Mechanical response and constitutive model of austenitic 304 stainless steel after exposure ISO 834 fire

Stainless steel is increasingly used in renewable energy sectors due to its advantageous mechanical properties, corrosion resistance, and aesthetic appeal. However, exposure to high temperatures can significantly alter these properties, potentially compromising long-term performance in renewable energy infrastructure. This study investigates the effects of ISO 834 standard fire on the constitutive behavior of austenitic 304 stainless steel through experimental analysis. The findings indicate that cross-sectional weakening has a minimal impact on the post-fire degradation of stainless steel structures. After sufficient cooling, the elastic modulus and strain hardening index of fire-exposed stainless steel are restored to pre-fire levels. However, both the nominal yield strength and ultimate strength are significantly diminished after fire exposure, with these reductions being positively correlated with heating duration. Practical formulas are provided for predicting the nominal yield strength, ultimate strength, and ultimate strain of stainless steel after ISO 834 standard fire. Additionally, a stress-strain constitutive model has been developed that accurately predicts the full strain range observed in post- fire tensile tests of austenitic 304 stainless steel.