Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Unknown Materials

Unknown Materials

Unknown Materials

O.K.  Here's the million dollar question.  I've got a bin in the shop that's full of small pieces of unlabeled metal stock.  It's easy to separate the aluminum from the titanium, but how do I differentiate between inconel and stainless?  Is there a test other than density and elemental analysis that will tell me what the heck I'm holding?  How can I tell 304 from 316?  I'm looking for simple tests here, because, if I was really serious, I'd just buy new material.  Any ideas would be appreciated.

RE: Unknown Materials

Would it make sense to rent a mobile analyzer for a day?

RE: Unknown Materials

OR… call a local metallurgical lab that provides for PMI (Positive Material Identification)services in the field. If you plan it correctly for a 1 day job, the cost for PMI is based on a daily rate for the field tech with the portable alloy analyzer.

RE: Unknown Materials

There are kits with various reagents in liquid form that do a nice job of PMI. In the past I've been successful in sorting 316 from 304 by using a magnet then checking for the presence of Moly. As for the nels (inconel/monel etc.) you just look for the presence of the odd element.
(I seem to remember that Walker & System Scientific offer alloy sort test kits)

RE: Unknown Materials

You could also find/borrow/rent a thermo electric analyzer.

The is a flow chart in ASM Stainless Steel Specialty Handbook.  Look in the chaper on Recycling Tchnology.
The first chart has you use color/magnetism/density/spark test to sort.  This covers ALL metals.
Then there is one that has you use four different acids and the sorting is based on the spot colors.  This one covers corrosion resistant alloys, SS and Ni alloys.
The third one uses thermoelectric to sort corrosion resistant alloys into basic groups.  Most of the SS grades can be identified this way.  You can further sort by analyzing for just one of two elements.

Your best bet is to clean everything up and get it organized.  Do a rough sort based on magnetism, density and spark colors.  The hire a lab to come in with a portable XRF unit and finalize it all for you.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

RE: Unknown Materials

Eltron, you have a bin of tooling material- i.e., metal good for your own use, to make jigs & fixtures.  Think about it- if you're truthful, you'll have to tell your customer "Geez, it MIGHT be Inconel 625"- and how many of them would accept that?  I know I wouldn't.  Even as good as the portable alloy analyzers are, I wouldn't trust them to sort a pile of unknown metal into definitive alloy designations that I'd make into parts and sell, and I hope you won't either.

Just my jaded two cents...


RE: Unknown Materials

".........if I was really serious, I'd just buy new material............"
Yep. can't argue with that.
I'm guessing that maybe by sorting what from which, your aim is to enhance the overall scrap metal value. No harm in that.
The temptation, once the material is identified, is to go ahead and use it. Even if the analysis is beyond doubt, traceability of the manufacturer/batch certainly would be. Thus, the ultimate responsibility of the material becomes yours to bear.

RE: Unknown Materials

Thanks for all of the replies, guys.  Looks like there's no simple tests out there, which is what I figured.  Lee is right.  I'm not going to use these materials for anything other than tooling or mock-ups.  I just need to have my guys get their crap in a pile enough to properly label the stuff they keep so we don't keep running into this problem.  Thanks again.

RE: Unknown Materials

Simple test? sure there are, Cheap test? that is a whole different question. PMI via Arc-Spark spectroscopy or hand held X-ray testers is EASY it just isn't CHEAP. And again, if you use it, you own the liability. If safety isn't an issue, that is one thing. But never use this stuff where if it fails someone could get hurt. The lawyers will OWN you. Material tracability in a workshop is not impossible but it does require some discipline on everyone's part. Making sure everyone understands what is at stake helps everyone buy into it a bit better. Tie it to thier year end bonus check and you'll never loose tracibility again =D.

RE: Unknown Materials

I can't remember the name of reagent.
the different is the color after dwelling

RE: Unknown Materials

cupric chloride and hydrochloric acid solution to the unknown metal and allow few mins dwelling. Shiny spot indicates the material is inconel.

RE: Unknown Materials

that may be true clocklight, but what flavor of inconel?

RE: Unknown Materials

at least you know what it is

RE: Unknown Materials

Theres a big difference between inconel x750 and say inconel 600.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close