I have a '72 with the ralley wheels. One of my trim rings is hard to get on and only 3 clips hold it(probably out of round) when I do get it to stay on. I saw a trim ring on ebay, but didn't bid on it cause it had rust on the back and looked like some was on the front also. My question......Could it have been cleaned up to or near show status? I understand these original rings were stainless, which I thought, would not rust. Thanks in advance.

 

Stainless can get surface rust from having other metal parts put on them and then moisture can get between them. Just like leaving an iron skillet in the stainless steel sink too long. You will get a rust spot on the sink. It will clean off with some scrubbing though.

Or, those are not really stainless steel.

 

I may be off track but there are different qualities of stainless (corosion resistant steel), and the higher the nickel content, the better resistance to corosion, and heat. also more expensive. I beleive it is possible that stainless rusts, because in general, commercial grade stainless is very poor in nickel.... maybe somebody on the forum can add to this, I'm not a chemiste by far....

 

Take a wire brush to any stainless and it will rust , It is not the stainless that is rusting but the iron particles left on by the iron brush. This rust is on the surface like paint, it is not the part rusting but a pickup that has staining the surface.

 

ferritic stainless steels (4xx) can oxidize due to higher % of iron. these grades are also slightly magnetic.

chromium is the major alloying element in stainless steels, not nickel.

stainless steels are often passivated. the acid dip removes iron from the surface of the metal only, making for a brighter finish and better corrosion resistance.

 

Cool,, its funny how we can do something for 20years and never question why, I passivate 17-7ph on a regular basis and never realy gave it a second thought, allways believed it had something to do with better adhesion for paint,,,.... interesting..... thanks

 

check this:
http://www.pfonline.com/articles/119806.html

 

Flitz does an excellent job. I used that on the stainless bow rails on the boat I used to own.

 

As usual, Norval makes some interesting comments, however from my sailing daze I can say there ARE some 'stainless' components sold for sailboat use that will 'weep' with rust stains, not sure of the series of stainless, I forget that detail...but I remember there are 3 primary series of stainless depending on various contents, 300, 400, 500, and not sure any long which is which...I just know that guns are made of one that IS detectable with a metal detector, not that another couldn't be used, but it's not by Fed govt demands....not commercially anyway...
the cleats I had on my boats tended to weep over wintertime, dont know why except they obviously had a higher iron content...

GENE

 

Bingo!! I helped my father build an ocean going yacht and read many books on the various stainless steels to use in the many areas & situations on a boat. The books were written by metallurgists specialising in st/st for use in ships cicumnavigating the world. They knew their stuff, had more letters after their name than I've got in mine & wrote books that were really dull to read. What they said was that all st/st will corrode in the right conditions, the tricky part is choosing the correct one for use, marine use being a real headache. What I remember is that stainless steel is steel (iron) alloyed with chromium. The chromium oxide that forms on the surface forms a protective barrier, much like the oxide layer on aluminium does (anodising makes use of this). Other metals are added such as Ti, Ni, copper, etc & some non-metals can also be added (I forget which). The Ni, that most people think is the "rust proofing" part, mainly strengthens the oxide layer (there's loads of fine detail to this & various different properties imparted by different elements). If the oxide layer is damaged it's self repairing, just like with aluminium. This needs oxygen present to occur (becoming passivated) & if you think about it you'll see that st/st can corrode under the surface in certain conditions, just like aluminium does.
I think the 3 series Gene mentions are austenitic, ferritic and Martenitic(? sp?) which use different metals in them, eg molybdenum, to give different properties. I think one of them is also magnetic? I'm not going to bore everybody with the way st/st corrodes in different conditions (contact with a dissimilar metal, as mentioned above, messes up the oxide film at the surface and promotes corrosion, sea water with myriads of salts, oxygen & chemicals in solution attacks in other ways, etc, etc, etc. It goes on for ever & is a science in itself). The important part that I picked up (from my perspective) is that a good way to prevent (or delay) st/st corrosion is to polish the surface (as all marine fittings are). Polishing helps remove small cavities, which can set up minute electrolytic cells to eat away under the surface, & exposes fresh chromium that then oxidises to form a barrier layer. It also removes any contamination that can cause corrosion. Or something like that :confused
Without making this post even longer, I've run st/st fastners on my bike for over 15 years & only one of the polished ones has ever shown a rust spot, but several of the unpolished ones have had rust spots appear (removed permanently by polishing).

So, if the corrosion isn't that bad (it can be far worse under the surface - just like the way steel rusts under chrome plate) it can be polished out. Polishing st/st isn't the easiest of jobs & can be a real bugger if there's any tricky edges to do. Using mops driven by a powerful motor makes it much easier to do.

 

Very informative post. Thanks!

 

Not a metal expert, but 400 series will rust in salt water.
316 type is used for fasteners in salt water environment.

As far as the trim ring goes, I would be cautious.
If you were selling it on Ebay, wouldn't you clean it first ?
It may be very tough to clean (if at all) without ruining the finish.

By "show quality", do you mean good looking or NCRS correct ?
For relatively cheap money, you can get an aftermarket set
and save the originals.

 

I meant good looking oem. I don't care for the after market ones. My car has originals and I was just looking for a chance to upgrade the bad one. This has definitely become an educational post.

Thanks

 

Best way to polish stainless in my opine, is to use steel wool. Works fine!