Galvanic corrosion testing standard!

[var10]

Hi,

I would like to know if there are any mil standards for testing galvanic corrosion between dissimilar metals. I was going to try salt spray and thought if I could validate the testing to mil spec it would be good.

Thanks,

V.

 

[EdStainless]

salt spray has nothing to do with galvanic corrosion.
There is no spec that I am aware of that deals with a galvanic couple or dissimilar metal crevice corrosion.

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Plymouth Tube

 

[var10]

Thank you EdStainless. Was under the impression salt spray speeds up corrosion while water is the electrolyte between my stainless steel screw and 6061 aluminium alloy. When I screw the bolt it scratches the conversion coating applied on the aluminium and had a feeling that now it has no layer of segregation between the two metals, this could result in galvanic corrosion. And doesn't conductivity increase in salt water?

I did find Mil-std-889B but not very useful.

 

[TVP]

There are a number of accelerated lab corrosion tests that are used for evaluating materials and assemblies, including joints with threaded fasteners. SAE J2334 (2003-12) Laboratory Cyclic Corrosion Test is one such test, and it uses the following conditions:

1. Humid Stage—50 °C and 100% humidity, 6 h in duration,
2. Salt Application Stage—15 min duration conducted at ambient conditions
3. Dry Stage—60 °C and 50% RH, 17 h and 45 min in duration

This sequence is then repeated for a number of cycles, typically between 60 and 80, to simulate years of automotive exposure.

 

[swall]

One galvanic corrosion test that I am aware of is in SAE J1703, which is the spec for automotive brake fluid. Test strips (available from SAE) made from tinned iron, bare steel, bare aluminum, brass, copper and zinc are bolted together and immersed in brake fluid with 5% water. It is obviously a very specific test and undoubtedly took years to develop. Such is often the case to meet specific needs. Ditto for the cyclic corrosion tests (such a s mentioned by TVP).