How Hot Is Forging Hot

Stacy E. Apelt - Bladesmith

Stacy E. Apelt - Bladesmith

ilmarinen - MODERATOR
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Knifemaker / Craftsman / Service Provider
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Lately I have seen a lot of advise that roughly says,"Get it hot and forge it....".

Lets think here...

How hot do you need to get a piece of steel to forge it...Red, cherry, maybe orange?
If steel quenches at 1550F isn't it a good idea to forge at a lower heat?

Most carbon steel forges at around 2200F, and you should stop forging at around 1600F. Some steels are even higher. If you forge until the steel is barely red, (or worse - black) you have gone way too cool.

To forge steel you need to be able to reliably get it to a yellow orange heat (2200F) and not burn it up with a lot of excess oxygen. A leaf blower in a charcoal grill or wood stove will get it that hot, but it will be a heavily oxidizing atmosphere. A cutting torch will do it too, but is hard to reliably heat the whole blade.
A simple forge made from a piece of any scrap 8-10" round metal (pipe, water heater tank, propane/freon tank, etc.) will do the job perfectly. You can use it to do the HT ,too.
I know a lot of folks started with a one brick forge, and that will work in a pinch. But for as little as $100 you can build a forge that will get you through several years of bladesmithing with good results. The first knife you sell might pay for it.

For ideas and materials, go to Darren Ellis' site - http://forgegallery.elliscustomknifeworks.com/
and click the refractory and knife supplies. There is a FAQ page that has a lot of info,too. Darren will help you if you are totally at sea (I may have dated myself with that statement). He is a first class fellow and knows his stuff. You won't beat his prices either.

This is where I chime in about the steel you forge....
All lawn mower blades are not 1080.
All springs are not 5160.
All files are not 1095.
All hammer heads are not O-1.
All 5160 from a Admiral is 5160.
All 1095 from a Crucible is 1095.
All O-1 from Pop's is O-1.
All 1080 form Aldo Bruno is 1080.

Using a know steel from a reliable source will give you:
1) A known steel.
2) Charts and temperatures to work with.
3) A place to ask questions and get good answers.

I think that is enough to (hopefully) get some of the newer knifemakers headed in a better direction, and to get some of the well intended advice redirected to folks with more experience (working "found" steel is fun....once you know how to determine what to do with it.).
Stacy
 
Stacy your statements above ring true and I, for one, appreciate the fact that you take the time to share your knowledge. I stock remove, but will soon (after attending Ashokan) will start my journey into forging. I think a lot of the seasoned makers / forgers forget sometimes that what they know as "forging heat" doesn't mean the same to those of us starting out. I expect that I will need a thermocoupler for some time to ensure that I have a satisfactory forge heat and then over time, learn the steel well enough that it will speak when it is ready to meet the blow of my hammer. Excuse the corniness of the last statement...
 
Good info, Stacy, BUT one correction.....all 5160 from Admiral is 5160 except for the 1 x 1/4 nominal size which is 9260:D And one more addition......all W2 from Don Hanson is GOOD!!!:thumbup: :D
All oil is not created equal when you are using it as a quenchant.
If you hit steel when it is too cool, you will eventually discover cracking and that sucks!!!!!!
If you get steel too hot for too long and don't do something to reduce it, you will discover grain that looks like beach sand when your blade breaks.....and it will......and that also sucks!!!
If you don't normalized properly after forging and grinding, you are highly likely to discover warpage.........and that REALLY sucks!!!!!
 
What about getting 5160 from a spring shop? It was recommended to me recently to ask for cutoffs at a local shop. Makes sense to me as shops should have mill reports and heat #'s for the steel they're using. I would agree though that junkyard steel might not be the best idea.
 
NDallyn said:
What about getting 5160 from a spring shop? It was recommended to me recently to ask for cutoffs at a local shop. Makes sense to me as shops should have mill reports and heat #'s for the steel they're using. I would agree though that junkyard steel might not be the best idea.
Click to expand...

In general, my feeling is that if steel is from a trusted source that knows what it's supposed to be, you're probably in pretty good shape. There is a huge difference between "our supplier sent us 5160, here are some drops" and "I remember that a 1938 Cadillac used 5160....I think". I don't think that Stacy is saying not to scrounge around for stuff, just make sure you scrounge around for known steels. I've gotten a lot of W1 and O1 cutoffs from a local machine shop for next to nothing, and I'll keep doing it since it's known good steel.

-d
 
Deker has it. Know the source. A lawn mower isn't a source. A car isn't a source. A spring shop is. A machine shop is (if they label the cut offs). As for the 5160/9260 from Admiral, I thought that would come back to bight me. There is little difference in working the steels, and the results will be comparable, so it wouldn't matter. The two have been interchanged without notice for years. 9260 make a slightly better blade, IMHO.
 
I learned a good while ago, when bladsmth talks, pay attention. :) :thumbup: Thanks for the wise words Stacy.
 
How do I know if I am running hot and oxidizing or hot and reducing(?)
I have a I.G./ Fogg vert forge. The temp I can measure to 2000 degrees
I have been working with small amount of flame coming out the forge opening, I thought I read that somewhere.Is that correct, what is a good way to know/guess
 
Tommegow said:
How do I know if I am running hot and oxidizing or hot and reducing(?)
I have a I.G./ Fogg vert forge. The temp I can measure to 2000 degrees
I have been working with small amount of flame coming out the forge opening, I thought I read that somewhere.Is that correct, what is a good way to know/guess
Click to expand...

If that little bit of flame coming out is orange, you're reducing. No flame coming out the opening is oxidizing. Neutral is somewhere in between.

Think of it this way, if flame is coming out the front, that's because all of the oxygen to sustain the reaction inside the forge is gone, so the remaining gas must burn off outside the forge. If no flame is coming out, you're burning all of the gas inside the forge and probably have extra oxygen left in there as well.

-d
 
Your pyrometer won't necessarily be accurate at 2200F, but you will have a good idea of this heat by the look and feel of the steel. At forging heat, most steel moves easily under the hammer.The look is a very bright yellow-orange. If the steel is throwing off sparks when you take it out ,you are too hot. If it is only a cherry red, it isn't quite hot enough. If the steel is stiff when hit, it may not be hot enough (unless it is D-2 or something that is hot hard).

Thanks for the kind words fellows, but I am no Guru.
I read a LOT, 5,000-10,000 pages a year (sometimes more). If you study metallurgy, and forging, and then apply it to your practical work....you can gain a lot of experience without the failures often encountered in the learning curve. This site is a vast fountain of information. Guys like mete, Kevin, and all the long experienced makers can teach you a lot.
Stacy
 
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