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

摘要: 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 based on modern approaches techniques non-linear dynamics – linear stability analysis, amplitude Ginzburg–Landau equations, bifurcation diagrams. general instability area identified as possessing a coefficient (SRS). mathematical technique developed present paper was applied specific alloy, Al–0.4%Mg–0.2%Si, yielded good results terms predicting regions “strain rate–temperature” parameter space. It clearly demonstrated that even though located region intermediate strain rates, qualitative difference exists between areas (relatively) fast slow rates: while first case dynamic behavior system supercritical, second it subcritical. highly undesirable because causes sudden onset stable stress serrations are difficult suppress (at given temperature), development gradual and, consequently, more easily controllable.