Hot-dip zinc aluminum magnesium silicon rare earth coated steel strips taking air as air source of air knife during production

Abstract

The invention relates to hot-dip zinc aluminum magnesium silicon rare earth coated steel strips taking air as an air source of an air knife during production. The coating material on the surface of the steel strips comprises the following components in percentage by weight: 9.9 to 12.1 percent of Al, 1.0 to 1.8 percent of Mg, 0.18 to 0.22 percent of Si, 0.01 to 0.3 percent of rare earth (RE), and the balance of Zn. Based on a quaternary component Zn-Al-Mg-Si in Nippon Steel, the rare earth (RE) comprising lanthanum and cerium is added into the coating material so as to become a quintuple component Zn-Al-Mg-Si-RE, and the content of the magnesium is reduced. Because of the addition of the trace RE, the component distribution of the coating can become more uniform, the organizational structure is more uniform, and the corrosion resistance is further improved based on the original corrosion resistance; and because the content of the magnesium is reduced properly, the coating can bear the blowing of the air knife and cannot be oxidized and discolored on the premise of ensuring high corrosion resistance, and meets the requirements of the corrosion resistance and apparent mass.

Description

technical field [0001] The invention belongs to the technical field of hot-dip galvanizing of steel strips, and in particular relates to a zinc-based alloy hot-dip steel strip whose coating chemical composition is different from that of the original hot-dip steel strip coating. Background technique [0002] The Zn-11%Al-3%Mg-0.2%Si (SUPERDYMA) hot-dipped steel plate invented by Nippon Steel in Japan and started commercial production in 2001 is currently the most corrosion-resistant hot-dip steel plate in the world. One of the plated plates is a hot-dip plate with the highest corrosion resistance in which the ratio of the two main elements Zn and Al in the coating is far from the ratio of the Zn-Al binary eutectic. The book "Modern Steel Strip Continuous Hot-dip Galvanizing" (Metallurgical Industry Press, first edition in January 2007), which is funded by the National Science and Technology Academic Works Publishing Fund, introduces this kind of hot-dip plate in detail. [0...

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Problems solved by technology

On the other hand, the higher the Mg content, the easier it is to cause poor appearance of the coating due to oxidation, which is difficult for customers to accept.