No Mn reading in SEM EDX composition analysis of plain carbon steel

[lcbf]

I have a surface composition reading (analysis using SEM EDX) for a thin steel plate which I expected to be a plain carbon or spring steel, such as CS70/1070. The results are showing no manganese to be present. I would expect to see a Mn reading for all plain carbon steels as Mn is always added to scavenge residual sulphur in the steel, so to prevent grain boundary embrittlement. I would also expect the EDX technique to pick up a Mn reading. The sample surface was ground, polished, etched and cleaned prior to examination under vacuum.

Has anyone come across a plain medium to high carbon steel with no manganese before, or had problems with the EDX technique in this way?

Many thanks in advance for your help.

 

[Dhurjati Sen]

Go for a chemical analysis, specially for Mn.

DHURJATI SEN
Kolkata, India

 

[EdStainless]

It could be very low, but you are correct to expect some.
Have someone do an OES (this will give you C also) or XRF analysis for you.

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P.E. Metallurgy, consulting work welcomed

 

Remember that EDX in an SEM is basically like PMI by XRF. It is semi-quantitative at best. And from experience (granted with older guns) PMI is quite poor with manganese.

I promise you, if it is steel, there is manganese there.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[mrfailure]

Even if you don't see Mn in your spectra, I would suggest to you to force the issue by including Mn along with Fe in semiquantitative analysis, plus any other peaks you see if present except for C and O, even if they are present. See how much carbon is computed under this scenario.

 

[EdStainless]

This could be an issue with surface prep. This is important.

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P.E. Metallurgy, consulting work welcomed