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kazeminezhad--mohsen
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An Investigation into the mechanical properties and micro-structure of Aluminum tube after Severe Plastic Deformation and Annealing
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Several SPD methods have been invented for processing rods and sheets, and their physical and mechanical properties have been investigated so far. The materials processed by these methods have not been industrialized thoroughly. Moreover, in previous investigations, few works have been carried out on tubular types of materials. Thus, in this study, aluminum tube goes through a tubular channel in order to achieve different values of strains. This method is named Tube Channel Pressing. The mechanical and microstructural investigations on aluminum tubes which have been processed up to 5 passes shows that ultimate strength increases 1.7 times and sub-grains size reaches to 360 nm. Applying final...
An Investigation Into the Energy Absorption of Severely Plastic Deformed Low Carbon Steel
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
So far many investigations was performed in the field of energy absorption of mono and bi-layer sheets. As respects, severe plastic deformation process causes grain refinement and strength increase, there is not any study in feild of energy absorption of the severely plastic deformed sheets. The aim of this project was to investigate energy absorption of constrain groove pressed sheets by using different methods such as tensile test and wedge tear test. In this project, low carbon steel was processed by constrain groove press and mechanical properties of sheets was investigated, by using tensile test. It has been observed that ductility reduced and strength increased with increasing the...
Effect of Rapid Annealing on Microstructure and Mechanical Properties of Severely Deformed Low Carbon Steel
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
A low-carbon steel, containing 0.05 C, 0.203 Mn and 0.0229 Si (all in wt%) rapidly annealed in temperature range 300 ºC - 900 ºC, after severe plastic deformation (SPD) by constrained groove pressing (CGP). Microstructure evolution was investigated by Scanning Electron and Optical Microscopy. Mechanical properties were evaluated by hardness measurements and Shear Punch Testing (SPT). The result showed a thermal stability at 300 ºC and 400 ºC, which recrystallization did not occurred in these temperatures up to 2 h holding time. By annealing at 500 ºC and 600 ºC, the onset of recrystallization observed after holding times of 10 min and 20 s, respectively. Predicting the kinetic of...
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Demand to structural and industrial materials with unique properties lead to produce unorthodox combination of metals. One of the most useful combinations is composites of Aluminum-Steel and this composites is mostly used as a sheet. Due to differences in melting point of two metals, preferred method for welding of this two metals is Cold Roll Bonding. For enhance of mechanical properties of this two metals, preferred methods is Severe Plastic Deformation. By the way, in SPD methods, two method was established for sheets. Accumulative Roll Bonding and Constrained Groove Pressing but ARB method produce multi-layer composites so preferred method to produce bilayer sheets is CGP. In this study,...
The Effect of Electropulsing on the Mechanical Properties of Cold Rolled Low Carbon Steel
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
In this research, low carbon steel rolled under 16%, 33% and 50% deformation and applied under electric pulses. Microstructure investigated by optical microscopy and scanning electron microscopy in order to observe grain size, precipitation size and distribution and hardness measured by Vicker's hardness test, after each electric pulse treatment. I order to investigate microstructure evolution as well as grain size, precipitates and hardness all the species with different deformation percentages applied under electric pulses with different total electric pulse duration, number of pulses and the off time between two successive pulses. To obtain required information about species with...
Modeling the Effect of Stacking Fault Energy on Severe Plastic Deformation of Metals
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Nowadays, modeling the deformation behavior of materials is an indispensable tool to describe the evolutions of microstructure and mechanical properties of materials during deformation. As previous investigations have shown, the dislocation density is the most appropriate parameter for investigating the deformation behaviour of materials. In present research, considering the effect of stacking fault energy (SFE), the deformation behavior is investigated. In this regard, at first a thermodynamics based modeling of deformation is presented. Previous studies have shown that due to heterogeneous distribution of dislocations during severe plastic deformation, it is needed to use multi-variable...
Modeling the Mechanical Properties of Aluminum Series 1xxx after Severe Plastic Deformation in Corrugation Die
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Nowadays, modeling the behavior of materials during forming processes is so important. The role of most of them is to investigate and predict the evolutions of microstructure and mechanical properties of materials during plastic deformation. Previous researches have demonstrated that the best parameter to investigate these evolutions is the dislocation density of materials. In this study, first, the dislocation-based models, which investigate the material parameters evolutions during plastic deformation, were investigated and it was revealed that among all presented models, only the two internal variables models can investigate the behavior of materials during severe plastic deformation. ...
