Post-fire mechanical properties of titanium–clad bimetallic steel in different cooling approaches

Abstract

Titanium-clad bimetallic steel (TCBS) consisting of titanium (cladding) and carbon steel (substrate) has been proposed to reduce the effects of corrosion on the durability of steel structures. Fire is a frequent disaster in steel structures. The elevated temperature caused by a fire and the cooling method to prevent it have a long-term influence on the mechanical properties of structural steels. In this study, the post-fire mechanical properties of a TCBS were investigated experimentally to accurately predict the residual service capacity of steel structures after a fire. The post-fire appearances of TCBS specimens were examined. The bonding interface of all TCBS specimens remained intact after exposure to elevated temperatures. The deformations of the cladding and substrate metals were coordinated before necking. Based on the fractured order, three different typical failure modes were determined in the TCBS. The differences in the cooling method and the exposure temperature resulted in differences in the nonlinear properties of the stress-strain curves. The effects of the exposure temperature and the cooling method on the yield strength, ultimate strength, elastic modulus, and percentage elongation after fracture were investigated and quantified using predictive equations. To comprehensively reveal the post-fire performance of TCBS comprehensively, the residual mechanical properties of different structural steels were compared.