Sharif Digital Repository

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... 

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... 

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 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... 

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... 

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... 

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... 

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,... 

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...