Research on mechanical properties of duplex stainless steel S22053 at elevated temperature and after fire

•Mechanical properties of stainless steel S22053 in fire and postfire were investigated.•The new constitutive models for stainless steel S22053 in fire and postfire were proposed.•The reduction formulas for stainless steel S22053 in fire and postfire were fitted.•The statistical parameters for mechanical properties of stainless steel S22053 were obtained. Stainless steel has advantages such as corrosion resistance, durability and esthetic appearance, with extensive application prospects in the field of construction engineering. In order to investigate the mechanical properties of duplex stainless steel S22053 at elevated temperature and after fire, 58 standard coupons were fabricated, with 4 coupons for tensile tests at ambient temperature, 18 coupons for steady-state tests at elevated temperatures, and 36 coupons for tensile tests after fire. The temperatures were set at 100 °C, 200 °C, 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C and 900 °C, in total of 9 temperature levels. Two cooling methods, water cooling and air cooling, were employed for the postfire coupons. Based on the test results, the expressions of stress-strain relations for duplex stainless steel S22053 under two fire conditions were proposed, and comparisons were made with existing models. The reduction formulas for 6 major mechanical parameters (E0, σ0.05, σ0.2, σ1.0, σ2.0 and σu) of duplex stainless steel S22053 under two fire conditions were obtained through data fitting. Reliability analysis was performed on the mechanical property parameters, and corresponding standard values were proposed.