Request steel info

tallwingedgoat

tallwingedgoat

Joined
Jan 13, 1999
Messages
1,422
Uncle Bill,

This is actually a two part question.

Once you posted a website that had information on all sorts of steels. Do you still have that?

Also, I think you answered this one before as well. What are your estimates of H.I. khukuri's Rockwell hardenss from edge to body and tang?
 
Hi Goat:

Here is what we try for: Edge: In the chopping area of the blade which takes the most grief we try for 56-58Rc. A couple of points less in belly and towards the tip. Back of blade softer per kami discretion. Tang should be dead soft.

We don't always get it but usually are pretty close when we are not under the gun and in a hurry. A customer in Colorado tested a blade that came in at 61 Rc along parts of the edge -- too hard and it had to be stoned down until the edge got down to where we wanted it. A couple of recent tang failures were the result of the kami getting the tang accidentally hardened. The forging and manufacture simply cannot be hurried. As I suggested to the kamis, it is better to make nothing than to hurry and make it wrong.
They agreed and have slowed down.

Village kamis usually make a bit harder blade, edge and back both.

Uncle Bill
 
Pardon me for being dumb, but what exactly is "dead soft?" I have had knives that were so soft that they could literally be bent like a paperclip. And then sometimes they'd break, or maybe you could straighten them a bit, but you could never really use them for anything.

After the tang-break scare, I took a good look at my 20in Sirupati. I was a bit worried about it, as it has some fold lines, so (being in an apartment where whacking on things would be considered anti-social) I stuck the blade between the top of the door and the doorframe, and hung, with about 3/4 of my weight, from the handle. I didn't use my full weight, since the door started to make strange noises and my hands hurt (I weigh about 210 right now, and hopefully less sometime soon). Anyway, the blade flexed a bit and one line, which I discussed with Uncle Bll prior to this as maybe being a fold or grind line, opened up just a bit. This left a small "scale" of metal sticking up from the line just enough to really catch a fingernail. So I got out the trusty Dremel to polish it down. Boys and girls, 5160 may not be a "wundersteel", but it sure is tough enough! I couldn't polish it down, so I changed bits and ground it down. And down. And down. There is now a small crescent-shaped pit in the blade of my Sirupati, about 1/2 inch long, and (guesstimate) 1/16th inch deep. And the fold line still runs along the bottom of this groove!

The upshot of all this being--ablade that is 3/8+ inch thick flexes enough to warp this small "wrinkle" in the blade. It turns out that this "wrinkle" goes down who knows how far into the blade (and I'm not grinding any further to find out) and the blade still returns to true. Not only that, but the untempered, "dead soft" tang, which is half or less in thickness (and is circular, therefore much, much less cross-sectional area than the blade) also returns to true.

In High school physics class, we had high-quality music wire 1/4 in dia snap in some of our experiments on torsion, torque, Young's modulus, etc., and with surprisingly little effort. Like I said, 5160 may not be a "wundersteel" but it is one tough "Sunny Beach" (Florida expression). So I'm having a hard time figuring out what "dead soft" means in relation to something that seems practically unbreakable.

Any ideas or opinions?
 
:
Tom.
Dead soft is "as manufactured" before heat treatment of any kind.
Or any metal that has been annealed back to as manufactured condition.
At least that's the way I understand it.

Uncle sent me the 20" Sirupati that failed. It is now back in service. I am getting some pix developed and will send them to Uncle. When he posts them I will tell everyone what was done.

------------------


>>>>---¥vsa---->®
The civilized man sleeps behind locked doors in the city while the naked savage sleeps (with a knife) in a open hut in the jungle.
 
Thanks, Yvsa. Years ago when I mapped a few HI blades down at a heat treating shop in El Cajon it seems I remember the tang was about 28-30 Rc which is pretty soft.

The village model I sent Cliff for destruction testing had a fold line near the bolster that scared me enough I would not sell the knife. If you read Cliff's test results you'll see this knife did better than any other, passing lateral strength tests that caused other knives to fail. It is tough steel when forged and heat treated properly.

I think the HI khukuris may have undergone more severe testing than any other knife and the only blade failure we have had is 1/4 inch gone off the tip of Julian's Purple Heart 18th Century model. Reground by Cliff and back in service with no problems. But we've had a couple of tangs and some handle failures over the years. Wood and horn is not as strong as steel.

I suppose I could have ignored the failures like most seem to do but that is not the way I play the game. If I am able to take any joy in success I must be willing to admit to failure.

Uncle Bill

 
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