Modeling on Mechanical Properties of Aluminum of 5xxx Series in Constrained Grooved Pressing Process
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Al-Mg alloys are used in many industrial fields, thus improvement of their mechanical properties is so important. Expressing mathematical models on the basis of physical and microstructural properties can be useful for this purpose. In this research, in order to study the microstructural evolutions and mechanical properties of the material, a dislocation based model and microstructural parameters such as grains and subgrains during plastic deformation and subsequent annealing are considered. In addition, a modification is used to make the model capable of justify the solute atom and temperature effect simultaneously. This makes the results to be more precise and accurate considering...
An Investigation Into the Annealing Behavior of Severely Deformed Copper
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Mechanical properties of commercial purity copper sheets are improved and grain size of material is refined into Nano scale after using a severe plastic deformation technique called constrained groove pressing (CGP). Since there are high levels of stored energy and non-equilibrium grain boundaries in nanostructure, annealing behavior and thermal stability of material should be investigated. Although there is not a clear distinction between annealing phenomena, it is essential to determine the intervals of annealing phenomena in order to control their sequences on mechanical properties and nanostructure. Also mechanisms of annealing phenomena should be determined to realize annealing behavior...
The Effect of Rapid Annealing on Microstructure and Mechanical Properties of Severely Deformed Copper
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Commercial pure copper sheets after primary annealing were severely deformed to amount of 2.32 by Constrained Groove Pressing (CGP) method. These sheets were undergone to electrical current at different heating times of 0.5, 1, 2, and 3 seconds up to four maximum temperatures of 150, 200, 250, and 300 °C without holding time. In order to compare the annealing by electrical current and without electrical current, four other samples were heated to 300 °C with holding times of 60, 90, 120, and 150 seconds in salt bath. Then, samples microstructure evolutions, hardness and shear stress values were investigated. Generally, the results depicted that inducing electrical current can accelerate the...
Prediction of Microstructure Evolution of Severely Deformed Pure Aluminum during Annealing
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Severe Plastic Deformation (SPD) Processes have drawn lots of attention due to their ability to refine grain size and develop some properties of bulk metals and alloys. After deformation, however, ductility and formability of metals are reduced. Annealing has been used as a solution for improvement of these characteristics after deformations even after SPD processes. On the other hand, there is a possibility that during annealing grains could grow, therefore it can neutralize the effect of SPD process. Consequently, predicting behavior and evolution of microstructure during annealing finds an important role. In this research, accordingly, vertex model have been used in order to predict...
Investigation of the Effect of Warm Rolling on Microstructure and Mechanical Properties of Severely Deformed Aluminum Sheets
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Lots of researches have been carried out on the severe plastic deformation (SPD) and annealing of the aluminum up to now. Due to the different annealing behavior of the severely deformed metals and on the other hand the necessity to the rollig for producing the thin SPD sheets, so the purpose of the recent study is producing the thinned sheets with applying the temperature simultaneously. Dislocations density increases by SPD so it confines their movement and cause to the higher strength of the material. Rolling of the SPDed sheets increase the mechanical properties. Grain boundary energy increases with this mechanical improvement and results in lower ductility. So, it is necessary to...
An Investigation into the Al-6wt%Mg work Hardening Behavior after Cold Rolling
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Al-6wt%Mg alloy has been enormously exploited in aerospace industry. Since for production of this alloy in the form of sheets of different thickness, the cold rolling process is used, thus to understand the final mechanical properties of the rolled alloy products, their work hardening should be examined. Also, one of the important phenomena that occurs in cold state of the alloy is dynamic strain-aging (DSA), which can cause serrations in realistic stress-strain curve. The aforementioned issue is discussed in the current study. Therefore, the work-hardening values for the mentioned alloy during and after rolling is determined, and then compared with the experimental studies. The results of...
The Effect of Warm Rolling on Severely Deformed Copper
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Since the increase in the strength of metals resulting from the severe plastic deformation (SPD) leads to a reduction in their ductility, recently, several studies have been carried out on the deformation of metals. One if the goals has been increasing the ductility while maintaining the strength. In this project, copper is undergone severe plastic deformation in a constrained groove pressing (CGP) process. According to previous studies, it has been determined that with an optimal annealing process, not only the strength is not decreased, but also it is slightly increased and also the ductility is enhanced. Thus, in order to improve the surface of copper after CGP and also optimize its...
