Internal defect and process parameter analysis during friction stir welding of Al 6061 sheets

Ramulu, Perumalla Janaki; Narayanan, R. Ganesh; Kailas, Satish V.; Reddy, J. Sreedhar

doi:10.1007/s00170-012-4276-z

Cited by 75 publications

(29 citation statements)

References 26 publications

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“…The vertical force as a function of processing time of AA6082-T6 alloy shows a behaviour that is in excellent agreement with the one obtained on AA2024 by Su et al [15], by Astarita et al [17], and by Trimble et al [18], on AA6061 by Janaki Ramulu et al [26] and on AZ31 Mg alloy by Forcellese et al [19]. Figure 5 shows the comparison between the F-t curves as a function of the ω and v values, with and without the dwelling stage.…”

Section: Resultssupporting

confidence: 88%

Influence of Process Parameters on the Vertical Forces Generated during Friction Stir Welding of AA6082-T6 and on the Mechanical Properties of the Joints

Forcellese

Simoncini

Casalino

2017

Metals

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Abstract:The influence of the process parameters on the vertical force generated during friction stir welding of AA6082-T6 aluminium alloy sheet blanks was studied by performing experiments with constant values of the rotational speed, varying between 1200 and 2500 rpm, and welding speed, ranging between 30 and 100 mm/min. The effect of the tool dwelling was also analysed. The force vs. processing time curve has shown a very complex behaviour during the lowering motion of the pin tool related to the occurrence of both primary and secondary plunging. The tool dwelling produces a quick decrease in the vertical force with growing processing time until reaching a constant value. It was also seen that the tool dwelling does not influence the vertical force in the subsequent stage. As the tool began its welding motion, the vertical force immediately gets to a constant value until tool pulling out takes place. Furthermore, it was shown that the growth in the welding speed and the decrease in the rotational speed lead to an increase in the vertical force. The mechanical properties of the joints were evaluated versus the process parameters and the relationships among the ultimate tensile strength and ultimate elongation and the vertical force were defined. Finally, the microstructure developed during the friction stir welding was investigated and related to the mechanical properties of the joints.

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Section: Resultssupporting

confidence: 88%

Influence of Process Parameters on the Vertical Forces Generated during Friction Stir Welding of AA6082-T6 and on the Mechanical Properties of the Joints

Forcellese

Simoncini

Casalino

2017

Metals

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“…In any process such as FSW, involving complex thermo-mechanical phenomena, the interaction between material and process variables determines the achievable process goals. Inspite of large amount of published work on role of tool pin profile in producing defect-free joints [10][11][12][13] , the influence of tool pin profile has not been meticulously correlated with force/torque acting on tool.…”

Section: Introductionmentioning

confidence: 99%

Role of Threaded Tool Pin Profile and Rotational Speed on Generation of Defect Free Friction Stir AA 2014 Aluminium Alloy Welds

Reddy¹,

Rao²

2016

DSJ

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Influence of threads on tool pin and rotational speeds on defect occurrence in friction stir welding (FSW) of aluminum alloy AA 2014 T6 plates has been studied. The effect of FSW forces on the evolution of mechanistic defects, caused in turn through a variation in heat generation during the process has also been examined. In case of conical tool pin, relatively lower rotational speeds resulted in unbounded zones and micro defects while high speeds caused excessive flash, thereby resulting in surface defects and voids inside the weld. The FSW joints were defect-free at moderate speeds, hinting an optimum heat generation and flow. Reaction forces on the tool pin, in the welding direction, were correlated with the defect formation. Tools equipped with a threaded conical pin profile resulted in sound welds, irrespective of the tool rotational speeds in the entire range of 400 rpm -2400 rpm. The threaded conical pin, with a relatively larger frictional area, may be contributing to higher levels of heat generation compared to a plain conical pin. Further, positive displacement of the hot plasticised material by the threads will carry away excess heat from the advancing-to-the-retracting side and simultaneously downwards, thus confining all heat within the weld zone.

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“…In the present work, the welding speed is varied at 90 mm/min (Level-I) and 100 mm/min (Level-II) at a constant plunge depth of 1.9 mm, tool rotation speed of 1400 min -1 , tool shoulder diameter of 18 mm, tool tilt angle of 2.5 8 throughout the process. The levels of parameters were selected by conducting a series of experiments with different parameters to achieve the , internal defect free' FSW joints [17]. The initial welding experiments were performed within chosen range of welding parameters like shoulder diameter, plunger depth, welding (traverse) speed and rotational speed.…”

Section: Experimental Materials and Mechanical Propertiesmentioning

confidence: 99%

Experimental evaluation and prediction of forming limit of FSW blanks made of AA 6061 T6 sheets at different weld orientations and weld locations

Ramulu¹,

Narayanan²

2013

Materialwissenschaft Werkst

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The main objective of the present work is to predict the forming limit of friction stir welded (FSW) sheets made of AA 6061T6, having different weld orientations, weld locations, and made at two different welding speeds. The predicted forming limit curves (FLCs) are validated with experimental FLCs. The thickness gradient based necking criterion (TGNC) and major strain-rate ratio based necking criterion (MSRC) are used to predict the forming limit. The significance of single zone model and double zone model in FLC prediction is discussed. A decrease in hardness is witnessed in the weld zone as compared to base material. With increase in shoulder diameter and decrease in rotational speed, hardness has improved in the weld zone. The forming limit predictions of un-welded sheets and FSW sheets coincide well with experimental results. The predicted FLCs of FSW sheets from TGNC and MSRC are equally accurate as compared to experimental FLCs in all the weld locations. Both TGNC and MSRC predict almost the same forming limit in 90 8 weld orientation, while TGNC showed better prediction in 45 8 weld orientation. FSW sheets with double zone models show better prediction accuracy than single zone models in most of the cases, except in the case of weld at centre location and at longitudinal orientation. There is only slight deviation between single zone and double zone model predictions. The failure location and failure pattern predictions are also agreeing well with the experimental FLCs.

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Internal defect and process parameter analysis during friction stir welding of Al 6061 sheets

Cited by 75 publications

References 26 publications

Influence of Process Parameters on the Vertical Forces Generated during Friction Stir Welding of AA6082-T6 and on the Mechanical Properties of the Joints

Influence of Process Parameters on the Vertical Forces Generated during Friction Stir Welding of AA6082-T6 and on the Mechanical Properties of the Joints

Role of Threaded Tool Pin Profile and Rotational Speed on Generation of Defect Free Friction Stir AA 2014 Aluminium Alloy Welds

Experimental evaluation and prediction of forming limit of FSW blanks made of AA 6061 T6 sheets at different weld orientations and weld locations

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