Don't Be a Sucker for getting hung up about blade steels!
You know THE most important thing about about knife steel is that it will do the job for you. Currently there is a paradox of choice when it comes to which blade steel. Raw material manufacturers will have you believing whatever but in most cases the top customers ("Bread and Butter" customers) for these manufacturers are NOT knife manufacturers but people in the business of Tooling and other industries. Now read those above lines again before getting on your high horse, I said "top customers" I didn't say "Only customers".
Next you have knife manufacturers all vying for pole position of their products. Re invention of all the classic blade designs: Drop points; spear points, Western Tantos'; Bowies' etc etc have been done to death. Why we re market old products under "new" fancy names like G10! Simply because it has a funky kind of scientific high tech sound to it. No one mentions this stuff has been around for donkeys years! Handles, well we see countless designs and materials being used; from synthetic to natural. I mean how many times can we reinvent the bicycle?
What has been lacking is a thorough pursuit of ergonomics in handle design, with only few manufacturers emphasising this all forgotten over blade design aspects.
THERE IS NO SUPER STEEL!
No, sorry to disappoint you there isn't. If there was there would be a clear market leader in the supply of raw materials and there isn't as yet. The reason is simple. It depends on the environment the knife is getting used in, will dictate what is the "best" alloy of choice for production and intended purpose.
I'm not sure how old you are, but I can remember very plainly when 440C was the "super steel" for knives, so much so that countless "el cheapo" knives were being labeled as such and certainly weren't made with 440C. Then came ATS34, BTW these two alloys contrary to ALL marketing hype, are still very good knife steels. Their "goodness" didn't change. The fact is, industry marketing fuelled by ill informed social media pundits, introduced new terms to trick the unwary like:
"Chipping"
"Folding"
"Rolling edges"
I'll put these terms into perspective now.
All knife edges will either "chip" or "roll" if they undergo enough force against a harder object or an immovable object.
Anyone who tries to tell you otherwise failed physics or simply didn't do it (ok I'll excuse you if you didn't do it but not excuse you for blindly believing the market hype).
P=F/A That's pressure equals Force divided by Area.
Since the area of the actual knife edge is very very small, any significant force will produce a huge pressure on the blade edge.
Correct heat treatment regimes are paramount to achieve the same specifications that raw material manufacturers state.
Correct heat treatment costs serious money on an industrial scale. It is a science and an art but firstly a science. Just look at the making of a Katana. I've watched them being made in front of me whilst living in Japan. Nothing is done by chance or "bucket chemistry".
Certain knife alloys are marketed towards gullible (no offence intended but most manufacturers of raw stock will list all of their Technical PDF's in the public domain- much can be learnt from them even if you aren't a metallurgist or the like) end users by referring to qualities that will only ever be apparent if used to make milling tools, not knives. Milling tools are subject to repeated and repeatable forces. Knives are not. Knives are controlled by our hands and everyone's hands are different and everyone will apply forces/use the same knife in a different manner in any test (biological/mechanical variation). This is a non repeatable process. There will be much variation involved here. It is for this latter point that attempting to judge how good a steel choice is for knives based solely on non scientific tests is pretty meaningless as it simply boils done to someones' opinion. That's OK but it is exactly that opinion UNLESS.......Even when the someone ( the same someone) does many tests. UNLESS that someone uses the correct statistics to analyse their results. Otherwise it's just an opinion. (I'm wearing my scientist hat now- sorry).
Once the raw product leaves the factory, no guarantees are given about the resulting knife steel as this is beyond their control. I've had problems with "high end" steel alloys and the manufacturer simply said it's the issue of the knife manufacturer- AND they were right.
The importance of Surface treatment of Stainless Alloys.
A/ Mirror Polished
B/ Polished
C/ Milled smooth (but milling marks present to naked eye)
D/ bead blasted/shot blasted/stone washed
E/ PVD (Physical Vapour Deposition- sometimes called Sputtering)-(including amorphous diamond- like carbon (DLC), nitriding, TiN etc etc.
F/ Teflon over milled
G/ Mil Spec blacking/chemical blacking/bluing/ etc.
For any given stainless alloy to have maximum resistance to corrosion then the type of surface finish is important.
According to my correspondence with technical staff of a large European steel producer, other than soluble Chromium, i.e. Cr not bound up as carbides, the final surface finish is critical to achieve the optimum resistance to corrosive forces all things being equal.
Point "A" is best
PVD will confer better resistance to corrosion over a basic milled surface alone.
Teflon is ok but is will wear out. It is cheaper to apply than a PVD process.
Stone washed is not going to be as effective as a super smooth surface at resisting corrosion for identical alloys.
"D" will not confer any added corrosion resistance to the alloy.
The carbon content
Guess what, it's not necessary to have any carbon these days in knife steel alloys LOL. There are other very hard components such as nitrides. Ok these alloys are not mainstream as yet.
Certain alloy's properties are more important to the knife manufacturer than the end user.
More to come!
There is a lot of great information here. But what about the comparison tests between different steels. You can't deny the results of certain steels being able to retain an edge better, their abilty to take a fine edge, some are more likely to chip rather than roll and this all depends on yes the heat treatment but also the metallurgy which makes it "tough" or "hard".
ReplyDeleteHi, yes a comparison is required. The trouble is I could do it in a laboratory setting but to really make it valid then U would need to test say all types of different blade geometries made by the same manufacturer against known objects. For example, if I were to test this out, I'd use same milling tool but in as many different steels as possible, set speeds/rpms the same and test against as many different objects as possible. Ok so this is how basically the steel manufacturers are doing this but it is not relevant to the world of the outdoor person/s. Alternatively, I could set up a given knife and test (repeatedly) it's cutting capacity until blunt on as many different objects as possible and also chopping tests. I would do this by mounting the knife in a mechanically actuated "arm" (remove human variation) so I could have repeatability for speed, pressure and impact forces. The "n number" would be my large sample size of say manilla rope all from the same manufacturer (there would be variation of course); kiln dried timber (all same species and same age) for chopping tests etc etc. The knives to test could or rather should only be from one manufacturer or alternatively a "test knife" (exact geometrical specifications) for each blade but of different alloys, all made by the same person (to reduce variability). There are machines for doing exactly this and or similar. The main reason why I think we don't see this being done is that there is simply not enough requirement from people for such data Vs the cost to produce "metallurgically optimum" test blades for such a test. The reason being that many (depending on the initial statistics) test blades would need to be made in order to understand the variability of the manufacturing process.
ReplyDeleteIf we were to look towards a manufacturer to perform such a test, unfortunately, there is currently no one manufacturer who produces a large gamut of knife alloys that would encompass from PM to Carbon steel, well ok some come close. I guess too that the main sales of knife steels are for industry where there is repeatability (well much less variation anyway) than say how one chops into or cuts up some meat or branches in the field.
So to answer your question, yes indeed some manufacturers have performs some of these tests and we would most likely come across this data from the kitchen implements and or machining cutting tools.
Finally, this might, and maybe already has been done for say a mechanical engineering honors student or MSc student, to conduct such tests (I'm sure they could get industry sponsorship LOL- for equipment costs. I don't think it is a PhD project (even if all the micro-structural analysis was done- it's not enough in my book.
But for me I'm out of the uni setting for now and cost simply doesn't warrant such a test/comparison. So yeah that's my "scientific" take on this. I've thought many times about such tests, just a brain exercise LOL.
Thanks for reading my work anyway, really appreciated!