Forging heats

**Tai Goo** · 05-04-2012, 11:02 AM

Originally Posted by NickWheeler

IMHO- one thing that can make a forged blade excell, is that every heat is part of the blade's thermal cycling. One thing that can really make a forged blade suck, is that every heat is part of the blade's thermal cycling.

I like that Nick.

Originally Posted by NickWheeler

Wait, is Tai talking about science? Thermal dynamics??? What?!?!?!?

shhhh... I feel so dirty and ashamed... I'm not ready to come out yet and it's been such a long time.

(I try to use science in speech as sparingly as possible and only when it's absolutely necessary, still don't like scientism and highly technical gibberish (or jargon) or science for science's sake though and probably never will.)

Most of the industrial papers I've seen on the "advantages and disadvantages of hot forging" tend to favor the advantages. However, a list of disadvantages usually looks something like this,... oxidation (scaling), decarb, grain growth and/or irregular/uneven grain size, and "hot working fatigue". Add to this possible damage to the steel from improper forging, like under heating (cold fracturing), over heating or burning, trying to move too much metal too fast ("hot fracturing"), and you start to get a pretty good picture of how complicated and risky it really is.

**panch0** · 05-04-2012, 11:31 AM

Originally Posted by NickWheeler

Wait, is Tai talking about science? Thermal dynamics??? What?!?!?!?

Frank, another thing is that 1/8" steel is pretty hard to forge when you're starting out. Especially if it's fairly wide, and it will want to fold over when you're hammering in the point, rather than draw out.

IMHO- one thing that can make a forged blade excell, is that every heat is part of the blade's thermal cycling. One thing that can really make a forged blade suck, is that every heat is part of the blade's thermal cycling.

You can "undo" a lot of the damage that forging can inflict with accurate thermal cycling, but I don't think a guy should go out of his way to screw up the steel because of that.

The very best thing you could do is find a good blacksmith or bladesmith and watch his process in person.

Thats exactly what was happening too. The steel would twist aI would have to straighten it out again. So after about 7 heats this is where I am at. I uess I need to get it hotter at the tip so it wont fold back as much? Thanks for all the feed back guys. I have searched for a local blacksmith and I havent found one. I have looked under the blacksmith group websites and havent found any anywhere close to me. Bladesmiths are even farther away, I think the only one I have heard of lives around San Antonio and that is a 4.5 hr drive for me. You guys are the best I got!

**Tai Goo** · 05-04-2012, 12:20 PM

On the points of thin wide stock I usually favor some type of stock reduction,... hot cut, score (or cold chisel) and snap, saw, grind etc.

**Rick Marchand** · 05-04-2012, 12:40 PM

This might be proper or it might not but if I want to forge down the width of a thin piece of stock most of my heat is in the middle. The steel moves toward the heat. So I heat the entire end of the bar, pull it out and lay each edge in the anvil to suck out some of the heat and through it back in the fire for a few more seconds. What I end up with is a bar that is hotter in the center than the edges. This way I can avoid the I-Beam effect... lol.

If I do cut an angle for the tip, it is always a back-cut opposite to my intended tip geometry. Then I forge the tip up as I do the bevel. This works great for damascus because it forces the grain to follow the edge.

**Tai Goo** · 05-04-2012, 12:48 PM

Originally Posted by Rick Marchand

If I do cut an angle for the tip, it is always a back-cut opposite to my intended tip geometry. Then I forge the tip up as I do the bevel. This works great for damascus because it forces the grain to follow the edge.

Good point (no pun intended).

I think "grain flow" should be a consideration and on any good list of the possible advantages of forging.

**Tai Goo** · 05-04-2012, 01:22 PM

While we’re on it,… Oddly enough, if you do some searching on the “advantages and disadvantages of hot forging”, you’ll usually see “grain refinement” listed as an advantage. However, I don’t think they are talking so much in terms of the crystalline structures,... but rather more in terms of grain flow, diminishing porosity, minimizing inclusions and impurities, getting everything into solution etc… “macrostructure stuff“, that can result in a superior blade.

Hot forging is a combination of thermal and mechanical.

... The hammer is your "magic wand" and your forge is the womb! LOL

**grizzled gizzard** · 05-04-2012, 03:10 PM

I forged some thin-ish 52100 down one time- eight blades, I just wanted to use it all up.

After acid etching, they looked stunning to me, with the way it almost looked layered, but I ended up with pin holes in the blades, and only 1 survived.

Was it just working the steel too hot/much that caused the pin holes?

**grizzled gizzard** · 05-04-2012, 03:17 PM

Originally Posted by Rick Marchand

This might be proper or it might not but if I want to forge down the width of a thin piece of stock most of my heat is in the middle. The steel moves toward the heat. So I heat the entire end of the bar, pull it out and lay each edge in the anvil to suck out some of the heat and through it back in the fire for a few more seconds. What I end up with is a bar that is hotter in the center than the edges. This way I can avoid the I-Beam effect... lol.

If I do cut an angle for the tip, it is always a back-cut opposite to my intended tip geometry. Then I forge the tip up as I do the bevel. This works great for damascus because it forces the grain to follow the edge.

Wow. What a great nugget on the I-beam effect. Pulling the heat out of the edges is something I hadn't heard before, but I could use that often. Thank you.

**Fred.Rowe** · 05-04-2012, 07:14 PM

One advantage of reducing large round or bar stock over flat barstock is the fish lips affect can be avoided. Shape the tip while the stock is still thick enough in cross section and hot enough to be forged, then draw the blade out to its desired length.

**zaph1** · 05-07-2012, 05:29 PM

Originally Posted by panch0

Thats exactly what was happening too. The steel would twist aI would have to straighten it out again. So after about 7 heats this is where I am at.

I'm dying to see updates pics from your next forging session, Frank!

**panch0** · 05-07-2012, 10:54 PM

Charles, I havent tried out the forge with the adjustment you suggested yet but I did get to pound it into submission. This knife will probably not get done, cause I just want to bang more out, not finish this one. Some one on here said a guy banged out 100 knives and by then he was pretty good.I have 99 more to go. I want to learn how to do this much better and more efficiently. Time will tell.

**bladsmth** · 05-08-2012, 07:02 AM

One part of hot forging that gets left out in many discussions is keeping the blade and anvil clean.
Brush the blade off with a wire brush when you take it out of the forge, and wipe the loosescale off the anvil every time you put the blade back in the forge. Hammering the scale into the steel is the cause of all those "pin holes" dings and spots on most forged blades. If kept clean and scale free, the finished blade can be smooth and pit free.

The other thing that gets missed is to curve your blade down like a banana, and then forge it back up to straight. This stretches the edge out as it lifts, and will help avoid warp later on.
If you have to straighten the blade by hammering the upward curved spine back down, you are compressing the edge. This may come back in HT as a wavy edge warp.