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Deformation characteristics evaluation of modified equal channel angular pressing processes
, Article Materials Transactions ; Volume 51, Issue 1 , 2010 , Pages 46-50 ; 13459678 (ISSN) ; Nagasekhar, A. V ; Yoo, J. H ; El Aal, M. I. A ; Vaseghi, M ; Kim, H. S ; Sharif University of Technology
2010
Abstract
In current studies, equal channel angular pressing process (ECAP) and modified ECAP processes are simulated under ideal conditions to compare the deformation characteristics. The deformation behaviour is more complicated and the strain induced during the processes is highly non-uniform in the modified ECAP processes except in the equal channel multi-angular pressing (ECMAP) process with Route C. The strain homogeneity is more of a possibility with ECAP and ECMAP with Route C processes. The deformation stress state is widely distributed in nature in modified ECAP processes than in conventional ECAP. In addition, the load requirements are also higher in modified ECAP processes with that of the...
Effect of Equal Channel Angular Pressing(ECAP) Parameters on Microstructure and Mechanical Properties of Strip Samples of AZ31 Mg Alloy
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh Changiz, Abbas (Supervisor)
Abstract
Equal Channel angular pressing (ECAP) is one of the most applicable Severe Plastic Deformation (SPD) Procedures which results in improvement of strength and ductility through grain refinement and an appropriate texture development. In this study, in order to achieve a proper orientation and microstructure, ECAP was performed in different routes and temperatures up to 4 passes on AZ31 magnesium alloy. Microstructure and mechanical properties were studied. X-ray diffraction analysis was performed to study the basal orientation variation and calculation of sub-grain size. In addition, cold rolling at room temperature was done on the fourth pass specimens, in order to study the effect of ECAP...
The Effect of Severe Plastic Deformation on the Microstructure and Mechanical Properties of Magnesium-Carbon Nanotube Composites
, M.Sc. Thesis Sharif University of Technology ; Karimi Taheri, Ali (Supervisor)
Abstract
In recent years, the light metal matrix composites with high specific strength have attracted great interests in electronics, aerospace, automobile,and medical industries. Additionally, employing sever plastic deformation is a matter of interest in industries in order to gaining micro and nano microstructure, and hence, proper mechanical properties. Considering two mentioned facts, in this project, the effects of sever plastic deformation parameters carry out by equal channel angular press on mechanical and microstructural properties of Magnesium AZ91-Carbon Nanotube composite are investigated.To do this, first the samples of mentioned composite were produced by casting, then their...
An Investigation into the Effect Of Severe Plastic Deformation by Equal Channel Angular Extrusion (Ecae) Process on Mechanical and Microstructural Properties of a Mg-Zn Alloy
, M.Sc. Thesis Sharif University of Technology ; Karimi Taheri, Ali (Supervisor)
Abstract
The specific properties of some of magnesium alloys have caused these alloys to be used in medical and industrial applications. Adding new elements and applying severe plastic deformation to these alloys have been considered as a clue for improving their mechanical properties. The aim of this project is to improve the mechanical properties of a magnesium alloy by using new alloying elements and applying the ECAP process.
In this project, a new magnesium alloy by composition of Mg-1.78Zn-0.72Si-0.41Ca was cast. After casting, solution treating and annealing of the alloy were studied. Then, the effect of ECAP process on microstructure and mechanical properties of the annealed and solution...
In this project, a new magnesium alloy by composition of Mg-1.78Zn-0.72Si-0.41Ca was cast. After casting, solution treating and annealing of the alloy were studied. Then, the effect of ECAP process on microstructure and mechanical properties of the annealed and solution...
Study of Microstructural and Textural Evolution and Mechanical Properties of 1050 Aluminum Alloy Through Ecap, Annealing and Rolling
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh Changiz, Abbas (Supervisor)
Abstract
In the present study, the microstructural and textural evolutions and mechanical properties of 1050 Aluminum alloy was investigated through ECAP processing. The effects of annealing and strain path change by cold rolling on the ECAPed specimens were also investigated. The number of ECAP passes, annealing temperature and reduction of area during cold rolling were chosen as the variable parameters. The results showed that the grains became finer by increasing the ECAP passes. It is shown that the volume fraction of low angle grain boundaries increased in the first two passes. However, the volume fraction of high angle grain boundaries increased in the next passes. Continuous dynamic...
The Effects of Temperature, Strain Rate and Number of Passes on Ecap Processing of WE43 Magnesium Alloy
, M.Sc. Thesis Sharif University of Technology ; Karimi Taheri, Ali (Supervisor) ; Akbarzadeh, Abbas (Supervisor)
Abstract
Equal Channel Angular Pressing (ECAP) is one of the most applicable severe plastic deformation procedures (SPD) which results in improvement of strength and ductility through grain refinement. WE43 magnesium alloy belongs to a group of alloys for medical industry because of its good biocompatibility. In this study, equal channel angular pressing was performed at different temperatures, strain rates and number of passes on strip-shape samples to achieve proper mechanical properties. Tensile properties, hardness and microstructural evolutions were evaluated and the results were analyzed according to the EDS test. Results shows that at 380 ℃ and 440 ℃ grain refinement was accomplished by...
