Solingen Machete hardness 45 HRC. Is RC as important as we think it is?

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FerFAL

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Aug 15, 2007
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Today I came across a very interesting writeup showing metalurgy testing on old Solingen Weyersberg and Kirschbaum swords and bayonets around the year 1880.
http://www.academia.edu/319632/A_contribution_to_the_understanding_of_Solingen_steel_in_the_19th.century
I was looking for information on my 1891 Machete de Artilleria made by this company. Its a fantastic collectors piece and I know of some that are users. The steel is supposed to be on the soft side and the test above (great read, by the way) seems to confirm that. Now these guys obivously did things for a reason, and I completely understnad that the 58-60RC obsession is to a point a marketing thing. Everyone want to have it "harder" than the nect guy these days.. :rolleyes: when maybe a good softer blade would be easier to resharpenas we often find out.
The article also mentions that the WKC steel had "excellent mechanical strength(> 1500 MPa) and great toughness" and goes on to explain in detail de heat treatment and their attempts to replicate it today.
An exact control of the temperature must alsobe ensured during the subsequent final heattreatment, which must be carried rapidly afterforging to prevent any further growth of thecrystallites from being promoted. Because thePearlite crystals (Troosite) form at the Auste-nitic grain boundaries, it is possible in this wayto increase the number of crystal nuceii andthus the rate of transformation of
γ
-Austeniteinto fine grained Pearlite [9,10]. If a fine grainedPearlitic structure is required in a steel of eutec-toidal or very similar composition, cooling mustbe carried out in a bath of molten Lead or mol-ten salts, whereby the isothermal transforma-tion of Austenite into fine grained Pearlite canbe achieved at temperatures between 580 ºCand 600 ºC. This fact is also clear from Fig. 9 [8],which shows the rate of growth of fine grainedPearlite as a function of the undercooling, thatis relative to the temperature at which crystalgrowth can only take place isothermally.
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FerFAL
 
I would say it is fairly important. It is understandable that swords and machetes were a bit on the "softer side," because they were going to be exposed to the stress of hard impacts. Plus, I think if a soldier of that era used his edged weapon in combat, he would most likely sharpen it afterwards so edge holding might have taken a back seat to toughness.

Most pocketknives nowadays that are at 60 HRC probably aren't going to be put through those kinds of impacts, except by the guys over at the spine-whackers subforum. Personally, I like having a higher HRC so I don't have to sharpen my knife after each use.
 
Even the best testing methods have a +-2 margin of error, and then within the different sections of the blade the hardness varies as well. Many of todays 58-60RC seem to be closer to 55-58 range in actual practice. S30V used in Leatherman's Charge seems to be pretty close to the hardness advertized and I find it sliglthy too hard for my taste, takes forever to resharpen while other "softer" steel sharpen much easier and still cut well for a long time. I dont know, seems that the more you use it, the more you appreciate steels that are easier to resharpen. Trying to fight that with ever increasing harder steel moot point, like those bloody ceramic knives. Worst piece of crap I ever spent money on.
FerFAL
 
This post goes to show just how important HRC is. Softer for something that needs to bend and not break under hard impact, harder for a tool that is meant to do any extended cutting chores.

Might as well be comparing moccasins to ice skates. Sure, both are worn on your feet, but they accomplish very different goals.
 
Longer edged weapons and tools are always run softer than smaller, shorter blades. It all has to do with use.

That being said, I find myself using a Victorinox SAK or Swiss Tool more oft than not and they use German DIN 1.4110 stainless steel at 56 HRC for these. Most steel snobs would laugh themselves silly if someone like Benchmade designed a new knife using this steel at this hardness. Marketing is a BIG, BIG part of it all.
 
If I recall, machetes don't even need to be that sharp and mostly rely on their blade geometry and weight to hack at things.
 
goodeyesniper said:
This post goes to show just how important HRC is. Softer for something that needs to bend and not break under hard impact, harder for a tool that is meant to do any extended cutting chores.
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I used to think that way too, but then throw into the equation that axes have a HRC of 50 to 55 give or take, and they are hard use tools for cutting wood, a heavy duty chore for any knife. Granted, the geometry is different but still, we're still talking about a heavy duty cutting task and not that impressive hardness by today's standards.
Then keep something else in mind.Grit of stone and sand, the small particles that dull any knife in the field will eventually dull a hard knife as well. It may take a bit longer with a harder blade but it will happen, and when it does putting a good edge will take more work. For a knife used a lot, seems that touching up the edge after each session on a softer steel makes more sense than working heavily on it after two sessions.
Finally, we have to keep in mind that hardness is only part of the final equation, steel composition and HT will have a mayor role as well on how well the knife performs. A knife may outperfom another knife yet both may have the same HRC. Having the same HRC one may none the less be more brittle, more prone to chipping and rolling and require more frequent sharpening.
XiaolongJackson said:
If I recall, machetes don't even need to be that sharp and mostly rely on their blade geometry and weight to hack at things.
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mm.. dull is still dull. I notice a big difference between using a Tramontina machete when its nice and sharp and when its not.
FerFAL
 
