Bark River Golok

[Grampa]

No, I was interested to see Cliff's triple tempered knife. But I'd like to see your brush and bowies as well! Always interested in knives creative people make!

 

[akennedy73]

Guess my point was that if the steel is too weak or brittle to take impacts, then this will happen to the edge just as easily as the blade as a whole. If the knife is missing inch deep scallops out of its edge, or cracked too deep to sharpen out, then that soft spine does no good. The knife is still dead. If the steel is good enough to take impacts with the edge when hardened, well, the steel doesn't know whether it's sitting in the spine or edge.

You point is well taken but I probably have not expressed what's at issue very well. So let me try again:

No one can make a perfect chop every time. In fact, many of us make only a percentage of perfect chops with a cutting tool. If the chop is not perfect, lateral forces will be applied to the cutting tool. If these lateral forces are sufficient, and the tool is sufficiently hard/brittle, it will snap.

To demonstrate this one could take a katana which has the same temper throughout the blade and perform cutting exercises. If one does not cut perfectly with it, it will eventually snap. On the other hand, if you take a high-quality katana with a soft spine and a hard cutting edge, an imperfect cut will not result in a broken blade.

Chopping with a golok is not much different than cutting with a katana except that the blade is shorter so lateral pressure is probably not as great given that the point of leverage will be closer to the point of impact. But lateral pressure is still there - hence I prefer the inherent safety of a soft spine.

Perhaps I am wrong about this - I certainly have no experience swinging katanas. But if I am wrong about this so are hundreds of years of swordsmiths' knowledge and experience.

 

[Cliff Stamp]

To demonstrate this one could take a katana which has the same temper throughout the blade and perform cutting exercises. If one does not cut perfectly with it, it will eventually snap. On the other hand, if you take a high-quality katana with a soft spine and a hard cutting edge, an imperfect cut will not result in a broken blade.

The edge quenched katana will warp and bend under far less force than what it would take to move a fully hardened one of the plastic region. You can find detailed discussions on this topic on Swordforums. The essential point is that with the blade so soft the strength will be so low that it will deform before the harder blade is even significantly stressed. In general, most edge quenches induce a hardened volume which is insignificant and thus the blade basically has the strength of annealed steel.

-Cliff

 

[Thomas Linton]

It is basically the wrong type of steel . . . ."

What steel is that? Mine is made of 0170-6, as were all those in existence. The next - second - batch will apparently be made of 5160.

(Off to research 0170-6.)

 

[Cliff Stamp]

Mine is made of 0170-6, as were all those in existence.

This is one of, if not the most common cutlery non-stainless steel used by several of the largers manufacturers under different trade names. Stewart has often promoted this as a specialty knife steel, in fact there are several common tool and alloy steels of overlapping compositions. This was discussed years ago on rec.knives when makers both spark tested and had elemental composition analysis done on the steel. It is basically a very low alloy high carbon steel which can obtain a very high hardness and retain 65/66 HRC after tempering. It works very well there in a high performance cutting knife. However like all low alloy steels it has a large embrittlement region around 500F which ironically is where it is often drawn to make it tougher and this in fact has the opposite effect. What should be done is switch to a lower carbon steel which is inhernetly tougher at a lower temper, 5160 is such a steel and is a much better choice for large impact blades, hopefully they also tapered the tang at the same time and refined the dynamic balance.

-Cliff

 

[Thomas Linton]

An article on your site references information from Mike Stewart that this is a steel sold under several different names and used by companies as large as Case and Camillus I located that reference in my Google search this evening, along with comments by some guy rolleyes: ) named Alvin who liks it a lot (using the name "50100B"). I think you know him.

Interestingly, some call it modified 1095, some call it modified O-1, and some call it miodified 52100.


To get back to the issue that I raised, if we might, I have little interest in what is "often" done -- indeed no interest at all. So I can be clear, you are saying that you know that the blades of these knives were "drawn at about 500F" creating the problem that you described?

 

[Cliff Stamp]

Yes, there are many ways to get to the same steel, you can take elements out of one, or put elements into another, or remove a particular aspect such as heat resistance or add it. You generally would just want to be more specific than "modified X" as that is like saying a fillet knife is a modified machete, or all steel is modified iron, true of course but not overly helpful.

The embrittlement zone at 500F, is a wide band which forms around that temperature and has a maximum effect close to that temperature for many steels, plus it is nicer to say 500F ebmbrittlement than 498F or 502F. A general non-temper resistant 1% carbon steel has a 58/59 HRC with a 500F temper. That unfortunately is the magic number aimed for a lot of heavy use cutlery.

