In particular, in steel of type X10CrNiTi18-10 or 321. Besides metal carbides, could carbon be present in pure state there?
You mean as graphite? No. Cr and Ti are very strong carbide formers; they will soak up all the C apart from a very small amount left in solid solution.
You mean as graphite? No. Cr and Ti are very strong carbide formers; they will soak up all the C apart from a very small amount left in solid solution.
I agree with Steve Roberts, but some stainless steels may present this element as solid solution just in austenitic phase, ferritic phase can not admit more than 0.005 wt. %, so carbides may form in present of Cr, Ti or Nb at grain boundaries and rarely intragranular
Typer 321 or type 304 austenitic stainless steel in which Ti, Cr are Carbide forming elements that stabilizing only austenitic state. It will increase the austenitic zone size but should not be increase the solubility range(2.03%C).
That is preference for carburizing. Nitriding will be in Ferritic zone. BCZ carbon solubility in Ferrite(0.0025%C), So, it is favour for nitriding.
Carbon presents in the form of carbides complex or in solid solution.
Carbides are the most available form for carbon in steel. However, Fe3C (Ferrite) is the main component.
Dear Mahmood,
Too many mistakes in few words:
Ferrite, austenite, cementite are phases not components.
Components of an atomic mixture are the constituents such as Fe, C, Ti,Cr
Fe3C is a stochiometric intermetallic phase known as cementite.
Ferrite and austenite are two different interstitial solid solutions each being a different phase
Dear Anastasia,
It depends on what you mean for "püre state". As carbon atoms: yes, as graphite may be under extreme non-equilubrium conditions, practically definitely no.
To find how carbon, Ti, Cr etc. partitition between intermetallic phases and Fe based phases search for the term "solubility product".
Thank you all for the answers!
I operate with this stainless steel at 100-200oC. As I understand now, at these temperatures it consists of alpha-Fe, cementite Fe3C and ferrite, which is a solid solution of C and other additives in alpha-Fe. Plus there are carbides of additives at grain boundaries.
Dear Anastasia,
You seem to be very confused with so different answers.
To clarify in summary.
Your alloy is an austenitic (gamma) stainless steel. Although pure iron is stable as austenite above 912 C, with carbon addition it may be stable down to 723C. 20%Ni (Ni is known as austenite stabilizer alloying element) addition (as in your alloy) makes austenite stable even at room temperature. So, as thebulk, matrix you should have "face centered cubic " FCC austenite phase with trace amount of carbon (and Nitrogen if present) dissolved in the austenite intersititially Already very low amount of carbon in the alloy must be bound as stochiometric compounds, such as TiC,Cr2C3, CrxCy because Cr and Ti are strong carbide nitride formers. Carbides will be presemt as small , sub microscopic particles called as precipitates, and most probably on the austenite grain boundaries.
For further information on properties see the following link.
Regards.
http://www.searchsteel.com/2011/04/property-of-stainless-steel-astm-a321.html
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