Water-quenching 5160 questions...

Jim March

Jim March

Knifemaker / Craftsman / Service Provider
Joined
Oct 7, 1998
Messages
3,018
Both Kris Cutlery and Himalayan Imports do water-quenching to harden the edges of 5160 blades. In the case of HI we've got pictures of them doing it by pouring water out of a teakettle right onto the hot blade.

As you get into longer thinner blades this could perhaps be sub-optimal. If you could dip the edge into water you could do finer control of exactly what area gets tempered and you could do both sides at once for a more uniform hardness pattern. Problem is, that kind of quench can cause the edge to "split" too often, ruining the blade.

So...my first reaction is, pre-heat the quench water? To where? Second, could something other than pure water as a quench medium control the reaction better?

Any other comments on doing differencial edge-temper in 5160 appreciated.

Jim
 
I guess my first question would be, Why do you want to water quench an oil hardening steel? 5160 can be heat treated into a superb using blade by following the procedures outlined over the last few years by people like Ed Fowler, Wayne Goddard, our own Ed Caffrey and virtually all the ABS smiths. They have all worked this steel every way imaginable over the last ten years I personally know of.

I heard the wonders of water quenching 5160 stories several years ago and tried it for a couple months and always ended up with broken blades. Even with an interupted quench the edge cools and hardens so much faster than the body of the blade that there is a sort of built in fracture line all along the quite visable temper line. It looks cool and cuts great but every time you put the blade under a little stress it breaks off in chunks along that temper line. Now I have no doubt that you can eventually find a sequence of events and temperatures that will eliminate that, but why bother when oil quenching it automatically solves the problem.

I am coming off kind of angry here, and that really wasn't my intention. But After all my failures with water quench on this steel and all my successes with oil quench, The story about HI and their tea kettle kinda get to me. Their blades are all hand forged if I'm not mistaken, and it's possible that forging so many by hand for production is allowing them to spend too much time in the fire and burning out so much carbon that it is no longer 5160 but maybe 5130 and requires a water quench to get it to harden successfully.

I think I've vented enough and probably made an a** of myself. Maybe Ed Caffrey or Jerry Fisk can jump in here and shed light on the question.

Take Care All,

GaryB
 
Jim,

The only way I know how to water quench and make it work, is to clay coat the blade first like the Japanese do. I haven't tried 5160 but I know some sword smiths who have used it and had good results using clay.

Hope this helps,
Ravenclaw
 
Jim,
Gary and Ravenclaw are both right. I've been working and experimenting with 5160 for over 15 years now. From heartbreaking, personal experience......don't water quench 5160, unless your using the clay tempering method. The reason this works is because the clay is an insulator, holding heat, and keeping the steel from cooling too quickly.
The reason you see maufacturers do this sort of thing is simple.....$$$$$$$(it takes less time and money to conduct this type of operation than to train people or purchase equipment to oil quench) This is the BIG difference between factories and custom makers. Although a company may say that they are using the "most advanced" or "highest quality", what they are really saying is that they are using the method/material that is most economical for their particular operation.
As for the temp portion of your questions, that will have little or no bearing from the standpoint of water quenching. Water boils at 212F, and will circulate almost 10 times faster than oil from hot to cool, this gives you very limited possibilities for a water/? mixture. You simply cannot pre-heat it to a point that will slow down the quench.
Talk to a bladesmith, and it is very likely that 99% will tell you to oil quench even the W-series steels (water hardening) to prevent cracking/breakage during the hardening cycle(s). I get the impression that many folks think that harder, equates to a better blade, nothing could be further from the truth. A high performance blade will have the capability to hold an edge, but it will also possess the characteristics of toughness, durability, and ease of sharpen. IMHO, water quenching 5160 is just looking for trouble. And should your name be on that blade, if and when it goes wrong, chances are that your reputation will suffer for many, many years to come.
As for the multiple quench, there is no doubt in my mind that it produces a far superior blade to one that has been single quenched. The best thing to do is to experiment, and find what works best for you. Who knows, you may find something that the rest of us have missed!
http://www.mtn-webtech.com/~caffrey

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Ed Caffrey
"The Montana Bladesmith"


 
Ah. Interesting stuff.

What kind of oil? Motor oil? Vegetable? Something available in Nepal...?

