Stainless steel(rusty)

Chet/Ma.

Chet/Ma.

Senior Member
What types of stainless steel will rust a little? Not all stainless is the same.
Do we have a metallurgist in the barn that can shed some light on this question? Thanks Chet/ma.
 
Not a metallurgist but series 400 S.S. will rust under the right conditions.
It is referred to as 'martinsitic' or (magnetic) :)
 
I've had some ss brakeline several years ago that got rust spots on it. I've since changed suppliers and the rust is not a problem.
 
The reason I asked about stainless rusting. I know of a 36 grill that was purchased 45+ years ago from a Ford dealership and was told at that time it was stainless.
It had no paint on it and has been stored all these years.
It shows little spots of rust on the surface. Would this happen with some types of stainless?
 
Some parts were stainless clad with a very thin thickness of high nickel steel. The amount of nickel in the mix is what makes it corrosion resistant. In aviation it is more refered to as CRES or corrosion resistant steel. Anyone who was ever working near the ocean with all the salt will let you know that stainless will rust away . It's just slower to go than regular iron and steel.
 
Hi,
51 merc is right on. Some of the 400 series will in fact rust a bit although not as bad as regular carbon steel. The 300 series (austenitic) stainless series have enough chrome and nickel to keep them in an austinite crystal structure, which will not rust. Martinsite and ferrite stainless can rust. I'm not a metallurgist but I taught basic metallurgy and heat treatment of metals for the Navy.
Kurt
 
Chet/Ma ..........................
I think that the best stainless has to be what they used in making the 1930-31 FORD headlights and grille shells. I have found them, where they have been outside for decades, with no rust whatsoever.
MIKE :)
 
We have a stainless steel outdoor sculpture that rusted. The artist came out and wire brushed the rust off and it came right back. Wire brushed it again and it came back. He was totally confused as he knew the stainless shouldn't rust.

I figured out that he was using iron wire wheel brushes and bits of iron were being imbedded in the stainless and that's what was rusting.
 
Barry Wolk said:
We have a stainless steel outdoor sculpture that rusted. The artist came out and wire brushed the rust off and it came right back. Wire brushed it again and it came back. He was totally confused as he knew the stainless shouldn't rust.

I figured out that he was using iron wire wheel brushes and bits of iron were being imbedded in the stainless and that's what was rusting.
Click to expand...


I think your on to a theory I would agree with. I weld a lot of stainless and have shown a few how to do sanitary welds in plumbing and occasionally I will see a welded section that will turn rusty if left outside in the weather & it is not polished correctly, the use of a (clean) Stainless brush is crucial in Stainless and Aluminum welding.
 
304 and 308 is what they use in commercial kitchens. it will get rust stains on it but will wipe off. i live 4 miles from the atlantic ocean and everything rusts here. 316 is marine grade stainless and seems to last forever around here.
 
Chet/Ma. said:
The reason I asked about stainless rusting. I know of a 36 grill that was purchased 45+ years ago from a Ford dealership and was told at that time it was stainless.
It had no paint on it and has been stored all these years.
It shows little spots of rust on the surface. Would this happen with some types of stainless?
Click to expand...

Being in storage that long, could those spots be "fly specks", especially if stored down here in Jawga ? LOL
 
Stainless that is machined with CARBON STEEL tooling will have bits of steel imbedded in the surface. A treatment used is called "passivation" and it involves an acid wash to remove the steel particles.
 
Iron dilution causes rust on stainless - using a wire brush, steel wool, etc. will impart little iron particles that will rust. Use a stainless steel wire brush, scotch brite, etc. Or I believe Nitric acid will also "passivate" the SS and increase its resistance to corrosion. I'm not a metalurgist, but that is my experience from being a stainless steel fabricator for 10 years. You have to be real carefull with your stainless and watch what rubs on it or what it is dragged across.
 
mike-- i agree. i have never seen rusted model a or 32 stainless no matter where it has been. however i`ve seen quite a few 34 headlite shells with little specs of rust on ones that have been sitting outside for along time here on the west coast. you can buff it off easily though. ford must have used different stainless on 34 headlite shells. all the ss trim on my `57 olds was highly magnetic much to my surprise but i never seen any rust. i have garden hose racks that i made by spot welding 304 stainless together and have had permenent brown rust stains only on the spot weld indents when left outside. you can sand it off but it always comes back.
 
Hi,
yes there are several kinds of stainless steel. Each has been formulated for a specific use. We want stainless steel mostly for cosmetic purposes. The best stainless for our use is grade 303. The problem is how do we know which is which when it is not marked. I found a simple method and it is to carry a small magnet with you when you go to the hardware store. Simply check the piece you want with the magnet. If it sticks to the magnet, it is not the type of stainless you want. You want a stainless that is high in chrome, and less steel. This works for me!


Big al.
 
I have been in tooling since 1965. The 400 series such as 420 will rust. The 300 series such as 306 does not. The Gateway Arch in St Louis is 306 SS. I don't remember the details but Henry bought out the production volume for a new chromium steel from maybe Bethleham Steel in late 1929. The difference in the types of SS largely to do with Chromium, Nickel and Molybdenum. However it is not as simple as that.
 
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