CT Corrosion 2

[bimr]

Ed,

Have you seen the numerous reports of stainless steel from the tesla cyber truck owners. Here is one today:

https://www.torquenews.com/11826/tesla-cybertruck-becomes-extensively-corroded-after-exposed-magnet

This doesn't appear to me to be a good application for stainless steel for numerous reasons.

 

[EdStainless]

304L with moderate cold reduction (20-25%) still has elongation over 25% and is profoundly magnetic.
To the point that to do Eddy Current Testing you have to run saturation coils.
It doesn't happen with 305, 309, 310 and some of the 200 (Nitronic) alloys.
It is a matter of the chemistry, and the Ni is so low in most grades that they are only meta-stable austenite.

 

[dik]

You could likely run some form of catalytic protection using the electric features of the vehicle.

 

[TugboatEng]

Cathodic? That only works if the vehicle is submerged in an electrolyte.

 

[MintJulep]

Rail cars made of 200 SS have been in service for decades, so it isn't the material per se.

301L and 304L have been used for rail cars since the 1950's.
201LN is more recent.

 

[dik]

Cathodic? That only works if the vehicle is submerged in an electrolyte.

I figured there had to be some sort of moisture to initiate most of the corrosion.

 

[TugboatEng]

Corrosion and cathodic protection are the same processes with the polarity reversed. They require the same conditions to exist. In the case of galvanizing where the, yes the metal is protected in moist environments. However, when there are discrete anodes, an very strong electrical connection is required which means it only works with full immersion.