416 SST versus 304 SST in corrosion

[drax]

We had some .50" Dia. shafts made out of 416 SST, now we make them from 304 SST. What is the extent of corrosion protection with the 416 SST material? I really would not want to recall the 416 ones it all depends on the corrosion protection on how it stack ups againest 304. The shaft would be exposed to water/rain typically and maybe some brackish water. Does anyone know the rate of corrosion or how it compares to 304 and how it stacks up againest mild steel?

thanks in advance

 

[mcguire]

416 isn't very close to 304 in corrosion resistance. It has only 12 Cr and some of that will be wasted as Cr23C6. It also has that nasty high sulfur.
In stainless we don't really talk of corrosion rates because you typically chose the stainless so that no corrosion occurs. That will be the case for the 304. I'm afraid the 416 will see significant corrosion, first pitting and then pretty general corrosion. Sorry.