How to Heat Treat 1080 Steel

1080 is an ideal steel to learn the basics of heat treating. It is very forgiving, and can be heat treated in a forge or temperature controlled kiln. If you are just starting to learn about heat treating, this is the one to try.

Preparation

You will need several things to effectively heat treat 1080 steel:

Heat source: You will need either a forge, temperature controlled kiln, or even a propane torch

Oil: Heat treating specific oils are the obvious best, but can be a big up-front cost. You can use canola oil as a substitute. Do not use motor oils as the additives are toxic. Canola oil should be hot when heat treating. You will need to heat it to the point where it is hot to the touch, but not too hot to touch.

Oven: either a home oven or a small toaster oven will work.

Magnet: You will need a magnet to check if the steel has reached the correct temperature. A long reach rare-earth magnetic pickup tool works great.

Quenching

Heat your steel slowly. Once the blade barely starts to glow, begin checking the steel with the magnet. At 1450° the steel will suddenly not be attracted to the magnet. Be careful to evenly heat the blade, as it is easy to over heat the edge and thin parts of the blade (for this reason it is sometimes easier to heat treat before grinding in the bevels). Once the blade becomes non-magnetic, continue to heat very slightly, as the goal is to get it to 1500°. Once you have heated the blade, quickly quench it in the hot oil. You will want to quench the blade with the tip down. Make sure to quench the blade straight up and down and do not move the blade side to side as it is cooling as this can cause it to warp.

Once the blade is cool to the touch, clean it with soap and water, and check to see if it is hard with a file. If it has hardened properly, the file will skate off the steel and not bite into it at all. If the file does cut into the steel, you will need to anneal the blade and repeat the heat treating process.

If your blade is hard, check for any warping. If there is any, you can try and correct it during the following step.

Tempering

At this point your steel is extremely hard but also extremely brittle like a ceramic. You need to temper the steel to make it more useable. If you used the knife at this point, you would chip the blade very easily and likely snap it in half. If your blade has any warping, clamp it to a piece of angle iron or other large piece of steel in order to straighten the blade. Heat your oven to between 350° and 450°. If your knife is going to be used for delicate tasks (like a paring knife) choose the lower range of temperatures. If it will be used for heavy duty tasks (like chopping) choose the higher end. The higher the temperature you choose, the softer the metal will become.

Place your knife in the oven and leave it at that temperature for 2 hours. Remove the blade and allow it to cool, then heat it again for 2 hours.

You have now successfully heat treated your knife. It should be hold an edge and perform well for years to come.