Examination of the High Tensile Ductility Improvement in an As-Solutionized AA7075 Alloy with the Aid of a Friction Stir Process

The ductility enhancement of an AA7075 aluminum alloy aided by a friction stir process (FSP) and various heat treatments was investigated and compared in terms of outcome with full annealing (O). The results indicate that a big improvement in the tensile ductility was achieved by freezing the sample...

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Main Authors: Ming-Hsiang Ku, Fei-Yi Hung, Truan-Sheng Lui
Format: Article
Language:English
Published: MDPI AG 2019-02-01
Series:Metals
Subjects:
Online Access:https://www.mdpi.com/2075-4701/9/2/196
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author Ming-Hsiang Ku
Fei-Yi Hung
Truan-Sheng Lui
author_facet Ming-Hsiang Ku
Fei-Yi Hung
Truan-Sheng Lui
author_sort Ming-Hsiang Ku
collection DOAJ
description The ductility enhancement of an AA7075 aluminum alloy aided by a friction stir process (FSP) and various heat treatments was investigated and compared in terms of outcome with full annealing (O). The results indicate that a big improvement in the tensile ductility was achieved by freezing the sample at temperatures below 0 °C after the solution treatment and water quenching (W treatment), and further improvement could be acquired via a friction stir process due to grain refinement (<6 μm). Thus, the observed improvement in tensile ductility can be explained by the fact that the W treatment and friction stir processing scheme had an increased strain-hardening effect and decreased the presence of intermetallic particles that are harmful to uniform tensile deformation, consequently causing strain localization in the early stage of tensile deformation, which suggests that these treatment are a potential solution for insufficient formability. In general, the elongation to failure values for the W and FSP-treated specimens (>40%) were at least 1.5-fold greater than that of the annealed alloy. In addition, serrated flow could be observed in the tensile flow curves, and both the Piobert⁻Lüders effect and the Portevin⁻LeChatelier (PL) effect could be observed. The enhancement in the tensile ductility was examined in terms of the existence of intermetallic particles and the supersaturated concentration of the solid solution.
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spelling doaj.art-ee8c49771d904b9c978cacaccb2466a72022-12-21T22:48:24ZengMDPI AGMetals2075-47012019-02-019219610.3390/met9020196met9020196Examination of the High Tensile Ductility Improvement in an As-Solutionized AA7075 Alloy with the Aid of a Friction Stir ProcessMing-Hsiang Ku0Fei-Yi Hung1Truan-Sheng Lui2Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, TaiwanDepartment of Materials Science and Engineering, National Cheng Kung University, Tainan 701, TaiwanDepartment of Materials Science and Engineering, National Cheng Kung University, Tainan 701, TaiwanThe ductility enhancement of an AA7075 aluminum alloy aided by a friction stir process (FSP) and various heat treatments was investigated and compared in terms of outcome with full annealing (O). The results indicate that a big improvement in the tensile ductility was achieved by freezing the sample at temperatures below 0 °C after the solution treatment and water quenching (W treatment), and further improvement could be acquired via a friction stir process due to grain refinement (<6 μm). Thus, the observed improvement in tensile ductility can be explained by the fact that the W treatment and friction stir processing scheme had an increased strain-hardening effect and decreased the presence of intermetallic particles that are harmful to uniform tensile deformation, consequently causing strain localization in the early stage of tensile deformation, which suggests that these treatment are a potential solution for insufficient formability. In general, the elongation to failure values for the W and FSP-treated specimens (>40%) were at least 1.5-fold greater than that of the annealed alloy. In addition, serrated flow could be observed in the tensile flow curves, and both the Piobert⁻Lüders effect and the Portevin⁻LeChatelier (PL) effect could be observed. The enhancement in the tensile ductility was examined in terms of the existence of intermetallic particles and the supersaturated concentration of the solid solution.https://www.mdpi.com/2075-4701/9/2/196AA7075 aluminum alloyfriction stir process (FSP)heat treatmenttensile ductilityPortevin–LeChatelier effect
spellingShingle Ming-Hsiang Ku
Fei-Yi Hung
Truan-Sheng Lui
Examination of the High Tensile Ductility Improvement in an As-Solutionized AA7075 Alloy with the Aid of a Friction Stir Process
Metals
AA7075 aluminum alloy
friction stir process (FSP)
heat treatment
tensile ductility
Portevin–LeChatelier effect
title Examination of the High Tensile Ductility Improvement in an As-Solutionized AA7075 Alloy with the Aid of a Friction Stir Process
title_full Examination of the High Tensile Ductility Improvement in an As-Solutionized AA7075 Alloy with the Aid of a Friction Stir Process
title_fullStr Examination of the High Tensile Ductility Improvement in an As-Solutionized AA7075 Alloy with the Aid of a Friction Stir Process
title_full_unstemmed Examination of the High Tensile Ductility Improvement in an As-Solutionized AA7075 Alloy with the Aid of a Friction Stir Process
title_short Examination of the High Tensile Ductility Improvement in an As-Solutionized AA7075 Alloy with the Aid of a Friction Stir Process
title_sort examination of the high tensile ductility improvement in an as solutionized aa7075 alloy with the aid of a friction stir process
topic AA7075 aluminum alloy
friction stir process (FSP)
heat treatment
tensile ductility
Portevin–LeChatelier effect
url https://www.mdpi.com/2075-4701/9/2/196
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AT feiyihung examinationofthehightensileductilityimprovementinanassolutionizedaa7075alloywiththeaidofafrictionstirprocess
AT truanshenglui examinationofthehightensileductilityimprovementinanassolutionizedaa7075alloywiththeaidofafrictionstirprocess