Yield strength is 550mpa grade refractory and weather-resistant earthquake-resistant construction steel and its production method

Abstract

The invention relates to a 550MPa-yield-strength fire-resistant weather-resistant earthquake-proof construction steel which comprises the following components in percentage by weight: 0.041-0.125% of C, 0.31-0.62% of Si, 1.81-2.40% of Mn, at most 0.008% of P, at most 0.002% of S, 0.041-0.065% of Nb, 0.007-0.020% of Ti, 0.41-0.63% of Mo, 0.07-0.10% of W, 0.0071-0.0098% of Mg and at most 0.0012% of O. The production method comprises the following steps: desulfurizing molten iron; smelting in a converter; carrying out vacuum treatment, and adding the Mg element; carrying out conventional continuous casting, and heating the casting blank; carrying out sectional rolling; and carrying out finish rolling, and cooling for later use. The steel has the following advantages: the chemical components and technique are simple, the yield strength of the steel plate is 550-700MPa, the earthquake-proof property is good (the yield-tensile ratio is at most 0.83), the fire resistance is favorable (the yield strength at 600 DEG C is not lower than 2 / 3 of that at room temperature), and the corrosion resistance is better than CortenB. Besides, the steel grade has excellent impact toughness and weldability.

Description

technical field [0001] The invention relates to a steel for construction and a production method thereof, in particular to fire-resistant, weather-resistant and earthquake-resistant construction steel with a yield strength of 550 MPa and a production method thereof. Background technique [0002] With the rapid development of high-rise steel structure buildings, new requirements have been put forward for steel plates used to make structural parts such as columns and beams in terms of strength, fire resistance, weather resistance, and earthquake resistance. This is because: the use of high-strength steel can Improve the strength grade of structural steel to avoid quality problems in the subsequent processing and welding process due to excessive steel thickness. At the same time, it can also reduce structural weight, reduce construction costs, reduce steel waste, and improve structural reliability; The damage to the structure caused by factors such as fire and earthquake can pr...

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Problems solved by technology

This document refers to a steel grade with a strength of 490 MPa. The elemental composition relationship in the steel is complicated, contains more precious elements such as Cu, Cr, and Ni, and does not have obvious fire resistance. After rolling, the steel plate needs to be kept at 300°C for at least 24 hours, which undoubtedly prolongs the production time and increases the process cost, which is not conducive to mass production

In addition, the content of P in the steel is relatively high, and it contains martensite structure, and martensite is an unstable structure, which can adversely affect the extension, bending, and impact toughness of the steel plate.

[0005] Common deficiencies in the above patent documents: the steel grades are relatively low in strength; steel plates do not have fire resistance and weather resistance at the same time;

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