Kinetics of growth and structure of coatings obtained on sandelin steels in the high-temperature galvanizing process

In the paper the author presents the results of tests defining the characteristics of behaviour of Sandelin steel in the high-temperature galvanizing process. The growth kinetics of hot-dip zinc coatings on the substrate of 0.05% Si steel in the temperature range of 540-580°C has been established. The structure of the coatings and their phase composition have been developed and the chemical composition of structural components of the coating has be defined. It has been determined that the coating is composed of a compact layer d1 and an area of a two-phase mixture of δ1 and Zn. The conducted tests confirmed the presence of phase G1, which does not form a continuous layer but it forms individual precipitates which are irregular in shape. The growth kinetics of the coating indicates that an increase in temperature causes a decrease in the coating thickness, which might prove that dissolving processes prevailed over the processes of diffuse coating growth.