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Post by exv on Apr 12, 2024 17:20:08 GMT
would L6 martensite and tamahagane martensite chip just the same?
I am curious if Howard clark's katana edge would chip just the same on hard targets as my nihonto katana. My Nihonto edge is extremely fragile and has chipped when I cut it on hard targets like coconuts (i deeply regret doing this). Anyone own a howard clark as well as a nihonto?
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Post by Lord Newport on Apr 12, 2024 17:25:14 GMT
would L6 martensite and tamahagane martensite chip just the same? I am curious if Howard clark's katana edge would chip just the same on hard targets as my nihonto katana. My Nihonto edge is extremely fragile and has chipped when I cut it on hard targets like coconuts (i deeply regret doing this). Anyone own a howard clark as well as a nihonto? Why are you chopping coconuts with a sword??? In Samurai culture and in the JSA community that would be considered very disrespectful of your sword. No quality sword is meant to be disrespected and abused. If you want to cut coconuts.. use the correct tool.. a machete
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Post by AndiTheBarvarian on Apr 12, 2024 17:55:54 GMT
Tamahagane after folding and forging has a similar amount of carbon as L6, perhaps a little less, 0,6 - 0,7 C. So quenched to a martensite edge it should not make a big difference. L6 has some nickel in it, which should make it tougher. It's possible that the hada welding lines in a Nihonto add chipping risks. In a blade to blade test with equal blades and heat treatment I'd bet on the L6. But I could be wrong. What I don't know is whether the bainite heat treatment tempers the martensite edge to make it tougher and less hard, just a little bit.
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Post by darknovashin on Apr 12, 2024 18:00:46 GMT
So, leaving aside the nature of the targets, your question unfortunately isn’t an easy one to answer. Steel as a material is surprisingly varied in characteristics, but differential hardening narrows that variation a bit since the desired structures of the steel are more predictable. For example, carbide size, the big focus of knife steels matters less here that raw carbon content. Silicon, maganese, niobium, and other alloying agents improve toughness, but as the steels are hardened, the effect is reduced.
Tamehagane is kind of a crappy base material as has been discussed before and very variable in content which makes comparison to modern steels difficult. Add in the skill of the smith to manipulate the carbon content in the edge and keep his laminations between layers (which increases risk of chips from any impurities caught there). Additionally, while there is an expected range of hardnesses for a nihonto’s edge, how steels behave under stress greatly depends on that hardness. A difference of 1-2 Rc can make the difference between a roll and a chip.
A Howard Clark L6 derives its strength from the Bainite spine providing a toughness beyond what would be expected out of L6. The edge on the other hand is just hardened l6 which I have read does better at the 55-60 Rc range (which I think is the lower half of traditional nihonto’s range). But it’s a lower carbon steel than say 1095, so it will generally have an edge more likely to roll than chip due to that. That being said, compared to a smith from the 1500s-1900s, Howard Clark will produce a more consistent product in general so you can expect failures between examples to be similar.
I haven’t seen/heard many if any complaints of chips in his blades, though rolls and deflections I have seen even in my own from hitting things that don’t cut. That being said, very few people have pushed one of his to failure and keep to more standard targets like mats, newspaper rolls, plastic bottles, etc. in the famous demo video, they strike directly onto mild steel reinforcements for a bench in the workshop and it looks to my eye there weren’t many visual chips though a number of rolls and deflections developed and opened up cracks in the hardened edge.
The next, and probably the dominant factor in edge damage of all types, is going to be the edge geometry and how fine that edge is vs the niku. A fine “grass cutter” thins dramatically at the edge and will be vulnerable to both chips and rolls. Given the coconut’s hardness and fibrous construction, I suspect you see more “crush” than “slice” when struck. A “heavy target cutter” with more niku will have the advantage.
