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Why does stainless steel have pitting?


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Old 02-23-2013, 06:29 PM   #11
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Stainless steel that is very good at resisting rust is a "300 series" alloy and it is not heat-treatable. So it is not usually strong enough for making a gun. It is non-magnetic; a magnet will not stick to it. The alloys that are suitable for making guns are the "400 series" alloys. They are heat-treatable, magnetic and not all that corrosion resistant. I got into this business of stainless steels when I was an engineer for a marine products company. Some stainless steels fall apart when exposed to sea water (oops!).
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Old 02-23-2013, 10:14 PM   #12
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Want to know whats funny,Here in Michigan where it's almost 100% humidity most of the year,my guns don't rust,but when my buddy from Colorado travels here with his guns,they start to rust quickly,even with the same model gun as I have,as if the metal is not used to the humidity.It's mind boggling how this can happen.
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Old 02-27-2013, 01:17 AM   #13
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Believe it or not, steel is porous like wood. It even has a grain. Keeping steel well oiled will help keep the pores filled with oil, making it more rustproof.

Bead blasting, I believe, pushes the pores shut with the surrounding steel, making it more rustproof.
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Old 03-16-2013, 06:38 AM   #14
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Quote:
Originally Posted by primer1 View Post
Believe it or not, steel is porous like wood. It even has a grain. Keeping steel well oiled will help keep the pores filled with oil, making it more rustproof.

Bead blasting, I believe, pushes the pores shut with the surrounding steel, making it more rustproof.
Not true. The higher the polish on metal the more rust proof it is. Polishing makes the pores smaller and harder for water to start rusting the metal. If anything the bead blasting will enlarge to pores.
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Old 03-16-2013, 01:18 PM   #15
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Quote:
Originally Posted by atrbertothy

Not true. The higher the polish on metal the more rust proof it is. Polishing makes the pores smaller and harder for water to start rusting the metal. If anything the bead blasting will enlarge to pores.
so why then does bead blasting make metal more rust proof?
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Old 03-17-2013, 12:40 AM   #16
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Bead blasting don't make your plane gun steel rust proof. The rate at which steel will rust depends on a few things. One the weather were you live (the biggest factor), the chemical make up of the oils in your hands, and then the alloy make up of the steel. If you live in a dry area and you don't have what is called acid hands your weapon won't rust as fast as if you lived in a swamp.

A good example is were I live in PA. I live by some wetlands. My 870 has a bead blasted parked finish and if I don't put oil on it it will rust but yet my Weatherby which has a mirrored finish has yet to rust. The finer the finish, the more rust proof it is. That goes for even for stainless steel.
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Old 03-17-2013, 01:14 AM   #17
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Poor choice of words on my part. I meant to say more corrosion resistant, not more rust proof.

I am aware of what causes corrosion, including the environment. I believe you might be confusing bead blasting with sandblasting. Bead blasting with glass or ceramic beads, does help to close the pores in metal, making it more impervious to salts, moisture, or acids, which cause corrosion.
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Old 03-17-2013, 03:32 PM   #18
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Quote:
Originally Posted by primer1 View Post
Poor choice of words on my part. I meant to say more corrosion resistant, not more rust proof.

I am aware of what causes corrosion, including the environment. I believe you might be confusing bead blasting with sandblasting. Bead blasting with glass or ceramic beads, does help to close the pores in metal, making it more impervious to salts, moisture, or acids, which cause corrosion.
Not confused with the two. I do know which is which. Sand blasting uses aluminum oxide instead of glass beads and is far more course then the glass beads, but they both work the same and you will have a greater chance that pores will be enlarged and not closed.
Like I stated about my 870. It has a bead blasted and parked finish. I know this because I did the finish, not someone else.
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Old 03-17-2013, 04:14 PM   #19
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Quote:
Originally Posted by nitestalker View Post
SS is simply more rust resistant not rust proof. I saw a Mdl. 66 S&W that was pulled from a creek. The Mdl. 66 had been under water for 2 years. The gun was as badly damaged as any other firearm left in the water for 2 years.
Hmmm.

I was taught to keep the stainless steel darkroom trays filled with water when they were not being used. This kept the air from getting to them and causing rust. Presumably the loose O molecules rose into the air and the O that was left was bound to the H.
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Old 03-18-2013, 03:34 AM   #20
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No stainless steel just takes time to rust. That is due to the alloys that are in the metal. Stainless is call slow rust in europe.
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