Marjan Razzaghi University of Tehran author Hamed Mirzadeh College of Engineering - University of Tehran author Massoud Emamy University of Tehran author text article 2019 eng The effects of the addition of Al, Zn and Mn along with the application of the hot extrusion process on the microstructural refinement and enhancement of mechanical properties of magnesium alloy were studied. Based on the Mg-2Al alloy, it was found that the addition of 0.5 wt% Zn to form Mg-2Al-0.5Zn alloy or 0.5 wt% Mn to form Mg-2Al-0.5Mn alloy is the effective way for grain refinement of α-Mg in the as-cast state. Moreover, further remarkable refinement of grain size can be achieved by the extrusion process in such a way that the average grain size of the extruded Mg-2Al-0.5Mn alloy was determined to be 1/165 that of as-cast Mg. The obtained refined alloys showed significant enhancement of yield stress and tensile strength, where the former was successfully related to the average grain size by the Hall-Petch relationship with the slope of ~ 309 MPa/µm0.5. By grain refinement, firstly the yield ratio did not change considerably while tensile strength, the work-hardening exponent, and the uniform elongation increased. However, after a transition grain size (~ 32 µm), the yield ratio increased sharply due to the large increase in the yield stress, and hence, it was not possible to further enhance the uniform elongation by grain refinement despite obtaining higher yield and tensile strengths. Shiraz University 2383-0042 6 v. 2 no. 2019 2 9 https://ijmf.shirazu.ac.ir/article_5432_28fb1306a61c6c1de75828de1d6fde2e.pdf dx.doi.org/10.22099/ijmf.2019.32218.1121 Mehdi Safari Arak University of Technology author Jalal Joudaki Department of Mechanical Engineering, Arak University of Technology, Arak, Iran author text article 2019 eng In this work, the finite element simulation of dissimilar friction stir welding process is investigated. The welded materials are AA 6061-T6 and AA 7075-T6 aluminum alloys. For this purpose, a 3D coupled thermo-mechanical finite element model is developed according to the Coupled Eulerian-Lagrangian (CEL) method. The CEL method has the advantages of both Lagrangian and Eulerian approaches, which means it can simultaneously solve the singularity in the large deformation problems and describe the physical boundary of the material accurately. In this paper, the effects of the position of the harder material (AA 7075-T6 aluminum alloy) and the tool pin profile on the temperature distribution and material flow in the weld metal and heat affected zone (HAZ) are investigated. The results show that the material velocity around the FSW tool is found to be higher using a grooved pin profile. Moreover, placing the harder material at the advancing side results in slightly lower process temperatures in comparison to the estimated temperature when the material is placed at the retreating side for all types of tool profiles. It has been proved that if the AA 7075-T6 aluminum alloy is at the advancing side, mixing happens in a thin layer below the tool shoulder, and the penetration of the harder material into the retreating side is found to be limited. In addition, good agreement between the temperature distribution obtained from the experimental measurements and numerical simulations is achieved and the accuracy of the numerical model is confirmed.          Shiraz University 2383-0042 6 v. 2 no. 2019 10 19 https://ijmf.shirazu.ac.ir/article_5430_d34526765408f306e7b7480589349fb0.pdf dx.doi.org/10.22099/ijmf.2019.5430 Amin Jaferi Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran author Z. Sadeghian Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran author B. Lotfi Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran author text article 2019 eng Friction stir processing (FSP) was used as a cladding method for the fabrication of a AA2024 clad layer on a AA1050 sheet. Crossover multi pass FSP with 50% overlap was considered as the cladding method. Effects of the number of FSP passes and post heat treatment on the microstructure and properties of clad layers were evaluated. Microstructural evolutions during the FSP and heat treatment were investigated by field emission scanning electron microscopy (FESEM). The results showed that a defect free clad layer and a uniform metallurgical interface between the clad layer and base material can be achieved by the FSP. Moreover, clad layers exhibited higher hardness values in comparison to the base material. T4 Heat treatment of the FSPed samples resulted in comparatively high hardness values after natural aging. The highest hardness value of about 160 HV was achieved after heat treatment of the sample obtained from 3 intersecting FSP passes. Tensile strength of clad layers increased to 317 MPa after three intersecting FSP passes, compared to about 70 MPa of Al substrate. Shiraz University 2383-0042 6 v. 2 no. 2019 20 29 https://ijmf.shirazu.ac.ir/article_5428_bf0aad463ae45adb1f02b1fd349a8387.pdf dx.doi.org/10.22099/ijmf.2019.5428 Mahdi Vahdati Shahrood University of Technology author text article 2019 eng The mechanism of Single Point Incremental Forming (SPIF) process is based on localized plastic deformation of a sheet metal using a hemispherical-head tool that follows the path programmed into the controller of a CNC milling machine. In this process, no die is used under the sheet metal for support. The researchers' findings show that by applying ultrasonic vibration in forming processes, metallic samples are subjected to plasticization transiently and considerably. The beneficial results of applying ultrasonic vibration in the forming processes are due to volume and surface effects that are related to the change in the properties of material and change of frictional conditions, respectively. In this article, the Ultrasonic Vibration-assisted Single Point Incremental Forming (UVaSPIF) process was simulated in finite element software. The results of numerical analysis showed that ultrasonic excitation of the forming tool and increasing of the