Sandblasting-free, directly-coated and weathering-resistant steel and production method thereof

Abstract

The invention discloses a sandblasting-free, directly-coated and weathering-resistant steel and a production method thereof. The steel comprises the following chemical components in percentage by weight: 0.04-0.12 percent of C, 0.20-0.50 percent of Si, 0.25-0.5 percent of Mn, less than or equal to 0.008 percent of S, less than or equal to 0.03 percent of P, 0.25-0.45 percent of Cu, 0.30-0.60 percent of Cu, 0.20-0.50 percent of Ni, 0.015-0.025 percent of TI, less than or equal to 0.03 percent of Als and the balance of iron and inevitable impurities. The protection method comprises the following steps: converter smelting, refining, continuous casting, heating, rolling, controlled cooling, reeling and finishing, wherein the controlled cooling is laminar flow cooling and adopts front section pulled cooling, and the concentration of Cl in laminar flow circulating cooling water is less than or equal to 100 mg / L; the reeling temperature is controlled to be 540-560 DEG C; a flatting roll is used for flatting, the surface textured roughness of the flatting roll Ra is 50-100 <mu>m, RPc is 45-70 pcs / cm, and the reduced quantity of the strip steel is 1-4 percent. The sandblasting-free, directly-coated and weathering-resistant steel has good weathering resistance, can be directly coated without a sand blasting pretreatment process, has a strong coating adhesion force and has low probability of falling off.

Description

technical field [0001] The invention relates to the field of iron and steel metallurgical materials, in particular to a weather-resistant steel directly coated without sandblasting and a production method thereof. Background technique [0002] Iron and steel products are exposed to the air for a long time during service, and are easily corroded and gradually destroyed by moisture, gas, microorganisms, and ultraviolet rays in the environment. Adding weather-resistant elements such as Cu, Ni, Cr, and Mo to steel or Coating coating of iron and steel products is two important means of anticorrosion of iron and steel materials. Among them, the quality of coating directly affects the performance of the coating, and also has a direct impact on the use value of the substrate. Studies have shown that the quality of steel surface pretreatment before coating is the main factor determining the protective performance of the coating. [0003] Before coating, the existing steel usually ne...

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Problems solved by technology

However, the sandblasting pretreatment has caused a lot of dust pollution in the production process, and the noise is loud, which seriously deteriorates the working environment; at the same time, the sandblasting pretreatment process increases the coating cost

[0004] At present, research on the direct coating of steel surfaces without sandblasting is mainly concentrated in the field of development and research of sandblasting-free coatings, which focuses on the research of coating technology and coatings. The scope of application is limited, and the coating quality often does not reach Requirement; In addition, CN102691004B discloses a kind of production method of exempt from sandblasting and shot blasting treatment container weathering steel, CN102690937A also discloses a kind of production method of thin specification exempt from sandblasting and shot blasting treatment of structural steel, these two The steels in this paper are formed by controlling the process parameters in the steel rolling process to form a dense Fe 3 o 4 The main oxide scale structure does not fall off during the forming process and provides a certain corrosion resistance. By adjusting the surface roughness Ra of the finishing stand rolls, it is hoped that the surface roughness of the steel plate can meet the coating requirements of the paint. However, in fact, during the hot rolling process, the surface of the roll is affected by alternating cold and heat, high temperature and high pressure, and the oxide film on the surface of the roll is in an alternating state of growth and wear. Under extreme conditions, the oxide film may even fall off. Therefore, the surface roughness of the hot roll It is difficult to maintain and achieve precise control. In addition, the disclosed Ra of 0.8-2.4 μm is far from the standard requirements of many coating applications

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