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Author: Subject: Steel temperature transformation range(s)
justender
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[*] posted on 4-6-2024 at 15:34
Steel temperature transformation range(s)


I've been doing some reading and ran across this:

"temperature range - The temperature at which a change in phase occurs or the limiting temperature of a transformation range. These critical points are denoted by symbols, e.g. Ac1 [obviously a transliteration to ASCII]; the temperature at which austenite begins to form on heating. There are 12 principal temperatures to which symbols are applied"

I've gone searching on "12 principal temperatures steel" and some other variations, but have not been turning up a nice list.

https://www.totalmateria.com/en-us/articles/principles-of-he...

lists these:

A1, the so-called eutectoid temperature, which is the minimum temperature for austenite
A3, the lower-temperature boundary of the austenite region at low carbon contents, that is, the γ/γ + α boundary
Acm, the counterpart boundary for high carbon contents, that is, the γ/γ + Fe3C boundary

Which look like maybe they're some of the ones I'm trying to find?

Another possibility:

martensite finish (Mf) temperature

Semi-related:
https://nickelinstitute.org/media/1699/high_temperaturechara...

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[*] posted on 5-6-2024 at 02:23


Welcome to the community.
Quote: Originally posted by justender  
e.g. Ac1 [obviously a transliteration to ASCII];

It looks like you want to write Ac1. So the website uses special syntax for this. I think its called "bbc tags"
Code:
normal text [sub]subscript[/sub] and then you can[sup]superscript[/sup]

Gives you "normal text subscript and then you cansuperscript"
There is a large set of these tags and can do all sorts of cool things, even draw pictures

This post here https://www.sciencemadness.org/whisper/viewthread.php?tid=64...
Goes into great detail about tag usage
If you click quote, in the upper right corner of a post, you can see the raw text showing how they used the tags.

Here is my favorite libary
https://archive.org/search?query=Heat-Treatment+of+Steel




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justender
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[*] posted on 5-6-2024 at 05:51


Thanks for the reply, btw.

If I knew what they were, my question would be answered.

Sorry I wasn't clear, I'm not looking for help with the bb code tags for use on the forum.

I'm looking for a list of temperatures (and preferably with a name/general description of what changes at that temperature), and the correct/widely used symbols for those temperature points - preferably a list that has the correct subscripts and superscripts and any Ελληνικά letters or other symbols (if I get a list of the 12, with only names/descriptions, I could probably be able to look up each symbol/ogy individually).

What I posted is what I found - ie: it (appears) they were unable to correctly use subscripts, but I don't *know* that from the context, I'd just be guessing.

I don't have a complete list. I can only find some snippets, which reference temperatures. I don't know if any of these (excluding the one listed in the original example) are the 'principal' temperatures. I suspect there may be more than 12 temperatures at which steel changes; I think hardening/quenching includes more than that, alone.

[Edited on 2024-6-5 by justender]
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bnull
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[*] posted on 5-6-2024 at 09:14


Quote: Originally posted by justender  
"temperature range - The temperature at which a change in phase occurs (...)"

I believe you mean "Transformation Temperature" (https://www.nass.org.uk/glossary/).

Quote: Originally posted by justender  
I've gone searching on "12 principal temperatures steel" and some other variations, but have not been turning up a nice list.

You should have looked for "transformation temperature of steel". If you had, you would have found the blog post Fundamentals of Carbon Steel Part 2 - Heat Treatment, which comments on some of these temperatures and has a couple of references at the end that, hopefully, deal with all the 12. It's probable that Internet Archive has copies of both.

One more thing. Since you're new to the forum, take a time to read https://www.sciencemadness.org/madscifaq.html#2.1_Board_topi....




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[*] posted on 5-6-2024 at 15:57


All the information you require will be found on the iron steel phase diagram.
It gives the temperatures you are after as well as defining the zones where more than one phase is present. You can then calculate the proportions of each phase present.

Note that the phase diagram does change if there are other alloying elements present. For example, the presence of Ni in stainless steels means that austenite is favoured at room temperature.
Note also that the phases you actually get and the form in which they appear depends on kinetics -- ie, rate of heating and cooling.

(I used to be so familiar with that diagram that I could give you all temperatures and compositions and draw the whole thing from memory. Alas, through lack of use, those days are gone.)
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justender
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[*] posted on 5-6-2024 at 16:58


Quote: Originally posted by bnull  
Fundamentals of Carbon Steel Part 2 - Heat Treatment, which comments on some of these temperatures and has a couple of references at the end


For anyone following along:
"1. THOMAS G. DIGGES & SAMUEL J. ROSENBERG, Heat Treatment and Properties of Iron and Steel, National Bureau of Standards Monograph 18, Issued October 3, 1960

2. EDGAR C. BAIN, Functions of the alloying elements in steel, Am. Soc. Metals, Novelty, Ohio (1939) 312 pages"

1) NBS Monograph 88 (1966-11-01) supersedes Circular 495 and Monograph 18, by Digges, Rosenberg & Geil, is located here:
https://nvlpubs.nist.gov/nistpubs/legacy/mono/nbsmonograph88...

2) _Functions of the Alloying Elements in Steel_ (1939) by Edgar C. Bain is available at link following, or as a single 111M (now 18.7M) download:
https://www.phase-trans.msm.cam.ac.uk/2004/Bain.Alloying/ecb...

[Edited on 2024-6-6 by justender]

[Edited on 2024-6-6 by justender]
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