Why is stainless steel non-magnetic?

A. I'm no expert on this myself, Thomas, but magnetism does not actually work on the individual elements of the alloy; it works on materials that allow the alignments of electrons to be pulled into a particular preferred orientation. The short answer is that some stainless steels, because of the way the nickel combines with the iron, produce a crystal structure that has the electrons aligned randomly and precludes the atoms from being free to move into the orientation that we identify as magnetic.

A. Hello Thomas!

Some stainless steels are magnetic: those whose atomic arrangement is in a body centered cubic or body centered tetragonal orientation can be strongly ferromagnetic. The stainless steel in your sink is usually in a face centered cubic orientation, and it isn't ferromagnetic.

That said, I think your question remains, and my best answer is "Heck, I don't know, and I've got a BS in Metallurgy". Guess I slept through that part of my solid state physics classes that covered the question, and explained then why pure nickel (FCC) and cobalt (Hexagonal Close Packed, which is close to FCC) ARE ferromagnetic.

I guess I'm also saying that the answer isn't obvious, by any means, and that it'd be difficult to give a full explanation to sixth grade students. I'd stick with Ted's answer.

Good luck!

A. Hi, Drew. I'd say that being non-magnetic warns the welder that the item is not plain steel, so s/he must give it up or at least proceed differently. But being magnetic is not ironclad proof (bad pun) that it is plain steel that will be easily welded.

Regards,

A. All stainless is not the same. Different types and ingredients. Different properties. There are tables to tell you this.

Look up "passivation".
This is a process that "lines up" the nonferrous molecules on the surface so the stainless does not rust and is nonmagnetic.

Old (more than 20 yrs) 304 stainless is usually nonmagnetic as they all did this extra step so the product didn't corrode. Try it on some old flatware sometime, and then on new. New 304 stainless is usually magnetic-most producers have cut the passivation step as a cost saving measure. Old stainless is usually NON magnetic.

A. Hello, C. Laza, thanks for your reply which is somewhat accurate, but not fully. Passivation does not have to do with magnetism; it is a chemical process that dissolves iron from the surface so as to deter rusting. 304 stainless steel is still (mostly) non-magnetic (but can become attracted to a magnet as a result of cold working). Stainless which is strongly magnetic is a different type of stainless -- not 3xx series but 4xx series. It is cheaper because it contains no nickel, but there are occasions where it's actually better like knife blades (304 cannot hold an edge).

Hi, Clarence. Some stainless steel is magnetic, some is not. In either case, stainless steel is not a precious metal like gold, nor even a semi-precious metal like silver. So I don't know exactly what meaning you have in mind when you ask whether it's "fake".

Regards,

A. I can shed some light on the question about stainless steel, jewelry and the "fake" question as its the exact reason I followed links to get to this site. I just ordered a fairly expensive watch on line that is purported to be stainless steel, but my curiosity led me to the internet when I noticed a magnet would not stick to either the watch or the ss bracelet. From the reading I've done here, I'm content with new information regarding the molecular arrangements possible and the reasons some stainless isn't magnetic. Thank you!

A. Hi, Gilbert. Stainless steel is not a "chemical process on the top of magnetic material". Stainless steel is a solid material where chrome and/or nickel and some other materials are mixed in with steel to produce an alloy that has different characteristics, including a resistance to rusting.

Regards,

Hi, Henry.

I'd say partial credit on that one :-)

You are correct that hematite (Fe2O3) is non-ferromagnetic and magnetite (Fe3O4) is ferromagnetic. But I think you'll find that once the materials are smelted into iron, it doesn't matter which oxidation state the iron was originally in, and both can be made into steel, magnetic grades of stainless steel, and non-magnetic grades of stainless steel.

Regards,

A. Austenitic Stainless steels are generally non-magnetic (face centered cubic structure) but Ferritic and Martensitic Stainless? steels usually are. A fairly graphic demonstration can be given by heating a piece of Carbon Steel with a magnet attached, when the steel reaches the Austenitic transformation temperature the magnet will fall off.