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Post by toddstratton1 on Apr 12, 2024 18:12:17 GMT
would L6 martensite and tamahagane martensite chip just the same? I am curious if Howard clark's katana edge would chip just the same on hard targets as my nihonto katana. My Nihonto edge is extremely fragile and has chipped when I cut it on hard targets like coconuts (i deeply regret doing this). Anyone own a howard clark as well as a nihonto? Your sword is not overly fragile if if it chips on a coconut. That is an extremely hard target well above what swords should be hitting. There are swords that can hit coconut and survive it fine but why take that risk? Beyond just Steel type it also depends on how fine of an edge the sword has, a sword with thicker edge profile won't chip as easily as one that is much thinner. But it also won't cut through certain targets as easily either.
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mrstabby
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Post by mrstabby on Apr 12, 2024 18:34:22 GMT
According to tests from knifesteelnerds L6 behaves pretty much the same as other carbon steels with 0,6-0,8% carbon when not Bainite-heat-treted. Chipping resistance on par with 80CrV2 or 1084 at the same edge retention levels. Bainite itself is rather soft according to many sources, and does not make that well of a cutting edge. You can also use other steel, like 52100, for Bainite heat treats, L6 just works the best (and it's still hella difficult). And as many have said edge geometry is much more important than steel type in the end. An then comes hardness, soft edges roll over, hard edges take more force but break off.
The shell of a coconut is one of the hardest woods out there BTW... Comparable to a human skull, quite the hard object.
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Post by larason2 on Apr 12, 2024 18:40:21 GMT
Tamahagane has some silicon and titanium carbides that give the edge micro serrations, so it makes it a good slicer. I've gotten some nasty finger cuts polishing them! However, for the multitude of reasons explained above, it's not as good at cutting hard targets as other kinds of steel. In particular, the welding and forging tend to leave small voids and imperfections. This gives it a very desirable aesthetic character, but that weakens it against hard targets. I'd advise against trying to fix it though. The chip is now part of its history.
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Post by Lord Newport on Apr 13, 2024 4:21:44 GMT
would L6 martensite and tamahagane martensite chip just the same? Anyone own a howard clark as well as a nihonto?I own four Howard Clark blades and a nihonto (that I used for Iai)...I can not offer any empirical evidence or theoretical conjecture on a comparison of chipping between the two martensite edges. I mentioned above, would never abuse any of my swords (or any of my other possessions for that matter) and therefore have no empirical data to offer. I will never understand the obsession of many in the online community with destructive testing of their swords. I also see it to a lesser degree in the knife community also smh at that but at least with knives, it's not as expensive. The hardest targets I ever cut were bamboo and on a poor cutting sequence using up too much mat, the wood peg the mat was impaled on. The big advantages of L6 in the JSA community was a sword that would never take a bend on a bad cut and the ability to get a lighter, quicker handling, thinner blade profile for grass cutting but have the strength and robust characteristics of a much heavier, thicker slower handling blade. The only destructive testing I was aware of on an HC blade was done by Howard on a flawed L6 bainite katana that Howard could not sell. That video has been widely viewed. The sharper the edge, the thinner/less mass supporting it and the more easily it will chip...no matter what it is made of. I would think L6 martensite steel would be a bit more robust than traditional tamahagane martensite but again I think the geometry of the edge versus the target is more important. Here is another clip (which I really enjoyed just seeing again) with Howard, my Sensei (Big Tony Alvarez), the late Keith Larman, James Williams (founder of Bugei Trading), my friend Ted Tenold (who polished and mounted all my HC's) discussing the L6...
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mrstabby
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Post by mrstabby on Apr 13, 2024 11:04:54 GMT
And now for the ultra-nerds: knifesteelnerds.com/2018/07/09/bainite-vs-martensite/
TL:DR It looks like Bainite heat treats (austemper) only make a big difference in some steels that form "plate martensite" when quenched. The difference in toughness on steels that don't, like 52100, is still there but far less dramatic. Also Martensite seems to have a maximum achievable hardness advantage over Bainite of ~14HRC (~47HRC vs ~61HRC) for 0,5% C steels and ~5HRC (60HRC vs 65HRC) on over 1% C steels.
Although these tests are for knives, which generally are tempered harder than european swords, the edges of differentially hardened Nihonto do venture in these hardness territories.
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