Material-Type Tester? 1

[Tarfu43]

Hi, Everyone,

I work in the aviation repair business, and on numerous occasions, I run into situations where I have materials (usually aluminum or steel) that I need to determine what type they are (7075-T6, 2024-T3, etc.).

Does anyone have any recommendations as to what type of material tester to purchase (ie: hardness tester or chemical tester)? I know it's possible to send out a sample to a testing facility for a detailed analysis, but what I'm looking for is a tester that we can keep on location, that can be used by the average person, and that gives relatively quick and accurate results. Am I asking for too much here?

Any comments would be greatly appreciated.

Thanks!

 

[CoryPad]

This technique is called Positive Material Identification (PMI), and usually involves chemical composition by x-rays. Here are some links to equipment providers. Note, this testing does not prove that material meets all requirements. Proceed with caution.

http://www.niton.com/en/metal-and-alloy-analysis/applications/pmi

http://www.bruker.com/products/x-ra...pplications/pmi/pmi-xrf-for-plant-safety.html

http://www.oxford-instruments.com/i...tions/metals/positive-material-identification

http://www.olympus-ims.com/en/innovx-xrf-xrd/

http://www.spectro.com/pages/e/p0101.htm

 

[WKTaylor]

CAUTION.
Material [alloy chemistry] determination is only part of the larger picture. Determining the temper is just as important: that determines strength!

Each alloy has it's own test methods/values for temper determination. USUALLY, not always, hardness is one of the primary factors considered. Other factors that may be important are: electrical conductivity; material form [forging, plate, sheet, bar, casting, etc]; grain flow and size; secondary processing [strain relief, etc] that may not be evident with conventional tests; and any special hot or cold stress relief operations [that also may not be evident with conventional tests].


Regards, Wil Taylor

Trust - But Verify!

We believe to be true what we prefer to be true.

For those who believe, no proof is required; for those who cannot believe, no proof is possible.

Unfortunately, in science what You 'believe' is irrelevant – "Orion"

 

[berkshire]

Short answer you need both, Material type i.e. XRF tester, and hardness tester i.e. Rockwell, shore, or Brinell
You then have to consider that with heat and age, the original material for example 2024-t3 may actually be harder than originally specified.
B.E.


You are judged not by what you know, but by what you can do.

 

[dgapilot]

Best solution is to have the manuals or drawings for the aircraft that identify the material. For most US aircraft that data is available. If you don't have the documentation, you shouldn't be working on it. That said, it is possible in many cases to reverse engineer it. The above posts provide a means to identify the material. Alloy and hardness are still only part of the picture. You need to they identify what other processes are used - coatings, corrosion protection, manufacturing methods, and the list goes on. Best is to get the drawing for the part so you have all the information.

 

[Tarfu43]

Everyone,

Thanks for the excellent replies. I figured I was probably shooting for a pie-in-the-sky scenario, hoping for a low-cost, accurate way of determining material type. Though I might be successful in getting my company to acquire a hardness tester, there's no way they would open the wallet for an XRF tester.

I agree whole-heartedly with dgapilot regarding obtaining the drawings/manuals. However, there are times when we do not have access to those documents because the part is manufactured by a vendor to the OEM. In that case, we could have our customer and/or the OEM try and obtain the needed documents, but there's no guarantee that the vendor would provide that. Also, in many cases, the check schedule requires an immediate answer which cannot wait for days to receive a reply that may or may not come.

Thanks again!

 

[edmeister]

Im surprised no one brought up the time-honored Cadmium-Sulphate solution method (shame on you wktaylor). For the common aluminum identifications of clip / straps / widgits around the fuselage - all that is required is using an eyedropper of this solution & placing a couple of drops of it on the bare metal surface. If the solution remains clear then its 2024. If black deposit forms then its 7075. You can confirm the 2024 by adding a drop of Sodium Hydroxide soln - if the clear now turns black - it a good bet that its 2024 - if it results in white deposit - then its either the clad or 1100 series.

Note of caution - material is to be "bare metal" & the alclad is to be removed (about .003" deep).
- Health & Safety .... when they get notified that "acid" solutions will be brought into the work place - be prepared for a day's worth of paper work & meetings .. & procedures & policies ..

Unless we are dealing with some british import and/or leading edge / nacelle components that requires "non painted surface" (odd alloys used here) - then almost all 2024 will be -T3 or T42 (same thing). 2024-T62 is a very odd one that is seldom seen. Most 7075 will -T6 or -62 (same thing). Unlikely any of these alloys will be install in the annealed condition. (except 1100)

3003 .. never seen sheet
2219 ... never seen sheet (bar & extrusion)
5052 ... never seen sheet
6061 .. check for a weld seam or used in very corrosive environments.
7050 .. only in plates (fittings)
7475 .. only in plates (fittings)
Hardness & conductivity tests will further reassure those of us that find it difficult to sleep at night.

Almost all aircraft primary structure will be identified in the SRM. Minor parts / custom parts / secondary parts will most likely be 2024 or 7075. In "very VERY general" terms .. 2024-T3 (T42) material will crack in bend radius or from rivet holes .. 7075-T6 (T62) will most likely be corroded (exfoliation). Although 2024 may have light surface corrosion & 7075 cracks due to its brittleness.

Check the SRM for material identification processes & solution compositions .. I will not provide the ingredients - look it up.

For steels we have magnetic / non magnetic / copper sulfate soln / sulphuric acid & grinder spark tests.
augment these with hardness & you should be getting close.

Hydrochloric acid will quickly identify magnesium (violent reaction) from aluminum (no reaction).

My comments above are very general & I expect someone to reply with exceptions ..
- but some "common sense" has to exist in the industry - to purchase a $40,000 XRF in order to determine the composition of some $5 clips is just incredulous. As previously stated - significant items will be detailed in the SRM; minor items are either 2024-T3 or 7075-T6 - or else you should not be there guessing!

 

[WKTaylor]

OK, OK... You want "real proceedures..."

ASTM E1476 Standard Guide for Metals Identification, Grade Verification, and Sorting
ASTM E1916 Standard Guide for Identification of Mixed Lots of Metals

DOD-HDBK-249 METALS AND ALLOYS, RAPID ON-SITE IDENTIFICATION OF (RECOMMENDED PROCEDURE FOR CHEMICAL SPOT TESTING AND ASSOCIATED PHYSICAL TESTS TO VERIFY METAL ALLOY CLASSIFICATION)

Regards, Wil Taylor

Trust - But Verify!

We believe to be true what we prefer to be true.

For those who believe, no proof is required; for those who cannot believe, no proof is possible.

Unfortunately, in science what You 'believe' is irrelevant – "Orion"