Iranian Journal of Materials Forming
Volume:9 Issue: 2, Spring 2022

The “Iranian Journal of Materials Forming (IJMF)” is an international open-access journal in the fields of materials deformation and forming processes, which was established at Shiraz University in 2014. The journal is pleased to receive papers from scientists and engineers from academic and industrial areas related to all manufacturing processes. In addition, all deformations, including the elastic and plastic behaviors of materials and deformations due to failure, are part of this journal’s field of interest. The quality and credibility of the journal have been ensured by appointing some of the most well-known professors in the world as members of its editorial board. Recently, some world-renowned scientists have also joined the editorial board, making it stronger than before. In addition, the wide range of the selected referees in this issue is a sign of its scientific quality. It is a matter of pride that for the second year, this journal has been successfully released quarterly, and the second issue was published in 2022.

Sheet metal forming is one of the most common manufacturing processes in the production of many mechanical components and auto parts. Therefore, accurate investigation of the effects of important parameters in the sheet metal forming process is of primary importance for engineers and designers. In the present study, the effects of grain size, punch radii, and sheet thickness on the springback in the W-shaped bending dies are evaluated. The investigated metal sheets are composed of pure copper with three thicknesses of 0.1, 0.3, and 0.5 mm. In this research, the annealing heat treatment process is conducted for 60 minutes at 500, 750, and 900 degrees on the Celsius scale to study the grain size in copper specimens, then the recovery process is performed at ambient temperature. The experimental results revealed that the rise of annealing temperature results in the significant variations of metallographic structure and grain size. According to the results, for a constant thickness, the mechanical properties changed by increasing the annealing temperature. As the grain size increased, the elongation and yield strength decreased. With a constant annealing temperature, the yield strength and elongation fell with a decrease in thickness. However, in both cases Young’s modulus does not change much. The results also indicated that by increasing the thickness of the sheet under the same conditions of grain size, the springback angle decreased as well, so that the springback angle minimized through selecting the radii of 0.3 mm for the punch. Additionally, it was concluded that the springback angle can be minimized with a decrease in t/d ratio for a constant sheet thickness. Based on these results, a multiple-choice regression model has been employed that the average error of this model for springback prediction was 8.08%.

In this paper, bulk sheets of multilayer Al-Ti composites were fabricated by cold roll bonding (CRB) at 50% thickness reduction and annealing in different conditions. The effects of annealing temperature and time on the bonding features of Ti-Al have been evaluated. The microstructural changes were studied by scanning electron microscopy (SEM) and focus ion beam microscope (FIB). A field emission electron microscopy (FEG-SEM) equipped with an electron backscatter diffraction (EBSD) tool was utilized to evaluate microstructural and textural changes. This study revealed that CRB composites of Ti-Al can produce the TiAl3 in relatively short times at annealing temperatures under the Al melting point. The results showed that just the TiAl3 intermetallic layer formed in the Ti/Al interface by 2 h annealing at 590°C. TiAl3 formation mechanism can be stated as following stages, Al phase elimination, Kirkendall voids formation, Ti and TiAl3 phase's volume increasing, micro-crack creation, and finally, easier formation of TiAl3. Mechanical evaluation of Al/TiAl3/Al layered composite showed that low ductility is related to growth and joining of Kirkendall voids around Al/TiAl3 interface that formed after a 2 h annealing at 590°C. Microstructural characterization by EBSD revealed annealing at this condition led to the creation of Al matrix with large grains (about 60 μm) and polycrystalline TiAl3 intermetallic containing small grains (average 5 μm). One of the main outputs from texture analysis is the recrystallization texture components changing after the formation of the TiAl3 intermetallic compound. The presence of large Ti aluminide particles resulted into the creation of a new strong P recrystallization texture component besides R5 and Q.

