Abstract
The feasibility and efficacy of improving the mechanical response of Al–Mg–Si 6082 structural alloys during high temperature exposure through the incorporation of a high number of α-dispersoids in the aluminum matrix were investigated. The mechanical response of the alloys was characterized based on the instantaneous high-temperature and residual room-temperature strengths during and after isothermal exposure at various temperatures and durations. When exposed to 200 °C, the yield strength (YS) of the alloys was largely governed by β” precipitates. At 300 °C, β” transformed into coarse β’, thereby leading to the degradation of the instantaneous and residual YSs of the alloys. The strength improvement by the fine and dense dispersoids became evident owing to their complementary strengthening effect. At higher exposure temperatures (350–450 °C), the further improvement of the mechanical response became much more pronounced for the alloy containing fine and dense dispersoids. Its instantaneous YS was improved by 150–180% relative to the base alloy free of dispersoids, and the residual YS was raised by 140% after being exposed to 400–450 °C for 2 h. The results demonstrate that introducing thermally stable dispersoids is a cost-effective and promising approach for improving the mechanical response of aluminum structures during high temperature exposure.
Highlights
Owing to their preferable strength-to-weight ratio, good corrosion resistance, and weldability, Al–Mg–Si 6xxx alloys are increasingly used in load-bearing structural applications, such as land-based vehicles, marine crafts, light rails, bridge decks, off-shore platforms, and building structures [1,2,3,4,5,6]. Such aluminum structures can be subjected to unintentional fire exposures; fire safety is a major concern in their design and applications [3,4,7]
The results reveal uniformly distributed, fine, needle-shaped precipitates in the aluminum matrix of all three alloy variants
Al–Mg–Si 6082 alloys experience predominant strengthening by the precipitation of Typically, Al–Mg–Si 6082 alloys experience predominant strengthening by the precipitation of nanoscale precipitates ( β”), which are formed during aging treatment [21]
Summary
Owing to their preferable strength-to-weight ratio, good corrosion resistance, and weldability, Al–Mg–Si 6xxx alloys (typically 6061 and 6082 alloys) are increasingly used in load-bearing structural applications, such as land-based vehicles, marine crafts, light rails, bridge decks, off-shore platforms, and building structures [1,2,3,4,5,6]. Such aluminum structures can be subjected to unintentional fire exposures; fire safety is a major concern in their design and applications [3,4,7]. Owing to the lower melting temperature of aluminum alloys compared to those of common structural metals (e.g., iron and steel), the temperature range representative of realistic fire events and relevant for the mechanical properties is 150–450 ◦ C [4].
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