Effect of Zinc Bath Compositions on Formability of Galvannealed Coatings
장세기Seky Chang, 최영민Young Min Choi
Abstract
Hot dip galvannealed coatings on steel sheet were evaluated with respect to minor additions of aluminum, lead or antimony in the zinc bath. The decrease of aluminum content in the bath increased alloying rate of the coating and promoted the growth of Gamma phase(Fe₃Zn_(10)) to deteriorate powdering resistance of the galvannealed coating. The variation of lead content in the bath did not noticeably change galvannealing behavior of the coating, but powdering resistance was deteriorated with lead addition. On the other hand, alloying rate of the coating increased with antimony addition, which inversely affected powdering resistance of the coating. The use of antimony tended to change a distribution of aluminum in the coating which influenced the zinc-iron allaying reaction at the interface of the coating and steel sheet.