Fire-resistant weather-proof steel plate for 690MPa-grade building structure and manufacturing method thereof

Abstract

The invention relates to the technical field of fire-resistant weather-proof steel plates for building structures, in particular to a fire-resistant weather-proof steel plate for 690MPa-grade buildingstructure and a manufacturing method thereof. The steel plate consists of the following chemical components in percentage by weight: 0.05%-0.10% of C, 0.10%-0.40% of Si, 1.20%-1.80% of Mn, less thanor equal to 0.010% of P, less than or equal to 0.003% of S, 0.7%-1.1% of Ni, 0.65%-1.10% of Cu, 0.20%-0.60% of Mo, 0.07%-0.12% of Nb, 0.05%-0.075% of V, 0.02%-0.035% of Ti, less than or equal to 0.0025% of B, 0.01%-0.04% of Al, and the balance of iron and inevitable impurities. The fire-resistant weather-proof steel plate adopts a two-phase region once thermal treatment process to obtain a reversetransformed austenite structure which is proper in proportion and stable, so that a multi-phase structure which consists of tempered-state martensite, a nano precipitated phase and retained austeniteis finally obtained. A smelting and continuous-casting process scheme realizes low-phosphor low-carbon control. The product has high strength and toughness, high plasticity, a low yield ratio, and excellent fire resistance, weather resistance and lamellar tearing resistance.

Description

technical field [0001] The invention relates to the technical field of fire-resistant and weather-resistant steel plates for building structures, in particular to a fire-resistant and weather-resistant steel plate for 690MPa-level building structures and a manufacturing method thereof. Background technique [0002] Construction steel accounts for more than 50% of steel production (mainly rods and wires), while my country's steel structure steel (steel plate and section steel) only accounts for 5%-6% of steel production. At present, the yield strength of domestic construction steel is generally 460MPa Next, the poor fire and disaster resistance and corrosion resistance of ordinary steel structures in the construction industry are facing severe tests. With the development and construction of high-rise buildings and key projects, the demand for high strength, long life and safety of building structural steel is becoming more and more urgent, and higher requirements are put forwa...

AI Technical Summary

Problems solved by technology

[0004] The complexity and diversity of technical features and indicators have significantly increased the difficulty of research and development of fire-resistant and weather-resistant steel for 690MPa-level building structures

First of all, the increase in the strength of the steel plate will increase the rolling deformation resistance, limit the deformation rate of the pass, and double the difficulty of grain refinement and control, while the increase in the thickness of the steel plate will lead to an increase in the temperature gradient of the thickness section and deteriorate the cooling and cooling in the thickness direction. Microstructure uniformity; secondly, the low yield ratio requirement of the steel plate will also intensify the strength-toughness contradiction, further increasing the difficulty of performance control

[0005] CN1354273A discloses "a kind of high-performance refractory and weather-resistant construction steel and its production method". Low

CN201110247615.0 discloses "a fire-resistant and earthquake-resistant building steel". This invention is limited to steels with a yield strength of 235-460 MPa. Does not have good weather resistance

CN103695773A discloses "the yield strength is 690MPa grade refractory, weather-resistant and earthquake-resistant construction steel and its production method". The steel alloy is added with W and Zr, which has high composition and high cost; in order to improve the strength, the Mn content is relatively high, so its welding The performance has been affected to a certain extent. The test is the impact energy at -20°C. Therefore, its impact toughness needs to be further verified at lower and more severe temperatures.

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