FerFAL said:
Even the best testing methods have a +-2 margin of error, and then within the different sections of the blade the hardness varies as well. Many of todays 58-60RC seem to be closer to 55-58 range in actual practice. S30V used in Leatherman's Charge seems to be pretty close to the hardness advertized and I find it sliglthy too hard for my taste, takes forever to resharpen while other "softer" steel sharpen much easier and still cut well for a long time. I dont know, seems that the more you use it, the more you appreciate steels that are easier to resharpen. Trying to fight that with ever increasing harder steel moot point, like those bloody ceramic knives. Worst piece of crap I ever spent money on.
FerFAL
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Pretty much my thoughts as well. I find myself appreciating knives around the hardness of a SAK these days. Hits the sweet spot in my opinion.

XiaolongJackson said:
If I recall, machetes don't even need to be that sharp and mostly rely on their blade geometry and weight to hack at things.
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I can chop wood with a dull axe, too, but it sucks. :D Sharp machetes work a lot better than dull ones.
 
If hardness were unimportant and only toughness mattered for cutting tools, then we could save a lot of money using 1018 mild steel for the blades, with a hardness so low it doesn't even register on the C scale. Perhaps those sabers would have fared better at 32 hardness instead of 45. Strength is a critical property for a cutting edge. What determines the amount of strength you want is the type of cutting and the type of material being cut.
 
I used a machete(friends dad's machete that he brought back from vietnam when he was in the army) for dozens of hours last summer cutting down buckthorn, small trees and leafy plants. And I hit rocks all the time so the machete became dull alot, but all I really needed was a craftsman bench grinder that had less than a 100 grit wheel on it, probably 50 or so. And when the machete was dull, it worked awful against wood. I usually only sharpened the first foot of the machete too. It was a long jungle machete with around 3/32 thick steel at around two feet of blade and this really uncomfortable plastic handle that gave me blisters.

Alot of steel only take advantage of certain traits like carbides at certain Rockwells also.
 
My recollection these are M1852 German pattern swords. Those swords are primarily thrusting weapons, though they are pipe backed and have a slight curvature, the balance of these swords is a little off for a cutting weapon.

Weyersberg & Kirschbaum made a lot of swords, for decades, and these swords were used in combat. I am certain, based on feedback, they came up with the proper balance of hardness and toughness necessary for cavalry swords that would work and stay together under the shock of a cavalry charge. You have a man and a horse going about 30 mph and the force of impact will bow the sword just before penetrating the target. Hard and brittle would likely shatter on impact.

If the sword is a little soft that is because that is the best properties for that type of sword. There are probably very good reasons why they did not make them harder.
 
FerFAL said:
I used to think that way too, but then throw into the equation that axes have a HRC of 50 to 55 give or take, and they are hard use tools for cutting wood, a heavy duty chore for any knife. Granted, the geometry is different but still, we're still talking about a heavy duty cutting task and not that impressive hardness by today's standards.
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Axe is more than a little different geometry, the impact dynamics do not even resemble those of a long blade.

Then keep something else in mind.Grit of stone and sand, the small particles that dull any knife in the field will eventually dull a hard knife as well. It may take a bit longer with a harder blade but it will happen, and when it does putting a good edge will take more work. For a knife used a lot, seems that touching up the edge after each session on a softer steel makes more sense than working heavily on it after two sessions.
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I use my knives a lot, and I cut a lot of abrasive stuff. For me, the difference between hard steel and soft steel is sharpening after use or stopping to sharpen during the job, sometimes several times. You value ease of sharpening over edge holding. I value edge holding over ease of sharpening. There are knives out there for both of us. that hardness may not matter to you, but it does to me.

Finally, we have to keep in mind that hardness is only part of the final equation, steel composition and HT will have a mayor role as well on how well the knife performs. A knife may outperfom another knife yet both may have the same HRC. Having the same HRC one may none the less be more brittle, more prone to chipping and rolling and require more frequent sharpening.
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That is true. Everything is a compromise. You have to pick the combination of traits that sacrifices the least for a given application.
 
