austenization explained for dummies

Seriously, I am just getting more confused. Anyone have the kindergartner explanation.

Specifically as it applies to heat treating and heat treating services like peters

I can fill you in on austenization, but I cannot speak for Peters HT or give you their thoughts definitions or approaches, you will have to go to them for that.

Austenization is simply the process of transforming the current phase the steel is in into austenite. Austenite (also known as gamma iron) is the solid solution of carbon dissolved in iron (carbon in ferrite). Under ideal conditions, at 1335F the iron atoms in the steel will shift in their stacking and create many little spaces for the carbon atoms to occupy. Iron carbide will begin to dissolve as the chemical bonds are broken by heat and the resulting free carbon will fill the spaces between the iron atoms to form the solid solution of austenite. With steels having less than .8% carbon more heat and time is required to move the carbon through the iron and get full solution. With steels having more than .8% more time or heat is required to dissolve all the carbide and get full solution but this is not really desirable. Maximum hardness only requires around .65% to .8% carbon in solution so any more is overkill or even detrimental to full hardness.

For the reason laid out in the previous paragraph you do not want to heat steels with more than .84% carbon much above 1475F, but you will probably need to heat steels with a less than .75% a bit above 1500F. Alloying changes everything and the heavier carbides can require much more heat or time to dissolve, this is why stainless or near stainless will have austenitizing temperatures a couple hundred, or more degrees, hotter than carbon steels, and require more soaking.

Wow Kevin, thanks that is probably the most succinct, wrap up the subject I have ever seen!

"Austenization for Dummies 101" :what!:

Even I can understand that, I think now I might be able to explain to some one else easier!:les:

I have tried to explain this and it is like my tongue gets thicker and thicker, until I am going, "do you understand what I am trying to say". Secretly I am praying they don't say NO, cause at this point I got nothing left!!! :lol:

Wow I think I get it. So when Peters' says, for their batch heat treating discount, the "same austenization temperature", there may be several different metals that fall into the same temperature. It does not mean the same type of metal. Is this correct.

Unfortunately I did not have time to ask them a lot of questions when I called, as something came up just as I got asking.

Can we make this a sticky??


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natenaaron said:

Wow I think I get it. So when Peters' says, for their batch heat treating discount, the "same austenization temperature", there may be several different metals that fall into the same temperature. It does not mean the same type of metal. Is this correct.

Unfortunately I did not have time to ask them a lot of questions when I called, as something came up just as I got asking.

Click to expand...

Now, that I must sympathize with Peters' entirely on. If all your alloys have roughly the same austenization range you can set your equipment to one temp and just run without interruptions. This is what I do when I heat treat a batch of my own knives. But occasionally I will have friends ask if I can run some blades through with my own and they never really understand how much work they create for me when they give me a half a dozen different alloys with different soak temperatures. Between austenization and tempering temperatures I often don't get to bed until around 4:00 a.m. and then my friends wonder why I am a little cranky about doing their knives. It gets even worse with tootie fruity damascus mixes that has my Rc tester going schizophrenic trying to get two identical readings. I don't think I could ever have the patience that those full time heat treating service guys have.

Great write up.

brilliant explanation.
That must have killed you to get it down to one paragraph Kevin..:biggrin:
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Search around on some of the other forums for information on batch treatement. Peters specifically had some information that they were using austenizing temperatures that were higher than typically recommended for some steels, enough that some other makers started to question it.