Study on Microstructure and Properties of 460 MPa Grade Fire and Weather Resistant Building Steel
Low-cost 460MPa grade fire-resistant and weather resistant building steel was successfully developed by using a low molybdenum microalloying design with the addition of titanium,nickel,chromium and copper and a reasonable controlled rolling and cooling process.The weatherability of the experimental steel in simulated industrial atmosphere was studied by salt spray and peripheral immersion experiments.The results show that the experimental steel is composed of granular bainite and ideal microstructure of M/A-island refractory steel.A large number of nano Ti carbonitrides precipitated at 600℃can interact with dislocations,hinder the movement of dislocations and improve the high temperature mechanical properties of the experimental steel.Compared with that of Q345B steel,the corrosion resistance of fire-resistant and weather resistant building steel improves by more than 30%.The rust layer of fire-resistant and weather resistant building steel is dense and stable,and that has high content of α-FeOOH,which can effectively prevent the corrosive ions from contacting the matrix.The change of corrosion rate and relative content of stable corrosion phase proves that the rust layer of fire-resistant and weather resistant building steel becomes more and more stable with time,and the weather resistance is better.
fire-resistant and weathering steelhigh temperature performanceweather resistanceperipheral immersionrust layer
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