Post-fire mechanical and corrosion properties of duplex stainless steel: Comparison with ordinary reinforcing-bar steel

This paper is a preliminary study on the merits of using duplex stainless steel (DSS) as concrete reinforcements. It looks into the post-fire mechanical and corrosion properties of the wrought DSS 2205 after annealing at 500 °C, and compare them with those of an ordinary rebar steel. Spinodal decomposition of the ferrite phase strengthens and embrittles the 2205 DSS. For the rebar steel, however, softening occurs. Even after the 2205 DSS is exposed to 500 °C for 1 week, its ductility as indicated by fracture strain is still comparable to that of the unannealed rebar steel. The present data show that after short-term exposure to temperatures under 500 °C, the ductility and retention of strength of the 2205 DSS are better than those of the the rebar steel. The corrosion performance of the 2205 DSS, both in 3.5% NaCl and in 3.5% NaCl + Ca(OH)2, is also better than that of the unannealed rebar steel even if the former is exposed to 500 °C for 1 week.