Low-aluminum low-magnesium zinc-aluminum-magnesium plated steel plate and method for producing same

Abstract

The invention provides a low-aluminum (Al) low-magnesium (Mg) zinc (Zn)-aluminum-magnesium plated steel plate and a method for producing the low-Al low-Mg Zn-Al-Mg plated steel plate. After a steel plate is annealed in nitrogen (N2) containing 0.5-30vol% of hydrogen (H2), the steel plate is impregnated with a plating solution, wherein the temperature of the plating solution is 40-120 DEG C above zero (the melting point of a zinc alloy); before the steel plate is impregnated with the plating solution, the temperature of the plating solution ranges from impregnating temperature to impregnating temperature + 50 DEG C above zero; the steel plate is impregnated with the plating solution for 2-10 seconds, and the steel plate is cooled at the speed of 10-50 DEG C per second after being impregnated with the plating solution; the plating solution comprises the following chemical components: 1.0-2.4% of Al and 1.0-2.0% of Mg, wherein the ratio of the Al to the Mg is more than or equal to 1; the plating comprises the following chemical components: 1.0-2.4% of Al and 1.0-2.0% of Mg, wherein the ratio of the Al to the Mg is more than or equal to 1, and Fe is less than or equal to 1%; the plating is formed by a Zn-rich phase, an Al-rich phase, MgZn2 and eutectic structures thereof; the thickness of an Fe-Al intermetallic compound between the plating and the steel-based interface is not more than 0.5mu m; and the content of Mg in the surface of the plating of every 1mu m is not less than 2%. The Zn-Al-Mg plated steel plate provided by the invention has good corrosion resistance, toughness and weldability, and the process for preparing the Zn-Al-Mg plated steel plate is simple and is suitable for industrial production.

Description

technical field [0001] The invention belongs to the field of hot-dip galvanizing, and in particular relates to a production method of a low-aluminum and low-magnesium zinc-aluminum-magnesium coated steel sheet and the coated steel sheet. Background technique [0002] In the field of hot-dip galvanizing, in order to improve the corrosion resistance of galvanized steel, zinc 5% aluminum 0.06% rare earth alloy coated steel (trade name Galfan), zinc 55% aluminum 1.6% silicon alloy coated steel (trade name Galvalume), but the zinc 5% aluminum 0.06% rare earth alloy only improves the corrosion resistance by 2 to 3 times. Although the zinc 55% aluminum 1.6% silicon significantly improves the corrosion resistance, it loses the cathodic protection performance of zinc. ZL00811491.9, ZL01804732.7, CN101812653A, CN101812654A, US6235410B1, TW201114946A, ZL200310119444.9 and other zinc alloy coated steel sheets containing aluminum and magnesium with good comprehensive performance, not onl...

AI Technical Summary

Problems solved by technology

The uniform distribution of aluminum and magnesium in the patented coating also cannot give full play to the role of aluminum and magnesium in improving the corrosion resistance of the coating, and the steel plate needs to be pre-plated with nickel before hot-dip plating, which not only increases the cost, but also increases the complexity of the process

To sum up, when the content of aluminum and magnesium is high, the corrosion resistance of the coating is better, but the toughness and weldability decrease; when the content of aluminum and magnesium is low, the corrosion resistance of the coating decreases

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