Heat Treating W2

Stacy E. Apelt - Bladesmith said:
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To answer your question:
You can cycle W2 steel in a forge by eye with reasonable results if you do not have a HT oven. It won't be the same as a long oven soak, but will help a lot. If possible, let the steel soak at steps 2, and 3 for a minute or two. Steps 4 and 5 can be pulled out as soon as the blade is at that temperature.
1) Heat to a bright red color (but not orange) and try to hold at that color for a few minutes. Let cool to black (probably 1600-1800°F)
2) Heat to a little less red and cool to black. (probably 1500-1700°F)
3) Heat to just barely red, and a little past where the magnet stops sticking ... cool to black. (probably 1400-1450°F)
4) Heat to just barely red and pull it out as soon as the magnet stops sticking .... Cool to black. (probably 1350-1400°F)
5) Heat to just past where the magnet stops sticking (like step #3) and quench in fast oil. (probably 1400-1450°F)
The steel now should have fine grain and good structure for your final HT.
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Thank you for clarifying. Looks like I need to ask Santa for a HT oven. I will give your recipe a go in my forge, fingers crossed. Currently making knives for old Army team members. They’re not too picky….
 
I agree that a HT oven is better, but ovens are a newer item in the knife world. HT was done in forges for several thousand years before the first HT oven was built. Even today the largest part of knifemakers do not have a HT oven.

Larrin did tests and showed how to HT in a forge. It wasn't the very best, but it wasn't bad, either.

The OP is best to stick with simple alloy carbon steels like 1084, 1080, 1075, and 23C3. These do pretty well in a forge.
W2 and 1095 will work in a forge, but you may not get better results than 1084 out of them.
 
Karl B. Andersen said:
Why?
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We’ve done a lot of testing and the most important thing in heat treating is austenitizing temperature. Prior condition and soak time is also very important. Uniform heating is also necessary.

Over the years, many makers have sent Larrin forge heat treated coupons for testing, in every case, >90% of coupons tested poorly. Every maker knew that they had an eye for and a advanced feel for heat treating in a forge.

Most steels have a very narrow band of austenitizing temperature.

15n20 for example heat treated from 1475’f has ~50 # of charpy toughness, heat treated from 1500’f the toughness drops to <10 # of toughness.

Learning to heat treat in a forge would be a lot more difficult than using a furnace.

Hoss
 
And that's just 25°F! I don't think there is a person in the world that could eyeball the difference between 1475°F and 1500°F. Granted, I've never tried myself, but it comes across to me as just almost impossible. I know about the magnet and salt tricks that get you right close to 1475°F, but even then especially with alloys that really need a soak, seems very difficult to do heat treating in a forge.
 
I tried using salt to check furnaces but it didn’t work for me. The time required (kinetics) for melting made it too difficult to get it to melt right at the melting temperature. It ended up being significantly hotter when the salt finally melted. This was with two thermocouples checking the temperature. I think for most people they would end up more confused than helped.
 
I never could get good results with salt, either.


Here are some tips I have found for HTing simple carbon steels in a forge:
First tip - Do HT at night or when it is cloudy if your forge is outside. Inside turn the lights down with just enough light to safely see. You need to see the color of the blade as clearly as possible. Bright light changes the way your eye sees the shades.
Second tip - Addin PID control to your forge can make it almost as accurate as a HT oven. This can be done with any forge but works best with a blown forge. It may be wise to build a simple forge for HTing. A single burner cylinder forge with a small blown burner can be built for around $100. A cheap PID, SSR, solenoid propane valve, and a TC are the main components for the temperature control. It costs around $100 to convert a forge. The plans are in The Stickys.

Rest of the tips:
1) Use a magnet when forge HTing. A welding magnet stuck on the forge near the opening will tell you when the blade is around 1420°F.
Salt doesn't work. Templi Sticks work but you have to learn how to use them. A magnet is the easiest and most accurate.
2) If your forge is not temp controlled, turn down the forge to the lowest flame it will run stable at. This is usually still hotter than you need for HT on most forges. Consider making a smaller HT burner for the forge to get lower heat.
3) Bring the forge up to normal heat and run for a while, then turn it down and let the forge settle down and soak the refractory at the lower temp. Test the temperature with a bar of steel. It should heat up to a temperature that stops sticking to the magnet.
4) Place the blade in the forge with tongs and turn it constantly. Keep the point in a cooler area by the wall if needed. Try to evenly heat the whole blade by watching for hot spots and moving the blade as needed.
5) If needed, pull the blade in and out of the forge to avoid overheating. A good way to keep the tip from getting too hot is to work it in and out of the back port opening.
6) Test the blade on the magnet regularly as it gets dull red. At the point when it suddenly stops sticking it is about 50°F below the target point for most carbon steels.
7) Switch to a fresh pair of tongs that are not hot and heat the blade just a tad more to be just a little redder (not much). At this point the edge is what you are watching. If the edge is the right temperature but the spine is a bit less red, you will be fine. If the edge is overheated the blade toughness may be affected.
8) Quench as soon as the edge is at the color you are looking for.
9) To get a longer soak time you can do things like pump the blade in and out the forge to keep it at the proper color and get a longer soak. This takes practice but is an age old method.
10) If the blade gets too hot, just pull it out of the forge for a few seconds to let the color drop back. Try to keep it non-magnetic, though.
 
