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A new method to characterize and model stress-relaxation aging behavior of aluminum alloys under age forming conditions
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2022 MMTA - Li & Shi Method characterise and model SRA-accepted version.pdf | Accepted version | 1.03 MB | Adobe PDF | View/Open |
Title: | A new method to characterize and model stress-relaxation aging behavior of aluminum alloys under age forming conditions |
Authors: | Li, Y Shi, Z |
Item Type: | Journal Article |
Abstract: | A new method that utilizes theories of thermally activated deformation and repeated transient stress-relaxation tests has been proposed and validated in this study for the characterization and modeling of the stress-relaxation aging (SRA) behavior of aluminum alloys and its dependence on stress and temperature. Using the new method, key deformation-related variables, i.e., stress components, activation volume, and activation energy, of the aerospace grade heat-treatable aluminum alloy AA7B04 have been obtained as a function of aging temperature (388 K, 413 K and 438 K), stress (both elastic and plastic), and SRA time (up to 4 hours). It has been found that the apparent activation energy Qa of the material remains constant in the elastic region but decreases with the increase in strain in the plastic region, and also decreases with the increase in temperature for all initial loading stresses. These characteristics contribute to a much higher degree of stress relaxation in the plastic region and at higher temperatures than in the elastic region and/or at lower temperatures. The obtained changing activation volume V and Qa indicate that the deformation rate is controlled by forest dislocation interactions in the elastic region (V decreases from over 200b3 to less than 100b3), and by a cross-slip mechanism at high stress levels in the plastic region (V decreases to a few tens of b3). Based on these theories and results, a novel and simple constitutive model has been proposed, with which the stress-relaxation behavior of AA7B04 at different aging temperatures (388 K to 448 K), preloaded from elastic to plastic regions for up to 16 hours has been successfully predicted. The proposed model eliminates the limitations of conventional SRA models which mainly deals with elastic loading and isothermal conditions, and provides a foundation to effectively predict the springback after advanced non-isothermal SRA forming of aluminum alloy structures in the aerospace industry. |
Issue Date: | 6-Feb-2022 |
Date of Acceptance: | 6-Jan-2022 |
URI: | http://hdl.handle.net/10044/1/94493 |
DOI: | 10.1007/s11661-022-06594-5 |
ISSN: | 1073-5623 |
Publisher: | Springer Science and Business Media LLC |
Start Page: | 1345 |
End Page: | 1350 |
Journal / Book Title: | Metallurgical and Materials Transactions A |
Volume: | 53 |
Copyright Statement: | © 2022, The Minerals, Metals & Materials Society and ASM International. The final publication is available at Springer via https://link.springer.com/article/10.1007/s11661-022-06594-5 |
Sponsor/Funder: | AVIC Manufacturing Technology Institute |
Funder's Grant Number: | N/A |
Keywords: | Science & Technology Technology Materials Science, Multidisciplinary Metallurgy & Metallurgical Engineering Materials Science DEFORMATION-BEHAVIOR FLOW BEHAVIOR PLASTIC-FLOW CU ALLOY MG ALLOY CREEP TEMPERATURE KINETICS Materials 0306 Physical Chemistry (incl. Structural) 0912 Materials Engineering 0913 Mechanical Engineering |
Publication Status: | Published online |
Online Publication Date: | 2022-02-06 |
Appears in Collections: | Mechanical Engineering Faculty of Engineering |