vibration amplitude reduced the friction force and the vertical component of forming force. In the following, the results of the simulation process were compared with the experimental results at a frequency of 20 kHz and 7.5 μm vibration amplitude. The study of the results showed that there was a very good agreement between the values of the vertical component of the forming force resulting from the numerical analysis and the experimental test. Shiraz University 2383-0042 6 v. 2 no. 2019 30 41 https://ijmf.shirazu.ac.ir/article_5433_38ccf96bbca584c4fa9f595ca7ea2ef1.pdf dx.doi.org/10.22099/ijmf.2019.32460.1124 Iman Kaseb Science and Research Branch, Islamic Azad University of Tehran, Tehran, Iran author Mohammad Moazami-Goudarzi Science and Research Branch, Islamic Azad University of Tehran, Tehran, Iran author Alireza Abbasi Science and Research Branch, Islamic Azad University of Tehran, Tehran, Iran author text article 2019 eng In this research, the effects of the powder particle size on the compaction and sintering of Hydride‌–Dehydride titanium powders are investigated. Commercially pure titanium powders with three different size ranges were utilized. Compaction was accomplished under applied pressures of 200 to 650 MPa. Sintering was carried out at 1100 to 1400 ºC temperatures. The compressibility behavior of the differently-sized powders was studied by measuring the density of the green compacts. The microstructure of produced compacts was studied using scanning electron microscopy. Results showed that the small powders have the least compressibility. The compressibility data was analyzed and studied by common compaction equations. The modified Heckel equation showed the best correspondence. In addition, measuring the density of sintered compacts showed that the small powders had the highest sinterability. The highest amount of sintered density (98% theoretical) was attained for the small powder compacted under 650 MPa and sintered at 1400 ºC. However, the sintering temperature of 1200 ºC was recognized as the most appropriate temperature for the middle and large-sized titanium powders. The results of hardness tests showed that the appropriate mechanical properties could be attained for commercially pure titanium powder compacts by vacuum sintering accomplished at the optimum sintering circumstances. Shiraz University 2383-0042 6 v. 2 no. 2019 42 51 https://ijmf.shirazu.ac.ir/article_5434_9d211567ce46658888289798d501da84.pdf dx.doi.org/10.22099/ijmf.2019.34264.1134 Mina Amiri Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz, Iran author Ramin Ebrahimi Department of Materials Science and Engineering, School of Engineering, Shiraz University, Iran. author text article 2019 eng The aim of the present study is to determine the feasibility of making a rectangular twist waveguide used to rotate electromagnetic waves. For this purpose, the process of fabricating an aluminum rectangular twist waveguide was simulated by making use of finite element method and Deform software. The optimum length and angle of the twist die for manufacturing a twist waveguide with inner cross sectional dimensions of 22.86 mm × 10.16 mm and a length of 50 mm and twisting angle of 90 degrees were investigated. Moreover, the effect of certain factors such as the length, thickness, cross section dimensions of the waveguide and friction on the optimum length of the twist die and cross sectional distortion was studied. The results of this study indicated that the length of the twist die had an influence on the amount of twisting, while friction was of no importance. In addition, comparing the values of effective stress and flow stress at the cross section of the workpiece behind the twist die depicted that the workpiece would not yield behind the twist die due to smaller values of effective stress. Shiraz University 2383-0042 6 v. 2 no. 2019 52 61 https://ijmf.shirazu.ac.ir/article_5439_a491136dfabe51f4a1c6e8edec1cc070.pdf dx.doi.org/10.22099/ijmf.2019.5439 seyed mohammad Mirbagheri School of metallurgy and Materials Engineering, Amirkabir university of technology University, Tehran, Iran author Mina Salehi School of metallurgy and Materials Engineering, Amirkabir university of technology University, Tehran, Iran author Amin Jafari Ramiani materials and metallurgical engineering Amirkabir University author text article 2019 eng The purpose of this paper is to investigate the work hardening behavior and energy absorption characteristic of metallic foams and functionally graded foam filled tubes, including single-, double- and triple-layer foams. Closed-cell A356 alloy and pure zinc foams are fabricated by casting method. The results illustrate that the metallic foams show partially brittle compressive deformation associated with cell walls’ bending and tearing. A nonlinear asymptotic model, , is proposed to represent the hardening behavior of metallic foams and graded foam filled tubes as a function of relative density. The development of a complementary model,               , leads to a more accurate estimation of crushing response considering the stress oscillations, particularly for the A356 foam with high degrees of oscillation and multi-layered structures containing distinct plateau regions. Therefore, the present model is fairly consistent with the experimental results. Greater density and strength of the zinc foam compared to those of the A356 foam cause the highest total energy absorption of 581 J in the zinc foam filled tube and the highest specific energy absorption of 459.2 J/(g/cm3) in the A356 foam filled tube. The presence of zinc foam results in the decrease of specific energy absorption. However, it plays a dominant role in adjusting the crash features of graded structures. The compressive properties of multi-layered structures can be controlled by varying the number and material of the layers at constant geometric features. Shiraz University 2383-0042 6 v. 2 no. 2019 62 81 https://ijmf.shirazu.ac.ir/article_5441_ac2efc980acf2424e9788296f49a1cd9.pdf dx.doi.org/10.22099/ijmf.2019.5441