Jump to content

Metal Surface Question


Recommended Posts

I know that chrome is a surface treatment as is powder coating and painting. I think an anodized surface penetrates deeper then the previous.

 

Now my question. Is a stainless steel a surface treatment or an alloy? If an alloy, then with proper 'sanding' can one go deep enough to eliminate any discoloration or scratch? 

Link to comment
Share on other sites

Stainless steel is not a surface treatment. Stainless is a mix of different metals , don't  know which ones, and is produced as such. There are different grades stainless as well. The best one is the one that never developes any rust. I have seen low grades of SS develop small amounts of surface rust.

  Yes you can sand SS and that's why you see polished SS on cars. The SS is sanded with various grades of grit going from rough,probably 500-600 to fine 2000-3000. Then after the sanding the polishing.

Link to comment
Share on other sites

you annodize aluminum, it is an oxide finish that is passivated on the surface of the alimunum, and can be colored, hardend or even change the lubricity of the surface.

 

powder coating, wet painting, ED painting are all just that, paint, not a "surface treatment" but a surface coverant.

 

stainless stays shiny because it forms a protective chromium oxide layer on its surface that doesn not "rub" off like rust on carbon steel, black oxide on aluminum, or the green oxide on copper.  Stainless oxidizes but oxidies the chromium in the metal instead of the iron tightly bonding to the surface (inlike iron oxide) thus staying shiny.

 

there is your metal finishing/metalurgy 101 basics for Wed.

Link to comment
Share on other sites

Stainless steel is an alloy, and the reason it is corrosion resistant is becuase of the Chromium that is contained within it. The chromium forms a passivation layer when it is exposed to Oxygen which protects it, almost like a very thin skin protecting it from corrosion. So if you sand the stainless you remove this very thin layer but then it "reforms" because the material still contains Chromium and its exposed to air. There are different grades of stainless depending on there Chromium content and they all have different tolerances for corrosive environments.

 

-Chris

Link to comment
Share on other sites

So then a stainless steel shaft for a machine and a stainless steel beauty trim may have a lot of chromium in them. One for durability and the other for beauty. A stainless steel pot may have even more. . . Interesting, thank you to all. 

Link to comment
Share on other sites

stainless steel is generic for a alloy containing a minimum amount of chromium with the lowest content at 10.5 to 11 % by mass and the higher the chromium, the higher the grade of stainless the alloy becomes...it can also be stainless by nature and yet be magnetic, it can also oxidize if the chromium content is low but usually will polish right back up with a bit of attention...

 

if you are truly wanting to rad up on stainless and its characteristics and grades...this is good reading...

 

http://chemistry.about.com/cs/metalsandalloys/a/aa071201a.htm

Link to comment
Share on other sites

I do not know about the sanding statement on the stainless steel.  I have used the stainless steel polishing kit from Eastwood on my 39 Desoto and this was done back in 1996.  I have not redone the SS since then and the SS still shows no sign of rust.  I just used the various grades of polishing compounds and buffing wheels.

 

So I do not think you sand but just buff out with the various grits and appropriate wheels.  Quality SS should not rust.  The original SSfrom when the car was made in 1939 was still onthe car and showed not rust only some small scratches.  So he original retained its shine from 39 to 1996. or 57 years as oroiginal.

 

Rich Hartung

desoto1939@aol.com

Link to comment
Share on other sites

When repairing damaged stainless trim or customizing it, it can be welded, filed  and then sanded and polished.  It also work hardens quickly which is part of the reason it's so hard to get dings and dents out.  The trim used for automotive purposes is probably on the high end of chromium content.

Link to comment
Share on other sites

I sanded all of mine after working on the dings and before buffing. The good pieces I used 600 the bad ones I started at 220 and I think went to 400 then 600.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.

Terms of Use