Replies to post #29043 on The Rising Influence of Rising Affluence

[Mufaso]

Stainless steel does not readily corrode, rust, or stain with water as ordinary steel does, but it is not stain-proof, especially with low oxygen, high salinity (salt water), or poor circulation in the environment.

Yes and no. There are different grades of SST. I do a lot of work in the process industries in corrosive environments with corrosive chemicals. In one environment I had experience with there were a lot of airborne contaminants (including chlorine) present. I would always specify 316 SST for instruments housings etc. which contains 2% Molybdenum (316SST is more costly than 304SST). 316 SST has much better corrosion resistance than does 304 or 301 Stainless. In this environment a lesser grade just would not hold up and was worse than epoxy painted aluminum. (painted aluminum was a poor choice as CL2 reacts with aluminum and paint chips/scratches would invariably expose the aluminum). Tesla uses something they call 30X stainless in the Cybertruck. According to Barron's ( https://www.barrons.com/articles/tesla-cybertrucks-rusting-fixes-f10209fb )

The Cybertruck is made from what Tesla calls a 30X cold-rolled stainless steel. Breaking that down a little, cold rolling is a steel processing term that imparts strength. It’s a reason the Cybertruck is bulletproof.

The 30X stainless term is a shorthand, most likely, for a 300 series stainless steel. That’s a variety of stainless with set ranges of chromium and nickel that often include elements such as manganese. All steels have a base of iron and carbon. Tesla didn’t respond to a request for comment about the grade, processing, or rust issues.

Here is more info on various grades Stainless steel and I wouldn't be surprised to learn Tesla is using the cheapest form of stainless steel possible or possibly some new non standard version:

https://www.evapco.com/sites/evapco.com/files/2019-08/EVAPCO%20-%20Stainless%20Steel%20White%20Paper%20FINAL%205.2019.pdf

I do think Tesla missed the boat on this one. They get the strength from the steel being cold rolled not it being stainless. (Does the 30X grade mean it's rolled 30 times?) Supposedly the Stainless steel was to provide corrosion resistance but the grade they picked is clearly causing issues. Personally if I had one of these Cybertrucks I would be pretty angry. Tesla should have known about this corrosion issue. Any traditional car manufacturer warranties against rust. Tesla marketing led one to believe the truck was not only strong but corrosion resistant. I bet you see a class action suit get some traction. Or maybe this is one more reason why Cybertruck production will becomes short lived.