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Hammer Forged Blades
- Thread starter pogo
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A question for those in the know:
Is "edge packing" comparable to strain hardening?
Is "edge packing" comparable to strain hardening?
"edge packing" is a myth..plain and simple
if you mean work hardening, I think anything(if) done would be negated by the heat treat process
some one help me here....but what happens if you actually "pack" or compress the atoms to make a material more dence?
if you mean work hardening, I think anything(if) done would be negated by the heat treat process
some one help me here....but what happens if you actually "pack" or compress the atoms to make a material more dence?
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I agree that modern metallurgy has made the forging of steel for a knife less crucial. However I think that differentially hardened, grain controlled hand forged steel is probably tougher in many respects than say your typical wonder stainless ground to shape and heat treated with paste in an oven to an overal general hardness. Both types of knives could serve different purposes though so its hardly and apples to apples comparison.
jdm61
itinerant metal pounder
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Most of us metal pounders forge because it is fun and it is the only way that you can make damascus unless you have mega-million dollar/euro metal sintering gear like Damasteel uses. The side benefit is slightly lower material costs and the fact that you are lest restricted in what size stock you start out with. A typical 2 inch wide dropped handle chopper made from M4 or S30V is going to require a piece of barstock that is over 2 inches wide to start with and will cost what? at least $50? I can do it with a 1 1/2-1 3/4 wide bar that cost me $3-4 and there is no way that I am going to use $45 worth of propane forging the blade. Where forgers "lose" money is in the time it takes to do the extra steps like forging, normalizing, annealing, etc.
While generally I'd agree with the differentially hardened etc. being tougher than the typical wonder stainless, the differentially hardened and grain controlled properties are certainly not limited to forging.
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Thanks for the link, that does explain a lot, essentially before the advent of the modern steel and heat treat process, forging and packing had a positive effect on the edge.
Where as with the wonder steels of today there is no advantage/further improvement achieved by packing the edge you may even weaken it, correct?
hmm....maybe you better look into stainless and it's heat treating a little more before you make a statement on it
remember were discussing forging and stock removal--not stainless vs. non
2 knives from the same steel, 1 forged 1 stock removal, heat treated the same will perform the same
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not exactly...
"Before the industrial revolution gave us methods to mass produce molten steel at our bidding, there was the age old process of bloomery steel. A bloom of metal reduced from iron ore never actually reaches a completely liquid state but instead relies upon the chemistry of reduction to create a spongy mass of metal particles that is virtually useless until the smith hammers it solid and forges useable tools from it. For centuries forging wasn’t just a way to make better steel, it was the only way to make steel at all."
forging refined the bloom into a solid, non pourous piece of steel- not just the edge
Where as with the wonder steels of today there is no advantage
not just the "uber stainless" but even non stainless
"all traditionally poured steels undergo heavy rolling and other mill operations very soon after their creation. It is funny that if one looks at it like this, even stock removers use forged steel. Compared to these massive reduction operations, our meager hammering is little more than mostly repeated heat treating and, if one approaches it from the standpoint that if we use the recommended forging temperatures, then it truly does all come down to the heat treat."
I don't know about forged cranks, but shot peening rods is definitely nice for fatigue resistance:
http://www.sae.org/technical/papers/950384
The way I've heard it explained eons ago is that the main beneficial mechanism of peening is to reduce surface imperfections (which act as stress risers) by collapsing/compressing them.
The synopsis of the paper above, on the other hand, talks about generating residual stress near the surface, which I take it will decrease the effective amplitude of a given cyclical load and increase lifetime thereby.
Not that any of that applies to knives..
http://www.sae.org/technical/papers/950384
The way I've heard it explained eons ago is that the main beneficial mechanism of peening is to reduce surface imperfections (which act as stress risers) by collapsing/compressing them.
The synopsis of the paper above, on the other hand, talks about generating residual stress near the surface, which I take it will decrease the effective amplitude of a given cyclical load and increase lifetime thereby.
Not that any of that applies to knives..
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It doesn't seem to work out that way. The big blades by Ontario, RAT, TOPS are much more expensive than my bolos or khukuris. And Bussekin are MUCH more expensive than any village forged blade I have. The first three aren't even zone hardened and none of them are as thick as my khuks. Could a Busse be made for less in India? If you were to bring a village kami over here would he charge $500 for a half inch thick, hand forged, zoned hardened blade? You show me a 12" bladed, stock removal, 5160, 3/8" thick chopper for $30 (what my bolos cost me) and I'll buy it. Proof is in the pudding.
Frank
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Okay... so the heat treating would simply expand molecules previously compressed by work hardening then?
I expect the advantage of post-heat treat, cold work hardening is limited to only certain applications... like scythe blades, rather than knives?
Sounds like a challenge to me. Got any pics? Modern methods are not limited to stock removal, though that certainly seems to be the preferred way. Set up some dies and power forge them in 3-4 strokes and make a couple of hundred a day and they could probably compete. I'd say Ontario, RAT and TOPS target a different customer base and feel they can charge more, sometimes argueably for less. There is no doubt Busse targets a certain customer base and they charge as high a price as they can get, just like the other companies. The only khukris I'm familiar with are from Himalayan Imports, and are typically more than the Ontario pieces, though certainly not as much as the TOPS knives.
I think I can help on the edge packing issue. a solids density is not based so much on the number of atoms per unit volume, as it is on the number of protons/neutrons in the nucleus. most atoms I think have electron clouds of realitlvly similar size, and even these are very far apart on the atomic scale.
lets take iron (Fe) and tungsten (W) density of tungsten is about 19.3, steel is about 7.8 (average -ish) so 19.3/7.8=2.5 therefore tungsten is about 2.5 times more dense. :thumbup:
the atomic mass of W is 183 Fe is 56 so 183/56=3.26 which means a W atom is 3.26 times as massive as an Fe atom :thumbup:
now obviously this does not explain all of it, the types of molecular bonds further complicate things etc. however for the most part the density can be explained by the atomic mass of the element, which leaves little to be influenced by mechanical means.
one can change the density of stuff by cooling, or heating it but this is not what you meant
edge packing IS A MYTH.
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I feel it more as an aesthetic and ode to good crafstmanship. A stock forger makes custom knives. Everyone is always a little bit different then the other. They can't be stacked to spec one on top of another. No performance advantage there, but uniqueness is always an attribute of a foraged blade. Second are little touches that forgers do, like draw out and taper the tang to save weight. Stock removers usually use lightening holes, but grinding off material to taper the tang is a lot of work so it is rarely seen.
A craftsman who is good at his craft is always something I'm willing to support if I have the means to do so. I like American companies and supporting to, but I prefer to support a craftsman first and foremost. Its part of my sense of ethic. I also like the look of hammer marks when blended into the finish. Also, guys who are good a putting a super sharp edge using stones. I have a tonne of respect for them.
These are all aesthetic things....but then again I buy a lot of my knives based on aesthetic choices. Otherwise, I'd probably have never gotten over the my mora and buck phase.
A craftsman who is good at his craft is always something I'm willing to support if I have the means to do so. I like American companies and supporting to, but I prefer to support a craftsman first and foremost. Its part of my sense of ethic. I also like the look of hammer marks when blended into the finish. Also, guys who are good a putting a super sharp edge using stones. I have a tonne of respect for them.
These are all aesthetic things....but then again I buy a lot of my knives based on aesthetic choices. Otherwise, I'd probably have never gotten over the my mora and buck phase.