how to add alloy elements to an existing alloy?

[martensita81]

Hi guys! hope you can help me with this issue I have.

I want to fabricate a 50gr-little piece of "new ferritic stainless steel".
So, I want to use a little piece of commercial ferritic stainless steel which I know it has the following composition:

Fe 81.06
0.12% C
16% Cr,
0.75% Ni
1.0% Mn
1.0% Si
0.040% P
0.030% S

My goal is that this "new 50gr-piece of ferritic stainless steel" has the following composition with more Cr and Ni:

Fe 81.06
0.12% C
25% Cr,
7 % Ni
1.0% Mn
1.0% Si
0.040% P
0.030% S

So, my question is how can I know the content of Cr and Ni that I should add in order to get that new composition?
Is there any special formula???

Im doing this as a practice of materials characterization, I want to show the micro structural difference in function of the composition, so, help will be greatly appreciated.

Thanks in advance.

 

[metengr]

Materials characterization? You need to melt the current alloy and add the necessary elements using a typical mass balance equation. This looks and smells like a homework problem.

 

[EdStainless]

You usually arc melt small buttons like this.
About half of the melt is usually a know alloy and then you use high purity metals (electrolytic) to make up the chemistry. It is simple algebra.
And the first alloy isn't ferritic, it is martensitic.
You second alloy is sort of a duplex, but way too much carbon.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[steelmtllrgst]

Definitely will need to use a button melter or a small induction coil.

At the end of the day, you will need to add virgin alloys of each element not just Ni and Cr due to dilution from the ~15% alloy addition you want to make.

Just in case this is homework, I will not do the work for you. But it is simple algebra as stated earlier. Easiest way is to convert all elements to how many grams of each you will need:

50g sample x .25Cr = 12.5g Cr... and so on for each element.

 

[bhollands]

Don't forget that by adding the Cr and Ni the percentage of all of your other elements will change as well.

There are no real special formulas its all basic algebra. In the real world you would have a chemical range that you needed to meet and not one specific number.

Bob

 

[mw1st]

Composition range is usually given for metals chemistry. For example 410SS C:.05-.15, Mn:1max, Si:1max, Cr: 11.5-13.5, Ni:.5max
If you have 100g of metal at .75%Ni and need to have 7%Ni concentration, then you need to add 6.25g of Ni.
Ferro Alloys will vary in alloy concentration, so you need to
know this value, for example, FeMn may have 76%Mn and 6.5%C. FeCr will have some Si , C and others, but small enough that can be ignored in your calculation. S and P at .04% are max. values, which should be, and are usually much lower. Some of your elements will get lost while you melt due to oxidation, so you should account for this, ie. if you aiming for .1%C, than calculate for .12%C or so.
I did simple spreadsheet in excel for your convenience, so you can
"play" with chemistry and weight%, can also modify any way you want, ie. add rows, columns for additional elements, etc., than copy/paste and/or create formulas in corresponding cells.
I will upload a file but I'm not sure if it will work, so one will be a "template", and second - with numbers already entered.
Good luck with your project.

Mark

 

[mw1st]

OK. it works fine, granted you have Microsoft Excel program on your computer, if you don't - you should. It's very useful tool.
I'll upload now just a template spreadsheet with no values entered, although first file can be used for calculations - no matter.

 

[deadrange]

Don't forget about thinking about recovery rates. Granted this is only a 50g sample you are trying to make, but you should still consider recovery efficiency in determining the amount of raw alloy you are adding.