A. Hi, Adrian.

I don't know what the item is made of, and I suspect that just cutting it in half and observing with the naked eye won't give enough info. But, as mentioned, some stainless steels including the 4xx series are magnetic, not much different from plain steel. The 3xx series are theoretically non-magnetic (although cold working may make them slightly magnetic). Good luck.

Regards,

A. Hi, Erik. No, I don't think that is stretching it at all.

18/8 (8% nickel) or 18/10 (10% nickel) is not only more expensive than 18/0 (0% nickel) because of the cost of the nickel, but it is more corrosion resistant. Yes, the manufacturer spent more on 18/8 or 18/10 and it is a better material for appliances.

If the appliance is magnetic it is not necessarily true that it is not stainless, so the manufacturer isn't necessarily misleading you -- but I personally would bring a magnet to the appliance store and not buy any appliance that a magnet sticks to.

Regards,

A. Dear Sir
We have been manufacturing magnetic 302 stainless steel wires with tensiles in excess of 3000MPA for decades. This is simply a property characteristic that results from producing zero stress relaxation arch wires for Orthodontics. It is commonly known as Australian Light Wire or A J Wilcock Orthodontic Wire. Initially, the raw material is Austenitic and non magnetic, however, after the processes of thermo-mechanical work hardening and repetitive dynamic strain aging it becomes Martensitic and highly magnetic. Some wires have been known to have yields in excess of 3000MPA in the straightened condition! We have made tons of the stuff over the last 65 years. Sincerely

A. Hi Izahur. As you have read, type 304 stainless steel can become somewhat magnetic from cold working, but there are many accurate test methods, and magnetism is not among them. A alloy sorter / scrap sorter [on eBay or Amazon] x-ray fluorescence machine can determine the answer instantaneously if you can find a test lab or a scrap yard that has one. Further, your certifications may constitute proof of construction material.

If the material is only slightly magnetic, it probably is type 304 and you should be able to prove it. But if the material is strongly magnetic, as magnetic as a piece of plain carbon steel of the same thickness, you might be looking at challenging your vendor rather than your customer because you certainly didn't cold work it to the extent that Arthur cold works his wire :-)

Regards,

A. Hi Thomas. Yes, I did say "I don't know exactly what meaning you have in mind when you ask whether it [stainless steel jewelry] is 'fake' ". The problem is I still don't.

Not really made of stainless steel even though real stainless costs "only cents on the pound"? Not really made by the company whose name is on the box?

Please complete the sentence: By 'fake', I mean that it isn't really ______ ________ ________"

Some stainless is magnetic, some isn't, and I'm still lost. Thanks.

Regards,

Q. Hi. Okay I'll put it this way. No Stainless steel is fake. This is because it is not a precious metal, so there is no reason to fake it. But nowadays stainless steel is becoming more popular in jewelry. Retailers are selling it and there is no accepted standard as to what quality should come with what price tag.

You can get a ss ring at one place for $10-$20, and seemingly the same ring at another (i.e., Walmart) for $100. So when I walk into Walmart I see a ss necklace for $90 next to a gold necklace for the same or even $150, no matter what the Kt of the gold. This is wrong and companies everywhere are getting away with it. They aren't breaking the law. It's not fake -- you can ask for $1000 for a pair of socks -- it's up to the consumer to decide. But we put a certain trust in companies like Walmart. So what should stainless steel be worth as jewelry? And when I say fake I mean a 10Kt gold ring being sold as a 24kt. We need a standard. Thanks.

A. Hi again. Okay, thanks, I understand you now.

You're right that stainless steel costs only a couple of dollars a pound whereas gold might be about $1000 an ounce. As long as you and other customers understand that stainless steel has no intrinsic value, and that you're buying artistry not metal, it's okay though. The same is true of tungsten and titanium jewelry. But the canvas and oils used by Renoir and Van Gogh only cost a few dollars a pound as well.

