Comparative experimental studies of high-temperature mechanical properties of HSSs Q460D and Q690D

The test data for both 460 MPa and 690 MPa steels commonly show discreteness in their high-temperature mechanical properties. In this study, a comparative experimental investigation was conducted on Q460D and Q690D steels at temperatures ranging from 20 °C to 900 °C using concordant test conditions, which eliminated the discreteness induced by different test conditions. The results showed that the differences in the reduction factors for the f1.0, f1.5, and f2.0 yield strengths between the Q460D and Q690D steels were negligible. A comparison of the test results with current standards and the available results showed that the difference between the 460 MPa and 690 MPa steels decreased significantly after excluding the effects of the test conditions. In addition, the f1.0 yield strength, as recommended by GB51249, was applicable to both the Q460D and Q690D steels, as were the f1.0 and f1.5 values recommended by BS5950, and the f2.0 values recommended by EC3 and AISC. Moreover, predictive equations were proposed for calculating the reduction factors of the mechanical properties of the Q460D and Q690D steels at elevated temperatures.