10
Jan
In this shorter than normal video I show you the basics of heat treating with a simple homemade charcoal forge. You harden a knife by heating it to between 1800 and 2000F and then quickly quenching it in oil or water.
The next step is to heat the blade up again this time to 400 degrees.
What temperature to heat treat a knife. There are those who want you to believe the only way to achieve a good heat treat is by using a temperature regulated heat treating oven soaking for 157 minutes normalized 23 times and then quenched in parks knife heat treating oil raised to exactly 1346 degrees Fahrenheit. There are many great tutorials online for creating your own forge see here here or here but the general idea is to create an environment that you can heat up to above 1450F and hold there while you wash your knife in heat until its non-magnetic. Heat treatment refers to the process where softer steel is hardened so that it stands up to use as a knife blade.
To heat treat steel I heat it up beyond cherry red to glowing red. For 1095 steel as this blade is this occurs at a temperature above 1335 F. Heat treat and quenching a knife blade.
The next step is to heat the blade up again this time to 400 degrees. This relieves the stress built up in the steel and softens it down a bit and you end up. Tempering a knife increases its toughness by making it less brittle.
Its done after hardening by heating the blade to a lower temperature 350-450F and letting it air cool. If you start to see discoloration it is ruining the heat treatment. That usually occurs at a few hundred degrees well over 300F so I think that they should be fine.
Tempering involves heating the blade to a non-critical temperature 350 450 F to slightly soften the steel I used a kitchen oven. A tempered blade will hold a. Thinner knives can be flexed much further without exceeding the strength of the steel even with identical heat treatment.
This is why those very thin fillet knives are so good at flexing 90. You can read more about all of these effects in. 5160 has very good toughness with a heat treatment using an austenitizing temperature of 1500-1525F and tempered at 375-400F.
That results in 585-595 Rc and very high toughness when heat treated with a cryo step. Skipping cryo may improve toughness slightly with a drop in hardness but this was not tested. The prior processing used in this study forging temperature normalizing and.
The goal of hardening is as its name suggests to harden the knife. You harden a knife by heating it to between 1800 and 2000F and then quickly quenching it in oil or water. The good news is that your blade is very hard after the quenching.
The bad news is that is also very brittle. Knifemakers heat treating at home will usually do small batches or even one knife at a time. But no human is going to hold the steel at temperature for exactly the same amount of time or quench in exactly the same way.
Knives come in different sizes and thicknesses which will change the heating rates and quench rates of the knife. The core of the knife will see less time at the peak temperature. How To Make A KnifeHow I Temper A KnifeYou need to temper the blade because it is brittle after heat treatingThis is a short video showing how I temper my.
You can compare how the file feels on the blade part of the knife with how it feels on the handle or on a piece of known soft steel. 7 Temper Blade Heat an oven to 400F. Clean off the quenching oil and put the blade in the oven for 30 minutes.
The extra carbon makes heat treating more complex. Heat to 1500 soak 10 minutes. Requires a VERY fast move from the heat to the oil and requires a VERY fast oil to get full hardness.
You can make a good knife out of it but it is hard to make a great knife. In this shorter than normal video I show you the basics of heat treating with a simple homemade charcoal forge. I heat treat a 18 inch thick knife blade.
Similarly tempering temperatures above 350C 662F should be avoided since this could give rise to brittleness and reduced corrosion resistance. Note that if the tempered blade is exposed to temperatures above the tempering temperature eg. During grinding the properties of the knife will be impaired.
Use the internet to research different ways to heat treat. Visit most any of the knife making forums and search for heat treating for 1095 1084 or 1080. They are all so close the only difference will be slightly different temperatures and resulting hardness.
This step should be carried out soon after heat treating within an hour or so but only after the blade has cooled to room temperature. Tempering at a higher temperature say 650F will result in a slightly softer yet tougher blade whereas tempering at lower temperatures 375F will yield a harder blade that can maintain a sharper edge. So it follows that if you intend to put your knife.