Establishing Mathematical Models to Predict Grain Size and Hardness of the Friction Stir-Welded AA 7020 Aluminum Alloy Joints

Proceedings of the Institution of Mechanical Engineers, Part E:

Asadi

Zolghadr

et al. 2017

In this investigation, the mechanical and microstructural properties of aluminum composites reinforced by different reinforcing particles including SiC, TiC, ZrO 2 , and B 4 C were optimized using neural network and NSGA-II. In order to obtain the best microstructural and mechanical properties of aluminum composites, different friction stir processing parameters such as rotational and traverse speed and different reinforcing particles type were used in order to fabricate composites. Results show that friction stir processing significantly affect Si particles size as well as dispersion and fraction of reinforcing particles at the stir zone. Moreover, reinforcing particle types influence the mechanical properties of composites due to difference in hardness and thermal expansion of each reinforcement as well as bonding quality between each reinforcement and aluminum matrix. In order to model the correlation between the friction stir processing parameters and microstructural and mechanical properties of the composites, an artificial neural network model was developed. A modified NSGA-II by incorporating diversity preserving mechanism called the " elimination algorithm was employed to obtain the Pareto-optimal set of friction stir processing parameters. Finally, an approach based on TOPSIS method was applied for determining the best compromised solution from the obtained Pareto-optimal set.

“…17 Due to high complex and nonlinear characteristics of the process, the optimum value of FSP parameters cannot be easily obtained using just the mathematical models of FSP. 19…”

Section: Introductionmentioning

confidence: 99%

Multicriteria optimization of mechanical properties of aluminum composites reinforced with different reinforcing particles type

Proceedings of the Institution of Mechanical Engineers, Part E:

Asadi

Zolghadr

et al. 2017

“…Friction stir welding (FSW) as a relatively new welding technique has been employed to weld different Al, 5–10 Mg, 11,12 and Cu 5,13–16 alloys, some of which are classified as practically unweldable alloys in use of conventional welding methods. The FSP has been invented based on the FSW for local modification of different materials microstructure.…”

Section: Introductionmentioning

confidence: 99%

Effect of tool pin profile on distribution of reinforcement particles during friction stir processing of B₄C/aluminum composites

Shojaeefard

Proceedings of the Institution of Mechanical Engineers, Part L:

Khalkhali

et al. 2016

Boron carbide /aluminum composites have been produced on an aluminum-silicon cast alloy using friction stir processing. Effect of pin profile on the distribution of boron carbide in the stir zone of the friction stir processed specimens was investigated experimentally and numerically. The material flow generated by the threaded and circular tool pin profiles, being the main reason for the distribution of particles in the metal matrix, was numerically modeled using a thermomechanically coupled three-dimensional finite element model. Numerical and experimental results show that threaded pin profile produces a more uniform distribution of B 4 Cp than other pin profiles. Hardness tests were performed in order to investigate mechanical properties of the composites. Wear resistance of the composite was evaluated and obtained results showed that the hardness and wear resistance of the composite significantly improved.

“…Because the larger the grain size, the lower the hardness, according to the Zener–Hollomon equation. 28 , 29 Therefore, the larger the better should be used in terms of the microhardness results. Similarly, the rotational speed is the dominant factor affecting the microhardness.…”

Section: Resultsmentioning

confidence: 99%

Optimization of microstructural and mechanical properties of brass wire produced by friction stir extrusion using Taguchi method

Proceedings of the Institution of Mechanical Engineers, Part L:

Asadi

2021

Friction stir back extrusion is used to produce brass wires from its chips, and then the process parameters are optimized using Taguchi L9 orthogonal design of experiments. The rotational speed, traverse speed, and the produced wire diameter are the parameters taken into consideration. The optimum process parameters are determined with respect to grain size, microhardness, and ultimate pressure strength of the produced samples. The predicted optimum values for output parameters are confirmed by conducting the confirmation test using optimum parameters. Analysis of variance shows that the rotational speed is the most dominant factor in determining the grain size and microhardness of the produced wires, and the tool traverse speed and the wire diameter are the second and the third effective parameters. However, in terms of the produced wires ultimate pressure strength, the traverse speed is the most dominant factor rather than the rotational speed. The optimum values for the rotational speed, the traverse speed, and the wire diameter are 500 r/min, 31.5 mm/min, and 6 mm, respectively, and the produced wire, by these optimum parameters, presents 14.17 µm, 127.1 HV, and 904.7 MPa for the grain size, the microhardness, and the ultimate pressure strength, respectively.