galvanic corrosion

[sollapalooza]

Hello, galvanic corrosion usually occurs when 2 different metals in contact, however does it also occurs over same materials with different ASTM code?
For example: saddle and pressure vessel shell connection;
Shell is using SA-516 Gr 70 but saddle is using SA 36.
Thanks!

 

[EdStainless]

Usually not, it takes a few hundred mV potential difference to drive most galvanic corrosion.
The same alloy in different HT conditions usually will not behave that differently, especially CS.

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P.E. Metallurgy, Plymouth Tube