Avoiding corrosion between steel, stainless steel and aluminium alloy

[drodrig]

Hi everyone,

We are building a support which is composed by 3 parts:

- A mounting plate in aluminium alloy 5083
- A horizontal arm in stainless steel 304
- A base in structural steel S275

This will be placed in a hall with a life expectancy of 20-30 years. There is not an aggressive atmosphere.

I am worried about the galvanic corrosion between the different parts. We will use positioning pins and screws to put everything together.

I see two problems: the corrosion between the main parts and the corrosion in the fasteners.

How can we avoid the corrosion? shall we use some "barrier" between the components?

Attached some pictures

thank you
regards,

 

[EdStainless]

If it is kept dry there will be no issues.
At least sealing so that moisture cannot get between the materials would be good precaution.
How much of it will be painted?

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P.E. Metallurgy, Plymouth Tube

 

[drodrig]

Won't be the moisture a problem??

How can we seal? Applying some layer (of paint?) in the joint once it is screwed?

We can paint as much as we want (as much as needed)

thanks

 

[EdStainless]

I would consult with a coating supplier, you may need different primers for different metals.
I presume that the SS will be left bare? Why else would you ever use SS.
I have seen joints like this sealed around the edges with a special sealant that is meant to be painted over, then the whole thing painted.

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P.E. Metallurgy, Plymouth Tube

 

[moltenmetal]

The aluminum to stainless joint won't be a problem for the aluminum or the stainless steel.

The stainless to carbon steel joint won't be a problem for the carbon steel, unless you're already in an environment aggressive to carbon steel.

Coat the carbon steel with something truly durable, and don't worry about it.

 

[drodrig]

Hi,
thanks for the answers.

Everything is more clear now

We use stainless steal because we are in a magnetic field and we can not disturb it

cheers,