Modares Mechanical Engineering

Modares Mechanical Engineering

Effect of severe plastic deformation by equal channel angular pressing on fracture toughness of Al-7075 alloy

Authors
mohammad talafi noghani
mohammad hossein shaeri
arezoo Esmaeili
ahmad razaghian arani
material science and engineering department, engineering faculty, Imam Khomeini International University, Qazvin, Iran
Abstract
In the current research, the effect of severe plastic deformation on microstructure and mechanical properties of Al-7075 alloy focusing on toughness was investigated. For this purpose, the Al-7075 alloy was subjected to ECAP process up to 4 passes by route BC at room temperature. Microstructure and fracture surface of the specimens were analyzed by optical and electron microscopy and mechanical properties were studied by hardness, tensile and impact tests. Dynamic and static toughness of the alloy were measured from the area under the stress-strain curve and impact test, respectively. The experimental data revealed that after 4 passes of ECAP, the grain size decreased from 40 µm to about 600 nm, and the hardness and strength of the specimen increased about 2 times in comparison with initial material. Static and dynamic toughness decreased about 62% and 30% after the first pass of ECAP, respectively. While, by increasing the pass number, the static toughness increased and dynamic toughness remained approximately constant. The fracture surface of specimens revealed that the fracture of all specimens was ductile. ECAP process caused a considerable increase in strength of Al-7075 (more than 100 percent), whereas, the toughness declined slightly during ECAP process (about 30 and 5 percent in dynamic and static toughness, respectively). So, it can be concluded that one the most advantages of ECAP process in comparison with common forming process is the notable improvement of strength without considerable sacrifice of toughness.
Keywords
ECAP process
Al-7075 Alloy
Dynamic toughness
Static toughness
Fractography
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Modares Mechanical Engineering
Volume 17, Issue 12
February 2018
Pages 11-20