Under normal exposure to the atmosphere, density of steel SA283 Grade D, bare steel forms a tight protective oxide film during the first few months of atmospheric corrosion. Sometimes architects choose bare steel structures because they want to get the appearance of uniform atmospheric oxidation on the steel surface, and sometimes they are to save the protective coating for economic purposes. To use these low-alloy high-strength steels in a bare state, the design must consider that the surface of the steel cannot be wet for a long time, and special attention should be paid to the special atmospheric environment to ensure that the corrosion rate of the steel is allowed under this condition.
Q420C steel belongs to low alloy high strength steel. Q420 is named as the steel with yield strength of 420MPa, C means the impact temperature is 0 ℃, and Q is the abbreviation of yield strength. Chemical composition of Q420C steel: C ≤ 0.20, Si ≤ 0.50, Mn ≤ 1.70, P ≤ 0.035, S ≤ 0.035, Nb ≤ 0.07, V ≤ 0.20, Ti ≤ 0.20, Cr ≤ 0.30, Ni ≤ 0.80, Cu ≤ 0.30, N ≤ 0.015, Mo ≤ 0.20. The mechanical properties of Q420C steel are: yield strength ≥ 340 Mpa, tensile strength 500-680 Mpa, elongation after fracture ≥ 18%, impact energy 34J. density of steel SA283 Grade D, Q420C steel has good mechanical properties and weldability, good cold and hot workability.
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