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Carving knives
Powder Keg:
So, If a fellow wanted to spot anneal a part how would he go about it? I have a stick welder with a tig torch and a spot welder.
Blade:
What I would try is heating at each point that you want anealed and sticking the blade in vermaculite or something that will retain the heat .You can try this idea on some scrap first if you have some.
Another way that I have used on material that is hard is to just blow holes in it with the cutting torch. Or drilling with carbide bits, a good alternate if carbide bits aren't available is masonry bits, I just sharpen them so that they wil cut steel.
Lew_Merrick_PE:
--- Quote from: Powder Keg on March 08, 2011, 01:27:49 PM ---So, If a fellow wanted to spot anneal a part how would he go about it? I have a stick welder with a tig torch and a spot welder.
--- End quote ---
Keg -- I've seen it done, but I've not done it myself. Basically the way I have seen it done is: Place a chunk of copper on either side of the part you want to spot anneal. Pass the welding current (and I have no idea what type of rod was being used) through the part until the spot in question is a bright "cherry red" (as I am dead colorblind to red courtesy of a "joke" played on me with a neon-argon laser in college, I have a hard time with this part) and then cover the whole thing with sand to let it cool. I have seen ash and vermiculite used in place of sand.
In essence, you need to heat the area in question to a temperature higher than the Curie point (where it loses magnetic attractive properties) and then not quench it. If the steel in question is an air-temper type of steel, you will need to slow the cooling to less than normal air radiation losses. In many (most?) cases just letting it cool without a quench should be sufficient. That's the short summary of what the ASM handbook says.
The alignment of a steel's crystalline structure changes from a body-centered-cubic (BCC) to a face-centered-cubic (FCC) type of structure once it is heated past the Curie point. (Mind you, more modern metallurgy texts use more detailed crystal structure designations. Mine are 40+ years old.) When you quench it from this temperature, you "freeze" the structure in this "less likely to slip along planes" crystal form. In this form, the steel is: harder, stronger, more brittle, and (believe it or not) less dense than normalized (annealed) steel. (Normalized steels run about .285-.287 lb/in³ -- hardened steels run about .281-.285 lb/in³.) Tempering is the process of relieving the stresses that make fully hardened steel brittle without changing much of the crystal structure that gives it the "hard and strong" properties.
Powder Keg:
Thanks Lew! Come to think of it, That would be dead easy with my spot welder. I'll give it a chance next time I make one of these.
Thanks again, Wes
ieezitin:
Keg.
I am assuming the thickness of the steel is a blades width? 1/16 3/32? If so turn around your tungsten leaving the blunt square end sticking out, crank your amps up and then stab the tungsten on the area your trying to heat don’t pull off or you will create an arc, let the area heat up to the color what Lew said then pull off quickly, it should work being the plate is so thin, don’t worry about the tungsten you wont hurt it, don’t look at it either as you pull off as you will get flash because if you get flash you would have to hit yourself in the head with a ballpein hammer so your eyes don’t hurt anymore!.
Happy days…….. Anthony.
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