Mini-14, NAA, Martinsitic Steel, Magnetic Domains
Is the Ruger Mini-14 made from a magnetic stainless steel? Is it possible that a NAA Derringer would attract a magnet? Why are some of my stainless steel firearms magnetic, and others are not? Are I am wondering if anyone here can explain martinsitic steel and what established the magnetic domanins in a material? Why are some stainless steels magnetic and others are not? Are stainless steels that are magnetic considered ferrous, or non-ferrous?
To err is human, to moo is bovine.
To err is human, to moo is bovine.
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Ruger uses 410 series (410, 416BQ/R/series 70, etc.) stainless in their firearms. It is magnetic and modestly priced stainless.
North American Arms mini revolvers and, I believe, most of their handguns are fabricated from 17-4PH. Possibly some of the barrels are 410 series. But if the barrel is an investment casting with rifling cast as a cored part, stressed parts are 17-4PH. This is a magnetic precipitation hardening steel with a level of corrosion resistance orders of magnitude greater than 410 series.
In gross terms MARTENSITIC steel is stainless steel that can be transformed (hardened) by heat treating similarly with conventional carbon steels.
Precipitation hardening steels and maraging steels are hardenable, but use a different chemistry to harden. Martensitic transformation occurs at lower temperatures. I'm not even sure one can call what happens "martensitic transformation." These steels are expensive to ungodly expensive. 17-4PH is the least expensive of the bunch.
Stainless steels that are non-magnetic or slightly magnetic are AUSTENITIC. 300 series, 20Cb-3, and so on are not hardenable by heat treating. There's stuff that can be done to improve mechanical properties, but they do not pertain to your question.
Another stainless steel class, that is magnetic but not easily hardenable, is FERRITIC. I've not used anything in this class. I cannot comment on it beyond letting you know it exists.0 -
Lance,
Thanks for the information! It sounds like a person cannot use a magnet to determine if the material is stainless steel or not. That is, a person shouldn't worry about trying to protect material just because it is magnetic. It may take a little more thought or research. Is there any good way you know of to tell if the material is a magnetic stainless steel?
I say "stainless steel", I know the proper term is "corrosion resistant steel" and was told that things like potatos may tarnish even these steels. Could I tell if something was made of corrosion resistant steel by seeing if it would tarnish if exposed to a french fries? Sounds like a dumb question I guess. Do you know what things (corrosive things) will attack stainless steels?
To err is human, to moo is bovine.0 -
What makes stainless steel stainless is the non-rustable materials added to the alloy, especially chromium. Non-magnetic stainless, as found in kitchens is not suitable for use in firearms because it lacks toughness provided by a higher ferrous content, and is too brittle in most forms. It is highly rust resistant, can be stained by acidic foods, but is usually easily cleaned as the stain doesn't penetrate deeply. It is practically impossible to rust kitchen stainless under normal conditions, but it will dent and crack. Stainless used in firearms contains less chromium leaving a higher percentage of ferrous material, hence more magnetism. Stainless used in firearms represents a compromise to obtain increased rust resistance offered by the chromium while retaining the toughness necessary for durability in a quality firearm. Stainless firearms will rust because of their higher ferrous content, given the right conditions of humidity and neglect. A good description of various alloys is found in Machinery's Handbook. 0 -
Thanks for this very interesting discussion, please bear with me while I try to get this stuff straight. Correct me if anything here is wrong.
I had no idea so many "corrosion resistant steels" or "stainless steels" used in firearms were actually ferromagnetic. It seems you are saying the more FERROUS the steel, the more magnetic it is. Ferrous is the term used to describe iron-like properties, such as the ability to attract a magnet, and those ferrous stainless steels would be magnetic, where austenitic stainless steels would not be magnetic, if I understand correctly what you two are saying. This is apparently a function of how much of the element iron is in the alloyed steels. Now, I have a question regarding the terms wrought iron, pig iron, and cast iron. I want to make sure I am correct.
