Steel structures are commonly used in engineering projects and infrastructure. Steel structures should have high bearing capacity and be able to resist fire, earthquake, and corrosion. A new type of Q235 refractory steel has recently been developed in China, and the residual mechanical properties of steel structures are key indicators for estimating structural damage and reusability. Therefore, in-depth research is urgently needed. The yield stress, residual elastic modulus, ultimate tensile strength, and ultimate strain at room temperature to 900 °C and under air and water cooling conditions were detected. The residual mechanical properties of Q235FR steel were compared with other structural steels, and it was confirmed through experiments that they are closely related to temperature and cooling methods. In the case of the above cooling methods, the loss of mechanical properties can be negligible when exposed to temperatures up to 600 °C. When the temperature exceeds 600 °C, the high temperature and cooling method significantly impact the residual mechanical properties of Q235FR steel. The advantages of Q235FR steel are high strength, good ductility, strong corrosion resistance, and fire resistance. The suggested predictive equations could be used to accurately evaluate the residual mechanical properties of Q235FR steel at high temperatures.

钢结构常用于工程项目和基础设施。钢结构应具有较高的承载能力，并能防火、抗震、防腐。我国最近开发出一种新型Q235耐火钢，钢结构的残余力学性能是评估结构损伤和可重复使用性的关键指标。因此，迫切需要深入研究。检测室温至900℃、空冷和水冷条件下的屈服应力、残余弹性模量、极限拉伸强度和极限应变。Q235FR钢的残余力学性能与其他结构钢进行了比较，通过实验证实它们与温度和冷却方式密切相关。在上述冷却方法的情况下，当暴露于高达 600 °C 的温度时，机械性能的损失可以忽略不计。当温度超过600℃时，高温和冷却方式显着影响Q235FR钢的残余力学性能。Q235FR钢的优点是强度高、延展性好、耐腐蚀性强、耐火。建议的预测方程可用于准确评估 Q235FR 钢在高温下的残余力学性能。