Investigation of the Effect of Combination of Severe Plastic Deformation (ECAP) and Shot Peening on Fatigue Properties of an Al-Mg-Si Alloy
, M.Sc. Thesis Sharif University of Technology ; Karimi Taheri, Ali (Supervisor)
Abstract
Production of nanocrystalline (under 100nm) or submicron materials (100-1000nm), has been created to one of the most important problems in engineering. A well-known method to create Ultra-Fined Grains (UFG) is imposing high strains to metals in order to break the structure. Among lots of ways forproducing UFG metals, Equal Channel Angular Pressing (ECAP) is one of the most famous and common ways. On the other hand, Shot Peening has been being used for a long time to improve mechanical properties of metals by introducing nanocrystalline layer at the surface of specimen. The aim of the work, is investigation of the effect of combination of ECAP and Shot Peening on High Cycle Fatigue of 6082...
Mechanical Property and Structural Changes of Pure Magnesium and AZ91 Alloy Using ECAP Process
, M.Sc. Thesis Sharif University of Technology ; Assempour, Ahmad (Supervisor)
Abstract
In recent years, severe plastic deformation processes have been widely used to correct the grain size of metals. One of these methods is equal channel angular pressing. In this research, the improvement of mechanical property and structural changes of pure magnesium and AZ91 alloy after the ECAP process are investigated. The mold is made of H13 steel with a 90-degree channel crossing angle and a zero-degree external curve angle. The purpose of this study is to find the smallest average grain size at the optimum temperature on these materials. First, pure magnesium and AZ91 are subjected to the ECAP process at temperatures of 250, 300, 350, and 400 °C to calculate the best operating...
Microstructure Features and Mechanical Properties Microtubes of WE43 Magnesium Alloys for Biodegradable Vascular Stent Application
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Magnesium and its alloys have gained much attention in medical applications, especially bio-degradable stents. However, they have not been used extensively due to their natural limitations, such as weak mechanical properties. WE43 magnesium alloy has gained attention as a bio-alloy due to its high temperature and good corrosion resistance. The present study aims to use a combination of ECAP and direct tube extrusion to fabricate thin wall tubes with good mechanical properties using WE43 magnesium alloy. In the first phase, the ECAP process at 370°C were conducted up to 4 passes on the homogenized samples to reach ultrafine grain structure. Subsequent to ECAP, direct tube extrusion at 230 °C,...
Strengthening study on 6082 Al alloy after combination of aging treatment and ECAP process
, Article Materials Science and Engineering A ; Volume 527, Issue 18-19 , July , 2010 , Pages 4758-4766 ; 09215093 (ISSN) ; Karimi Taheri, A ; Smith, C. W ; Sharif University of Technology
2010
Abstract
Equal channel angular pressing (ECAP) was used before and after various aging treatments in order to strengthen a commercial 6082 Al alloy. Experiments were carried out to study the strengthening of the alloy due to pre and post-ECAP aging treatment. It was found that aging before and after ECAP processing is an effective method for strengthening of the alloy. An increase in both strength and ductility of the ECAPed specimen was achieved via appropriate post-aging treatment. This was in such a manner that for maximal strengthening, post-ECAP aging is best conducted at temperatures lower than those usually used for aging if prior work hardening is not undertaken. Pre-ECAP aging was also...
An Investigation on Production a Biomedical Mg Alloy-carbon Nanotube Composite Using Mechanical Alloying, Sintering & Hot Equal Channel Angular Pressing Process
, M.Sc. Thesis Sharif University of Technology ; Karimi Taheri, Ali (Supervisor)
Abstract
Nowadays, the research of biodegradable alloys with high corrosion and strength properties, along with a modulus of elasticity close to that of bone tissue, especially the magnesium alloys, which has a good biocompatibility and can be used as a biomedical material, has been considered by the medical industry. On the other hand, carbon nanotubes have been used as an reinforcing phase in composites due to their high mechanical properties. The aim of this project is to produce a biocompatible composite with magnesium alloy and carbon nanotube by powder metallurgy. In order to achieve this, first the raw powder of the alloying elements in the matrix without reinforcement and then with weight...
Softening behaviour of alumina reinforced copper processed by equal channel angular pressing
, Article Materials Science and Technology (United Kingdom) ; Volume 30, Issue 2 , February , 2014 , Pages 220-226 ; ISSN: 02670836 ; Maghsoudi, M. H ; Serajzadeh, S ; Sharif University of Technology
Abstract
In this present work, the softening behaviour of Cu-1·1 wt-%Al2O3 alloy containing nanometric alumina particles was investigated. Single pass equal channel angular pressing was first applied on cylindrical specimens, and then, the deformed samples were subjected to annealing treatments in the temperature range of 700-1000°C. Afterwards, finite element analysis, microstructural observations, Vickers hardness and shear punch testing were employed to study strain distribution as well as the recrystallisation behaviour of the examined alloy. It was found that the alloy is softened at 800°C or above, which shows its high thermal stability. Furthermore, a very fine completely recrystallised...
