Batch Hot Dip Galvanized Coatings,Batch Hot Dip Galvanized Coatings,Batch Hot Dip Galvanized CoatingsHOT DIP GALVANIZING is a process in which an adherent, protective coating of zinc and zinc/iron compounds is
developed on the surfaces of iron and steel products by immersing them in a bath of molten zinc. The protective coating
usually consists of several layers (Fig. 1). Those closest to the basis metal are composed of iron-zinc compounds; these, in
turn, may be covered by an outer layer consisting almost entirely of zinc.
The complex structure of layers that comprise a galvanized coating varies greatly in chemical composition and physical
and mechanical properties, being affected by chemical activity, diffusion, and subsequent cooling. Small differences in
coating composition, bath temperature, time of immersion, and rate of cooling or subsequent reheating can result in
significant changes in the appearance and properties of the coating.
Hot dip galvanized coatings are produced on a variety of steel mill products, using fully mechanized, mass production
methods. This article, however, is concerned primarily with the hot dip galvanizing of fabricated articles in manual or
semiautomatic batch operations. For information about continuous coatings, see the article "Continuous Hot Dip
Coatings" in this Volume.
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