Iron and Iron-Carbide Phase Diagram

What does your instructor in Materials Science say about this?

Is this a test question, or just homework?

If one Googles, "Iron and Iron-Carbide Phase Diagram" one gets 89,600 results.

This seems an easy enough chore that the OP should have been able to accomplish in the same length of time as it took me. Just a thought.

A look back in time also adds to my suspicions.

Re : Dislocation versus Microfissure

By all means, feel free to provide any help to the OP that you wish.

Cheers.

Not at all. No offense taken.

Many times we get students who would rather be given the answer, rather than searching for it.

Many members spend much time explaining things that could just as easily have been gleaned from a text book, or a web search.

Iron-Iron Carbide Phase Diagram.pdf and many other web sources are from educational institutions and text books, leading those of a more cynical nature (me) to believe that a practicing engineer would have already been through this course in school.

Some foreword could explain the request for this information and put many of us old cranky guys at rest, however that is rare.

Student or not, this is actually a good question, poster seems the have some fluency in Physical Metallurgy.

Student or not, if I recall, some of the text books (especially in PM) were to a certain degree, can be ambiguous at times.......

Keeping an eye on this post,..... just out of curiosity.

I'm not far from entering my 4th quarter century, and there are more than a few people who consider me expert in a number of fields, but I'm still eager to learn more. I believe that qualifies me as a student, and metallurgy is one of the areas where I really do need more knowledge, but I don't have time to take any formal classes, so I hope to see some more answers to this thread.

I went back and re-read the original post, and I get the impression the OP is more like me than like a lazy college student trying to avoid studying.

Agree..... I never stop learning...... Even as refresher I can be corrected.

DKWarner, Esq.,

Dear Sir,

Thank you so much indeed for your noble expression.

Surely, you are the most respectable indeed.

Thank you again, Sir.

Regards.

Fe C diagram valid across most alloying elements. The single biggest influencer of the phase transformation process is Chromium. Cooling rate for austenite to martensite transformation is majorly effected by Cr.

makes it brittle.

Dear Sir,

Thank you for your reply to my query.

Gleaned from an entry didactic text of materials science,

a. A phase diagram is a plot of equilibrium conditions.

b. Formation of martensite results from quenching (such as a burning hot piece of
steel dipped in a pool of cold water, at a cooling rate so rapidly that equilibrium is not
ordinarily considered attainable).

c. Is it nickel being mentioned to keep martensite stable down to the room temperature?

Could martensite appear on a phase diagram?

Thank you again. Regards.

This is a wide topic.

Each type of alloying element added into Fe-C will influence the phase diagram, some will only shift forming of Austenite/Ferrite/Bainite/Martensite & etc to different temperature or different wt% contain of Carbon. While some alloying element will form something new with Fe-C, then they probably will precipitate hardening and give additional strength to the steel.

Lot of researches have been done on effect of alloying element added into steel.

If you refer to material (steel) handbook there are many phase diagrams for reference.

Or you can try searching some keyword, you will get surprising result. Enjoy the search & read.

Dear Sir,

Thank you so much indeed for responding to my query.

So, I have looked around in the neighborhood and found,

http://www.calphad.com/martensitic_stainless_steel_for_knives_part_1.html

Would like to seek help for interpreting,

a. M23C6, M7C3.

b. Is Gamma-phase = Austenite ?

c. Is Alpha-phase = Iron-Carbide ?

The phase diagram is generated by,

Thermo-Calc

coupled with TCFE2000 thermodynamic database.

Is Thermo-Calc endorsed by ASTM ?

Thank you again. Regards.

a. M23C6, M7C3.

This is chromium-rich primary carbides (refer to your first link), which mean chromium added into this stainless steel reacted with carbide forming chromium-rich carbide. Carbide will exist when there is excess carbon in steel, in other word steel is saturated & can't dissolve any more carbon. When no other alloying element added, carbide remains as carbide alone; when alloying element like chromium added into steel, carbide might react with chromium forming chromium-rich primary carbides. This carbide might precipitate and grow larger when steel is cooling down.

b. Is Gamma-phase = Austenite?

c. Is Alpha-phase = Iron-Carbide?

Yes, Gamma = Austenite. No, Alpha = Ferrite.

https://en.wikipedia.org/wiki/Ferrite_(iron)

Is Thermo-Calc endorsed by ASTM?

Sorry, I know nothing about Thermo-Calc.