12. Creep Damage Quantification and Post-fire Residual Strength of 5083 Aluminum Alloy

One of the major concerns regarding the use of lightweight materials in ship construction is the response of those materials to fire scenarios, including the residual structural performance after a fire event. This paper presents a study on creep damage evolution in 5083 marine-grade aluminum alloy and its impact on residual mechanical behavior. Samples were tested at 400 ° C and at different stress levels and times selected to achieve specified creep strain levels. Scanning electron microscopy (SEM) and high resolution optical microscopy were utilized to characterize the creep damage. The damage is primarily manifested as cavitation, grain elongation, and dynamic microstructural evolution. The cavitation morphology, orientation and grain structure evolution were investigated on three perpendicular sample surfaces (rolling, transverse, and normal faces). The competing process between cavitation and grain structure evolution were studied to develop an understanding of the creep damage mechanism. The post-fire residual strength of the Al5083 at 400 °C reveals that the cavitation counteracts the strengthening by grain elongation.