Batch galvanizing of silicon killed steels

he formation of reactive coating structures during hot dip batch galvanizing of silicon killed steels has long been a problem for industrial galvanizers. The worldwide significance of the problem was recognized when large volumes of continuously cast steel began to be produced. This steel, of course, contains residual levels of silicon which cause extreme modifications to the coating structures formed during galvanizing. The nonmonotonic behavior of coating thickness as a result of silicon variation in the steel was first recognized by Sandelin in 1940. It was shown that coating thickness depended on the morphology of the layers which make up the galvanized coating. Sandelin reactivity is a term used to describe the modification of stable coatings, which are made up of uniform layers of the Fe-Zn intermetallics, to thick irregular coatings made up of a mass of zinc penetrated ;The aim of the present work was to gain a better understanding of the galvanizing reaction on silicon killed steels through investigation of surface effects, phase equilibria in the Fe-Zn-Si system, and the kinetics of coating formation. With a thorough knowledge of these aspects of the reaction we were able to modify the model for the formation of the reactive structures on Sandelin peak alloys and explain in a consistent manner the mechanism of formation of the zinc penetrated...