الفهرس 
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Abstract
Equal channel angular pressing (ECAP) is a severe plastic deformation (SPD) tech- nique for producing ultrafine grain structures in submicron level by introducing a large amount of shear strain into the materials. In this study multi-pass ECAP processes for
cylindrical work-piece are investigated by using experimental studies. The samples were made by means of the powder metallurgy route (PM). Aluminum metal matrix composites (AI MMC) with commercially pure aluminum as the matrix material and 60
urn SiC particulates as the reinforcement forms four volume fraction of the reinforce-
ments (2.5, 5, 7.5 and 10%) were produced. AI - SiCp MMC is subjected to ECAP at room temperature using an ECAP die with a cha~nel die angle equal 1200 by using route A.
The microstructure and mechanical properties were studied for the four volume frac-
tions. The evolution of the homogeneity of the particle distribution in the material dur-
ing ECAP is investigated by optical and SEM microscopes. As cold compacted Al -
SiCp samples showed fairly uniform distribution of particles. The sintering process re -
duces the porosity found in samples significantly and it was improved also after extru-
sion process and when ECAP passes carried out. There are improvements in the particle distribution after extrusion and ECAP processes which approved by Quadrat method. It
was found that ECAP technique has a great effect on particle size refinement which re-
duced SiC particles from 60 to less than 0.5 urn in some cases. Applying ECAP process
) improves the mechanical properties of the composite. As the number of ECAP passes
increases the hardness and compressive strength have significantly improved.
Deformation behavior of Al MMC samples in ECAP process is analyzed using three
dimensional simulation by finite element methods (FEM) using the DEFORM-3D
Standard software. The investigations include the distribution of strain, load-stroke pre-
diction and influence of friction. It is observed that in the steady state zone, the effec-
tive plastic strains are much uniform and larger compared with those in the tail and
head zones. The corner gap size reduces with increasing number of ECAP passes. A
higher pressing force is required when increasing the SiC particle content. The friction
has a relatively small influence on the deformation distribution of the workpiece, but a
great influence on the pressing force and corner gap size.