If the artistry of the jewelry doesn't attract you to want to spend that kind of money to have it, stick with gold. And since it's mass produced, the artistry is probably not worth the money. Best of luck.

Regards,

! You did understand the first part of what I was talking about with the stainless steel. About me saying it is fake is it truly meaning fake it's meaning quality. But with that portion settled the next comment was asking about a stamp on the inside of the stainless steel necklace; she was under the impression that that stamp represented the quality of the stainless steel. Normally it would represent that but, as we both have stated, stainless steel is not of any value and this is where the problem lies.

You said there is no reason or point in counterfeiting it as there is no market for it and you used the word counterfeiting because she used that word we both know that you can't count because it is not real in the first place but a lot of the general public do not know that and this is what I was talking aboutIn the second part if you were to go to a jewelry store and there were two $2000 gold necklaces that seemed identical but after buying one you found out you bought 10 karat gold necklace and the other one at the same price was 24 karat, that would make you pretty mad; extremely mad if you ask me.

This is exactly what these companies are doing that are selling the stainless steel chair -- not breaking the law by doing this it is not illegal, simply immoral, it's taking advantage of the general public to come to a jewelry store and expect to have fine jewelry. I know it's stainless steel but they are tricked into believing stainless steel is worth something when it isn't. If companies are going to start selling these stainless steel jewelry pieces for hundreds of dollars simply put there needs to be a law put in place, where it is mandatory for the piece to be stamped with what kind of stainless steel. It is the reason this is not down on law yet is because of what I said earlier there is no standard for which kinds of stainless steel might be better quality. Obviously the higher quality stainless steel would be the kind that is harder to make; it is true stainless steel, nonmagnetic. The magnetic times like 440 are made much cheaper; they're done this way to save money and in my opinion it shouldn't be stainless steel at all at that point, or at least it should be stamped with a much lower grade. They have been stamped; it's just the stamps have never represented quality just the type ... so, concluding, selling a 24 " gold necklace and a 10 carat gold necklace without you knowing which one it is for the same price would be the same as selling a stainless steel necklace that is nonmagnetic compared to one that is magnetic; the standard isn't there and it needs to be because the general public is being taken advantage of by companies knowing that they don't know the difference and there is a difference but they're making money off of it so there is a market for it.

A. Magnetism is a hunting electron to other side, so some stainless steels have a different type of molecule combination (according to its carbon or other material contents) and it can be attracted with a magnet. Is it a fake steel? Truely: it's not a fake but this kind of steel may not be approved by someone or company. If your work does not intvolve magnetics (if there is no problem with magnetic poles) you can choose that type of steel.

A. Stainless steel has such a broad definition it's hard to communicate facts about it. "Surgical grade" is one of my favorite nothings. Sounds like the Indian guy us pulling a fast one on his customer though.

A. Hi Tina. Yes, '316' probably means Type 316 Stainless Steel. As mentioned earlier, stainless steel costs only a few dollars a pound (thousands of times less than gold, 10-100 times less than silver) so there really isn't much market for 'counterfeiting' small items that would have a scrap value of only 50¢ if genuine. So I think your jewelry is 316 stainless. Enjoy it.

Regards,

Degaussing

Ferromagnetism

Hi Arun. If you could please tell us who you are, what you do, and why you want to know I am confident that you will get a more helpful and insightful response. Readers tell us that they find vague questions dull & repetitive but are often intrigued by people's actual situations :-)

Magnetism (where the piece in question attracts other iron objects) can be removed by degaussing, generally pretty easily. But when people talk about iron being "magnetic" they usually actually mean "ferromagnetic" (a magnet will attract the item in question). I do not know of any way of 'turning off' the ferromagnetism of an iron object; but obviously you can alloy iron with sufficient other ingredients as to make it non ferromagnetic like Series 3XX stainless steels.

Regards,