Abstract
The alloy phases of the galvanized steel have been examined in order to clarify the effect of phosphorous added in the steel substrate on the galvannealing behavior. SEM observation have revealed that the density of the ζ-ZnFe crystal decreases and that the size of the ζ-ZnFe crystal becomes large as a function of the P content in the steel. The amount of the Al-Fe alloy as an inhibition layer for the alloying between Fe and Zn have been increased as a function of the P content. The Al-Fe alloy layer has been observed by TEM. AES and XPS analyses have revealed that P in the steel segregates to the surface of the steel and that the amount of segregated P increases as a function of P content of the steel. P has been also detected in the Al-Fe alloy layer for the steel having a high P content. The results suggest that the alloying between Fe and Zn is suppressed because the amount of the Al-Fe alloy inhibition layer increased. Therefore the number of the nucleation site of the ζ-ZnFe crystal can be reduced, because the Al-Fe alloy is altered for the phosphorus added steel.
