When you feel comfortable enough with your abilities to make a decent looking knife from mild steel or aluminum, you're probably going to want to start with actual heat treated blades. This will require a forge to heat up your blade to an even red heat. Scroll down the page to find my personal method for building a forge, or just google it. I should also mention that heat treating consists of two steps; hardening, and tempering. To heat treat a blade, IT MUST BE CARBON STEEL. Mild steel will not harden. A cheap carbon steel that works great is 1095. You can buy 5 feet of 1095 from admiral steel for like 10 bucks.
Hardening your blade is the first step, and is getting your entire blade up to a red heat so that it is non-magnetic, and quenching it in oil. On a molecular level, the austenite in the steel turns to martensite when it is hardened. Austenite is the softer structure of steel, and martensite is the harder crystalline structure of hardened steel.
Prior to hardening your blade, you will want to do what is called normalization. Normalization is heating the blade to a red heat, then letting it cool all the way back down. Do this a few times to relieve any stress in the metal prior to heat treat.
When you're blade, and a little bit of the tang of your knife are red hot, you want to quickly quench the blade into the oil, which will harden it. Take it out when it has cooled down to about 500 degrees, and check for warpage.
I should mention that when you quench the knife blade into the oil, you want to do it very quickly so that it cools evenly, and to tilt the blade so that the edge goes in first, and gets the hardest. Also when you've quenched it and checked for straightness, you DO NOT WANT TO HIT IT. It will break if you try to straighten it with a hammer. Use a vise. If you hit it with a hammer after it's been hardened, it will shatter into several pieces.
To check your hardening once it has cooled all the way down after removing it from the oil, rub a file against the surface. If it skates across, you properly hardened it. If it does not, you might want to try again. It takes some practice to get good at hardening blades, so keep at it.
Hardening your blade is the first step, and is getting your entire blade up to a red heat so that it is non-magnetic, and quenching it in oil. On a molecular level, the austenite in the steel turns to martensite when it is hardened. Austenite is the softer structure of steel, and martensite is the harder crystalline structure of hardened steel.
Prior to hardening your blade, you will want to do what is called normalization. Normalization is heating the blade to a red heat, then letting it cool all the way back down. Do this a few times to relieve any stress in the metal prior to heat treat.
When you're blade, and a little bit of the tang of your knife are red hot, you want to quickly quench the blade into the oil, which will harden it. Take it out when it has cooled down to about 500 degrees, and check for warpage.
I should mention that when you quench the knife blade into the oil, you want to do it very quickly so that it cools evenly, and to tilt the blade so that the edge goes in first, and gets the hardest. Also when you've quenched it and checked for straightness, you DO NOT WANT TO HIT IT. It will break if you try to straighten it with a hammer. Use a vise. If you hit it with a hammer after it's been hardened, it will shatter into several pieces.
To check your hardening once it has cooled all the way down after removing it from the oil, rub a file against the surface. If it skates across, you properly hardened it. If it does not, you might want to try again. It takes some practice to get good at hardening blades, so keep at it.