Heat Treating and Metallurgy Discussion of heat treatment and metallurgy in knife making. |
04-10-2015, 12:57 PM
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Join Date: Apr 2015
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First Ever Post, and First Question on Heat Treating
Hello Knifenetwork; this is my first post, so I just wanna say hello
Ok, so me and friend are looking at making some nice knives, he's profiled and ground a few, but never had the proper steel. So after a bazillion calls I found that I could get a disk off of a shaft of 9.5" of 4140, he told me it was heat treatable. I got an 1/8" disk, and after reading some other forum posts, I found some info that told me 4140 was actually a crappy knife steal, so if it is don't be afraid to call me a dummy (but hey, it was cheap) Now, my question is how to heat treat it (if I even can) If neccesary we'll be building a simple forge/furnace instead of using a torch. I'm still pretty new and ignorant on this, so anything helps!
Thanks!!!
TravisLang13
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04-10-2015, 01:11 PM
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Join Date: Mar 2012
Location: Alabama
Posts: 554
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If you keep the blade under, say 5" one can use a torch. Get a magnet before starting. Using the torch, heat the blade portion evenly, start near the tang as it will be the hardest to get up to temp due to the mass of the handle portion sucking the heat away. I'll put my torch in a vice so I can have both hands available, but you can hang the magnet. As the blade heat up touch it with the magnet, be sure not to burn yourself. When the magnet stops trying to stick, give a little more heat then quench point first into canola oil. Clean the blade up and temper it @ 350F for an hour. It will stink up your house, so if you have a good toaster oven you can put in your shop do it.
That should get you going. 4140 is a good steel, for tools but not for knives as it lacks carbon.
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04-10-2015, 01:28 PM
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Join Date: Sep 2006
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The man didn't lie to you, 4140 is heat treatable. It just doesn't have enough carbon in it to make a good knife blade but it can make a knife blade, just not a good one. If you want to heat treat it I would wait until you have built a forge. Bring the blade up to where it becomes non-magnetic and then get it just a little brighter then allow the steel to air cool to a black heat and the steel becomes magnetic again. Repeat that twice more. Then bring it back up to that point and soak it at that point for a minute or two to dissolve the carbon evenly into the iron matrix. Quench in warm canola oil and allow it to cool to the point where you can handle the blade. Scrub the remaining oil off in hot soapy water and put it into an oven to temper at 300? for one hour. With carbon that low one cycle should do it.
To get a little better up to speed on heat treating, which is really involves all aspects of manipulating steel structure by temperature, go to the KnifeDogs Forum. From there scroll down to Knife Makers Area and click on it. There will be a sticky at the top of the page Your Heat Treating Tool Box. Read through the posts there. It would also be better if you started out with a steel that will make a better blade than 4140. Try The New Jersey Steel Baron. He, the famous Aldo Bruno, specializes in knife steels and is a real good people to deal with. His 1084 is highly recommended for beginners with simple equipment.
Be aware that getting a steel with a higher carbon content will modify heat treating a bit.
Doug
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04-13-2015, 12:50 PM
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Join Date: Apr 2015
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Thank you Doug and imcustomknives!
That all helps! If I have any other questions, I'll make sure to ask around, as well as check out the info you guys provided.
Thanks!
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Tags
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blade, building, carbon, first post, forge, handle, heat, how to, iron, knife, knives, make, making, post, shop, simple, steel, tang, temper, tools |
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