Non-temper resistant steels simply mean they are not very high in elements like chromium or molybdenum which delay the onset of tempering and thus tend to require very high tempers to soften them significantly and tend to have a strong secondary hardening responce so will rebound in hardness at temperatures around 1000F.

These steels also have embrittlement zones due to pretty much the same reasons, carbide precipitation, but they are shifter to a much higher temperature because alloy carbides are much heavier and need more heat to diffuse. The embrittlement regions are also usually more complicated and can have multiple minima simply because there are a lot of competing reactions at the same.

-Cliff

 

[the possum]

On the other hand, if you take a high-quality katana with a soft spine and a hard cutting edge, an imperfect cut will not result in a broken blade.

The edge quenched katana will warp and bend under far less force than what it would take to move a fully hardened one of the plastic region. You can find detailed discussions on this topic on Swordforums.

Yes, katana do bend easily with a botched cut. You can indeed find all kinds of writing on that subject on swordforums. A through hardened blade can be tempered to bend a little, or a lot, or not at all before snapping- your choice. But it will take a lot more force to do any damage to it. Katana make up for this weakness by being so thick in comparison to western blades.

Check out this thread for an example of how much a difference we're talking about here. Tim Zowada did a demonstration at Ashokan showing the difference in force it takes to permanently deform (bend, not flex & return true) a piece of soft steel & hardened steel of the same dimensions. The hardened steel took about four times as much force to damage. Bending & busting steel.


Back to the topic, I would be very interested in a batch of these goloks made of 5160. (well, if I had any money that is.) And yeah, taper the tang at least. And maybe add some weight at the butt to optimize the pivot points.

 

[akennedy73]

The edge quenched katana will warp and bend under far less force than what it would take to move a fully hardened one of the plastic region. You can find detailed discussions on this topic on Swordforums. The essential point is that with the blade so soft the strength will be so low that it will deform before the harder blade is even significantly stressed. In general, most edge quenches induce a hardened volume which is insignificant and thus the blade basically has the strength of annealed steel.

-Cliff

Thanks for your response, Cliff. I guess I'm just contending that a bent blade is preferable to a broken one. Swinging a 16" blade golok is serious business. Hit a hidden inclusion and well.... guess I'd rather be left with a bent blade than the potential consequences of a broken one.

The Bark River Golok has an 11" blade length - I guess I'd feel okay swinging it into knotty wood given it's relatively short blade length. But let's say BRKT produced a golok over 15" that was through hardened - just can't imagine myself feeling really comfortable chopping into knotty wood.

Given the fact that machetes throughout the world are all either low in strength or have insignificant volumes of hardened steel (like the valiantco goloks), I think there is a good reason. The same reason through-hardened swords are frowned upon. But this is, of course, just my very non-expert opinion.

 

[the possum]

"A bent blade may be preferable to a broken one." No, I don't want either one to happen to my blades. I don't want them to break or bend. If it comes right down to it, I can agree in an ultimate sense, but neither one makes the top 100 list of things I want to see happen to my blades. If we only harden the very edge & leave the rest of the blade dead soft, then we're practically gauranteeing that the blade will bend with rough use.

If I'm using it so hard that a through hardened blade made from a tough steel breaks, then that only means it would have already been bent into a noodle and beaten somewhat straight again about 50 times if it were edge quenched. And then it probably would have broken long before anyway, from being bent back and forth so many times.

The same reason through-hardened swords are frowned upon.

I don't want to turn this into a katana vs. western sword thread, but I think you need to realize there were lots of cultures that through hardened their swords. The Japanese arrived at a solution that met their needs, just like everybody else.

 

[akennedy73]

I don't want to turn this into a katana vs. western sword thread, but I think you need to realize there were lots of cultures that through hardened their swords. The Japanese arrived at a solution that met their needs, just like everybody else.

You're right - I didn't mean to imply all swords, I should have said katanas. The Japanese, as you pointed out, opted for heavy swords with zone hardening. I can only speculate that they wanted the weight to drive the blade deep into the target with a slashing cut. And the weight required the spine to be annealed to prevent the blade snapping when it was torqued against a fulcrum. Western fencing styles tended towards thrusting cuts - enabling lighter blades which allowed for through-hardening.

It's just that when I pick up a large Valiantco golok, I don't see much difference (except about 10 inches of length) between it and the Bugei Crane Katana I have. They're both heavy blades. I guess that's why I intuitively am comforted by the idea that there is going to be some flex if I ever torque it against a fulcrum point. Maybe I'm paranoid... I guess maybe the broken-off portion would remain in the target and the part in my hand would not swing back into myself. Perhaps my concern is unfounded...

