
KAWANO Takashi HAMADA Etsuo SATO Kaoru
Focused ion beam (FIB) is a powerful technique for nano-level analysis on local structures of material surfaces, because it allows us to make a sample of the specific point on sample surfaces. In this paper, the results of cross-sectional analysis of steel surfaces using FIB are presented. It is revealed that the promotion in galvannealing reaction on the thiourea treated P-added steel is due to the formation of fine grain structures in surface region caused by a pinning effect of (Mn, Fe)S particles formed during annealing. It is found that initial alloys formed in the galvanizing processes on Si-added steel have partly peculiar shape and phase. It is suggested that these initial alloys prevent the following galvannealing reaction.