A question about Iron/Zinc alloys during hot dip galvanizing. 2

[michaelbeijer]

I am not sure if this is the right place for this, but I have a question about 'hot dip galvanising'.

I am translating a text from Dutch into English, and the following is what I have so far for a certain section of my text:

'Hot dip galvanising is a galvanising process that aims to protect steel against corrosion. If this layer is pierced, the zinc acts as a sacrificial anode so that the iron is protected by the zinc (this is also known as ‘cathodic protection’). During galvanisation, three alloys are formed: first of all an iron-zinc alloy, followed by a zinc-iron, and a zinc alloy.'

I am not so sure the last sentence makes sense. Can someone with actual experience in the field of hot dip galvanising tell me whether this makes sense?

The Dutch text says that 'During galvanisation, THREE alloys ('drie legeringen') are formed: first of all an iron-zinc alloy, followed by a zinc-iron alloy, and a zinc alloy.''

This is the Dutch:

'Bij het verzinken worden drie legeringen gevormd een eerste ijzer-zink, een tweede zink-ijzer en een derde zink.'

I don't entirely understand the difference between the first two, and the third is surely not an alloy if it consists of only zinc?
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Is my Dutch text wrong, or am I misunderstanding something here about these THREE alloys that are formed during the galvanisation...?

I think it might be that the author is referring to the fact that as you proceed with the hot dip galvanising process, from the inner layer to the outer layer, the percentage of iron will decrease, until you are left with 100% zinc on the outside. So, in effect, two alloys are created, and one pure zinc layer (not three alloys).

Might it not be better to translate this as:

'During galvanisation, three layers are formed, each with an increasingly lower concentration of iron: first of all an iron-zinc alloy, followed by a zinc-iron, and finally a layer of pure zinc.'

Michael

 

[stanweld]

The galvanizing bath may not be pure zinc, could by a zinc-aluminum alloy so the final "pure zinc" layer would not be true.

 

[TVP]

Michael,

Here is a good technical description of the coating that forms during hot-deip galvanizing, including an image of the microstructure:

http://www.galvanizeit.org/about-hot-dip-galvanizing/what-is-hot-dip-galvanizing/the-hdg-coating

 

[michaelbeijer]

Thanks guys,

I think I understand what is going on now, especially after reading the great description posted by TVP!

Michael

Michael Beijer
Translator & Terminologist
(Dutch/Flemish into English)