Jim
 
Hi Jim,

Sorry I kinda jumped down your throat the other night. Wasn't really very constructive. Whats the term for PMS for guys???

For a low tech oil quench you can use a mixture of motor oil and Automatic Tranmission fluid. Never use old, used motor oil though as it is likely to have unburned fuel in it from piston blow-by. That could get explosive. Also vegetable oil would work. Jim Hrisoulas recommends olive oil as it smells like cookies baking when the hot steel burns the oil. The idea is to slow down the cooling rate from what water would be.

More later about differential tempering. Someones beating on the door.

Take care,

GaryB
 
Amen Ed!!! as for quench oil, I think that there's a lot of bs from the manufactrers of the very expensive commercial heat treat oil that can be ignored.All that is geared for industrial production and has not necessarily much to do with our neeeds. I buy the cheapest grade of 10 weight hydraulic oil("R & O") for less than $12.00 for a 5 gallon bucket. Works great. BTW If you quench a blade(submerge it) and then pull it up above the surface while it is still red hot, it will ignite the hot fumes in a big red-orange whoomp that is very startleing, but not hot enough or of a duration to do much more than sing the hair off your arm. I have this urge to swish and dip that I have to stiffle.
 
I diff heat treat 5160 quit often. I have found that the ford type trans fluid is just right for me anyway.. I preheat to about 150..then go for it.. It chops like a bulldozer.. Take a lickin and keeps on tickin..
As for water. YIKES!



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Web Site At www.infinet.com/~browzer/bldesmth.html
Take a look!!!




 
Gary, don't sweat it, I didn't take it personally at all.

I have a question about what the Nepalese kamis are doing with those Khukuris, though: is it possible that because of the extreme thickness of the blades (5/8ths at the spine is common - on SMALL ones) the Hamon/border of water-hardened steel at the edge is somehow "V-shaped" within the blade? Err...in other words the transition area isn't uniform from one side to the other; at the hamon itself there may be a softer core continuing down past the hamon line *inside* the blade, because with that much thickness it doesn't penetrate all the way?

Remember that they pour water on one side and then the other. Bill Martino says that by taking a rough hardness measurement on one side versus the other he can tell if the kami was right-handed or left! The first side of the blade to get the water gets a hair harder
smile.gif
. That's what suggests to me the possibility of a softer core right at the hamon, and that in turn is what's keeping the hard edges from breaking off of the soft spine?

Aaaaanyways. Whatever they're doing, they ARE doing it well. Cliff Stamp and many others can attest to this.

My concern isn't the Khukuris per se; they're about to experiment with another blade type of "longer, skinnier" dimensions. I can't go into details here but I can describe it in private with a well-known bladesmith or two. Basically, I'm concerned that what worked for Khukuris for the last 400+ years may not translate well to the new project.

All advise has been helpful and is well appreciated. I've also pointed Bill Martino and Pala to this thread, they may in turn pass it to Gelbu in Nepal who's acting manager with Pala away and is online.

Jim
 
Interesting thread, Jim -- and good reaponses, all! I've been wondering about the same thing. The HI khukuris really do deliver excellent performance, and not simply because they are so massive; edge retention is very impressive, too. But their stated heat treat and general manufacturing method seems to go against conventional wisdom or logic. Jim, your speculation about a hardened "V" cushioned by a softer core is interesting. Am curious to hear replies from folks here. Thanks for a good thread --

Glen

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“How unfortunate that youth is wasted on young people." Mark Twain

 
I seldom get outside my own forum these days but Jim invited me over to read and comment.

Years ago I suggested to the kamis that oil might be easier than water and they resisted. I am not sure exactly why but I suspect it was familiarity versus strange territory.

I have tried water quenching and got poor results -- cracks and warping -- but I am a neophyte and know little about true blade making. I was experimenting in a pursuit of knowledge and understanding. However, when I used the method the kamis used, pouring slowly from a pitcher I had better results but found oil or transmission fluid to be much more forgiving of my lack of knowledge and experience.

In defense of the kamis and their own way of doing things they make an astoundingly good quality blade and our failure rate is maybe one in a thousand and these are usually tang failures rather than blade.

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Uncle Bill
Himalayan Imports Website
Khukuri FAQ

 
I want to ask a question of the bladesmiths here: let's say the kamis (Nepalese for bladesmith, if that isn't already clear) are doing a long straight piece...say, a 40" blade. Say it's fairly thin and light by Nepalese standards, something like a heavy rapier...total height maybe 1.5" edge-to-edge. That's NOT the "special project" but it gives a close idea of the engineering.

