Aluminum alloys are increasingly being used in a broad spectrum of load-bearing applications such as lightweight structures, light rail, bridge decks, marine crafts, and offshore platforms. A major concern in the design of land-based and marine aluminum structures is fire safety, at least in part due to mechanical property reduction at temperatures significantly lower than that for steel. A substantial concern also exists regarding the integrity and stability of an aluminum structure following a fire; however, little research has been reported on this topic. This paper provides a broad overview of the mechanical behavior of aluminum alloys both during and following fire. The two aluminum alloys discussed in this work, 5083-H116 and 6061-T651, were selected due to their prevalence as lightweight structural alloys and their differing strengthening mechanisms (5083strain hardened, 6061precipitation hardened). The high temperature quasi-static mechanical and creep behavior are discussed. A creep model is presented to predict the secondary and tertiary creep strains followed by creep rupture. The residual mechanical behavior following fire (with and without applied stress) is elucidated in terms of the governing kinetically-dependent microstructural mechanisms. A review is provided on modeling techniques for residual mechanical behavior following fire including empirical relations, physically-based constitutive models, and finite element implementations. The principal objective is to provide a comprehensive description of select aluminum alloys, 5083-H116 and 6061-T651, to aid design and analysis of aluminum structures during and after fire.

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Aluminum alloys are being increasingly used in lightweight transportation applications such as naval vessels and passenger rail. The primary aluminum alloys considered are Al-Mg (5xxx) and Al-Mg-Si (6xxx) due to their mechanical strength, corrosion resistance, and weldability. A major concern in the use of aluminum alloys for lightweight structural applications is fire exposure. Aluminum mechanical properties begin to significantly degrade at temperatures above 300°C. After fire exposure, structural integrity will be governed by the residual, post-fire strength of the aluminum. However, scarce data is available regarding the post-fire mechanical response. The post-fire mechanical properties were characterized for several aluminum alloys: 5083-H116, 6082-T651 plate, and 6082-T6 extrusion. The alloys were exposed to elevated temperatures in a furnace to simulate a fire environment. Tension tests were performed to determine the mechanical response of the alloys. Vickers hardness measurements were also performed on specimens exposed for varying durations and temperatures to quantify the time and temperature-dependent behavior. The observed behaviors were explained in relation to the microstructural strengthening mechanisms for each alloy. Correlations were developed between the mechanical properties and Vickers hardness indentations.

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