 

[the possum]

The Japanese, as you pointed out, opted for heavy swords with zone hardening. I can only speculate that they wanted the weight to drive the blade deep into the target with a slashing cut. And the weight required the spine to be annealed to prevent the blade snapping when it was torqued against a fulcrum. Western fencing styles tended towards thrusting cuts - enabling lighter blades which allowed for through-hardening.

I would personally speculate that they rather came up with a solution to work with their limited resources. I remember seeing one collector say, "Japanese armorers always seemed to ask themselves the question, "How can we provide adequate protection while using as little steel as possible?"" Likewise their swords (and knives) used a sparing amount of good steel, and used the softer stuff for the core or back. Because of the softer steel in the blade, it had to be made thick to compensate. And because it was thicker, and a person can only swing so much mass effectively, the blade had to be single edged to still allow good cutting ability. Whereas western swords could be made thinner due to stronger steel throughout, they could have two edges if desired and still have good cutting ability. (Of course some double edged Japanese swords exist, and lots of western swords only had one edge.)

Western swordsmanship styles used both the cut and thrust to great effect. Take a look at some stuff from the Liechtenauer tradition.

If you're this concerned about breakage, you owe it to yourself to try some good blades and see what it really takes. It took a full force blow into a steel rod (accidental of course) to break my old stainless bowie, and even then pieces didn't go flying. It just got a fatal crack. And stainless has like half the impact resistance of good tool steels. My 5160 bowie has seen nearly full impacts on concrete and steel and only needed 10-15 minutes of sharpening. My next blades from L6 should be even better.

 

[akennedy73]

Western swordsmanship styles used both the cut and thrust to great effect. Take a look at some stuff from the Liechtenauer tradition.

But wasn't Liechtenauer a prelude to the eventual development and relatively widespread adoption of the rapier? Perhaps I'm wrong but my sense is western swordsmen saw their way to the advantage of quick thrusts vs. slower slashes. You'll have to pardon my ignorance in these areas - I have limited knowledge about swords and steels.

I remember seeing one collector say, "Japanese armorers always seemed to ask themselves the question, "How can we provide adequate protection while using as little steel as possible?"" Likewise their swords (and knives) used a sparing amount of good steel, and used the softer stuff for the core or back. Because of the softer steel in the blade, it had to be made thick to compensate.

Thanks for the info - that makes sense to me. The economy of available resources usually trumps all other considerations of form and function. But I am wondering about the softer steel used in the core and back of katanas - was it of such poor quality that it could not be sufficiently hardened? Do you know why the Japanese were unable to obtain higher quality steels?

What's your opinion of why Valiantco goloks are zone hardened? Is there no advantage? Just a useless tradition passed on to the Indonesians?

And thanks for taking the time to inform the uninformed!

 

[Cliff Stamp]

I would personally speculate that they rather came up with a solution to work with their limited resources.

Lee notes this in his book on sharpening. The Japanese often made their steels and since only the edge cuts it is a massive waste to use all of that high quality cutlery steel on the rest of the tool. You get the exact same cutting behavior if only edge is cutlery steel. Plus it is also much easier to grind to shape. Of course the low strength is a concern.

And stainless has like half the impact resistance of good tool steels.

Way less, the tougher tool steels are a order of magnitude tougher than the high carbon stainless. It would be like comparing the dynamic cutting ability of your large bowie to a Buck 110.

...why Valiantco goloks are zone hardened?

Tradition, ease of production, cost, etc. . I really like the cutting ability, balance and grip of the Valiants, but the low hardness of the spine and most of the edge has its problems. Note those blades are also zone quenched, the tip and the choil of the blade is left unhardened. I discussed this with a traditional maker who came from a line of makers and he was unware of the effect of tempering and this makes a large difference on how you can heat treat blades. The Valiants would be much better if the entire blade was spring hard and then the edge raised to a cutting hardness. The blade would be much stronger and it is still extremely difficult to actuall fracture or put a bend in spring hard steel.

Swinging a 16" blade golok is serious business. Hit a hidden inclusion and well.... guess I'd rather be left with a bent blade than the potential consequences of a broken one.

Generally this isn't a concern with a proper tool steel, all you will do is just indent the edge.

Given the fact that machetes throughout the world are all either low in strength or have insignificant volumes of hardened steel (like the valiantco goloks), I think there is a good reason.

Machetes are basically the extreme of low end production where you have to produce mass output for minimal cost, this is why they have a very inefficient grind, basically stamped stock and a sabre/flat profile. Machetes are however through hardened, usually 45-55 HRC. The spines on edge quenched blades are much softer, 20-25 HRC.

