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    Aluminum Alloys with Identical Plastic Flow and Different Strain Rate Sensitivity
    (SPRINGER, 2010) Picu, R. C.; Ozturk, F.; Esener, E.; Li, R.
    Mg-rich and Si-rich aluminum alloys from the AA6XXX class are considered to demonstrate that standard heat treatments can be used to produce materials with identical plastic flow (yield stress and strain hardening) and different strain rate sensitivity. The Mg-rich alloy exhibits lower strain rate sensitivity and a different variation of this parameter with the stress (Haasen plot) relative to the Si-rich alloy. This is due to the instantaneous component of the strain rate sensitivity being smaller in the Mg-rich alloy. Hence, the underlying mechanism is not related to the presence of free, fast diffusing Mg atoms, but rather to the different nature of precipitates forming in the two alloys. A simple model is used to demonstrate that it is possible to tailor the strain rate sensitivity while preserving the flow stress by controlling the nature of precipitates and that of the dislocation-precipitate interaction.
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    Influence of aging treatment on mechanical properties of 6061 aluminum alloy
    (ELSEVIER SCI LTD, 2010) Ozturk, F.; Sisman, A.; Toros, S.; Kilic, S.; Picu, R. C.
    Aluminum-magnesium-silicon (Al-Mg-Si) alloys show medium strength, excellent formability, good corrosion resistance and are widely used in extruded products and automotive body panels. The major advantage of these alloys is their age hardening response during the paint baking process as well as the fact that they exhibit no yield point phenomenon and Ludering. In this study, the mechanical properties of a commercially available AA6061 alloy aged to various levels were studied. Peak-aged conditions were reached in this particular alloy after a 2 h heat treatment at 200 degrees C. The variation of the yield stress, ultimate tensile strength, ductility and strain hardening rate with aging time is measured and discussed in relation to the microstructural changes induced by the heat treatment. (C) 2009 Elsevier Ltd. All rights reserved.
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    Strain Hardening and Strain Rate Sensitivity Behaviors of Advanced High Strength Steels
    (JOURNAL IRON STEEL RESEARCH EDITORIAL BOARD, 2013) Ozturk, F.; Polat, A.; Toros, S.; Picu, R. C.
    The mechanical properties of commercial dual phase (DP), transformation induced plasticity (TRIP), and high strength low alloy (HSLA-340) steel sheets are investigated and compared at various strain rates ranging from 0.0017 to 0.17 s(-1) at ambient temperature. TRIP steel outperforms the other two materials, having comparable ductility and twice as large strength relative to DP steel. TRIP has larger strength and much larger ductility than HSLA-340. The exceuent ductility of TRIP800 is due to its high strain hardening capability, which promotes stable plastic deformation. It is observed that the strain hardening rate in TRIP800 does not decrease to zero at failure, as common in most materials in which failure is preceded by necking.