friction stir welding (UaFSW) is an hybrid welding technique, where high frequency vibration is superimposed on the movement of a rotating tool. The benefit of using ultrasonic vibration in the FSW process refers to the reduction in the welding force and to the better welding quality. The UaFSW system is being developed and its mechanism needs to be understood using both the experiments and the numerical simulations. In this paper, FE simulations of FSW and UaFSW using ABAQUS/Explicit were carried out to examine plunge forces during the plunge phase of FSW and UaFSW, respectively. First, the simulations of the conventional FSW process were validated. Then, simulation of UaFSW process was performed by imposing sinusoidal horizontal ultrasonic vibrations on the tool.

Sign in / Sign up

Export Citation Format

Share Document