Experimental study on post-fire mechanical performances of high strength steel Q460

Abstract

A series of experimental tests for investigating the post-fire mechanical (PFM) and post-fire fracture (PFF) performances of high strength steel Q460 are reported in this paper. All Q460 coupon specimens are heated up to a designated temperature which is selected from 100 to 900°C and then cooled down naturally to room temperature. Tensile tests are conducted to obtain their completely full-range post-fire stress-strain curves and the corresponding mechanical properties. The obtained experimental results show that with an increase in the heating temperature, the post-fire yield strength and ultimate strength of the Q460 structural steel decrease particularly when the heating temperature is over 650°C, but the post-fire elongation enhances. Ductile fracture behaviour of the coupon specimens under axial tensile loading can also be observed through the tensile coupon tests. The obtained experimental data are compared with the other results found in the open literatures on Grade 460 high strength steel. Based on a wider range of experimental data sets, predictive equations for evaluating the PFM properties of Grade 460 high strength steel are proposed. The experimental results presented in this study will provide benchmark data for the future calibration of complex ductile fracture parameters applied in numerical simulation.

Cyclic Performance of Structural Steels after Exposure to Various Heating–Cooling Treatments

“…The post-fire mechanical properties of high-strength steels were found to be quite different from those of mild steels [3,4]. For Chinese hot-rolled Q235, Q345, and Q420 steels and ASTM A572 Gr.50 steels, their post-fire mechanical properties changed significantly after exposure to temperatures above approximately 700 • C [1,5].…”

“…The post-fire mechanical properties of European standard high-strength steels, including S460, S690, and S960, are not obviously affected until the temperature reaches above 600 • C, and they begin to degrade after cooling down from the temperatures beyond 600 • C up to 1000 • C [3,6,7]. Furthermore, the critical temperatures turn into approximately 400 • C-700 • C for the Chinese high-strength steels Grade Q460 and Q690 when cooled by air, water, and firefighting foam [4,[8][9][10][11][12]. For cold-formed steels, the post-fire mechanical properties are reduced after they have been exposed to temperatures exceeding 300 • C [1,13].…”