On 08/03/2014 12:29, MattyF wrote:
On Sat, 08 Mar 2014 08:41:09 +0000, harryagain wrote:

Yes it will corrode in the absence of air but it's not a problem in your
case is it?

The plates will be against the timber, thus an absence of air...

Unless you are planning to keep the timbers permanently under water,
enough air will get to the steel to keep the surface film of chromium
oxide intact.

Colin Bignell