Weathering steel and manufacturing method thereof

Abstract

The invention discloses weathering steel, which comprises the following chemical compositions in percentage by weight: 0.06 to 0.12 percent of C, 0.20 to 0.40 percent of Si, less than or equal to 1.6 percent of Mn, 0.08 to 0.22 percent of P, less than or equal to 0.008 percent of S, 0.01 to 0.06 percent of Al, 0.20 to 0.80 percent of Cu, 0.40 to 0.75 percent of Cr, 0.12 to 0.40 percent of Ni, 0.001 to 0.006 percent of Ca and the balance of iron and inevitable impurity elements. The weathering steel is manufactured by a thin strip continuous casting process. The manufacturing process comprises the following steps of: performing deep desulfurization on molten steel, performing composite blowing on the top and bottom of a converter, performing RH vacuum circular degassing process, and simultaneously performing calcium treatment; performing twin-roll continuous casting, and making the temperature of the molten steel in a molten bath not lower than 1,535DEG C; controlling rolling in the reduction ratio of not less than 30 percent; controlling cooling at the speed 30 to 50 DEG C/s; and coiling at the temperature of between 600 and 650 DEG C. The weathering steel of which the texture is acicular ferrite has good weatherability and can be widely applied to structural materials.

Description

technical field [0001] The present invention relates to weathering steel and its manufacturing method, in particular to weathering steel with acicular ferrite and its manufacturing method. Background technique [0002] In the field of engineering, the commonly used structural materials are generally carbon steel and low alloy steel after microalloying. These steels have excellent mechanical properties and low market prices, but are prone to rust in atmospheric environments. When these steels are exposed to the atmosphere for a long time, they will react chemically or electrochemically with water vapor, oxygen, carbon dioxide, sulfur dioxide, etc. in the atmosphere, resulting in corrosion of steel materials. The metal equipment and materials scrapped due to corrosion every year in the world account for about 20-40% of the annual metal output, and the metal loss due to corrosion reaches more than 100 million tons. According to the statistics of some developed industrial coun...

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Problems solved by technology

[0006] (1) Long process flow, high energy consumption, many units and equipment, and high infrastructure costs lead to high production costs

[0007] (2) There are many quality defects, and the yield is low. Weathering steel contains relatively high content of phosphorus and copper and other elements that are easy to segregate. Due to the slow solidification and cooling speed of the traditional process, it is easy to cause local macro-segregation of phosphorus, copper and other elements, thus Lead to the anisotropy of the slab and the appearance of macroscopic cracks, and the yield is low

[0008] (3) The weather resistance is not high, and the weather resistance of weather-resistant steel mainly depends on the joint action of phosphorus and copper in the steel

However, there are no Cu, Cr, Ni and other elements added to the steel composition of this document, which does not belong to the category of weathering steel

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