Post-fire performance of iron-based shape memory alloy: Experimental study, prediction equations and constitutive models

To expand the application of iron-based shape memory alloy (Fe-SMA) for fire resilience improvement, this paper presents a systematic investigation on the mechanical properties of post-fire Fe-SMA. In tests, the specimens of China-made Fe-SMA were heated to target temperatures up to 1000 degrees C, then cooled to room temperature in air or water, and finally subjected to tensile tests. The variation trends of mechanical properties with different cooling methods were analyzed, accompanied by the residual factor comparison with high strength steels Q460, S460, A36, A572 and A992, as well as with austenite stainless steel S30408. Finally, the prediction equations of residual factors and the post-fire constitutive model of Fe-SMA were proposed. Experimental results indicate that the exposed elevated temperature and cooling method significantly influence the post-fire performance of FeSMA. Compared with commonly used high strength steel and austenite stainless steel in civil engineering, FeSMA has unique post-fire performance, with a noticeable enhancement after exposure to elevated temperatures below 800 degrees C. Therefore, the targeted theoretical prediction of post-fire Fe-SMA performance is significant and can be used as the investigation foundation for the fire resilience improvement application of Fe-SMA in civil engineering.