Mechanical Properties of Superhigh-Strength Q960 Steel at Elevated Temperatures Considering the Tensile Strain Rate

This investigation delves into the impact of temperature and tensile strain rate on the mechanical characteristics of high-strength Q960 steel. The inherent strength and stiffness properties of steel undergo degradation as temperatures rise, necessitating meticulous consideration in the fire-resistant structural design of steel constructions. Meanwhile, tensile strain rate will influence the mechanical properties of the steel at high temperature. Due to the absence of data specifically tailored to high-strength Q960 steel, design standards assume its high-temperature strength variation is equivalent to that of conventional mild steel. To fill this knowledge gap, tensile tests were conducted on Q960 standard specimens in the temperature range of 25°C–800°C, using three different tensile strain rates: 0.001/min; 0.02/min; and 0.2/min. In accordance with the stress-strain curves, mechanical properties parameters and corresponding reduction factors of the steel were obtained. The test outcomes were contrasted with those of other high-strength steel specimens. This comparison shows that the rate of strength and stiffness loss with temperature increases with increasing steel grade. The test results were also compared with the mechanical properties suggested in pertinent design codes or standards. A new predictive formula has been introduced specifically for the assessment of material properties of Q960 steel in high-temperature environments.