Effect of strain path change on mechanical properties and final microstructure of Cu-Al2O3 in equal channel angular pressing
, Article Materials Science and Technology (United Kingdom) ; Volume 29, Issue 2 , 2013 , Pages 210-218 ; 02670836 (ISSN) ; Serajzadeh, S ; Akhgar, J. M ; Kamankesh, A ; Sharif University of Technology
2013
Abstract
In the present work, the process of equal channel angular pressing of dispersion strengthened Cu-1̇1 wt-%Al2O3 containing nanometric alumina particles was investigated by means of mathematical modelling and experimental testing. Through the modelling, deformation parameters such as hydrostatic pressure distribution and strain field were determined, and the effect of deformation path on these parameters was estimated. Equal channel angular pressing as well as mechanical and microstructural evaluations were also conducted to assess mechanical properties, grain structure and void volume fraction after deformation in different routes. The results indicate that distributions of plastic strain and...
The effects of combination of severe plastic deformation and Shot Peening surface treatment on fatigue behavior of 6082 aluminum alloy
, Article Russian Journal of Non-Ferrous Metals ; Volume 56, Issue 2 , 2015 , Pages 206-211 ; 10678212 (ISSN) ; Irani, M ; Karimi Taheri, A ; Sharif University of Technology
Abstract
In this paper, the effects of Equal Channel Angular Pressing process (ECAP) followed by Shot Peening process (SP) on the fatigue properties of 6082 aluminum alloy are investigated. Several samples of the alloy are ECAPed and SPed and then their mechanical behavior are characterized using tensile, micro-hardness, and fatigue tests. The results indicate that shot peening and then polishing the specimen after one-pass ECAP is an effective method to improve the fatigue life of the alloy. Moreover, by increasing the number of ECAP passes before shot peening, a local work softening occurs at the subsurface layer, leading to a significant decrease in the fatigue life of the alloy. The results of...
The effect of ECAP die shape on nano-structure of materials
, Article Computational Materials Science ; Volume 44, Issue 3 , January , 2009 , Pages 962-967 ; 09270256 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
2009
Abstract
A general flow line model is developed to investigate the deformation behavior of Cu and Al through Bc route of Equal Channel Angular Pressing process at curved and sharp dies. Considering the Taylor theory, the obtained strain and strain rate from the flow line model and also using a modified version of ETMB model, the evolutions of nano-structure in the processed Cu and Al are predicted. Comparison between the modeling results and experimental data is carried out and a reasonable agreement is achieved. The results show that the deformation in the sharp die occurs in a narrow zone with higher strain rate than that in the curved die. Also, the cell size of the processed Cu is smaller than...
Simulation the ultra-fine microstructure evolution during annealing of metal processed by ECAP
, Article Computational Materials Science ; Volume 43, Issue 2 , August , 2008 , Pages 309-312 ; 09270256 (ISSN) ; Sharif University of Technology
2008
Abstract
A Monte Carlo model is modified by using Turnbull-Fisher nucleation rate model to simulate the ultra-fine microstructure evolution during annealing of pure copper processed by equal channel angular pressing (ECAP). The simulation is utilized to predict the grain size of pure copper samples at different annealing temperatures and pass numbers of ECAP. Also, in the simulation the constant nucleation rate model is assumed and a good agreement is achieved between the simulation results and experimental data. Thus, it can be concluded that the constant nucleation rate is prevailed during the microstructure evolution. © 2007 Elsevier B.V. All rights reserved
Degradation behavior of the as-extruded and ECAP-processed Mg-4Zn alloy by Ca addition and hydrothermal coating
, Article Journal of Materials Research and Technology ; Volume 20 , 2022 , Pages 1204-1215 ; 22387854 (ISSN) ; Mohammadi Zerankeshi, M ; Nobakht Farin, F ; Alizadeh, R ; Mahmudi, R ; Sharif University of Technology
Elsevier Editora Ltda
2022
Abstract
Coating is an effective approach to address the high corrosion rate of biodegradable Mg alloys, as their main challenge toward their extensive use. In this regard, it was tried to control the degradation process of an Mg-4Zn alloy by Ca addition, equal channel angular pressing (ECAP), and hydrothermal coating. The obtained results indicated that excellent grain refinement induced by Ca incorporation and ECAP simultaneously, improved both mechanical strength and corrosion resistance of the Mg-based substrate. The achieved grain refinement resulted in a thicker, more compact and integrated coating, where the ECAP-processed Mg-4Zn-0.5Ca alloy exhibited the best coating quality with no...