This research aims to construct a three-dimensional numerical model for modeling friction stir extrusion using the completely Lagrangian method, smoothed particle hydrodynamics (SPH). For extrusion simulations, the Finite Element Method (FEM) is extensively utilized; however, it has limitations due to excessive element deformation. Because the particle-based method eliminates the usage of volumetric elements, SPH can be a viable alternative. The performance of the SPH model was evaluated using different particle sizes. The results showed that the smaller particle size improves the temperature results as well as the shape of the wire produced. Then the mechanical and microstructural properties of the produced wires were investigated. The results show that the grain size in the center of the wire is larger than its perimeter due to the lower strain rate in this area. Increased strain reduces grain size in the produced microstructure by increasing nucleation sites during recrystallization, as is well known. The wire microhardness in the centre is 121 HV, whereas it is 129 HV in the periphery. Grain size is the main reason of increased hardness near the sample's periphery. Manuscript profile

In this research, Al-SiC composites were produced using FSP tools with different pin shapes to investigate the distribution of reinforcing particles in the base metal. First, to obtain the optimal rotational and traverse speed and tilt angle, several tests were performed on different parameters. The results showed that the rotational speed of 1250 rpm and the traverse speed of 100 mm/min in all tools produced flawless samples. Then, tools with different tool pin profiles of triflate, cylindrical, threaded, triangular, square, and hexagonal were utilized in this study. The distribution of reinforcing particles in the base metal was studied using a light microscope. The results showed that the cylindrical tool was not able to distribute particles in the base metal even after four passes of the process and was not a suitable tool for composite production. Tools with flat surfaces, such as square and triangular tools, have performed better in distributing reinforcing particles in the base metal. The results showed that the presence of a kind of eccentricity and pulse production in these tools had improved the distribution of particles. Threaded and hexagonal tools have the best performance in the distribution of reinforcing particles in the base metal and can be introduced as a suitable tool for composite products in the FSP process. The results of this study also showed that the change in the direction of tool rotation improved the distribution of reinforcing particles in all tools. Manuscript profile

Al-Si alloys are widely used in the manufacture of automotive parts such as pistons and cylinders. Although it has desired properties for use in pistons, some microstructural properties of this alloy, such as dendrites or the presence of needle-like silicones, reduce the performance of the parts produced. In this research, to modify the microstructural properties and thus improve the mechanical properties of the alloy, the friction stir processing (FSP) method is used. Also, the effect of process parameters such as rotational and traverse speeds as well as the shape of the pin on the microstructural and mechanical properties of the samples, are studied. The results show that the FSP process improves the microstructural properties of the base metal, and thus improves its mechanical properties. Furthermore, by increasing the rotational speed or decreasing the traverse speed of the tool, the silicon particles become finer, and consequently, the microstructural properties are improved. Manuscript profile