[hot-dip galvanizing Summit] galvanized products have become the only way for the survival and development of iron and steel enterprises.

SMM10 March 20: at the 2020 China International Hot Dip galvanizing Technology and Market Application Development Forum held by SMM, Professor Gao Bo of Northeastern University brought the keynote speech "Research Progress of Hot Dip Alloying of Steel Plate".

Gao Bo said that several commercial multi-alloy coatings include Zn-55Al-1.6Si coating (Galvalume), Zn-5Al-0.1RE coating (Galfan), Zn-23Al-0.3Si coating, Zn-4.5Al-0.1Mg coating (Superzinc), Zn-11Al-3Mg-0.2Si coating (Super Dyma), Zn-0.5Mg coating (DYMAZINC), Zn-6Al-3Mg coating (ZAM). The above seven kinds of coatings have been produced on a large scale and have been developed by foreign iron and steel companies, but they are protected by foreign patents.

Among them, the Zn-5%Al-0.1%RE alloy coating developed by (CRM) of Liege Metallurgical Research Center in Belgium was funded by the International lead and Zinc Research Organization in the 1980s, and its trade name is Galfan. The composition of the coating is developed by adding rare earth elements to the eutectic structure of Zn-5%Al system with a melting point of 380C. The purpose of adding 0.1%RE (mixture of cerium, lanthanum and rare earth) to the alloy bath is to reduce the surface tension of the bath and improve the wettability of the bath to the steel substrate, so as to improve the phenomenon of plating leakage.

The Galfan coating has layered structure, and there is no brittle alloy layer between the substrate and the coating, which makes the coating have high corrosion resistance, excellent formability and paintability. its corrosion resistance is 2-3 times higher than that of ordinary galvanized coating, and its formability is better than that of other hot-dip galvanized coatings, which is equivalent to that of electrodip galvanized coating. This coating is mainly used for continuous hot-dip galvanized sheet and galvanized steel wire. The phenomenon of coating cracking and spalling will not occur during bending, stamping and deep drawing of Galfan coated steel plate, so it is widely used in automobile, home appliances, construction and other fields.

Comparatively speaking, the development of iron and steel galvanizing industry in China lags behind relatively, and the products are mainly hot-dip galvanized steel. In addition, the complete sets of equipment and technology of hot-dip galvanizing are mostly imported from abroad.

China's iron and steel output has ranked first in the world for more than ten years in a row, but it has been faced with the situation of overcapacity. There is no obvious profit in the production of ordinary steel, even facing the embarrassing situation that the more the production, the more serious the loss. The production of high-quality, high value-added, competitive advantage products (such as galvanized products) has become the only way for the survival and development of iron and steel enterprises.