Experimental Study On Seismic And Fire Resistance Of Hot Rolled Bainite High Strength Steel

Q460FRW steel is a new type of seismic and refractory building steel obtained by adding alloy elements and using controlled rolling and controlled cooling technology on the basis of 460 MPa high-performance building steel.In this paper,the seismic performance and refractory performance of hot rolled Q460FRW seismic refractory steel,and the effect of different fire temperature and time on seismic performance,and the effects of different fire temperature and time,and the effect of different loads on fire resistance are studied by scanning electron microscope,tensile testing machine,multifunctional internal friction instrument and thermal simulation testing machine.The results shows that:1)The hot rolled Q460FRW seismic refractory steel structure is mainly granular bainite,which contains some finely dispersed M/A components.As the holding temperature increases and the holding time increases,the ferrite matrix grows and the M/A component structure decomposes.2)The Y/T（yield-to-tensile strength）ratio of Q460FRW seismic refractory steel increases with the increase of fire temperature and the duration.When the fire temperature is lower than 550℃and the duration is lower than 1 h,the yield ratio of Q460FRW seismic and refractory steel is lower than 0.85,and the seismic performance meets the requirements of national standards.However,when the fire temperature is higher than 600℃,the seismic performance of Q460FRW seismic and refractory steel is rapidly degraded,which cannot meet the requirements of the national standard.3)With the increase of fire temperature,carbides of Q460FRW seismic refractory steel are continuously precipitated.After holding at 650℃for 1 hour,the precipitation of carbides reaches a maximum of 67.07%.As the temperature of the fire increases,the seismic performance of Q460FRW seismic refractory steel continues to decline.4)Q460FRW seismic refractory steel has good high-temperature structural stability.When the load is less than or equal to 1.1 times R_p0.2（289 MPa）,instability fracture does not occur within 600℃for 2 h,and the overall creep ratio is within 4%.When the load is 1.2 times R_p0.2（316 MPa）,instability fracture occurs after holding at600℃for 4435 seconds.When the load is 1.2 times R_p0.2（343 MPa）,instability fracture occurs after holding at 600℃for 1422 seconds.And the large-scale strain mainly occurs in about 8 seconds before fracture.