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Conner Michaux

Couple questions

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Is there a website that has pictures of all the different types of bowie knives? I want to make a mini version of one...I really like small knives.

 

Okay heres my main question, Ive seen a few videos on instagram of people heat treating there knives with liquid salt?  How, and why? Also what are the benefits of using molten salt?

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The benefits of salt include good thermal control (due to the mass of the salt), and really good heat transfer (making a uniform HT easier).  The downsides include the salt vapor rusting everything around it, having liquid that hot is dangerous (especially the hidden dangers of remelting a large slug of it), and needing a stainless steel pot to melt it in to begin with. You can have high temp salts for austenitizing, and low temp salts for quenching (especially useful for mar-quenching).  

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How hot does salt need to be to melt?    

51 minutes ago, Jerrod Miller said:

having liquid that hot is dangerous

 But thats the fun part isn't it! you get a personal volcano! :lol::P

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It's not table salt, it's a blend of assorted chlorides and borates.  And it goes liquid around 1100 degrees F (and can go up to 2400 or so before it starts vaporizing) for the high-temp stuff, 350-400 for the low-temp.  And not only a personal volcano; if any water touches it it explodes in your face, and if the top is solid when the bottom goes liquid it either blows up the tube or launches the solid top like a mortar round.  It is lava hot, even hotter in most cases.  Plus the low-temp is often potassium nitrate, aka saltpeter.  Any spills will render organic objects like benchtops, rags, etc. highly combustible.  It's not something to idly play with.  In fact, salt pots are potentially the most dangerous thing we can use as far as fire hazard and severe personal injury resulting in wishing it had merely killed you.  But the results can be worth it if you're doing production work.  Zero scaling, zero decarb, zero warping.  You can heat treat sharp blades in it.  

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I'll just point out that was molten table salt at around 600 degrees F.  At 1550 degrees the results are far more spectacular. :ph34r:

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7 minutes ago, Alan Longmire said:

Zero scaling, zero decarb, zero warping.  You can heat treat sharp blades in it.  

Wow thats really cool, maybe someday I will try it out..

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So you have to find a way to heat the hole crucible evenly or you will literally have a volcano.

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3 hours ago, Conner Michaux said:

So you have to find a way to heat the hole crucible evenly or you will literally have a volcano.

Not necessarily.  If you heat from the top down, it seems to be pretty safe.  The other thing people do is put a graphite cone in the liquid before it freezes, so that it has differential melting during heating.  You could also pour it out while it is liquid and break it up after it solidifies so you are melting a powder/grain again, not a solid block.  The problem is when you have a solid plug stuck in a pipe then heat expanding liquid below that.  Pressure builds...etc.  So whatever you do to prevent a solid cap that would cause pressure to build should eliminate that issue.  

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