Positive Material Identification (PMI) 1

[ritsa p]

We performed PMI testing on surface of some unknown base metals.
The results of chemical composition are mentiοned below:
1. Fe A-9 [-230.4]
2. Fe S-7 [-74.4]
3. Fe S-5 [-223.2]
4. Ni Alloy690 [-398.1]
5. Cu-Tramp Cu TrampMax [-232.9]

Could you please me inform me for the, material grade ( Gr.P11, Gr.P22 etc. ) or P.No. ( ASME IX) , as per results above?

 

[XL83NL]

What do those numbers even mean? Do you have a print or report on the measured chemical content? Have you tried comparing those numbers yourselves to a known or published spec (e.g. A335) to determine a possible match?

 

[btrueblood]

Those results look like the PMI machine is attempting to identify the alloy, not reporting constituent atomic percentages. As XL83NL says, you need to get the output in the form of atomic percentages; you also need to determine the lowest element atomic weight the PMI is capable of measuring and use that to help inform your search for possible alloys.

 

[EdStainless]

Did you prepare and clean the surface?
Did you use your machine in the high precision mode (long sample time)?

 

[ritsa p]

What do those numbers even mean? Do you have a print or report on the measured chemical content? Have you tried comparing those numbers yourselves to a known or published spec (e.g. A335) to determine a possible match?

Attached file include measurements of chemical content.

 

[btrueblood]

Uh, that spreadsheet has chemical constituents all over the map - iron content varying from 9% to 90%??? What or who generated this?

 

[EdStainless]

Was the surface abraded and cleaned?
Is the part metal?
Is it magnetic?
Tell us what the part looks and feels like.

 

[dgeesaman]

I think you're asking too much of PMI in this exercise. A couple of your samples don't add up to 100% composition. So to Ed's point - is the data good?

PMI is great when you have samples of alloys and you are comparing it to a known list of alloys. The PMI tool often stores common material definitions and performs the comparison for you. PMI is not intended to take any material and tell you with certainty what it is.

In many ways the name Positive Material Identification is misleading - for me it's really Probable Material Confirmation.

 

[EdStainless]

PMI is for identification, not compositional analysis.
It sis intended to answer the question, 'does this match that' and that is all that it does.
I put portable PMI tools in the same place as hardness testers that read to 00.0, it has no real meaning.

 

[mrfailure]

You cannot put the PMI probe on an unprepared surface - results will be nonsense. You have to grind away surface contaminants and oxides first.