In this study, aluminum/alumina composites with 1 and 3 vol% reinforcement particles were produced using powder metallurgy (PM); this was then followed by simple shear extrusion (SSE). Three SSE inserts with different distortion angles (α) were used in the SSE equipment. Three pressure values of 400, 600 and 800 MPa were selected for powder compression. Additionally, three different temperatures of 530, 550 and 570°C were chosen to evaluate the suitable sintering temperature and achieve the optimal SSE process. The effect of post-sintering annealing treatment on SSE feasibility was also investigated. In addition, porosity was measured by the Archimedes method and the microstructure of samples was evaluated using optical and scanning electron microscopy. Evaluation of the crystalline texture was examined by the X-ray method. It was found that the pressure of 800 MPa was the optimal value for the cold compression of powders and the temperature of 570℃ was the best sintering temperature. It was also observed that the temperatures 400℃ and 450℃ had no effect on increasing the number of SSE passes. Porosity of the Al-3 vol% alumina sample was changed from 5.75% to 5.02% after three SSE passes with α=10°. A preferred crystallographic texture was not seen due to the amount of effective strain and the presence of micro-pores, but a very low intensity cube texture {001} <100> was seen in some regions.

The many benefits of ultra-fine grained (UFG) tubes in the industry have led researchers to devise methods to increase the strength of tubes. Tubular channel angular pressing (TCAP) process is a new severe plastic deformation (SPD) technique to produce UFG tubes. In this research, at first, one pass of tubular channel angular pressing process with trapezoidal channel geometry is applied on Al-6061 samples. Then, mechanical properties such as yield strength, ultimate strength, hardness, and microstructure of the TCAPed samples are compared with the initial ones. In addition, effective strain and stress, processed load and deformation geometry during different stages of the tubular channel angular pressing process were investigated by finite element modeling. Finally, the results of the analytical model with finite element simulation were compared. It should be noted that the trapezoidal channel geometry has been used due to the high strain homogeneity and low force required for this channel geometry compared to other channel geometries. The microstructural results showed that the grain size of the initial samples was reduced from 92 µm to 785 nm in the TCAPed samples. The results of compression test showed that the yield strength and ultimate strength of the samples increased by 90% and 52%, respectively. The hardness of processed samples was also increased by 56% compared to the initial ones.

Single point incremental sheet forming is a die-less forming technology in which the sheet metal is formed progressively by the movement of a tool in the specified path. In this paper, the single point incremental forming of the AA3105-St12 two-layer sheet is studied through numerical and experimental approaches. Numerical simulation of the process is done based on the finite element method. The validity of the numerical model is evaluated via a comparison between the obtained numerical and experimental results. The force applied to the forming tool, the thickness distribution of formed sheets, and the maximum thinning that occurred in aluminum and steel layers were studied. The effects of the parameters of the two-layer sheet including total thickness, thickness ratio of layers, and arrangement of layers were investigated as well. The results showed that regardless of the contact of the steel or aluminum layer with the tool, increasing the ratio of the thickness of the steel layer to the thickness of the aluminum layer reduces the thinning in the aluminum layer and increases it in the steel layer. Hence, thinning becomes more severe in each layer when it is in contact with the forming tool.

In recent years, many new material configurations have emerged from which hybrid materials such as microcomposites have shown promising applications. In the current study, the microencapsulated-based epoxy composites were simulated in micro and macro-scales using numerical modeling. A single-microcapsule was simulated by finite element method  (FEM) to estimate the effect of compression on a representative equivalent volume (REV). FEM sensitivity analysis was conducted for different conditions of encapsulation efficiency, i.e., full, half-full and empty, varied diameter (50, 100, 200 μm) and thickness (2, 6, 10 μm) of capsules to study the influence of each governing parameter on the load-deformation behavior of the composite. The composites containing microcapsules with full content showed an improvement in the elastic modulus in comparison with the neat epoxy, while half-full and empty composites exhibited lower elastic moduli. Moreover, the results showed that the diameter of the capsules significantly influences the stiffness of the composite. Indeed, the overall elastic modulus of the 50 μm microcapsules was slightly affected by the encapsulation efficiency while the 200 μm microcapsules showed a drop of 28% in their elastic modulus from the full to the empty capsule condition. Finally, the load-deformation behavior of the composite was studied in macro-scale based on the elastic moduli calculated from micro-scale modeling of an REV.