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Annealing at home: is it truly impossible, or just myth...


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So ive poured over PDF files, and forum posts. Even asked questions thru social networking.... But I find the most insightful, soumd, and logical information to be here, on this forum... It is just so difficult, sometimes, to find a clear, to the point answer in all these posts... So what I am curious about is the annealing process of salvaged steel. For conversation sake, let's say a piece of 5160 leaf spring that's been cut off of an old F150. From what I can understand, I need to anneal this piece of steel, before I begin to shape it, if for any reason, to make sure it's as strong as can be... In my readings and research, I was informed that it is nearly impossible to "accurately" anneal any piece of steel at home, for heating to temp than cooling at room temp is to fast a cooling cycle. I've been using a toaster oven for tempering... Would it be too in-accurate to heat to critical, than slowly cool in my little oven? For me, in theory, the idea seems doable... However, I've proved time and time again... That I know NOTHING!

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Annealing makes the steel *soft*.   It will also help with work hardening; but will not cure any fatigue cracking already there.

Annealing temp is in the glowing zone. I don't know of any toaster oven that goes to around 1400 to 1500 deg F.

Then bury it in vermiculite or sifted wood ashes.  If it's a small piece you need to have a "helper piece" of steel heated to the same temp to make sure it cools slowly enough.

Heating to critical and then cooling in still air is not annealing it's normalizing and won't work for thin cross sections of alloys that may air harden.

Please define your "strong": maximum tensile strength, max yield strength, max charpy test results (toughness), maximum hardness,...?

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Thank you Thomas, I just deleted my long rambly reply. :)

Bliziak, there're a lot more variables involved and methods to compensate. One variable that can REALLY get complicated is the Alloy. 

Digest these bare bone basics and see what you come up with next. ;)

Frosty The Lucky.

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What those guys said.

It's also important to look at it this way:  What is it you're trying to accomplish?

If all you are after is softening up the steel enough so that it's easily machined then the absolute best possible annealing is not necessary.  If you're just trying to minimize the effort and wear and tear on your abrasives, files, or drill bits then you just need "soft enough," nothing more.   That is completely doable as TP described using dry sifted wood ashes or vermiculite.  You could even do a sub-critical anneal and probably get the desired results.  That amounts to bringing the steel up to just barely glowing temperatures (still magnetic) and letting it cool down.  Slower is probably better on the cooling, but even just cooling in still air should make it well within the machinable range.

As anvil pointed out, if you're going to go directly to forging without any machining there is no real benefit to annealing first anyway.

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Caution: massive oversimplification ahead!

On a metallurgical level, this is all about grain structure. Smaller grains interlock better with each other and make the steel less malleable. Larger grains deform more easily, which makes the steel more malleable.

Annealing is heating the metal until the grain structure disappears and then cooling it slowly, which allows the grains to grow larger. The methods described above all do this by insulating the workpiece from heat loss, so that it cools very slowly indeed. Commercially, this is often done in large ovens with sophisticated temperature controls, but that's not necessary for simple carbon and low-alloy steels. However, high-alloy steels often require very specific temperature changes at very specific intervals, so these are often beyond the range of smiths with simple tooling.

 

 

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See... Lime I ended my post with...

"I KNOW NOTHING!" Lucky for me, I have the super bonus of hundreds of thousands of individuals that came before me, who actually know what they are doing. 

Now, since I am going straight to the forging process, I now understand that annealing isn't as necessary as I previously understood it to be. That being said, I am, if nothing at all, grateful for ALL the knowledge that gets bestowed upon me, mainly because I don't have money for lessons, nor an opportunity for some kind of apprenticeship, or trade of services. Therefore, anytime knowledge is shared with me... Well... You know. Yes I know my toaster oven doesn't go to a thousand degrees, I was being a bit facetious. But I appreciate the input. A big thanx to all!

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Oh, one other option for annealing: heat your workpiece and another chunk of steel to the workpiece's critical temperature, and then wrap them both in kaowool. That'll give you a nice, long, slow anneal just like mama used to make.

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Since you missed it, notice we have 2 sections devoted to heat treating, one for blades due to the thin sections involved requiring different methods at times.  Sorry you missed that, I will relocate your post there with the other heat treating info including a few pinned threads for you to read through

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  • Mod42 changed the title to Annealing at home: is it truly impossible, or just myth...

Big thanx to Steve Sells! Yea I did miss that. Like I said, I seem to get add after spending long amounts of time pouring over text looking for a specific answer. So much so in fact that I missed that! So again, much appreciation for the course correction. Going to head there right now and start reading! Thanx to all!

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3 hours ago, bliziak said:

"I KNOW NOTHING!"

You'd be surprised at the advantage you have over folk who can't or won't admit not knowing. I may know quite a bit about blacksmithing and am constantly being proven wrong. Truth is I THINK I know things but am happy to be proven wrong. I'd rather know than think I know.  Know what I mean? :ph34r:

Frosty The Lucky.

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I truly admire the way you put some things, Frosty! And yes, I DO know what you mean. So let me speak about something that I KNOW. 

I know that it has been quite some time, years in fact, since something has brought me the copious amounts of joy that learning to blacksmith has brought, and continues to bring me everyday! Plus I cant remember anything where I get just as excited failing, as I do when I succeed. And isnt that what it's all really about? Happiness? Joy? A sense of fulfilment? Well, that's what it's about for me. At least for the time being, that is... I think life is too short for anything else... So unroll something changes, I intend to continue swinging a hammer, and asking questions. Thanx everyone!

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I think working hot iron is different things too different people but whatever, if it puts a smile on your face its good. One of the things that sings to my soul is being able to use two of humanity's oldest tools, fire and something to bash with and have my way with steel, the very backbone of human civilization, a universal symbol of strength and durability. 

I also love it for the lifelong learning curve it offers, I can do things I've done before and learn little or try something new and exercise my failure analysis skills. Either way, comfortable routine to relax by or explore something new, it's good. Very Zen in many aspects, as good a form of meditation as any.

Frosty The Lucky.

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Well put, sir... And I see what you mean when you say "working hot iron is different things to different people." Like I said earlier, getting as excited over a failure as I don a success is truly, as you said, a Zen experience. For it means, at least for me that is. That I learned yet another way not to do something...

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