The Effect of Strain Rate on Multi-directional Forged Aluminum
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
In this study, multi directional forging as a severe plastic deformation method is applied on pure aluminum at the different strain of 0.5, 1.5, 2.5, and 3.5. Annealing has been applied to samples at 150 C, 250 C, 350 C, and 450 C for one hour. In the next step, compressive test is carried out on MDFed and annealed MFDed pure aluminum through strain rate of 0.01 1/s, 0.001 1/s, and 0.0001 1/s. Based on experimental data, when the number of MDF is passes increased, because of increasing the dislocation density and grain boundary area, yield stress is increased. As an example, the yield stress of 7 passed MDFed aluminum is 2.25 times of that of 1 passes MDFed aluminum. Annealing would...
On the Microstructure and Mechanical Properties of Aluminum after Low-temperature Multi-directional Forging
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Severe Plastic Deformation (SPD) has been used as an effective approach to access fine grain (FG) and ultra-fine grain (UFG) materials.the Temperature of SPD is a dominant parameter to controlling ultimate properties. SPD at room-temperature and the high temperature was used widely in literature but the low-temperature process (sub-zero and cryogenic temperatures) was not used comparably. In this study, Low-temperature Multi-Directional Forging (LMDF) was applied on commercially pure aluminum and room-temperature MDF (RMDF) was attained for contrast temperature effects, and resulting in more fine grains. The grain refinement was attributed to the fragmentation process with a limitation in...
The Natural Aging Modeling of 2024 AL alloy after Multi-directional Forging
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Metallurgical phenomena modeling help the researchers to understand the influence and contribution of different factors on the alloys properties. One of the most interesting phenomenon is the aging process occuring in age-hardenable alloys like 2xxx aluminium series. A factor which has high impact on aging and there are not proper models for evaluating that, is the contribution of plastic deformation. This factor has contribution not only on the dynamic precipitation (during deformation) but also on the natural aging after plastic deformation. So in this research a model containing the role of plastic deformation on dynamic precipitation and the contribution of dynamic precipitation on total...
The Effect of Direct and Cross Rolling on Mechanical Properties and Microstructure of Severely Deformed Aluminium
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Recently, the severe plastic deformation (SPD) is known as one of the most used methods in decreasing the grain size and increasing the strength of metals. In this study, aluminum 1100was subjected toconstrained groove pressing (CGP) at room temperature. The CGPed samples in nanoscale structure, with different CGPed passes were direct rolled and cross-rolled in different rolling strains. Finally, all of the samples were annealed at temperatures of 100, 200 and 300 ° C for 30 min. It was observed that with increasing number of CGP passes and rolling strain the structure became more laminate and finer. With increasing rolling strain, the cross-rolling had greater effect on the microstructure...
The Effect of Hot and Cold Rolling on Microstructure and Mechanical Properties of Al-Mg6
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
In this research, a comprehensive examination on hot and cold deformation of Al-Mg6 alloy has been performed. In order to find out hot deformation behavior of Al-Mg6, hot compression tests at 350, 450, and 550 oC and at strain rates of 0.001, 0.1, and 1 s-1 have been carried out. After the correction of the curves due to friction and adiabatic heating effects, constitutive equation of this alloy has been derived. Corrected curves show the occurrence of dynamic recovery. A new method for developing strain dependent constitutive equation has been employed using normalized stress and strain curve. After normalization, the curves at all deformation conditions follow a similar behavior.Rolling of...
The Effect of Non-isothermal Annealing on the Microstructure and Mechanical Properties of Severely Deformed Aluminum 1xxx
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Multi-directional forging is used as a severe plastic deformation process for producing ultrafine grained materials in which a sample undergoes consecutive compressive strains and as a result, coarse grains break to smaller grains. The strength of multi-directionally forged material increases because of grain refinement, although the high strain energy reserved in a sample after large plastic deformation lessens its ductility. Metals experience non-isothermal heating cycle during annealing till they reach the target temperature. Non-isothermal heating cycle can affect microstructure and mechanical properties of severely deformed material due to its high strain energy. Thus, investigation of...