Iranian Journal of Materials Forming
Volume:9 Issue: 1, Winter 2022

The mechanical behavior of the material is very important during both the manufacturing process and the service of the components. The phenomenon of deformation is studied from the three viewpoints of mechanics, physics and metallurgy. The goal is sometimes deformation and sometimes, such as creep and the different aspects of failure, the opposite way around to prevent deformation. Therefore, there are a lot of processes and phenomena which are involved with the deformation. On the other hand, despite a long history of research in the field of deformation, this concept has always been associated with modern sciences and advanced technologies due to the fact that different fields of research are somehow involved with this field. All of these shed light on the wide scope of the journal, despite its specific title.  In fact, it is expected to receive papers from scientists and engineers from academic and industrial areas related to the processes involving deformation, the failures accompanied with it and all the mediated dislocation phenomena. 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. In addition, some world-renowned scientists have also recently joined the editorial board, making it stronger than before. Moreover, the wide range of the selected referees in this issue is an indicator of its scientific quality. With the publication of the first issue in 2022, a fruitful year is wished for all the readers of the journal. Hopefully, 2022 will be the beginning of great improvements for IJMF.

In the present study, aluminum foams with a relative density of 0.38 were fabricated through powder metallurgy route by using carbamides as space holders. The effect of using double and single action die pressing methods to produce green compacts, were studied on the mechanical and energy absorption capacity of the fabricated foams. Carbamide space holders were removed by being leached in water, whereafter the samples were sintered at 640oC for 2 hours in air. Mechanical properties and energy absorption capability of the fabricated foam samples were evaluated by the means of compression test. The results proved that double action die pressing method can significantly improve mechanical properties and energy absorption capacity of the fabricated foam by creating more uniform density distribution in foam structure. Therefore, for foams with a relative density of 0.38, using double action die pressing process caused nearly 95 % increase in plateau stress and more than 24% improvement in energy absorption ability for the fabricated foam.

The plastic deformation behavior of nano-single crystals of the equiatomic CoCrNiFeMn high entropy alloy (HEA) with the face-centered cubic structure has been studied in tension as a function of temperature from 10 K to 1000 K using atomistic simulations. It was found that the critical stress for the slip was decreased with the increase in temperature. The results showed that the temperature had a substantial effect on the deformation mechanism. Intrinsic stacking faults and dislocations observed extensively at 10 K but not substantially at a temperature of 1000 K. Plastic deformation at a temperature of 10 K has occurred by means of partial dislocations slip whereas slip and amorphization is observed at 1000 K.

In this study, the evaluation of hot forming behavior of an advanced high-strength steel (AHSS), namely Nb-Contained dual phase (DP) steel, is carried out using hot compression tests at temperatures of 850, 900, and 950ºC with strain rates of 0.001, 0.01, and 0.1 (s-1). The resulting flow curves indicated the occurrence of dynamic recrystallization (DRX) at all different conditions of testing. Furthermore, based on the measured stress-strain data, material constants and activation energy (Q) were calculated for the peak stress. Additionally, the values of these constants were estimated for different true strains and the correlation between them and the strain has been illustrated by various diagrams. The comparison shows that the derived Arrhenius equation has an accepted accuracy for predicting the values of flow stress.

The uncertainty on the values of the measured residual stresses in hole-drilling integral method, the most widely used technique for measuring residual stress, will be called hereinafter as residual stress noises, which initiate high sensitivity of stress to strain measurement errors due to ill-conditioning of inverse integral equations. This study aimed to investigate the use of Chebyshev points to decrease residual stress noises in the hole drilling method. The Chebyshev points were extended to hole-drilling increments from surface to specified interior depth. The bending of an aluminum beam was used to validate the extended method, and the results were compared with the standard reduction noises technique, Tikhonov-Morozov, and optimum steps technique. The result obtained from the extended method was shown to lead not only an accurate determination of de-noised residual stress, but also a simple calculation procedure in comparison with the Tikhonov-Morozov and optimal steps method. The results indicate that the use of modified Chebyshev points decreased the mean absolute error of residual stress to 8.17 MPa from 14 MPa in Tikhonov-Morozov and 10.52 MPa in optimum steps methods.

In this study, the microstructural evolutions, formed phases, micro- and macro-hardness changes and shear properties were evaluated in the as-cast, homogenized, cold-rolled and annealed AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA). These studies were carried out using X-ray fluorescence (XRF), scanning electron microscopy (SEM), Rockwell C and Vickers hardness testing as well as shear punch testing (SPT). The microstructure after cold rolling followed by annealing was consisted of an elongated phases/grains in the direction of cold rolling and in almost equiaxed phases/grains. The homogenized specimen has the minimum amounts of hardness and yield/ultimate shear strength. Due to the presence of both elongated and equiaxed structures in the cold-rolled and annealed sample, the hardness and yield/ultimate shear strength of this specimen is between that of as-cast and homogenized cases.

In this research, the effect of applied load on sliding wear characteristics of as-cast and heat treated ZK60 Mg alloy was investigated. The as-cast alloy was homogenized at 450°C and aged at 170°C for 10 and 35 h. The dry sliding wear behavior of the as-cast and heat treated alloys was investigated using a pin-on-disk wear test under various loads in the range of 10-160 N at a sliding velocity of 0.1 m/s for 1000 m. The worn surfaces were evaluated using scanning electron microscopy equipped with energy dispersive spectroscopy analysis. The results confirmed that the wear mechanism was dependent on the applied load. Findings revealed that the most dominant wear mechanisms under low, intermediate and high loads were oxidation, abrasion/adhesion and delamination, respectively. The heat-treated and as-cast alloys showed almost similar wear resistance under low loads, however, the heat-treated alloys showed better wear resistance than the as-cast ones at high loads.