Thread: stainless rusting?

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I spent a lot of time making up a stainless dash panel that fits nicely on my stock dash to fit some small guages. I sanded it to a nice finish and installed it.
It's been about a month and it's all rusty. Even the back side that I didn't sand is rusty.
What's the deal? Is there a product I can put on it to seal it from moisture and air? If so, where does one buy it?

It does not seem to be stainless if it rusts! I guess the easiest fix is to sand it down again and treat it to a spray can paint job, maybe followed by some shelving contact paper to look like wood grain if the rest of the dash is woodgrained. Real stainless steel will not corrode/rust and can be buffed/polished to a shine that will last.

Don Shillady
Retired Scientist/teen rodder

Well, it prolly wasn't, sand it back down, get a nice magnent you know is strong, try sticking it to the stainless, if it attaches itself well, theres your problem, magnents don't stick to stailness steel, you can judge quality of stainless with a magnent, by if it does stick, how hard does it stick, you need a strong magnent and test it with regular steel to be shure of it's magnetic power, then you can test quality, if it sticks compleatly, not stainless or stainless coated ( like some cheap stainless sinks ), sticks a little, could be a good coating or cheap stainless, dosen't stick at all, good quality stainless. Stainless don't rust, unless it's not really stainless.

I read somewhere though that if you sand too deep into stainless it can rust just like regular steel because most of the chromium is in the outer layer.
A magnet does stick to this stuff though, but it is stainless, regular steel doesn't polish up like this is doing, I can get it like a mirror.

http://www.azom.com/details.asp?ArticleID=1140

Stainless Steel is non magnetic.

301 stainless is slightly magnetic, I don't know the alloys involved. It will polish to a brilliant shine. Not sure if there is enough, I would guess IRON, in it to rust? Oh yeah, 301 isn't cheap!

304 stainless will rust and is magnetic but doens't generally rust as fast as your panel did. Now 316 stainless won't rust at all and a magnetic won't stick to it. Sounds like as stated above, that isn't stainless steel.

I have bought 4 sets of mirrors for my truck, all of them "stainless". They have all started rusting within a month! The cheap stainless'es rust like mad. I rather think they have trace amounts of chromium, etc and so some marketing liar will call them stainless. Realllll annoying.

You may have gotten a sheet of this psuedo stainless. In other words you need to get actual ASTM rated stainless for your projects.

tcodi... i work in a machine shop... if you want, let me know what size piece you need, and I'll ship it to ya for the price of UPS... we have 20' dumpsters full of 316 scrap

thanks for the offer, but I also have full access to a machine shop. I grabbed some stainless, I guess it was cheap stuff.
I'll have to try and figure out what it was that I grabbed.
I wasn't aware of all the grades of s.s., I should have figured though. I suppose I may have to just paint this panel.

Polish it up again and seal it with a rattle can of clear laquer or enamel to keep moisture in the air off it. If its on the inside of a car it should last forever without rusting once its sealed. You can buy mega expensive stuff like Zoopseal, but you really don't need to ---try your local NAPA store.

316 is the most corrosion resistant alloy. Also, heating stainless steel into the sensitized range 800-1400 degrees F or C, can't remember, will cause carbide precipitation which is when carbon combines with chromium to form chromium carbide. Normally a layer of chromium oxide forms on the surface of stainless steel, chromium carbide does nothing to protect from corrosion. The solution is to quench through the sensitized range. Brittleness from quenching isn't a problem with 300 series stainless steels like it is with mild steel because they are in their austenitic state. When you quench mild steel, austenite transforms into cementite and bainite which are both brittle. Slow cooling results in pearlite. Quenching does cause warping and anybody who has welded stainless knows what a pain it is to control warpage. So, instead of quenching, you can buy 316L, a low carbon modification of 316 which you can heat all you want and won't have any serious carbide precipitation problems. When you weld it, use 309L or 310Cb filler. 310Cb has columbium in it which combines more readily with carbon than chromium combines with carbon, so the carbides will be formed with the columbium instead of the chromium and the corrosion resistance of the steel will not be diminished. 310Cb is expensive and hard to find, but 309L is readilly available and works just fine. There are also 347 and 348 which contain titanium instead of columbium, but it serves the same purpose. 347 and 348 are used for nuclear applications.

Even better yet, instead of making an entirely new dash, just buy a rattle can of clear laquer or clear coat and laquer the dash. Do some wet sanding and polishing and it will look great.