FerFAL, that article was a pretty interesting read and I thank you for it.
The machetes that I use run about 10 points higher HRC than your Solingen saber articles describes, but I'm still seeing deformation rather than chipping as my only edge failure mode, and I've never broken one at all. Given that I'd rather be working than sharpening (and I spend a lot of time sharpening as it is) I prefer the heat treat used on my machetes to the one described. Of course, I'm not a cavalryman.
With respect to the crystalline structure of the blade there has been a great deal of discussion with respect to heat treating to produce bainite in the production of some swords to improve toughness. You might want to investigate the industrial process of "austempering" to manufacture very tough steel with reduced hardness, giving mechanical properties roughly similar to those described in your article. These properties occur as a result of a high temperature quench, which is also mentioned in your article, which prevents martensite production and favors bainite. The article specifically identifies the saber structure as being fine grain pearlite, and what I've read suggests that modern knife makers avoid pearlite formation to improve toughness.
 
helobite said:
My recollection these are M1852 German pattern swords. Those swords are primarily thrusting weapons, though they are pipe backed and have a slight curvature, the balance of these swords is a little off for a cutting weapon.

Weyersberg & Kirschbaum made a lot of swords, for decades, and these swords were used in combat. I am certain, based on feedback, they came up with the proper balance of hardness and toughness necessary for cavalry swords that would work and stay together under the shock of a cavalry charge. You have a man and a horse going about 30 mph and the force of impact will bow the sword just before penetrating the target. Hard and brittle would likely shatter on impact.

If the sword is a little soft that is because that is the best properties for that type of sword. There are probably very good reasons why they did not make them harder.
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Agreed. Context is everything in determining why something was built the way it was, especially when made by skilled craftsmen. For the swords in question it makes sense. I'd be interested in knowing the results of a similar test on a true cutting sword and on a machete by the same manufacturer. They made all three classes of blades.
 
I think to some degree hardness doesn't matter so much for large blades like a machete. If you are going to be whacking stuff with it at full strength, a super hard blade probably chips or breaks, even some of the harder blades used in your typical folder would probably not hold up. A softer steel could take the beating without breaking but would require sharpening more often, though even a dull machete can still be an effective tool where as a dull pocket knife is pretty useless.

Also consider for the force involved in machete use. Now, 45 sounds pretty low to me for any blade but in the low 50's wouldn't be bad for this purpose. You wan something you can cut cardboard with for ever you probably want a harder blade, you want to clear brush, softer blades probably are more practical.
 
Hardness is just one feature of a blade, the alloy, shape, edge geometry all play a part.

In general, the larger the blade, the less expensive the alloy, and the more spring tempered. Larger blades have to endure much heavier impact forces, and the costs of attempting to get triple the blade finished in high alloy go up exponentially. A high alloy blade is defined as one that has higher abrasion resistance, and higher resistance to chipping or breaking. Those characteristics are more easily obtainable in longer blades by tempering softer on the RC scale, which brings in the benefit of being less likely to suffer a major fracture or break. It also makes them a lot more affordable. It doesn't take days to grind one to shape, temper it, test it, and then see it fall apart into three knife blank sized pieces that could have been finished already. Much less grind out an inclusion that depreciates the value by 50%. No profit in that.

RC is important - getting the correct level of hardness for that specific tool isn't something where "more is better." It would only make things worse, and that's why longer blades have lower alloy and RC.
 
tirod3 said:
Hardness is just one feature of a blade, the alloy, shape, edge geometry all play a part.

In general, the larger the blade, the less expensive the alloy, and the more spring tempered. Larger blades have to endure much heavier impact forces, and the costs of attempting to get triple the blade finished in high alloy go up exponentially. A high alloy blade is defined as one that has higher abrasion resistance, and higher resistance to chipping or breaking. Those characteristics are more easily obtainable in longer blades by tempering softer on the RC scale, which brings in the benefit of being less likely to suffer a major fracture or break. It also makes them a lot more affordable. It doesn't take days to grind one to shape, temper it, test it, and then see it fall apart into three knife blank sized pieces that could have been finished already. Much less grind out an inclusion that depreciates the value by 50%. No profit in that.

RC is important - getting the correct level of hardness for that specific tool isn't something where "more is better." It would only make things worse, and that's why longer blades have lower alloy and RC.
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Bingo. Personally I find 55 about perfect for a machete but I wouldn't want to go lower than 50.
 
Swords are of a special nature. Some have HRC as low as 40, others as high as 70+ HRC.

It all depends on the usage. You won't use a 70 hrc blade against a plated and armored opponent, you'd use a 40 HRC~ steel blade and preferably a heavy one.
 
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