Knifemaking and other cool hobbies...

[UncleAl]

A knife is art, technique, and materials. Pattern welding, Damscus (true wootz) and samurai steels, and talonite are among the really trippy materals when you get your act together.

http://www.carbideprocessors.com/Knives/

All of them have grain and must be worked to optimize grain orientation vs. the cutting edge. You'll never go back to 400-series SS or crude carbon steel.

[Boerseun]

UncleAl - I've got a couple o' damascus blades I'll send you some photos of. The trick lies in the different hardening layers coming out once your blade is done, and you dip the little sucker in some acid.

Basically, you take sheets of metal, heat-weld them together and whack the bejesus out of them, and then form your blade. Its a bit tricky, though, cause you only know you've got it right once you do the acid bath - which is the very last step.

The other thing I want to try is to make the acid-patterns (seeing as the acid eats the softer, less-hardened steel quicker to make the patterns) by heat-treating the blade in segments. I was playing around with making patterns in the steel through a different kiln-design, and heating the blade in segments. That also creates patterns in the acid bath, but getting fine patterns like damascus through heat-treating has only been done on the cutting-edge in the quenching process.

I'd like to hear your ideas on buckling, though!

[Boerseun]

What!? * GASP *

Cain't anyone o' you fellers here help me with them darn bucklin' blades?

[STAMPS FOOT] pops a piece of chewin' tabaccy, spits, aims for the spittoon and misses [/STAMPS FOOT]

[GAHD]

LOL, I'm reading some mettalurgy books to find out exactly that right now, Boerseun.
While I havn't found much more on what could be causing your warping (other than impurities), I am learning quite a bit about sand-casting Iron in your back yard. Smelting too.

Have you ever tried any of that? If you're going to splurge on a new kiln anyways; have you considered building a cupola(blast furnace) to do everything, including salting to get those impurities out?

[Boerseun]

Sheesh - now you're talkin' big bucks...

I hope you find something in them book things, GAHD, 'cause I've tried an' tried, and all I can think of is that it's simply uneven heating in the kiln. If it turns out ot be impurities, I'll just have to whack it on the anvil some. But that's tedious. I'm just wondering - if it is impurities, how much impurity do you need to cause a warp? 'Cause the steel is pretty uniform? I'm using 12C27.

[C1ay]

Originally Posted by Boerseun

Cain't anyone o' you fellers here help me with them darn bucklin' blades?

Try this.

First anneal and stress relieve after you have formed the blade by bringing it up to around 1800°F through out and cooling as slowly as you can. I will generally put tools that I want to do this to in the heat treating furnace, bring it up to temperature and then should it off and leave it to cool down over night. Alternatively I will bury them in sand to insulate them so they cool down slowly but this does not work well for tools with thin sections. This step should remove all of the internal stress in the metal that would tend to bend the metal.

Now heat treat. The whole piece needs to be heated as uniformly throughout as possible and then quenched as uniformly as possible. A similar piece that I encounter is a long drill bit I have fashioned. I try to use oil hardening stock but sometimes water hardening steel is needed for the hardest applications. To quench these I have a wire rack in the bath such that the surface is barely above the surface of the water. I place the heated bit on this rack and then add water at the edge of the bath so that the water rises to quench the entire length of the bit at once. If the water hits the bit in any one place before the rest it will bend at that point and step one is required again to get rid of the stress.

HTH,

[nkt]

Well, I'd pop round and show you how to stop it buckling, but...

Seriously, you wouldn't call a locksmith if you needed one, because he posted on the same boards as you?

Anyway, you didn't say which way the kinves tended to buckle? If it is upwards, so it curves upwards, like a fish would (Tail and head in the air) it is probably just because the side that is exposed to the air is cooling faster than the side that is still in contact with the warm oven floor.

I would suggest that you want to try the old Japanese way of doing this, which is to wrap the back edge of the blade in clay before heating, to keep the body a little softer and springier, while heating the cutting edge as normal. The clay should kep the heating and cooling more uniform during your long slow cooling off, preventing tension from twisting or curving the blade.

Edit: I should have added forging as one of my things, too. I've got a gas furnace that will melt brass/copper, but not steel. I also made a knife forge, you can see it at http://www.rubbertreeplant.co.uk/popup.php?ID=110

[Boerseun]

Water-quenching is notorious for fatally screwing up blades because of the size of the bubbles water makes as it comes into contact with 1200C steel. It flashes into steam and barely touches the steel, but where it touches its by no means uniform. So the steel warps.
Oil is best for it does flash into flame and boils, but the bubble size is a lot smaller. I normally use a tall pipe filled with oil so that there's not a lot of surface area where the oil comes into contact with oxygen. Minimal flames. I suppose the ultimate would be to have a pipe filled with molten lead, and let the steel cool down from 1200C to about 600C in the lead, and then take it out just above the melting point of lead and then dip it in oil. IDEA!!!
Gonna go buy me some lead tomorrow!!! That should be pretty damn even?

[nkt]

You could always add detergent to the water, to increase the wetability of it. The problem with that (and water) is you are going to wind up with a harder blade than you really want. If the back of the blade is that hard, it will likely shatter if you hit it against another blade, or something hard like a rock.

Using lead would be bad for you, and you would have trouble with the lead wetting the steel - it just won't. I've tried getting lead solders to stick to steels, and they don't. They tend to boil instead.

[Turtle]

Originally Posted by Boerseun

Sheesh - now you're talkin' big bucks...

I hope you find something in them book things, GAHD, 'cause I've tried an' tried, and all I can think of is that it's simply uneven heating in the kiln. If it turns out ot be impurities, I'll just have to whack it on the anvil some. But that's tedious. I'm just wondering - if it is impurities, how much impurity do you need to cause a warp? 'Cause the steel is pretty uniform? I'm using 12C27.

___My metallurigal skill is largely with non-ferous metals in relation to jewelry & small castings. If you have room in the kiln, you might try reorienting your blade & see if the location of the buckling changes or the buckling is absent. This may at least narrow down the cause.