Improving the Quality of the Coating at Hot-Dip Galvanizing of Machine Steels in the Zinc Melt with Microadditives of Nickel

Abstract:

The technology of microalloying zinc melt by nickel is widely used to control the thickness of the zinc coating when the machine steels are subject to hot-dip galvanization. However, in some cases inclusions of Ni-Zn-Fe dross are formed on surface of the products, which leads to their deterioration. The aim of this work is to investigate the microstructure, mechanism of formation and elemental composition of this dross. Conditions for the formation of different phases in the coating were analyzed using Ni-Zn-Fe ternary diagram. It was found that Ni-Zn-Fe dross is a ζ-phase containing about 0.5 at. % nickel and isomorphic with FeZn13-phase. The main reasons for the formation of Ni-Zn-Fe dross are Zn-Fe contamination in the melt, the excess nickel concentration (more than 0.06 at.%), and the irregular nickel concentration in the melt. Methods for preventing this type of defects in hot-dip galvanization have been proposed.

• Periodical: Key Engineering Materials (Volume 685)
• Pages: 380-384
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.685.380
• Online since: February 2016
• Authors: Olga Bondareva, Alexey A. Melnikov
• Keywords: Dross Phase Formation, Galvanizing Baths, Hot-Dip Galvanizing, Iron Zinc Nickel Alloys, Machine Steel

References

[1] N.P. Lyakishev, Phase Diagrams of Binary Metallic Systems, Handbook in 3 volumes, Vol. 2, Engineering, Moscow. (1997).

[2] O.S. Bondareva, A.A. Melnikov, A.P. Amosov, Influence of Hot-Dip Galvanizing Temperature on Formation of Zinc Coating on a Steel with a High Silicon Content, Adv. Environ. Biol. 8 (2014) 943–948.

[3] G. Kong, J. Lu, J. Chen, Q. Xu, L. Liu, Review on progress of technigalva, Corrosion Science and Protection Technology. 13 (2001) 223-225.

[4] Z.W. Chen, J.B. See, Dross phases formed in galvanizing baths containing (0-0. 1) wt% nickel at 450°C, ISIJ International. 33 (1993) 307-312.

DOI: 10.2355/isijinternational.33.307

[5] E. Frank, M. Dubois, J.S. Kim, Zinc-based steel coating systems. Minerals, Metals & Materials Society, San Antonio, Texas. (1998).

[6] V. Raghavan, Fe-Ni-Zn (Iron-Nickel-Zinc), Journal of Phase Equilibria. 24 (2003) 569-560.

DOI: 10.1361/105497103772084642

[7] X.P. Su, N.Y. Tang, J.M. Toguri, Thermodynamic evaluation of the Fe-Zn system, Journal of Alloys and Compounds. 325 (2001) 129-136.

DOI: 10.1016/s0925-8388(01)01273-7

[8] S.M.A. Shibli, R. Manu, V.S. Dilimon, Effect of nickel-rich barrier layer on improvement of hot-dip zinc coating, Applied Surface Science. 245 (2005) 179-185.

DOI: 10.1016/j.apsusc.2004.10.007