REACTION BETWEEN SILICON-CONTAINING STEEL S AND LEAD-ZINC MELT

Fe specimens containing 0.3-0.9 mass% Si were annealed in Pb-Zn melt a t 733K. Formation and growth kinetics of Fe-Zn alloy layer on the surf aces of the specimens was examined. A Fe-Zn alloy layer with a continu ous and protective structure was formed in the melt containing less th an 40 mass% Zn. The Fe-Zn alloy layer consists of delta(1) and zeta ph ases, its thickness increases with annealing time according to a parab olic rate law. A fragmentary delta(1) layer composed of small discrete delta(1) crystals embedded in a matrix of the eta phase was formed in the melt containing more than 40 mass% Zn. Although a coherent delta( 1) layer exists between the fragmentary delta(1) layer, and the substr ate of the specimen, its thickness is very thin. The Pb-Zn layer on th e surface of the alloy layer can be removed if the specimen is immerse d in pure Zn melt, but the fragmentary delta(1) layer is formed after a short time immersion even though the Fe-Zn alloy layer with the cont inuous and protective structure previously exists on the surface of th e specimen.