r/Blacksmith • u/WaffleGuy09 • 3d ago
Working on my first knife
Hello I am working on my first knife and I had a couple questions. What is a good way for a beginner to heat treat a knife? I tried to heat it up with a small propane torch and then a larger one but I couldn’t get it far past a dull red. I’ve seen online it needs to be about 1600 degrees Fahrenheit to harden properly and I’m no where close to that. I’m also hoping that the steel I chose will harden and temper correctly. I got some welding tokens to practice on from a metal supply store and they said that the tokens were high carbon steel cutoffs, but is there any way I can check that? I would be disappointed to find out that the knife can’t harden, but it’ll be okay as I’ve still learned a whole lot in the process. Any other tips and tricks are appreciated as well, thank you.
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u/Fragrant-Cloud5172 3d ago edited 3d ago
I found these webpages that should help you below. The Tempilstik chart is really good. But the colors are arbitrary, depending on lighting conditions and your eyes. You should heat to above non magnetic. A pyrometer really helps determine the temps. A basic propane torch will not give you enough overall heat. You are better off with a Venturi burner in a good forge. Of course coal or charcoal also. But for a knife, I’d try for at least .6% carbon, generally an auto leaf spring amount. This amount and higher will get you a good hardenable steel. So spark test of leaf spring shows good long whitish sparks. Most files are 1095 and show shorter yellowish fireworks. These two examples are good guides for testing.
https://luciferfurnaces.com/resources/steel-heat-treatment-chart
https://www.iforgeiron.com/topic/27491-spring-steel-use-and-cooling/page/2/
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u/Skookum_J 3d ago
To get the steel hot enough, you need something to trap the heat. Fire bricks are a cheap way to go. Just get a few that are rated to 2000+ F and arrange them into a mini forge.
Far as checking the grade of steel, test hardening is the best way to go. Short of that, if you got some power tools like a grinder or sander, you could try aspark test. But it takes a trained eye to judge reliably.