As I understand it, pig iron is a very basic form of iron, poured from the smelting pot into ingots called "pigs". It is my understanding that this "pig iron" is very basic, raw material that is not really the element iron, but is mostly iron with a very high carbon content that makes it brittle, and this basic material is used to make other alloys. If I am wrong here, let me know.
From the following site, called the "history of steel", they say that "wrought iron" is really a form of steel. http://www.fantasysteel.com/steelhistory.html . This looks like he says "Wrought iron is steel that is roll formed into round rods, flat bars, angle, 3 sided channel, I beam and other shapes". Is that reasonably accurate?
Now, for the term "cast iron" I find two definitions in on-line dictionaries. One from http://www.hyperdictionary.com/dictionary/cast-iron that says "an alloy of iron containing so much carbon that it is brittle and so cannot be wrought but must be shaped by casting" and one from http://www.yourdictionary.net/cast_iron.html that says almost the exact same thing. Cast iron is so brittle it cannot be shaped by forming, it has to be cast, so it sounds like this "brittle" property would not be a form of iron you would use in a firearm. From what I am learning, "cast iron" is really only suitable for things like pots and frying pans and door stops and stuff. That seems to be what most of the sites I have been looking at say.
So, I hope you see this question coming: If wrought iron is actually a form of steel, as the one site says, and cast iron is too brittle to be used for much outside of frying pans and decorative door stops, how much real "iron" was ever used in firearms? Wasn't it "steel" that was actually used? Outside of the really old antiques, have firearms really been made mainly out of "steel", rather than "iron"? Of course, I understand that steel is mainly iron. But should the song about the Ranger with the "Big-Iron" on his hip probably be the "big steel" on his hip?
To err is human, to moo is bovine.0 -
In order to increase the resistance to "rusting", of "ferretic" type stainless steels ...The steel is normally "pickled" in an acid bath.. This removes the intergranular iron (ferrous) particles exposed to the surface, thus there is no ferrous material(iron) exposed to be "rusted".. I once sandblasted a Ruger stainless bull barrel that came from the factory too shiney to hunt in the sun with. The sandblasting operation dulled the finish to perfection, but from then on, I had a rusting problem with that barrel... Some research proved that when I sandblasted the surface of the material, I exposed some more of the Iron particles (removed by the initial pickling process) that when wet just rusted....The barrel required "re-pickeling"(sp?)to stop the rusting... This was done by application of a Pickleing paste, waiting the required time, and washing off with water.. It worked... 0 -
Very interesting. Nice to have some experts around.
I thought Stainless steel also had a high nickel content as well?
JM0 -
One last bit of information pertaining to the original question: Stainless steel is "stainless" because its surface has an extremely thin layer of chromium oxide. And this layer constantly renews itself in air -- that is, in oxygen.
Nickel need not be present.
The ratio of chromium to carbon in 400 series must be high enough to have free chromium available to create and renew the chromium oxide surface. Elements that bind with carbon include, for example, vanadium. This is the reason that no one can furnish a specific ratio, such as 8x chromium to carbon, or 12x. The more complex the alloy, the more you "try it and see." Used to be that metallurgy was one of the few remaining trades that you could learn on-the-job. Dunno if it still is.
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I think an analogy might be zinc covering carbon steel. The zinc acts as a sacrificial barrier. It gets destroyed so the carbon steel can remain intact. But zinc, not being an integral part of the steel it protects, has no automatic way of renewing itself. Hey guys, if the analogy is wrong, sorry.
Boeboe: for verifying stressed gun stainless steels, I would bet that they are all magnetic -- except, perhaps for 304 screws. I refer to receivers, cylinders, hammers, springs, etc. Some spring steel could be non-magnetic, but I doubt it for firearms' springs.
And wrought iron is not steel. It is wrought iron, carbon free.0 -
It seems there are a few definitions of wrought iron. I found this site that does a pretty good job of clearing up the confusion.
http://www.nomma.org/support/wrought/wrought.htm0
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