Experimental study on residual mechanical properties of Q235 steel after water cooling from elevated temperatures
The mechanical properties of Q235 steel after water cooling from elevated temperatures were experimentally investigated.Firstly,the specimens were heated to 500,600,700 and 900 ℃ respectively to simulate fires at different temperatures and then the elevated temperatures specimens were immersed in water and cooled to normal temperature.Then the tensile tests were conducted on the specimens to observe the tensile fracture characteristics of Q235 steel under water cooling condition,and the stress-strain relationship curve and the main residual mechanical properties parameters were obtained.The effect of fire temperature on mechanical properties of Q235 steel under water cooling condition was discussed through analysis of experimental results.At the same time,based on the existing research results,the effects of fire temperature on the residual mechanical properties of Q235,Q345 and Q355 steels with similar strength grades after water cooling from elevated temperatures were compared and analyzed.Finally,combined with the experimental results,the prediction equations of the yield strength,tensile strength and other mechanical properties of Q235 steel after water cooling at 20～900℃ with the change of fire temperature were proposed,which can be helpful for the evaluation of residual mechanical properties of Q235 steel after extinguishing with water.
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