I picked up several rods that seem to be made from stainless steel (as
everything else at that place had specks of rust).
However, they are slightly magnetic. Clearly much less magnetic than
regular steel, but magnetic enough to make magnetic darts barely stick
to them and not fall.
What material can it be?
The rods are about 1 3/4" diameter and several feet long.
One of the 4xx series?
The 410 SS sheet that I have been able to test would hold a magnet about as
well as mild steel. My guess is 304 that was substantially work hardened
from cold rolling. I've seen plenty of 304 nuts in sizes from 1/4-20 on
down that would stick to a magnet from the work hardening due to forming.
On Mon, 15 Feb 2016 18:20:05 -0600, Ignoramus21354
Best guess: 302 or 304.
Those two are the austenitic grades that gain the most magnetic
permeabiity from work hardening. (They start off in the annealed state
with virtually none.) And austenitic stainless grades are by far the
most common types.
Almost all other series' of stainless are much more magnetic. It's a
matter of their ferrite or martensite content. In austenitic grades,
you produce some martensite when you work it, converting a bit of the
austenite. But not much.
If it is cold-rolled (likely for such rods) it is work hardened,
and work-hardened stainless is slightly magnetic.
And, IIRC, 416 (and the other 400 series) are less "stainless"
and slightly more magnetic.
At some point (given what you do), you may want to get one of
those magic guns which can analyze a metal and tell you what alloy it
I see Ebay has some used for $5500 to $9,000, plus there is a $40
service to analyze samples for you. Although, I think it is overseas,
the English seems to be a second language. There are other services.
You can get an analysis done for around $50. That seems to be the
going price. If it was for a big load of scrap, and if it only came up
once in a while, that would be the way to go.
Again, though, someone like Iggy has to ask what the value is of
knowing the alloy with that much precision. With some experience and
some good test samples, you can do a reasonable job with spark
I've never seen compessed-air testing done, but that's another option,
and supposedly it is a bit more accurate than spark testing with a
I've been thinking that he might like to know the alloy *before*
he bids on the lot -- and they are unlikely to let him take a sample to
have analyzed. The gun would give the answer very quickly -- and unlike
taking a portable grinder to the lot, would be less likely to get him
banned from the auction site. :-)
How does the compressed-air test work? Any web site someone
You heat it red-hot with a torch and blow a jet of air over it. The
sparks supposedly are similar to those you get with grinding, but
I don't see a lot online, but there's this:
...which I think they got from this:
I came across it years ago -- probably from the same old books -- but,
as I said, I've never seen it being done.
I'm sure that Iggy has this all figured out from the discussion, and
knows what is practical for him to do, but my guess is that he's going
to eyeball materials and make a rough estimate and a judgment about
buying them, and then -- perhaps -- try to figure out the alloy before
he sells them. In this case, for example, he was trying to figure out
the material that constitutes the bars he already had bought.
I don't know that business works these days, but I do know that
single-alloy purshases used to be for relatively big trades, in
ferrous metals. In our shop in Princeton, we had a barrel for
stainless turnings, and it was a mix of 304, 316, and some unknowns we
got from customers. We weren't going to get more for them by
separating the grades.
In aluminum, however, we had one barrel of 2024 and another of 6061.
We DID get a premium for keeping those two separate. 2024 will
contaminate 6061 with copper; it contains around 15 times as much as
In stainless, I think they just dump the grades all together and
remelt, and then de-carbonize the batch to get it down to 304 or 316
levels. That's how they make 304 out of 302 (or general 18-8), to
begin with. Alternatively, they could make it all 302 and sell it for
making kitchen flatware and architectural shapes. I have heard of that
So there didn't used to be premiums for separating austenitic
stainless grades. Maybe they're more sophisticated today; I don't
I think some of the problem of finding something is many that posted
them have passed and their web pages are down for non-payment. And
many changed sites due to company changes. The Metalworking drop-box is
one as example. Now not on a company server, but on a private one.
On 2/18/2016 4:10 AM, Ed Huntress wrote:
On Tue, 16 Feb 2016 11:12:53 -0600, Ignoramus21249
It depends on what you'll do about it, once you determine the alloy.
If you're just trying to sort scrap, knowing whether it's 302 or 304
generally won't make any difference -- unless you're selling scrap by
the ton to a premium scrap dealer, who will give you more for
single-alloy scrap. That's essentially what Ford is doing with their
For what you probably need, I would think that spark testing and/or
compressed-air testing would be plenty accurate enough. YouTube is
good for showing you what to look for, but the ideal is to have some
known samples you can compare to the unknown metal you're testing.
It doesn't hurt to know standard applications, either. For example, if
you have a pile of architectural-trim stainless, count on it being
basic 18-8 (grade 302), and not ferritic or martensitic.
On Tuesday, February 16, 2016 at 12:12:56 PM UTC-5, Ignoramus21249 wrote:
Interesting. Prices may come down in a couple of years. One of the analysers Ed mentioned is a xrf. But the other one is a laser induced breakdown spectroscopy (LIBS) I really have no clue, but suspect the LIBS might be cheaper to make.
My scrapper uses an XRF - but the settings for this and that odd Molly
or whatever is so high it sees only Iron when looking at ballistic
steel. I finally just hid the expensive steel under the other A-36.
It weighs many times that of A-36 due to the high content of heavy metal
(not lead) and they pay for the price and get it mixed in.
When I take in Nickel or copper - then the XRF is useful.
On 2/18/2016 3:24 PM, firstname.lastname@example.org wrote:
But the other one is a laser induced breakdown spectroscopy (LIBS)
I really have no clue, but suspect the LIBS might be cheaper to make.
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