Producing ultra fine grain pure aluminum tubes using tubular channel angular pressing (TCAP) / Mohsen Mesbah
Poly-crystalline ultra fine grained and nano structured metallic materials have superior mechanical properties compared to conventional poly-crystalline metals. Therefore, many attempts in the past 20 years have been made to produce ultra fine grained and nano structured materials by many researc...
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| Format: | Thesis |
| Published: |
2013
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| Subjects: | |
| Online Access: | http://studentsrepo.um.edu.my/8185/4/MASTER_THESIS.pdf http://studentsrepo.um.edu.my/8185/ |
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| Summary: | Poly-crystalline ultra fine grained and nano structured metallic materials have
superior mechanical properties compared to conventional poly-crystalline metals.
Therefore, many attempts in the past 20 years have been made to produce ultra fine
grained and nano structured materials by many researchers around the world.
Relatively large number of methods for producing bulk metallic materials ever
offered, however, despite the widespread need for tubes with high strength to
weight, less work is doing to produce ultra fine grained and nano structured tubes.
In connection with the manufacturing of UFG tubes two methods of ASB
and HPTT have already been provided. These procedures have disadvantages, such
as; microstructure and strain inhomogeneity, requires complex and expensive
equipment, large forces, adhesion between the layers and low Industrial
capabilities. Therefore, providing an effective, inexpensive, with industrial
capability and high productivity is required for tubes. Recently a novel method
entitled Tubular Channel Angular Pressing (TCAP) has been developed by Faraji in
2011 in Iran who is consultant of current project. They have presented a method
that is able to overcome most of the disadvantages of previous methods. Faraji et al
have applied TCAP on AZ91 alloy but this method has not been applied on
aluminum alloys. In this project this new method with the advantages of low cost,
having no dimensional limitation for the tube, imposing severe plastic shear strain,
high hydrostatic pressure and the ability to produce ultra-fine tubes and
nanostructured metal tubes with high strength are applied to aluminum tubes for the
first time. Ultrafine grained (UFG) cylindrical tubes were produced via recently
developed tubular channel angular pressing (TCAP) through different passes from pure Aluminum. The microstructure and mechanical properties of processed tube
through one to three passes of TCAP were investigated. Microstructural
investigation shows notably decrease in the grain size to around 350 nm from
the primary value of ~56 μm. Microhardness of the processed tube was increased
to 49.4 Hv after one pass from an initial value of 32.9 Hv. An increase in the
number of passes from 1 to higher number of passes has not more effect on the
microhardness. Yield and ultimate strengths were increased 2.5 and 2.28 times
compared to as cast condition. Notably increase in the strength was achieved after
one pass TCAP while higher number of passes has not more effect. |
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