Strain-rate sensitivity limit diagrams and plastic instabilities in a 6xxx series aluminum alloy. Part I: Analysis of temporal stress-strain serrations

Sergey Rashkeev, Michael V. Glazov, Frédéric Barlat

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Abstract

A method for the construction of "processing windows" to avoid negative strain-rate sensitivity and associated serrated flow in some aluminum alloys is described. The method is based on modern approaches and techniques of non-linear dynamics - linear stability analysis, amplitude Ginzburg-Landau equations, and bifurcation diagrams. The general instability area is identified as possessing a negative strain-rate sensitivity coefficient (SRS). The mathematical technique developed in the present paper was applied to a specific aluminum alloy, Al-0.4%Mg-0.2%Si, and yielded good results in terms of predicting the negative strain-rate sensitivity regions in the "strain rate-temperature" parameter space. It was clearly demonstrated that even though the instability area is located in the region of intermediate strain rates, a qualitative difference exists between the areas of (relatively) fast and (relatively) slow strain rates: while in the first case the dynamic behavior of the system is supercritical, in the second case it is subcritical. The second case is highly undesirable because it causes a sudden onset of stable stress serrations that are difficult to suppress (at a given temperature), while in the first case the development of instability is gradual and, consequently, more easily controllable.

Original languageEnglish
Pages (from-to)295-309
Number of pages15
JournalComputational Materials Science
Volume24
Issue number3
DOIs
Publication statusPublished - 1 Jun 2002
Externally publishedYes

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ASJC Scopus subject areas

  • Materials Science(all)

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