Everyone - PLEASE do not take this as an attack on Devin. I greatly respect Hoss and his knowledge. He is a Hall of Fame member for good reason.
This is not an argument, just two different opinions on HT. To be clear, I use my HT oven for almost all HT. I agree it is the best method for HT.

However, I don't consider a forge HT "Non-quality" if done well.
For every 100,000,000 blades that have been made with a forge HT a few million have been done with a HT oven (not exact numbers but representing the range difference). I think it is a stretch to say that all those blades were low quality.

Bill Moran, William Sagel, and a host of other great knifemakers never used a HT oven. I only had one of Devins knives, but would happily trade 20 of his for one of their "Low Quality" knives any day of the week.

I will drop this now as there is no need for it to go farther.
 
Stacy E. Apelt - Bladesmith said:
Everyone - PLEASE do not take this as an attack on Devin. I greatly respect Hoss and his knowledge. He is a Hall of Fame member for good reason.
This is not an argument, just two different opinions on HT. To be clear, I use my HT oven for almost all HT. I agree it is the best method for HT.

However, I don't consider a forge HT "Non-quality" if done well.
For every 100,000,000 blades that have been made with a forge HT a few million have been done with a HT oven (not exact numbers but representing the range difference). I think it is a stretch to say that all those blades were low quality.

Bill Moran, William Sagel, and a host of other great knifemakers never used a HT oven. I only had one of Devins knives, but would happily trade 20 of his for one of their "Low Quality" knives any day of the week.

I will drop this now as there is no need for it to go farther.
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Sure, please send us a few forge heat treated coupons for testing so you can back up your comments.

Hoss

Coupon size is 2.5 mm x 10 mm x 55 mm, 3 coupons per alloy or condition.
 
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Thanks, I'll do some short bars of 1084 in the forge and in the HT oven when I get a chance. I would really like to know the test results. I was thinking 3"X1"X.125" ... is that OK or is any particular size needed?
 
DevinT said:
We’ve done a lot of testing and the most important thing in heat treating is austenitizing temperature. Prior condition and soak time is also very important. Uniform heating is also necessary.

Over the years, many makers have sent Larrin forge heat treated coupons for testing, in every case, >90% of coupons tested poorly. Every maker knew that they had an eye for and a advanced feel for heat treating in a forge.

Most steels have a very narrow band of austenitizing temperature.

15n20 for example heat treated from 1475’f has ~50 # of charpy toughness, heat treated from 1500’f the toughness drops to <10 # of toughness.

Learning to heat treat in a forge would be a lot more difficult than using a furnace.

Hoss
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I can set my huge vertical forge and hold any temp you choose between 1420 and 2300. And it actually varies/cycles LESS than my Even Heat oven. And I also get ZERO scale.
Every time a heat treating in a forge conversation comes up it seems everyone thinks that a propane forge only has one temp and that all heat treating is done by eye.
I've never understood that.
I've had the same conversation on You Tube with Larrin and it seems he thinks the same thing.
The difficulties most makers encounter is because - and I've been doing this for 25 years+ - most of them use worthless LITTLE horizontal forges with flames blowing/aimed directly at knives with very small heat zones. Far as I'm concerned, those forges are anchors at best. All they do is burn up steel. The guy that inventoed those things should be drawn and quartered.
I guess it's time I do a video.
 
Karl, I've always admired your work! I would love to see a video of your setup. You have me pegged with that second sentence! That is what I always assume, but I do realize (somewhere way back in the recesses of my rusty cranium) that there are forges with controllers, too!
 
Look in the stickys or search for my "PID Controlled Forge Burner" and "Two-stage forge burner" .
nickandersonart

Thread 'PID Controlled Forge/Heat Treat oven plans & WIP'

So after going through the stickys a couple weeks ago and finding all of the amazing plans for different PID controlled forges, tempering ovens, salt pot etc, I've switched gears fully to creating a really high-functioning PID controlled forge & heat treating oven.

First off, thanks to other members who shared all of their information on this, especially Stacy.

I won't be back home for another several weeks so at the moment I am in the planning & scheming phase, which has been a lot of fun. I won't rehash all of the information from other stickies but can provide links to other...
 
And make no mistake - mine is NOT! PID controlled. That's a bunch of unnecessary equipment and expense.
It's about being able to regulate air/fuel/line pressure. That's all it is.
And have a LARGE vertical forge so you're heating steel with thermal mass.
This is an idea of the forge and how I use it to weld. (I use four different forges to make knives and steel)
Heat treating is a different set of rules with the same forge.
 
If a knife is heat treated in a forge and it cuts the things it was intended to cut, is it still a low quality failure? It's all about perspective. 50 years from now we might be talking about how temperature controlled electric furnaces are worthless for heat treating and be on to the next best thing.
 
Contender Machine said:
If a knife is heat treated in a forge and it cuts the things it was intended to cut, is it still a low quality failure? It's all about perspective. 50 years from now we might be talking about how temperature controlled electric furnaces are worthless for heat treating and be on to the next best thing.
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That's an entirely different topic.
"Cut" is determined by geometry. Not steel type or heat treatment.
You ever get a paper cut? It didn't cut you because of its type or because it was hard.
It cut you because it was thin.
 
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