Monitoring of the condition and development of package systems for continuous hot-dip galvanizing of thin-sheet steel products

Abstract

The paper discusses the technical features of modern package systems for continuous hot-dip galvanizing, a distinctive feature of which is a module layout that not only ensures the timely replacement of breaking down individual sections of a continuous line, but also allows to enter/withdraw the equipment in the manufacturing process as needed, which makes it possible to produce the strip with different types of coatings on the same machine. The analysis of the main types of alloys used for hot-dip galvanizing has shown that coatings of all four types of alloys are used for products undergoing cold deformation and cold stamping. It is advisable to coat multi-phase steels for cold deformation with coatings based on Zn, ZnFe or ZnAl. The ability to deform and weldability of products is higher, the greater the thickness of the coating. Consequently, coatings based on ZnFe and ZnAl alloys with a thickness of 18.0 microns and 19.3 microns are suitable for deformable and welded products. To reduce the cost of galvanized metal by reducing the consumption of expensive zinc, one-sided galvanizing of steel sheet is promising. The chemical compositions and applications of the four most widespread zinc-based coatings, namely zinc, zinc-iron, zinc-aluminum and aluminum-zinc, are considered. It is indicated that on modern hot-dip galvanizing lines, the coating on the strip is applied from two sides. However, technologies for unilateral application of zinc coating on a steel strip are currently being developed, the use of which will reduce the consumption of expensive zinc and, consequently, the cost of finished products. Some effective methods and devices for one-sided galvanizing are presented and described