HOME | DD

Description
Previous Step: [link]

Step 2: Hardening

To harden carbon steel, tool steel, and stainless steel you have to get the knife to critical temperature and then rapidly cool it, which is called quenching. But quenching is more commonly referred to when using a liquid for hardening rather than air.

Again, different metals require different processes to harden. Which means you will have different temperatures to take your metal to, with different heat soaking times, and you will have to use either water, oil, or air to get the best result. There is also quenching brine, but we will stick with the three that are most common.

Air Hardening: Steels like the A series and D-2 tool steels fall under this. Depending on the size, we use air to cool the metal. In some cases Air Hardening can be the same process as normalizing carbon steel, but in other cases it is air blasting the metal to reduce the temperature.

Water Quenching: W series, 10XX series for the most part can be water hardened, along with lower level carbon content metals. While there are metals that can be water hardened, most are considered oil hardening metals because of the fact that water could crack the blade. This process is more common in low carbon leveled metals, but its also used in higher leveled as well. It's wise to test your metal in water and oil first. Water give more of a hard quench, which could be disastrous for a knife. An example is these: [link] while I did get them hotter than I should have, the result could have been prevented if I had used oil. Depending on the metal you can heat the water or leave it at room temperature.

Oil Quenching: O-1, L-6, 5160, 10XX series fall under this type. It feels more forgiving to the touchier metals. Most of them are suggested to heat the oil up before quenching. I suppose I could go into detail about how the structure and density of the oil vs water can make all the difference in the world. But who really wants to read all that?

I do a triple hardening cycle on all of my knives. Since I'm doing carbon steel, I will be using oil to quench my metal.

First thing I do is put the torch in the vise like so: [link]

You want to take your time with the heat. Allow the entire blade to be blue before taking it to critical temperature. The reason I say this is because there is a chance, if you heat the blade to quickly, you could shock the steel and it could crack. At the very least heating it to fast could warp your blade. So make sure to get the whole knife warm, hot, then go to critical just to be on the safe side.

I start with the thickest part of my knife first and then when we get past the dark blue color, then I focus more on the blade, because I am going for a defined hamon line, by means of differential hardening.

The reason I keep the torch in the vise for this part, is turning it off and then loosening the vise will waste my heat. If I were doing 1095, which needs to be cooled within the second, I would miss my chance of hardening the blade. Plus this makes it less hassle.

I have my mineral oil heated to about 120F. I like to check to make sure that the oil bath will cover at least 1/2 of the height of the blade for a solid edge harden.

I like to keep a magnet close to check the knife and make sure that the knife has reached non-magnetic temperature. It isn't in the picture, because with my free hand, I'm using the camera.

Once the knife is at critical temperature, I edge quench the knife I count to 7 before I submerge the entire knife in the oil. Once it is submerged, I count to 10 before taking it out of the mineral oil and dipping it in room temperature water until the knife is completely cooled off.

I then repeat this same process two more times. After the third cycle, the knife will look similar to the bottom picture.

Usually I don't even bother sanding the knife at this point. I take a rag or paper towel and clean off the knife and continue on to tempering.

Next Step: [link]

www.pearceknives.com <- For all those times that stabbing people to death with spoons took too long.

Logan Pearce
www.pearceknives.com
Facebook-> [link]

Description
Previous Step: [link]

Step 2: Hardening

To harden carbon steel, tool steel, and stainless steel you have to get the knife to critical temperature and then rapidly cool it, which is called quenching. But quenching is more commonly referred to when using a liquid for hardening rather than air.

Again, different metals require different processes to harden. Which means you will have different temperatures to take your metal to, with different heat soaking times, and you will have to use either water, oil, or air to get the best result. There is also quenching brine, but we will stick with the three that are most common.

Air Hardening: Steels like the A series and D-2 tool steels fall under this. Depending on the size, we use air to cool the metal. In some cases Air Hardening can be the same process as normalizing carbon steel, but in other cases it is air blasting the metal to reduce the temperature.

Water Quenching: W series, 10XX series for the most part can be water hardened, along with lower level carbon content metals. While there are metals that can be water hardened, most are considered oil hardening metals because of the fact that water could crack the blade. This process is more common in low carbon leveled metals, but its also used in higher leveled as well. It's wise to test your metal in water and oil first. Water give more of a hard quench, which could be disastrous for a knife. An example is these: [link] while I did get them hotter than I should have, the result could have been prevented if I had used oil. Depending on the metal you can heat the water or leave it at room temperature.

Oil Quenching: O-1, L-6, 5160, 10XX series fall under this type. It feels more forgiving to the touchier metals. Most of them are suggested to heat the oil up before quenching. I suppose I could go into detail about how the structure and density of the oil vs water can make all the difference in the world. But who really wants to read all that?

I do a triple hardening cycle on all of my knives. Since I'm doing carbon steel, I will be using oil to quench my metal.

First thing I do is put the torch in the vise like so: [link]

You want to take your time with the heat. Allow the entire blade to be blue before taking it to critical temperature. The reason I say this is because there is a chance, if you heat the blade to quickly, you could shock the steel and it could crack. At the very least heating it to fast could warp your blade. So make sure to get the whole knife warm, hot, then go to critical just to be on the safe side.

I start with the thickest part of my knife first and then when we get past the dark blue color, then I focus more on the blade, because I am going for a defined hamon line, by means of differential hardening.

The reason I keep the torch in the vise for this part, is turning it off and then loosening the vise will waste my heat. If I were doing 1095, which needs to be cooled within the second, I would miss my chance of hardening the blade. Plus this makes it less hassle.

I have my mineral oil heated to about 120F. I like to check to make sure that the oil bath will cover at least 1/2 of the height of the blade for a solid edge harden.

I like to keep a magnet close to check the knife and make sure that the knife has reached non-magnetic temperature. It isn't in the picture, because with my free hand, I'm using the camera.

Once the knife is at critical temperature, I edge quench the knife I count to 7 before I submerge the entire knife in the oil. Once it is submerged, I count to 10 before taking it out of the mineral oil and dipping it in room temperature water until the knife is completely cooled off.

I then repeat this same process two more times. After the third cycle, the knife will look similar to the bottom picture.

Usually I don't even bother sanding the knife at this point. I take a rag or paper towel and clean off the knife and continue on to tempering.

Next Step: [link]

www.pearceknives.com <- For all those times that stabbing people to death with spoons took too long.

Logan Pearce
www.pearceknives.com
Facebook-> [link]