Iron-Carbon Phase Data

F

FunkCoaster

Joined
Nov 2, 2010
Messages
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Regarding the iron-carbon phase diagram, ie https://upload.wikimedia.org/wikipedia/commons/8/8e/Steel_pd.svg

Does the data behind this diagram exist somewhere? I've only ever seen the pictorial representation.
I know that some specific data is called out, like the A1 boundary temperature, but not necessarily for the 'curved' boundaries.

The goal is to create educational resources, to answer questions like :
"For steel with 0.7% carbon at 1500F , what state is it in?"

I have similar questions about TTT diagrams and the like.
The data appears (?) to be experimentally observed data owned and licensed by research organizations, ASM International, and the like. But it seems like the data might/should have made it into public domain at some point.
 
Get a copy of any metallurgy book and the data will be explained. For specific steel charts and data, a copy of the ASM Heat Treater's Guide is invaluable.
 
The binary equilibrium phase diagrams are made with thermodynamic calculations. Many years ago I could have looked up the data and made one for binary systems with common metals. No longer. 😖.

The answer to your question or one like it regarding temperature and composition comes straight from the chart/diagram.

The TTT diagrams were originally made experimentally with much time trouble and expense. I suspect the are done using calculations now. Different steel manufacturers may do them for their own steels, but done experimentally, they are quite a bit of work.

The thing to keep in mind is they are binary (2 component) equilibrium diagrams, and neither condition is common in typical application.
 
i4Marc said:
Marc,

Where did you find all those PDFs?
Click to expand...

If you know how to use google to it's full potential, if it's on the internet, it can probably be found. I've developed a few techniques for scouring the internet for such things. I spent about 3 days digging till I found the jackpot.
 
Re: books. Yes, I have "Metallurgy Theory and Practice" by Dell K. Allen, and the Verhoeven pdf. I've not read them cover to cover, but I'm certainly acquainted with the diagrams and what they represent.

me2: That lines up with what I was guessing. I realize that even "simple" steels like 1095 have alloying elements that make them deviate from the binary experimental data anyway.

I guess the punchline is that the data is not freely available. Freely meaning available for redistribution / repurposing. Part of what started this search is that charts are a representation of data, but they are not necessarily The Data. It is unclear if the charts that I've seen include estimates, data extrapolation, or curve fitting lines, such as the "top forging temperature". Just exploring the rabbit holes to see what pops out.
 
I'm not sure what data you are after. The data used to do the calculations to make the charts is decades old. The issue may lie in knowing where to look. There are programs that will build a chart for any binary system you want with additional elements held constant. These programs have huge data bases of the data your looking for. The charts almost certainly include extrapolations estimates, and curve fitting, along with some empirical information from industrial practice. The original generation of the data was most likely done experimentally, and estimates, curve fitting etc was certainly used there.
 
Indeed, my request for data was a bit broad. As an example, I'm looking at the Liquidus boundary in the Iron-carbon phase diagram, where primary austenite begins to solidify. I can guess that for 1% carbon, it's about 2680F, but I could be off by as much as 50 degrees because I'm looking at a paper grid.

My questions are rooted in finding the origins of these graphs. The 'rectangular' or straight-line portions are easy enough, since most of those have exact data values called out for them, and intermediate values can be guessed based on interpolation. But I don't always know if those are valid assumptions.

If the programs mentioned have databases, then that is presumably what I'm looking for. But if it's licensed/proprietary information, I can't really do anything with it. I was trying to discover information/data that could be used to recreate these diagrams in a freely-distributable, open-source fashion.

I respect that organizations spend money to make these measurements, and do not want to steal from them.
 
Have you had trouble finding the diagrams on line? I understand what your after now buti think it's a bit impractical. The readily available charts are used regularly and the accuracy is adequate. With all the things that can change the values in a chart, they are only used as Ann approximation any way. If you could get all the data and make a chart from it, it most likely would end up looking like the ones already available.
 
look at the references listed in formal published research papers or metallurgy textbooks.


for example, if someone's PhD thesis is about the effect of adding manganese, they may have listed references for the base Fe-C data they used


other people's data - OPD ;)
 
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