Effect of the silicon content in steel on the hot-dip zinc coating microstructure formation

• Published in: IOP conference series. Materials Science and Engineering 2016-11, Vol.156 (1), p.12015
• Main Authors: Bondareva, O S, Melnikov, A A
• Format: Article
• Language: English
• Subjects: Contact melting; Decomposition reactions; Eutectic decomposition; Eutectic reactions; Hot dip coating; Hot dip galvanizing; Immersion coating; Iron silicide; Silicon; Substrates; Thickness; Zinc coatings
• ISSN: 1757-8981; 1757-899X
• DOI: 10.1088/1757-899X/156/1/012015

The aim of this study was to clarify the effect of the silicon content in steel on the structure of hot-dip galvanized zinc coating. It was found that in steel samples containing the silicon in an amount of about 0.1% and 0.5% the increased thickness coating was formed. This fact was associated with structural features of the ζ-phase. Energy dispersive microanalysis had shown the maximum concentration of silicon in the coating was observed in ζ-phase on St3 steel (Si = 0.1%) and in the fine mixture of δ and ζ-phase on 09G2S steel (Si>0.5%). This phenomenon was analyzed using a Zn-Fe-Si system diagram and its polytermic sections. It was found that there were eutectic reactions of decomposition the liquid to mixture (ζ+η+ FeSi) phases at the content of silicon in steel about 0.1% and more than 0.5%. Particles of FeSi-phase were involved in the dissolution of and δ phases, which led to a direct contact of the melt and the steel substrate. This process was accompanied by the intensive ζ-phase formation and the rapid growth of coating thickness.