A fire-resistant and weather-resistant steel for welded structures with yield strength ≥ 550mpa and production method

Abstract

Welding structure fire-resistant and weather-resistant steel with the yield strength being 550 MPa or above comprises components, by weight percent, 0.035 wt%-0.085 wt% of C, 0.25 wt%-0.45 wt% of Si,1.20 wt%-1.55 wt% of Mn, 0.003 wt% or below of P, 0.002 wt% or below of S, 0.05 wt%-0.12 wt% of Mo, 0.25 wt%-0.55 wt% of W, 0.05 wt%-0.12 wt% of Cr, 0.15 wt%-0.37 wt% of Cu, 0.15 wt%-0.35 wt% of Ni, 0.042 wt%-0.068 wt% of Nb, 0.023 wt%-0.044 wt% of Ti, 0.0020 wt%-0.0042 wt% of Ca, 0.0015 wt%-0.0045 wt% of Hf, 0.0020 wt%-0.0047 wt% of N and 0.0025 wt%-0.0045 wt% of O. A production method comprisesthe steps that a casting blank is heated section by section, rough rolling, finish rolling and cooling are sequentially carried out, and air cooling is carried out until the room temperature is reached. According to the welding structure fire-resistant and weather-resistant steel with the yield strength being 550 MPa or above, ReL is 550 MPa or above, Rm is 750 MPa or above, ReL / Rm is 0.78 or below, the ductility A is 30 % or above, the Z-directional performance is 65 % or above, -60 DEG C KV2 is 300 J or above, excellent fire resistance, weather resistance, lamellar tearing resistance, the welding performance, the cold and hot processing performance and the large-deformation resistance are achieved, preheating is not needed before welding, and heat treatment is not needed after welding.

Description

technical field [0001] The invention relates to a steel for welding structures and a production method thereof, in particular to a fire-resistant and weather-resistant steel for welding structures with a yield strength ≥ 550 MPa and a production method thereof. Background technique [0002] With the continuous development of iron and steel metallurgy technology, structural parts such as columns and beams of steel structures have put forward new requirements for steel plate strength, fire and disaster resistance, corrosion resistance, and earthquake resistance, while ordinary steel structures are poor in the construction industry. The ability to resist fire, disaster and corrosion is facing a severe test. In recent years, metallurgists at home and abroad have actively carried out research on fire-resistant, weather-resistant, and earthquake-resistant steels. The use of fire-resistant and weather-resistant steels can not only make up for the shortcomings of ordinary steel stru...

AI Technical Summary

Problems solved by technology

However, it is mainly researched and developed for steel for railway vehicles. It is produced by hot rolling and coiling process. The steel contains a large amount of Cr element, which is not conducive to steel plate welding and low temperature toughness. In addition, the steel type does not have fire resistance

It also cannot meet the development requirements of structural parts such as columns and beams of steel structures.

[0008] In addition, Chinese Invention Patent Publication Nos. CN103695772A and CN103695773A respectively disclose "Steel for Refractory, Weather-resistant and Earthquake-resistant Construction with a Yield Strength of 550MPa and its Production Method" and "Steel for Refractory, Weather-resistant and Earthquake-resistant Construction with a Yield Strength of 690MPa and its Production Method", respectively. These two inventions are steel for construction, which contain C, Si, Mn, P, S, Nb, Ti, Mo, W, Mg, O, in addition to Sb or Zr or a mixture of two of them in any proportion, and the rest are Fe and unavoidable inclusions; processes such as desulfurization of molten iron, converter smelting, vacuum treatment, addition of Mg elements, conventional continuous casting and heating of the slab, segmental rolling, and cooling after final rolling, but the invention contains more High Mo content leads to higher cost of the alloy, and contains more Mg, Sn or Zn elements, which easily form large complex inclusions in the steel, which reduces the low temperature toughness, welding performance and corrosion resistance of the steel. It cannot meet the development requirements of steel structure columns, beams and other structural parts

Images