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The closed-cell aluminum alloy foams were fabricated by the molten body transitional foaming process. In this research, the closed-cell aluminum foams were successfully fabricated with different zinc contents (4, 8, and 12wt%) using the melt-foaming method and blowing agents. Calcium was used to increase the melt viscosity and CaCO3 was used as a foaming agent. Uniaxial compressions tests were performed on the foams to investigate the effects of zinc addition on the mechanical behavior of fabricated Al–Zn foams. The effects of zinc additions on the foam properties such as density, porosity, pore diameter, yield strength, plateau stress, and energy absorption were investigated. According to the X-ray analysis results, the reaction between Al–Ca–Zn leads to the formation of oxide phases in the melt and increases the melt viscosity and also the cell wall thickness. Foam with 4wt% Zn has a good yield strength and longer plateau region than pure aluminum foam due to the uniform cell structure. The foam density and the absorbed energy per unit volume of Al–Zn foams increase with increasing zinc content to foams.

To characterize and evaluate the workability of pure copper, the hot compression test at temperature range of 673–1073 K, strain rate range of 0.001–0.1 s − 1 and two initial grain sizes (IGS) of 20 and 50 μ m with 60% deformation were performed. The results of the true stress-strain curve showed that the processing parameters including IGS, temperature, strain rate, and strain have a significant effect on the elevated temperature behavior of pure copper. As the flow curve of finer grain size at lower temperatures has higher flow stress than the larger grain size which is reversed by increasing the temperature due to changes in the deformations mechanism. A hyperbolic-sine Arrhenius model and strain-compensated Arrhenius constitutive equation with good accuracy were developed to describe and predict the hot flow behavior of this material. The activation energy was determined in different processing conditions for two different IGS and the results showed that this energy increases with increasing strain, and its values are greater for finer grain sizes. The investigation of the deformation mechanism showed that the mechanism of cross-slip and dislocation climb controlled the deformation process are dominant mechanisms for IGS of 20 μ m whereas self-diffusion is the dominant mechanism for IGS of 50 μ m . To determine the safe and optimal conditions for hot deformation, the processing maps were drawn based on DMM theory at different strains. Finally, by examining and evaluating the microstructure under different processing conditions, the dominant mechanisms were identified for the two investigated IGS at different temperature ranges and strain rates, and the safe and unsafe domains were specified for the hot deformation of copper.

This study was carried out to evaluate the microstructural and mechanical properties of resistance spot-welded Inconel 625 alloy. The effects of welding current, applied force, and holding time of resistance spot welding (RSW) process were investigated by optical microscopy (OM) and scanning electron microscope (SEM) images, microhardness tests, and also tensile shear tests. Microstructural investigations showed that the nugget structure consisted of homogenous columnar dendrite structure, which epitaxially grew along the electrode direction, and the microstructure of the heat-affected zone (HAZ) included a fine-grain recrystallized zone (FRXZ), coarse-grain recrystallized zone (CRXZ), and recovery zone (REZ). The effects of welding parameters on the mechanical properties of the spot weld in terms of peak load, fracture energy, and failure mode were investigated.

A 2D axisymmetric electro-thermo-mechanical finite element (FE) model is developed to investigate the effect of current intensity, welding time, and electrode tip diameter on temperature distributions and nugget size in resistance spot welding (RSW) process of Inconel 625 superalloy sheets using ABAQUS commercial software package. The coupled electro-thermal analysis and uncoupled thermal–mechanical analysis are used for modeling process. In order to improve accuracy of simulation, material properties including physical, thermal, and mechanical properties have been considered to be temperature dependent. The thickness and diameter of computed weld nuggets are compared with experimental results and good agreement is observed. So, FE model developed in this paper provides prediction of quality and shape of the weld nuggets and temperature distributions with variation of each process parameter, suitably. Utilizing this FE model assists in adjusting RSW parameters, so that expensive experimental process can be avoided. The results show that increasing welding time and current intensity lead to an increase in the nugget size and electrode indentation, whereas increasing electrode tip diameter decreases nugget size and electrode indentation.

The mechanical properties such as hardness and ultimate tensile strength of metals depend on the grain size, which have to be properly controlled and optimized to ensure the better economy and desirable mechanical characteristics of the metals. In order to study the microstructure evolution of AA1070, many experimental tests were conducted at different cold working and annealing conditions. Utilizing the experimental results, the static recrystallization and grain growth behavior of AA1070 have been investigated and the developed equations that can be used to the FEM of the annealing process have been obtained. The agreement between numerical modeling and experimental results is reasonably good for this material. The results showed that the recrystallization and grain growth behavior of AA1070 was evidently affected by both the annealing temperature and plastic strain.