Would it be possible to heat it and then quench the edge in a long skinny trough made of half of a 3" pipe cut lengthwise, filled with, say, new motor oil? Or a vegetable oil, whatever...you fill the pipe to maybe a 3/4th inch depth and quench the whole edge in one shot?

How well would that work? It seems to me you could very accurately control how much of the edge is hardened by controlling the oil depth; I had originally thought of this with water but Pala quickly informed me that water would cause the edge to crack if you did a full-tilt "dip" of any sort, and now I see why: it's an oil-hardened steel, technically.

What concerns me is that on a long thin piece poured-water hardening techniques will be very difficult, if you want a uniform edge.

Again: this thread shouldn't be seen as criticism of the khukuris! Wasn't my intent nor do I feel the khukuri I own already is in any way flawed, if I had to chop wood with it I wouldn't hesitate despite it being on the light side for a khuk.

Jim

[This message has been edited by Jim March (edited 18 November 1999).]
 
Uncle Bill,
You don't need to say anything in defense of the Kamis. If what they are doing works, then they are doing it the right way.

Jim,
What you proposed should work fine. It is a very common practice in the ABS(American Bladesmith Society for those who don't already know)to edge quench blades just as you described when extreme toughness is required. You will still have to temper the blade at least twice at 375 to 425 F to bring the edge hardness down to the Rc 57-58 range where it needs to be so it wont crack. The spine of the blade, not having hardened much, will be much softer than the edge. This is the part you have to play with to get exactly the performance you want. If the body and spine don't harden at all they may be so wimpy that they bend too easy. Preferable would be that they harden just enough to make them strong and springy.

Another way to achieve this is to harden the whole blade, Temper it twice or three times then put the edge in water to keep it from heating up and draw the spine back with a torch till it shows pale blue oxidizing colors then quench in water quickly to stop the heat from transferring to the edge.

Hope all this rambling helps,

GaryB
 
Mostly. Thing is, the kamis have no torches.

Ponderponderponder...

Jim
 
Jim,

BOY!! You just make this tougher and tougher. Try this on for size. To draw the spine without a torch get a hunk of steel as long as the blade (like the pipe you edge quenched in) put it in the forge and bring it up to a strong red hot, pull it out of the forge and lay it on the ground. Put the spine of the blade on the red hot steel and again watch for the oxidizing colors and quench when you get a strong blue. Less and less precise all the time but it works with practice. What ya think?

Gary B
 
Hell. Gary, you're gonna hate me. The spine will indeed be non-sharpened but the whole thing is curved like a cavalry sword.

OK, lemme throw this out: what if we did a "mild water quench" on the spine side and a full oil quench on the cutting edge? On the spine, what if you passed it edge-up over a damp rag, one quick swipe after doing the oil number on the edge, so there's already a bit of cooling?

Jim

[This message has been edited by Jim March (edited 18 November 1999).]
 
Bill, the kamis already know how to "spring temper" the spines, right? They're not "dead soft"? Just confirming...they must be springy, Cliff and others have managed to bend the hell out of 'em and they pop back.

Jim

[This message has been edited by Jim March (edited 18 November 1999).]
 
Is it possible to use a quench medium between water and oil? Like brine?

Or a multi step quench where the whole blade is first quenched in a barrel of oil, and then water quenched?

Or how about interrupted quench like old Medival days?

How hard is it to do clay coated hardening?
 
Another problem is the steel itself. Sometimes HI get's mystery steel to work with like 9260 and 6150, so I imagine that really causes some headaches.
 
WOW! The last four posts have me a bit confused. To give sound advice on how to best accomplish the given task we first need to know the specific type of steel, the limitations on equipment, and the desired outcome. We were talking about 5160, is that still true?
The post concerning the curve in the blade is no big deal, you can still edge quench by keeping the level of oil in the quench tank to about 1/3-1/2 the blade width and "rolling" the blade forward and back during the quench. If your seeking to create the curve during the quench, I would suspect that the only way your going to get good results are with some type of clay type hardening method.

http://www.mtn-webtech.com/~caffrey

------------------
Ed Caffrey
"The Montana Bladesmith"


 
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