-Cliff

 

[Thomas Linton]

Cliff, thank you for the additional information.

However, because you said that these actually-existing Goloks had a certain problem due to being drawn at 500F, I asked if you were saying they were, in fact, drawn at 500F. I sure don't know. Can I take it that you don't know either?

 

[akennedy73]

Thanks for the clarification, Cliff! I really had no idea tool steel was so reliable, but it makes sense given what is required in tool & die fabrication.

 

[Cliff Stamp]

However, because you said that these actually-existing Goloks had a certain problem due to being drawn at 500F, I asked if you were saying they were, in fact, drawn at 500F.

If I show you a ATS-34 blade at 60 HRC then you can't tell if it was tempered high or low because you can hit the same hardness either way and they have fairly different properties. However steels with no temper resistance don't have this complexity. If you are told the steel is a certain HRC then you know how it was tempered because there is only one way to get there.

Now of course there are many ways you can screw up the hardening and still get a specific HRC, but even if you do everything right you can't avoid the 500F embrittlement because there are fundamental reactions at that temperature which is why you are warned heavily not to draw steels in that zone. Again, this doesn't mean exactly 500F, there is a wide band around that temperature and that band is exactly the tempering temperature which produces the cited hardness.

To be really rigid you can get to that hardness without that temper in those steels but it would require reduce the carbon content in the austenite which is extremely difficult due to the speed at which carbon dissolves (seconds), or induce a large amount of retained austenite by interrupting the quench and stabilizing the austenite, or induce a dual phase bainite/martensite structure.

You can be very confident none of these are happening because the first two would be absurd for several reasons and the latter is exceptionally demanding and if it was being done then you can bet it would be heavily promoted. It would be like proposing that Japanese sword polishers are hand finishing the blades and Phil Wilson is individually hardening the blades but they are keeping it a secret. Yes you can be confident neither of those is happening either.

-Cliff

 

[akennedy73]

My 5160 bowie has seen nearly full impacts on concrete and steel and only needed 10-15 minutes of sharpening. My next blades from L6 should be even better.

Just checked out your thread about dispatching that 'coon - I'm impressed! I've got new respect for how well tool steels deal with impact!

 

[Thomas Linton]

However [with] steels [like 50100B/0170-6] with no temper resistance, f you are told the steel is a certain HRC then you know how it was tempered because there is only one way to get there.
. . . [Y]ou can't avoid the 500F embrittlement because there are fundamental reactions at that temperature which is why you are warned heavily not to draw steels in that zone. Again, this doesn't mean exactly 500F, there is a wide band around that temperature and that band is exactly the tempering temperature which produces the cited hardness.

-Cliff

Cliff,

I can find noone selling this steel and no tables of suggested tempering temperatures for it.

I do find data for 52100, another steel that may meet your definition of a "non temper-resistant steel" ("not very high in chromium" = 1.5%?). You have noted its similarity to 5100B (1.15% carbon vs. .95% for 50100B). Crucible suggests tempering 52100 at 350F to reach 60-61 RC, 450F to reach 58-59 RC, and 500F for 56-57RC.

Does "chryo quenching" have any inpact on the inevitability of embrittlement that you posit if this steel (50100B) is run at 58 RC?

 

[Cliff Stamp]

Temper resistance is basically a measure of how an alloy responds to tempering. Alloys with no temper resistance like 1095 will directly soften as you raise the tempering temperature while alloys like BG-42 won't soften significantly and will then actually increase at about 1000F where they undergo secondary hardening. 52100 doesn't have enough chromium to give it significant temper resistance. You can see its responce specifically in the BG-42 PDF file by Timken, Carbon V has an even lower temper resistance than 52100.

As noted the embrittlement region is quite wide, it extends from about 400 to 600F for the minimal plateau. I have seen no data that cold treatments would prevent secondary carbide precipitation which is what causes the embrittlement. This by the way is a very well known behavior of low alloy tool steels, you will find it in any metallurgy text or reference for tool steels. It is the same essential reason why there are constant warnings about tempering high chromium steels very hot because while they often have the required hardness there, the carbide precipitation has strong detrimental effects. In that case it is chroimum carbide precipitation, for the low alloy steels it is cementite.

There is a massive difference in toughness between the low alloy steels which hit 57/59 HRC with a low temper and the ones which do so when drawn at close to 500F. The latter one are really brittle there which is why they in general should not be used for that application. They will also naturally form plate martensite which you would want to avoid for a tough blade also. They also have a lower grindability and a lower ease of sharpening at that hardness due to the lower strength/carbide ratio.

-Cliff