SS 304

You can't. Not without chemical analysis or an analyzer such as you can find by searching the web.

I'll leave it to you to find the appropriate tool.

I will make some assumptions here., I would assume there is no paper work from the supplier such as the Heat Numbers from the mill. And that you are looking for corrosion resistance.

Otherwise there really is no way to do it cheaply and conclusively, with the exception of seeing if its magnetic even this is not conclusion.

If its is magnetic, then it isn't 304/304L SS.

Austenitic structures such as 304 are not magnetic. while 400 and 600 series stainless are ferritic and martensitic.

Now if you don't have the heat sheets, but have the P.O. number of when it was ordered. That was order with in a reasonable time. Your supplier will have the records for tracablity.

Just as long as the material can be identified to match the Purchase Order (P.O.).

The engineer at our plant has a set of "juices" he applies on different types of SS to determine it`s type.

As far as I know, this is a commercially available test set.

May be some internet search in this direction may give you the clue!

That is interesting, I would like to know about this......

I hope its not someone who likes to pull someone's leg like this

Sounds like the moly test (molybdenum). that differentiates 316 from 304, as 316 has it and 304 doesn't.

You just need a test kit...

http://www.koslow.com/manuals/1499.pdf

I see the kit includes reference material coupons.... nice to know.

looks to be using a test similar for a eddy current quality test. we did in college in physical metallurgy classes. We needed a baseline known metal for this also.

Haven't read it all the way through, but seems to have been a good find.

Thanks,

But this test kit is only to verify ss316. isnt it ?

Rudimentary but its help

In the town where I was born
Lived a man who sailed to sea
And he told us of his life
In the land of submarines

http://books.google.es/books?id=OrlG98AHdoAC&pg=PA127&lpg=PA127&dq=metal+materials+obtained+by+grinding+spark+color&source=bl&ots=huMHXyvbA-s&sig=4phN

http://www.wiete.com.au/journals/GJEE/Publish/vol15no3/05-Dalke-R.pdf

http://opensourcemachine.org/wp-content/uploads/2008/10/us-army-machinist-course-metal-properties-characteristics-uses-and-codes-od1643-ww.pdf

http://en.wikipedia.org/wiki/Spark_testing

WP

When talking about the magnetic properties of SS, it is important to understand that even the Austenitic ones such as 316, 304 etc. can become ferromagnetic if the job is heated or even if cold formed. The magnetic properties generally appear to be uneven in these jobs (stronger near the heated or formed parts and non-existent elsewhere).

So magnetic testing is not necessarily a confirmation of type, but the intensity and regularity of ferro magnetic attraction can give you a ball park idea.

There is a test kit called a Surfox Walter kit which is used for determining the different grades. It can generally determine 200 from 300 series and 304 from 316 by the use of various reagents and colour changes in the test equipment.

There is something called as PMI - Positive Material Identification. I dont know this in detail but we used to specify PMI for all materials. QA Engineer is the person to do this test and specify the incoming material.

Ask your stores or QC fellow if you have one in your company.

You can easily find the chemical composition of SS304 in the internet, then you have to check by special tools the percentages of the elements. Be careful that the measuring equipment must show the carbon content. If you shall weld the SS304 the low carbon type is recommended (SS304L).

If you are sure it is some form of "stainless", dunk it in some "pickling" acid. (15% nitric and 5% hydrofluoric) True higher grade ss will erode slowly and develop a fine patina similar to bead blasting. We use this to remove weld "heat" marks. Cheap stuff will give off an orange vapor as the carbon based steel reacts with the acids. The cheapest ones will cause a rolling boil. (saw this once when the plant manager tried to help a friend of his pickle his "stainless" - quite impressive, but rather costly when it ruins 1500 gallons of the pickling bath and definitely very dangerous as numerous employees were choking on the vapors)

Lawyer alert - Note - this is a very dangerous acid bath, as the HF is extremely aggressive to humans and will attack bone structure if not neutralized with a calcium based agent. DO NOT try to mix this yourself - buy a commercially available pickling bath and let the pros mix it for you. This stuff is also available as a paste in small containers which would suffice to do some spot tests, but is still very dangerous if it gets onto your skin.

"......True higher grade ss will erode slowly and develop a fine patina similar to bead blasting......."

Of course one would need a base reference material to compare it against.

Yes---Very corrosive---Think,……. "Breaking Bad"…..

Well... the concentration is no where near that level. At 5% you have a minute or so to get to a water rinse and then better get the calcium loaded solution on too. Under the finger nails is really painful, because you'll probably not get it all and not get the calcium solution to it either. About 24 hours later the burning sensation starts and there is no stopping it then, as your finger nails turn a dull grey - just bear it until it quits. I've had it on me and survived. Heck you used to be able to buy a wheel cleaner with a similar concentration at your local K-Mart or auto parts store until too many people got burned with it. I thought my finger nails were going to drop off - actually wished they would.

It's really neat what it does to a glass acid bottle too - HF disolves glass bottles in less than 24 hours, even at just 5%.

Thank you! I was not aware of the dangers of even lower concentrations. I do remember that Auto Parts wheel cleaner stuff. There were several out there, if I recall, that carried some dire warning for improper use…Know a guy who used a spray on wheel cleaner, then when rinsing, hit it with a spray nozzle, and dilute concentrations flew all over the place. Red spots on lots of people that didn't clean thoroughly..

One of the metal scrapyards here has a pistol-shaped spectrometer which carries a database of hundreds of alloys and which can identify some interesting and uncommon types of stainless steel. The instrument is "costly". Maybe you can get one of these yards to favour you with a free scan.

If you are sourcing 'new' product you will find that SS wholesale suppliers can provide a written pedigree on a batch by batch basis.

Search terms /Non-destructive testing/

I used to do this with Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray Fluorescence (EDX or EDXRF). Sample of the metal in question and a sample of a reference and see if the unknown has the same ratio of elements that the reference has.