Abstract The mechanical properties of high strength structural steel (HSSS) at elevated temperatures are the basis for fire-resistant design of HSSS members and structures. Previous studies on the mechanical properties of HSSS at elevated temperatures were mainly conducted on QT (Quenched and Tempered) HSSS, while few studies were conducted on TMCP (Thermo-Mechanical Controlled Process) HSSS. In order to identify the effect of manufacturing process on the mechanical properties of HSSS at elevated temperatures, an experimental study was carried out by steady-state method on TMCP Q690 HSSS, considering nine elevated temperatures ranging from 200 to 800 °C. Results showed that the elastic modulus and strength of TMCP Q690 HSSS decreased significantly as the temperature increased over 400 °C, while the ultimate elongation increased as the temperature increased above 500 °C. Formulas for calculating the reduction factors of mechanical properties of TMCP Q690 HSSS at elevated temperatures were proposed. Comparing the results of TMCP Q690 HSSS with those of QT Q690 HSSS previously studied, it can be found that the reduction on elastic modulus and strength was more severe for TMCP Q690 HSSS than QT Q690 HSSS in most cases, which was explained in the microstructure level of HSSS.

中文翻译：

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TMCP Q690高强度结构钢高温力学性能

摘要 高强度结构钢（HSSS）在高温下的力学性能是HSSS构件和结构耐火设计的基础。以往对 HSSS 高温力学性能的研究主要是在 QT（淬火和回火）HSSS 上进行的，而对 TMCP（热机械控制工艺）HSSS 的研究很少。为了确定制造工艺对 HSSS 在高温下机械性能的影响，采用稳态方法对 TMCP Q690 HSSS 进行了实验研究，考虑了 200 至 800 °C 的九个高温。结果表明，TMCP Q690 HSSS 的弹性模量和强度随着温度升高超过 400 °C 显着降低，而极限伸长率随着温度升高到 500 °C 以上而增加。提出了TMCP Q690 HSSS高温力学性能折减系数的计算公式。将TMCP Q690 HSSS的结果与之前研究的QT Q690 HSSS的结果进行比较，可以发现在大多数情况下，TMCP Q690 HSSS的弹性模量和强度的降低比QT Q690 HSSS更严重，这在微观结构层面得到了解释HSSS。