Commercially pure aluminum with random texture was prestrained either by rolling or by uniaxial compression, and then tested in uniaxial tension to study the transients in flow stress, work hardening and r-value induced by the strain-path change. New experimental results are reported on the variation of the r-value and the permanently reduced work hardening subsequent to the strain-path change. A continuum plasticity model was developed that can reproduce the observed behavior. The model applies a second-order "delayed pointer" tensor to represent the microstructural anisotropy and was implemented into the finite element software LS-DYNA. The model was calibrated to the experimental data, and a simulation of early strain localization subsequent to an orthogonal strain-path change was compared to strain fields measured by a digital image correlation technique.2

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AlMn alloys are often used for the production of automotive heat exchanger ns. During brazing at about 600• C, recrystallization and grain coarsening resulting in the reduction of the strength and possible buckling of the n can occur. In order to obtain a good recrystallization resistance, the alloy should contain a dense and homogeneous distribution of second phase particles. The eect of Si and Fe addition on the recrystallization response of AlMnZr alloys direct-chill cast in the laboratory conditions and twin-roll cast in the industrial conditions was examined. Microstructure of the alloys was characterized during downstream processing. The particles were analyzed by light metallography, energy dispersive X-ray spectroscopy and by means of electron backscattering diraction. Computer assisted quantitative particle analysis was carried out on eld emission gunscanning electron microscope micrographs. Vickers hardness and electrical conductivity were measured at thicker sheets, while at the nal gauge of 65 µm the 0.2% proof stress was evaluated. The best recrystallization resistance had twin-roll cast alloy containing 0.5 wt% Si and 0.2 wt% Fe.

High-resolution crystal plasticity-finite element method (CPFEM) simulations are performed to provide new reference values of the Taylor factor M and the isotropic yield surface exponent a for high stacking fault energy face-centred-cubic (FCC) polycrystalline metals with random orientations. The visco-plastic Taylor factor with strain rate sensitivity M is introduced and linearly extrapolated to its zero strain rate sensitivity limit to give the new reference value of M. The linear extrapolation technique is also employed to define the new reference value of a . The obtained new reference values are 2.7 and 6.9, for M and a , respectively, which are much smaller than the reference values currently used for FCC materials based on full constraint (FC) Taylor model calculations, i.e. 3.07 for M and 8 for a. Other state-of-the-art Taylortype models, e.g. ALamel, ALamel with the type III relaxation (ALamel-T3) and the visco-plastic self-consistent (VPSC) models, can also give values for M and a much smaller than the FC-Taylor calculations. The performance of the CPFEM and these state-of-art Taylor-type models in terms of resolving deformation and stress fields within the aggregate can only be assessed in a statistical manner since all are statistical aggregate models. Selected statistical distributions are analysed for all models, by means of local deviations of the velocity gradient tensor, of the plastic deformation-rate tensor and of the stress tensor etc., for uniaxial tensile deformation. The ALamel models are found to provide similar statistics as CPFEM, whereas the VPSC model results are 2 qualitatively different. The intra-grain analysis for CPFEM demonstrates that the intragrain interactions are as much important as the local interactions at the grain boundaries.

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Uniaxial tensile tests were conducted at room temperature, 100°C and 150°C, for obtaining necking-corrected stress-strain curves until fracture. The necking correction is based on specimen contours estimated from images recorded during testing. Axisymmetric tensile specimens of an AA6082 alloy artificially aged at different times, were tested. The radius of the minimal cross-section area a and the necking-curvature radius R were experimentally obtained. For all cases, a/R as a function of the strain after onset of necking ε – εu shows a characteristic nonlinear transition into a linear asymptotic relationship. Based on the tests, a new two-parameter curve was proposed for the a/R relationship. The slope of the linear part of the new model equals 1.1, as in the Le Roy model. An additional parameter is introduced, which controls the part of the curve with the non-linear transition. This region increases at increased testing temperature and varies for different ageing times. The proposed equation and the necking corrections were verified by finite element modelling analysis.