Differential treatment question

D

Dangus

Joined
Aug 12, 2000
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I have a blade I am planning that will be a viking/celtic-style blade that has a full length fuller running down it. Obviously a fuller adds a lot of stiffness to the blade, and this is good, but on the other hand, I am facing a risk of a blade that won't survive repeated flexing as well. So I have an idea. Can I insulate the fuller to slow it's quench, and leave the edge exposed to speed up it's cooling? My initial thought was to fill the fuller with clay, but that would not stay in place I think. What I really need to do is to place some sort of steel piece the same size as the fuller into it to keep the oil from directly hitting it. Maybe I will forge up some clamps to make this easier to keep in place.

Does anyone here have any experience with differential treating, and does my idea sound logical/feasilbe/useful?
 
I would use the clay.You just need to wrap wire around the blade and that will lock into the clay and hold it in place while you heat treat...Remember you do have to let the clay dry before you do the heat treat so the wire will hold it in place.
This is how the Oriental blades are done and so it should work fine for you
Good Luck,
Bruce
 
Dangus, I assume that this will be double edge. The clay will work well but remember, what you do to one edge, you need to do the same to the other.

If you use more clay on one side than the other you can expect a curved double edge sword. On a Katana this is good. On a Celtic it is not. The amount of curve depends on a lot of things like the type of steel and how you quench. I've had them (Katanas) warp so little you couldn't tell and I've gotten the full beautiful curve. So prepare carefully before you fire it.
 
yes peter, this will be a straight, double edge sword, and I want to fill the fuller groove down the center on both sides with clay or some other refractory that will insulate it somewhat during quench, to make the edges hard and the center soft.
 
Dangus, if you want hard edges you need to use the clay on the edges not the fuller.
 
Dangus , I'v never tried this on a sword but it worked ok on a 12 inch blade. I hardened the whole thing and then ran a torch down the center of the fuller. I did both sides not letting the dark blue past the ridge of the fuller. If it even starts :eek: quench in water and start to heat again. Try for an even dark blue.:D
(If you run the blue out onto the edge, aneal, reharden and start over. done that too :rolleyes: ) I don't know about the clay thing. but this worked for me, watch your tempering colors:eek: :mad: :( and don't be afraid to try again:rolleyes: practice makes perfict:D
 
Dangus, if you want hard edges you need to use the clay on the edges not the fuller.
Click to expand...

That makes no sense, why insulate the edge if you want it to cool faster?
 
It doesn't seem to make sense Dangus and I'm not a mastersmith so I can't tell you all the reasons for it. The simple fact is that that's the way it's done and it works. If you look at a clay hardened blade you can see the Hamon (temper line) the edge that was clay coated is harder and therefore has more gloss then the rest of the blade after etching.

It has something to do with how the clay holds the heat because properly done the clay itself will glow just like the steel when it reaches critical temp.

It's time for one of the big boys to step in and explain the process.
 
Question
is the difference you get in the clay added hardening process going to make that much difference after tempering? why not change the hardness by tempering?
 
That's a good point Eric. I was addressing the clay because Dangus seemed to want to use it but I really think your suggestion of drawing the temper from the fuller out is a much better idea.

I am still wondering if he won't have some serious warping problems using the clay on both edges.

Anyway Dangus, just trying to point out some of the pitfalls, but I'm not trying to tell you how to do your work. It's obvious you've given it a lot of thought and research.

Good luck and post pictures
 
Dangus...

My understanding is that the clay coating interrups the quench making the coated parts of the blade softer and providing a nice temper line to show on 1040-1084 series steels...

Filling the fullers with 1/8 inch clay would "ruin" the hardening of the quench and give an RC in the 40's...

Traditional Katana sword blades would have been coated completely with a thin mix of clay and then a thicker layer would be formed on the back, working it down towards the edge...This application would allow you to define the "Hamon" pattern as you wish...You could do this to your fullers and create a nice pattern...

This would give you the hard edge and soft center after heat treating...

Don Fogg covers this on his webpage:
http://dfoggknives.com/sword_notes_page_2.htm#Heat treating the swords

I hope he won't mind the link:D

You could also fully harden and then differential temper as has been suggested...

Running Dog
 
Well I was ready to tell Running Dog he had it A&& Backwards so looked it up in "Differential hardening with clay by Bob Engnath"
That's sorta the holey Grail to me....
Guess who has it A&& backwards.

My apoligies Dangus. The same warning about warping stands true, just in reverse. and thank you Running Dog for setting the record straight before I got my foot further in my mouth.
 
Peter...

It's easy to mix this stuff up if you don't do it everyday...I had to think about for a minute...:confused:

Part of the problem is all of the different things you can do during the heat treat to get different effects...


Annealing
Normalizing
Full blade heating
Partial blade heating
Full quench
Interrupted quench
Edge quench
Marquenched (salt bath)
Triple quench (i.e. 52100)
Full tempering
Partial temper
Triple temper
Drawing back the spine
Clay coating for Hamon
Cryogenics
Plunging the red hot steel into a handy slave...Well, that one has gone out of style...:D

And once you work this out for one steel, you get to start all over when you try another!


Why it's more fun than Pat Boone singing Heavy Metal! :barf:

Running Dog
 
Thanks Running Dog. That sounds a lot better then saying....Gee peter....did you take your medication today.
 
I bet you could use clay to keep your bath away from the spine on a partial quench,


just thinking about some practical uses for this



thanks for the lesson :D
 
I work almost exclusively with 5160. Any advice about this? I mean, with this metal is it worth making the center a bit softer, or will that actually make a weaker blade?
 
Dangus...

5160 responds well to this type of heat treat manipulation...

I think you won't have any problems, but you'll just have to try it and see...

I know it's tough putting so much work into something, and then feel that you have to test it to the point of possible damage, but if you want to have a real sword this is what you will have to do...

My suggestion? After heat treat, get a test handle on your sword. Put an edge on your blade and test it with a file...If it's hard, have at some 2X4's to see how it goes...Give it some real good chops :)

If it survives :D and you feel comfortable with how it feels, go ahead and finish your blade...

If it bends :eek: or chips, go back and do the heat treat over again and chalk one up to experiance :cool:

Running Dog

P.S. When you break enough blades, make a wind chime out of them...A nice treat on a breezy summer's day!
 
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