XRF analysis of 430F vs. 430FR

[djhurayt]

Will I be able to distinguish which identical geometry parts are made of 403F 430F and which are 430FR.

Situation: I had two groups of samples annealed. Unfortunately there appears to have been parts mixed as my two bags of samples no longer contain the same number they went out of with.

My understanding is that these devices are pretty good with Silicon, that being the biggest difference in material composition between these two alloys

david

 

[btrueblood]

I'd think the Cr content would be the kicker, much greater difference in content between that element for the two alloys.

 

[djhurayt]

btb, are you sure?

I was under the impression that both material were basically the same with the expectation of more Silicon in the FR to increase the resistivity for better magnetic properties.

There is indeed a difference in the min max values for CR but the values also overlap. Were as the Si content should define the material as one or the other.

So as far as my original question (for anybody with experience with on of these XFR units):
Do you think one of the XFR analysis units will be able to tell the difference between parts made from 430F and the same part made from 430FR?

david

 

[EdStainless]

Maybe.
Surface prep will be critical.
You will also need to run in 'high precision mode' or whatever your machine calls it.
This will likely be 60 sec per shot or longer in order to get enough counts on Si to have a reasonable chance at sorting them.
You could always just measure magnetic properties.
That should be faster.

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P.E. Metallurgy, Plymouth Tube

 

[btrueblood]

Sorry, not sorry -- you typed 403 in your original post, which has a typical chromium level of 10-11%.

 

[MagBen]

Si in 430FR is normally 3 times higher, which indeed is the main difference. Two purposes for higher Si:
1. to increase resistivity for a better magnetic performance, particularly less eddy current losses. Ed recommendation to measure magnetics is valid.
2. to increase hardness for less deformation (peening). since this is annealed condition, you will see difference in hardness. 430FR is harder. Hardness measurement maybe the easiest way in this world.

 

Based on the table, Mn would be your only hope of differentiating these two alloys with XRF.
My experience is that PMI does not like Mn, usually overstating it significantly.

I'm not familiar with 430FR, but I find the combination of very low Mn and high S very curious.

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

 

[djhurayt]

btb, you are indeed correct about my original posting, thanks

Ed, this is only the core of the solenoid, no windings or anything else yet

david

 

[MagBen]

if core loss measurement is an issue, you can try to run a BH curve to get HC or max permeability. Si also decreases magnetocrystalline anisotropy, leading to a lower Hc and higher perm.

 

[EdStainless]

I was suggesting to build a test stand using a coil and picking a field level that would allow you tell these two grades apart.
It might be as simple as a small AC coil around one end and a search coil near the other end.

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P.E. Metallurgy, Plymouth Tube

 

[MagBen]

I doubt you can get a core loss data, or other meaningful data with AC exciting coil and search coil.

I am thinking maybe you can use a DC coil one end and a search coil on the other coupled with a Gauss meter. Gradually increase the exciting DC current, and you will get different Gauss readings. The reason doing that is, if current too small, there is no much difference in initial perm for these two alloys, while if current is too large, material will be close to saturation, you will see no much difference too.
Another thing to do is to attach pole pieces to form a close circuit. In an open circuit, I bet you can hardly be able to find the difference.

Magnetic testing can be very trick, if you are not an expert or without an expert to help, do not even try. These two materials are basically not very different in terms of magnetics.

 

[remetaper]

I think there no difficulties to separete 430 FR and 430 F by use MPI. Also the spark of MPI( Spectrum or ARL) is a little be different.In any case, the value of Mn is wrong. Normallly , value of is Mn < 0,5% in order to increase the resistance corrosion for free machining ferritic SS and for other reasons. Carpenter ,Valbruna , Daido , Ugine and other ones, have in their QA dept. a system of MPI test before supply. Technicians for this testing are able to separate also different heats of same grade of 430FR using MPI process. ( Such as ARL, Spectrum or other kind of device)
About this subject, I suggest to take a sample of 430FR + test by MPI then take of 430F + test by MPI. Verify both results not only for main alloy elements such as Cr, Si, Mn without forget Ni and the others oligo- elements able to identify the differences between both grades. A differences surely will exist. Other way to separete both grade by ET could show some difficulties due to little difference between grades when fully annealed or magnetic annealed. Magnetic testing by yoke or coercimeter according to ASTM 341 could be a other choise but this depends on geometry of pieces/blanks. And could be expensive in case of yoke testing if applcable ( geometry of piece).

 

[EdStainless]

remetaper, don't confuse real spectrographic analysis (ARL XRF or Specro OE) with PMI.
There are a few orders of magnitude difference in accuracy and precision.

I figured since they were building an electromagnetic device that they would be able to test that way.

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P.E. Metallurgy, Plymouth Tube

 

[remetaper]

Ed,
I didn't refer to spectographic analysis apparatus such a - for instance- Thermofischer mod.4460 ( ex ARL) used for final heat analysis certified by steel maker where "precision and accurancy" is mandatory. I did talk about OES mobile and XRF mobile ( such as Specro )widely applied by most important steel makers or by drawing/grinding shops before the delivering of bars or tubes or other shapes in order to avoid a mix of product. These devices are reliable if the technician knows what are looking for /search , what have to do and the limit of this kind of analysis. As in this case of Djhurayt.
In addition to my post of May,24,I suggest to Djhurayt to veryfied both certificates of steel producer (430FR and 430F )and evaluate/compare the chemical analysis.Surely it will exist an element/s whose difference allows to identify one of steel grade by OES mobile or XRF mobile.
I didn't find any difficult to separated bars of alloy 1 and alloy 2 of ASTM 838.
At the of story, it would be important to know how many pieces, shape/dimension in order to evaluate the cost.