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Evolution of microstructure and mechanical properties in a hypoeutectic Al-Si-Mg alloy processed by accumulative back extrusion

Title
Evolution of microstructure and mechanical properties in a hypoeutectic Al-Si-Mg alloy processed by accumulative back extrusion
Author
Kawasaki, Megumi
Keywords
Accumulative back extrusion; Al-Si alloy; Grain refinement; Mechanical properties; Severe plastic deformation
Issue Date
2016-01
Publisher
ELSEVIER SCIENCE SA
Citation
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, v. 651, Page. 269-279
Abstract
This study demonstrates the evolution of microstructure and mechanical properties of a hypoeutectic Al-7Si-0.4Mg (A356) alloy processed by accumulative back extrusion (ABE) at temperatures ranging from 200 to 500 degrees C. ABE processing is one of the new severe plastic deformation techniques enabling one to produce relatively large ultrafine-grained materials in a cylindrical shape. One complete pass of ABE was estimated to introduce a reasonably homogeneous effective strain of similar to 3 as calculated by finite element analysis. Microstructural observation showed that globular alpha-Al primary phase was subdivided into fine substructures and Si particles having a fibrous shape were fragmented and spheroidized within the eutectic constituent through ABE processing. There was no evidence of homogeneous distribution of the fine Si particles in the alpha-Al phase after ABE. Mechanical testing at room temperature showed that both yield strength and ultimate tensile strength of the A356 alloy dramatically increased through ABE, especially at lower processing temperatures, as compared with the as-cast condition whereas there was no significant reduction in ductility at all processing temperatures. The experimental results were discussed with emphasis on the microstructure evolution involving dynamic recrystallization and deformation behavior including strengthening mechanisms and strain hardening in the Al-Si alloy. (C) 2015 Elsevier B.V. All rights reserved.
URI
http://www.sciencedirect.com/science/article/pii/S0921509315305293?via%3Dihubhttp://hdl.handle.net/20.500.11754/30575
ISSN
0921-5093; 1873-4936
DOI
10.1016/j.msea.2015.10.066
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > MATERIALS SCIENCE AND ENGINEERING(신소재공학부) > Articles
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