Thermal history and microstructure during friction stir welding of Al–Mg alloy

Friction stir additive manufacturing is a newly developed solid-state additive manufacturing technology. The material in the stirring zone can be re-stirred and reheated, and mechanical properties can be changed along the building direction. An integrated model is developed to investigate the internal relations of process, microstructure and mechanical properties. Moving heat source model is used to simulate the friction stir additive manufacturing process to obtain the temperature histories, which are used in the following microstructural simulations. Monte Carlo method is used for simulation of recrystallization and grain growth. Precipitate evolution model is used for calculation of precipitate size distributions. Mechanical property is then predicted. Experiments are used for validation of the predicted grains and hardness. Results indicate that the average grain sizes on different layers depend on the temperature in stirring and re-stirring processes. With the increase in building height, average grain size is decreased and hardness is increased. The increase in layer thickness can lead to temperature decrease in reheating and re-stirring processes and then lead to the decrease in average grain size and increase of hardness in stir zone.

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“…It is validated by experiments. The equivalent strain rate is calculated according to the size of pin and the rotating speed [26,[39][40][41],…”

Section: Integrated Modeling Of Microstructure Evolution and Mechanical Propertymentioning

confidence: 99%

Integrated Modeling of Process–Microstructure–Property Relations in Friction Stir Additive Manufacturing

Zhang

Tan

et al. 2019

Acta Metall. Sin. (Engl. Lett.)

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“…At the same time, as during the process of FSW melting of the parent metals does not occur, the friction based heat (almost 75%-88% of the temperature of melting of parent metal) plasticizes the metal along the line of joint, thereby resulting in the generation of finely refined and homogenously distributed grain structures in the zone of nugget [15]. Thus, FSW process can be regarded as an innovative, entirely hazard free, solid phase welding process which is capable enough to fabricate flaw free superior quality longitudinal weldments, especially butt, for a wider range of metals of different thickness [16,17].…”

Section: Introductionmentioning

confidence: 99%

Parametric based optimization of friction stir welded wrought AZ80A Mg alloy employing response surface methodology

et al. 2023

Mater. Res. Express

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An endeavour was put forward to friction stir weld flat plates of AZ80A Mg alloy by employing the central composite based design technique of response surface methodology, taking into consideration the parameters namely tool rotational speed, traverse speed, tool’s tilt angle, and pin geometry of the employed tool. Numerical model was formulated to correlate the relationship amidst the employed parameters of FSW process and the responses, namely tensile strength and elongation percentage of the AZ80A Mg alloy joints. The formulated model was also optimized to attain AZ80A Mg alloy joints possessing highest value of tensile strength. Competency of the formulated numerical model was validated employing the analysis of variance and the observations of the affirmation experiments plotted in the form of scatter diagrams revealed an appreciable agreement with the values of the anticipated models. Response and contour plots generated from the established numerical model was employed to understand the interactive impacts of the parameters of FSW process on the variables of the response. AZ80A mg alloy joints fabricated during the employment of tool possessing straight cylindrical geometry at atilt angle of 0.630, rotational speed of 962.077 rpm, tool traverse speed of 2.105 mm sec−1 possessed the highest tensile strength of 195.299 MPa and was proven to be free from flaws.

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“…However, when it comes to the welding of dissimilar metals, most studies are restricted to the heat conduction models, and the significant effect of solidification parameters on the microstructure and mechanical properties has not been fully invesitgated. The temperature field calculated by heat conduction equation and microstructure evolution during friction stir welding (FSW) of Al-Mg were investigated by Skeikh Ahmad et al [11]. The correlations of thermal characteristics and microhardness during LBW of AA 6165 and AA 6056 aluminum alloys were studied by Yang et al [12] using a three dimensional fluid flow model, but the effect of the solidification parameters on the microstructure was not considered.…”

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Investigations of Solidification Parameters and Mechanical Property during Laser Dissimilar Welding

et al. 2018

Metals

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Laser beam welding (LBW) has been considered an effective fusion welding method for the dissimilar welding of 304 stainless steel and Ni. However, the principles governing the correlations between the heat input, weld dimension, solidified microstructure and mechanical properties have not been fully studied before. Therefore, LBW experiments with variable heat input were carried out. A transient, three-dimensional model considering liquid metal convection was developed, and solidification parameters such as temperature gradient (G), growth rate (R), and cooling rate (GR) were calculated through thermal analysis to validate the experimental results. Then, microhardness tests were carried out to verify the predications made by the simulation. Energy dispersive spectroscopy (EDS) measurements were performed to study the mass transfer. The results indicate that the joints produced by LBW were nearly defect-free. The heat input per unit length is more effective at characterizing the influence of heat input on weld dimensions. The heat input has a greater influence on the cooling rate (GR) than the morphology parameter (G/R). The results demonstrate that both the solidification characteristics and mechanical property are greatly affected by the thermal behavior in the molten pool.

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Thermal history and microstructure during friction stir welding of Al–Mg alloy

Cited by 29 publications

References 28 publications

Integrated Modeling of Process–Microstructure–Property Relations in Friction Stir Additive Manufacturing

Integrated Modeling of Process–Microstructure–Property Relations in Friction Stir Additive Manufacturing

Parametric based optimization of friction stir welded wrought AZ80A Mg alloy employing response surface methodology

Numerical and Experimental Investigations of Solidification Parameters and Mechanical Property during Laser Dissimilar Welding

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