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The Relationship Between Grain Size and the Surface Roughening Behavior of Al-Mg Alloys



Mark R. Stoudt, Richard E. Ricker


The inhomogeneous surface deformation generated during metal forming presents significant challenges to the use of high-strength, lightweight alloys in automotive applications through the initiation of strain localizations that produce both tearing during metal forming and increased friction between mating die surfaces. Thus, a generic understanding of the relationships between plastic strain, grain size, and deformation-induced roughness at the free surface is needed before forming models can be fully developed to accurately predict the behavior and, ultimately, the changes in the friction within the dies. This research examines the roughening behavior of a solid solution strengthened, commercial Al-Mg alloy. The results of this evaluation indicate that the standard roughness measures increase with uniaxial plastic strain in a manner that can be represented by a simple linear estimate. The results also demonstrated that the roughening rate (dRa/dεPI) is dependent on the grain size in this alloy, and the relationship between the roughening rate and grain size also appears to be linear for the range of grain sizes included in this evaluation. However, examination of the roughened surfaces reflect that the roughening process is a highly complex combination of mechanisms and it is strongly influenced by grain size. As a result, representing the complex changes that occur during roughening of a free surface by plastic deformation with a single number calculated from profilometry scans may be too coarse of a measure to represent these changes when modeling roughness-dependent behavior or properties.
Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science
No. 9


aluminium alloys, metal forming, profilometry, strain localization, surface roughness


Stoudt, M. and Ricker, R. (2002), The Relationship Between Grain Size and the Surface Roughening Behavior of Al-Mg Alloys, Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science, [online], (Accessed May 29, 2024)


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Created September 1, 2002, Updated February 17, 2017