Reaction between S35C and Liquid Zinc

Abstract

To study the effect of alloying element in steel on the reaction between solid iron and liquid zinc, S35C samples were immersed into pure molten zinc for 60-6 000 s in the temperature range of 713 K-873 K. Structure and thickness of alloy layers were examined. Iron mass loss, iron dissolved into the zinc bath and iron remained in the alloy layer, were measured. The results are as follows :
(1) The alloy layer consists mainly of (i) ζ layer at 713 K-753 K, (ii) (δ₁+η) mixture layer at 773 K-813 K, and (iii) δ₁, layer at 833 K-873 K. In the alloy layer, rows of Fe₃ZnC particles are found in the direction perpendicular to the steel/alloy layer interface.
(2) In the temperature range of above-mentioned (i) and (ii), the alloy layer thickness decreases as immersion temperature increases. In these temperature range, the alloy layer contains liquid zinc and grows faster.
(3) Iron remained in the alloy layer depends on the alloy layer phase, and iron dissolved into the zinc bath depends on the "drop off" of the alloy layer. The total loss of iron in determined by combination of these two reactions with zinc depending on immersion temperature.
(4) Though alloying elements in steel do not affect the Fe-Zn reaction in the temperature range of 773 K-873 K, they affect the formation and growth of the ζ layer and make the Fe-Zn reaction active below 753 K.