Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Post-fire mechanical behavior of Q345 structural steel after repeated cooling from elevated temperatures with fire-extinguishing foam
Abstract This study aims to investigate the post-fire mechanical behavior of Q345 structural steel after being repeatedly cooled from elevated temperatures using fire-extinguishing foam. The Q345 structural steel specimens were first repeatedly cooled 1–3 times from target temperatures of 200 °C, 500 °C, 800 °C and 900 °C to ambient temperatures using fire-extinguishing foam, respectively. After being repeatedly heated and cooled, the Q345 structural steel specimens were then subjected to the uniaxial tensile tests to obtain their post-fire mechanical behavior. A Scanning Electron Microscope (SEM) was used to observe the tensile fracture surfaces of the representative specimens to analyze the different tensile fracture characteristics induced by repeated heating and cooling. Meanwhile, the changes in stress-strain curves, yield strength, ultimate tensile strength and ductility were discussed by comparing with the experimental data of Q345 structural steel in the as-received state. Furthermore, the changes in the macro-mechanical properties of Q345 structural steel after repeated heating and fire-extinguishing foam cooling were explained in combination with the fracture morphology and phase transformation. It is observed that Q345 structural steel was able to remain its initial mechanical properties unchanged after being repeatedly cooled from temperatures of 200 °C and 500 °C using fire-extinguishing foam. In contrast, significant reduction can be observed in the mechanical properties when Q345 structural steel was repeated cooled from temperatures of 800 °C and 900 °C using fire-extinguishing foam. The yield strength, ultimate strength and ductility significantly reduced with the increase in the number of heating and cooling cycles. When the Q345 structural steel was repeatedly cooling from 500 °C to 900 °C, the shape and size of ferrite grains increased sharply, whereas those of the pearlites decreased accordingly with the increase in the number of heating and cooling cycles.
Graphical abstract Display Omitted
Highlights Repeated heating and cooling has an effect on the mechanical properties of Q345 steel. Mechanical properties of Q345 steel can maintain unchanged when exposed to 200 °C and 500 °C. The strength of Q345 steel decreased after repeated heating and cooling. The effect of repeated fire-extinguishing foam cooling on ductility is complex.
Post-fire mechanical behavior of Q345 structural steel after repeated cooling from elevated temperatures with fire-extinguishing foam
Abstract This study aims to investigate the post-fire mechanical behavior of Q345 structural steel after being repeatedly cooled from elevated temperatures using fire-extinguishing foam. The Q345 structural steel specimens were first repeatedly cooled 1–3 times from target temperatures of 200 °C, 500 °C, 800 °C and 900 °C to ambient temperatures using fire-extinguishing foam, respectively. After being repeatedly heated and cooled, the Q345 structural steel specimens were then subjected to the uniaxial tensile tests to obtain their post-fire mechanical behavior. A Scanning Electron Microscope (SEM) was used to observe the tensile fracture surfaces of the representative specimens to analyze the different tensile fracture characteristics induced by repeated heating and cooling. Meanwhile, the changes in stress-strain curves, yield strength, ultimate tensile strength and ductility were discussed by comparing with the experimental data of Q345 structural steel in the as-received state. Furthermore, the changes in the macro-mechanical properties of Q345 structural steel after repeated heating and fire-extinguishing foam cooling were explained in combination with the fracture morphology and phase transformation. It is observed that Q345 structural steel was able to remain its initial mechanical properties unchanged after being repeatedly cooled from temperatures of 200 °C and 500 °C using fire-extinguishing foam. In contrast, significant reduction can be observed in the mechanical properties when Q345 structural steel was repeated cooled from temperatures of 800 °C and 900 °C using fire-extinguishing foam. The yield strength, ultimate strength and ductility significantly reduced with the increase in the number of heating and cooling cycles. When the Q345 structural steel was repeatedly cooling from 500 °C to 900 °C, the shape and size of ferrite grains increased sharply, whereas those of the pearlites decreased accordingly with the increase in the number of heating and cooling cycles.
Graphical abstract Display Omitted
Highlights Repeated heating and cooling has an effect on the mechanical properties of Q345 steel. Mechanical properties of Q345 steel can maintain unchanged when exposed to 200 °C and 500 °C. The strength of Q345 steel decreased after repeated heating and cooling. The effect of repeated fire-extinguishing foam cooling on ductility is complex.
Post-fire mechanical behavior of Q345 structural steel after repeated cooling from elevated temperatures with fire-extinguishing foam
Zhang, Chuntao (Autor:in) / Gong, Meiqi (Autor:in) / Zhu, Li (Autor:in)
17.02.2022
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Dynamic mechanical behaviour of Q345 steel at elevated temperatures: experimental study
| British Library Online Contents | 2010