Post-fire Structural Properties of Hot-Rolled and Cold-Rolled Duplex Stainless Steel Reinforcing Bar

• Published in: Fire technology Vol. 58; no. 4; pp. 2283 - 2311
• Main Authors: Rehman, Fazal-ur, Cashell, Katherine A., Anguilano, Lorna
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.07.2022; Springer Nature B.V
• Subjects: Austenitic stainless steels; Carbon steels; Characterization and Evaluation of Materials; Civil Engineering; Classical Mechanics; Cold rolling; Concrete structures; Corrosion resistance; Duplex stainless steels; Engineering; Fire resistance; Grain boundaries; Heat resistance; High temperature; Hot rolling; Mechanical properties; Metallurgical analysis; Physics; Rebar; Rehabilitation; Reinforced concrete; Reinforcing steels; Stainless steel; Structural integrity; Residual properties; Metallurgical assessment; Post-fire; Stainless steel; Tensile test; Duplex alloys
• ISSN: 0015-2684; 1572-8099
• DOI: 10.1007/s10694-022-01261-y

This paper is concerned with the behaviour of duplex stainless steel reinforcing bar following exposure to elevated temperatures from a fire followed by subsequent cooling. The study focuses on duplex grade 1.4362 reinforcing bar, and includes both hot-rolled and cold-rolled variants. Grade 1.4362 duplex stainless steel reinforcement has become a popular choice for reinforced concrete owing to its excellent combination of outstanding mechanical behaviour and corrosion resistance as well as cost-effectiveness. There is no information on the post-fire performance of duplex 1.4362 reinforcing bar available, despite being necessary for an engineer that may wish to study the structural integrity of a relevant structure following a fire. To address this gap in the existing knowledge, this paper presents a detailed discussion and analysis based on a series of laboratory experiments comprising mechanical and metallurgical testing. It is shown that grade 1.4362 duplex stainless steel reinforcing bars perform unlike any other types of carbon steel or austenitic stainless steel rebars, owing to the austenite-ferrite grain boundary, and the associated instabilities. Based on the results presented in this paper, a series of recommendations are proposed for the post-fire mechanical property retention factors that can be used in assessment and design. Finally, this paper aims to highlight the potential for rehabilitation and salvage of existing reinforced concrete structures following a fire, and aid in the prevention of unnecessary demolition and replacement.