Dear Sir

Regarding the solubility of nitrogen in austenite check the following reference (springer editor):

Bulletin of Alloy Phase Diagrams

August 1987, Volume 8, Issue 4, pp 355-377

The Fe-N (Iron-Nitrogen) system

H. A. Wriedt, N. A. Gokcen, R. H. Nafziger

Concerning the influence of Mn on the solubility if you don't find any data in the literature you can undertake the following experiments: heat you sample in the austenitic domain at a given temperature, hold it for equilibrium then quench it vigorously in ice brine water and keep it immediately in a freezer. Repeat this experiment at different temperatures. You can used the Tomographic Atom Probe (TAP) technique to quantify the Nitrogen content. For that matter check the publications (and site) of the Groupe de Physique des Materiaux of Rouen (France), especially the publications of Frederic Danoix who work on the carbon solubility in austenite. TAP is a very powerful tool!

Alain Guillet

Dear Dr. Guillet,

Thank you very much for your valuable comments on the topic. I will definitely proceed with my experiments as per your suggestion. 

Sincerely,

Manidipto Mukherjee 

Hello Manidipto,

in my opinion, based on research experience in melting of high Mn steels, the solubility of nitrogen is about 500 ppm at 1600°C  in 12%Mn, 1%C steel. But in solid state the solubility of N is higher and depends on the temperature and Mn content. For example in Fe-10Mn alloy the solubility of nitrogen decreases from about 700ppm at 1000°C to about 500ppm at 1200°C  [after: Schenck H. et al., Stahl Eisen 83, 1963, pp. 93-99]. I have several articles in this subject. If you need I may send you them by e-mail.

Regards

Sebastian Sobula

Hi Manidipto,

The papers suggested to you are very nice. On the other side, you may calculate the N solubility by a computational thermodynamic software like Thermocalc or FACTSage. I may calculate it to you but I am sure that there is somebody near you who may do this. Please, let me know if you need the calculation.

Cheers,

Flavio Beneduce 

Hi Sebastian,

Thank you for  the insightful answer. Before planning my experiments I would like to read the related articles you mentioned in your comment. I will be very happy if you kindly manage to send some of those articles into my e-mail address. My e-mail is [email protected]. 

Thank you in advance.

With best regards,

Manidipto

Dear Dr. Beneduce, 

Thank you for the valuable insight on the measurement technique of N solubility. Till date, unfortunately, I do not have much exposure on the computational thermodynamic software like Thermocalc or FACTSage due to non-availability in my institute and nearby. However, I am eager to get knowledge on the relevant matter. Kindly enlighten me with the details. The only knowledge that I have related to these software is that the chemical composition of the alloy system is taken as an input variable to derive phase diagrams. It is a sluggish knowledge that I posses and thus I required your help in this matter to improve.

Kindly send me an e-mail to   [email protected]  so that I can further privately discuss with you regarding my experimental data of Fe-Mn ASS weld metals.

Looking forward for your kind and obliging response. 

Thank you in advance.

With best regards,

Manidipto

I have experience with production of high nitrogen Mn-based austenitic stainless steels, it is sure that you can soluble 2500 ppm easily  that you can extend up to 3000 ppm but less than 2000 ppm and greater than 1000 ppm is very common practice in Mn based stainless steels, otherwise austenite phase can not stabilize fully even the Mn contains high side (9-12%wt) in the steels.

Thanks with best regards

K.Chandra Sekhar

Hello Chandra Sekhar, thank you for your suggestion. 

High nitrogen  is used primarily to stabilize austenite in case of low nickel stainless steel. Nickel is a well known austenite stabilizer. But, in case of low nickel stainless steel, some other austenite stabilizing alloying element needs to be added. Mn is the cheapest option but there is limit to its addition as it causes work hardening impairing hot workability. Cu can be added to compensate it but again there is a limit to it. Nitrogen can therefore be added which may may go upto 2000 ppm in certain steel. Kindly note that solubility of Nitrogen is influenced by other alloying elements and austenite formation and its stability. Therefore, no single value can be assigned to its solubility. You need to determine it through ThermoCalc or FactSage.

Thank you Mr. Kumar for your valuable insight.