mono v clad; ground v forged

[Larrin]

I've done a bit of reading about elastic modulus recently (thanks to Larrin), and it also still blows my mind that it's not effected by HT. However, different steels do have different elastic properties... So it doesnt shock me that a blade made of a composite of steels "A" and "B" would have different harmonics and transmit vibration differently than one made of just steel "A".

However, it also seems obvious that factors like thickness, grind, balance point, handle construction and material would all be significant attributing factors to what often gets attributed just to blade construction. Until
Someone makes some knifes that are identical in every way but blade construction, this is going to be just another matter of personal opinion and taste. -but I guess that's really all that matter in the end.

Differences of elastic modulus between different steels is pretty small, I don't think it would be perceptible. That's what I would like to know: if there is a real difference, and if there is a real difference is it because of poor lamination.

Edit: When I say a real difference I don't mean between young's modulus of the different steels I mean between clad and not. This whole idea of the "condom" thing came from one or two people and spread like wildfire and I'm still skeptical about the whole thing.

 

[WillC]

Have you got a link to your bit about elastic modulus differences please Larrin?

 

[Larrin]

Have you got a link to your bit about elastic modulus differences please Larrin?

http://www.engineeringtoolbox.com/young-modulus-d_773.html

 

[StephanFowler]

one thought to consider is that the slightest flaw in the weld with San-Mai will act as a harmonic dampener.

a good way to check a bar of damascus for solid welds is to hold it lightly 1/3 from the end and lightly "ring" the end of the bar with a hammer. It should produce a clear bell like tone with no rattle and a good bit of sustain.

if it's a dull thunk or the ring pans out quickly then there is a bad weld in the bar somewhere.

the same concept would apply to San-Mai construction

 

[mpukas]

...I don't think it would be perceptible...

Not debating/doubting your theory on modulus, but have you compared cutting with a laser and a clad gyuto side by side? I have, as have others. I certainly notice a big difference in tactile feel and prefer the feel of a mono laser for most tasks.

I don't know that much about steel and knife construction, but in the vids I've watched of san-mai blade construction, it's very different than damascus forging. From what I've seen (by Carter and Moritaka) a soft piece of metal is heated, shaped a bit into a block; and then a harder piece of edge steel is basically hammered into to the red-hot cladding block. From there it's pounded into shape. I can see how this technique will result in a less feedback due to the amount of (presumably) softer, cheaper steel, Saying that, I think the quality of the cladding will have an impact on tactile feel.

Two other points to address;

reactivity - this is dependent on the cladding metal; I've found the cladding can be more reactive than the edge unless it's some SS variation.
durability - cladding, to me, does nothing to protect the edge; it can protect the entire blade from breaking due to being dropped, but it won't protect the edge from chipping.

I've seen Carter say he likes clad clad blades because they are stronger (meaning the softer cladding will protect the core steel from shattering) and easier to sharpen over time due to the cladding being easier to thin as the edge gets worn down.

 

[Cadillac J]

Why?

Because the feel issue isn't as apparent with single bevels so I've heard(I don't use them), and to get a monosteel single bevel knife you are usually, if not always, talking a relatively expensive honyaki.

I can for sure feel a difference between all the cladded/non blades I've owned when making cuts, and I just prefer non-cladded overall. In no way am I saying that cladded blades are inferior...just not my cup of tea if I have the choice.

 

[mpukas]

[video=youtube;UapXrxQxevY]http://www.youtube.com/watch?v=UapXrxQxevY&feature=related[/video]

I'm not seeing any welds, or am I missing something? What is the powder put in the groove before the AS bar is placed in it?

 

[WillC]

Borax, to act as flux, in this case as he has not cleaned the scale out from the slotted cladding it will help dissolve the scale too. I'm surprised he put two core pieces in. I suspect he was just forging the first piece down further into the cladding rather than welding, refluxed added the second, the next heat would have been the weld heat. Hard to guage heats from a video.

 

[mpukas]

I'm surprised he put two core pieces in.

Are you sure you watched that correctly? He's doing more than 1 blank; 1 core peice per blank.

Thanks for the info on the flux - that's what I suspected.

 

[WillC]

Ha ha, yes your quite right, its getting late here. borax allows you to make the weld at a lower heat as well. But yeah, he hadn't made the welds yet then by the look of it, just seating the core.

 

[Larrin]

Not debating/doubting your theory on modulus, but have you compared cutting with a laser and a clad gyuto side by side? I have, as have others. I certainly notice a big difference in tactile feel and prefer the feel of a mono laser for most tasks.

I don't know that much about steel and knife construction, but in the vids I've watched of san-mai blade construction, it's very different than damascus forging. From what I've seen (by Carter and Moritaka) a soft piece of metal is heated, shaped a bit into a block; and then a harder piece of edge steel is basically hammered into to the red-hot cladding block. From there it's pounded into shape. I can see how this technique will result in a less feedback due to the amount of (presumably) softer, cheaper steel, Saying that, I think the quality of the cladding will have an impact on tactile feel.

Two other points to address;

reactivity - this is dependent on the cladding metal; I've found the cladding can be more reactive than the edge unless it's some SS variation.
durability - cladding, to me, does nothing to protect the edge; it can protect the entire blade from breaking due to being dropped, but it won't protect the edge from chipping.

I've seen Carter say he likes clad clad blades because they are stronger (meaning the softer cladding will protect the core steel from shattering) and easier to sharpen over time due to the cladding being easier to thin as the edge gets worn down.

I can't tell the difference between clad and not.

I'm aware of the forging methods of making clad knives. I addressed the differences in hardness earlier in the thread.

Reactivity, durability, and ease of sharpening are of course reasons to use san-mai, but I assume you're not bringing them up in regards to damping.

 

[Larrin]

one thought to consider is that the slightest flaw in the weld with San-Mai will act as a harmonic dampener.

a good way to check a bar of damascus for solid welds is to hold it lightly 1/3 from the end and lightly "ring" the end of the bar with a hammer. It should produce a clear bell like tone with no rattle and a good bit of sustain.

if it's a dull thunk or the ring pans out quickly then there is a bad weld in the bar somewhere.

the same concept would apply to San-Mai construction

That's what I suggested earlier in the thread that I should have emphasized more. I'm interested in whether the blades that some have perceived differences in them have perceivable faults in the welding.

 

[slowtyper]

My head, down here. This thread, up there.

 

[MWhtrader]

I have read some literature on the perception of feel, and its mostly comprised of sound and touch. In the golfing world, forged clubs from 1018 steel are regarded to have the best feel, while stainless steels or multimaterial construction are usually described as feeling harsh or disconnected. Also, Mizuno golf uses harmonics (sound) to fine tune the feel of the clubs, where its usually accepted that sound in golf matters more to feel than forge or cast.

Good thing here is that the knife is a simple geometry, which is a quasi cantilever beam, so I am going to approximate with the simple equations. we would be talking about resonance, which is most affected by length and spring constant(or elasticity modulus ). While I might be stretching a bit, but usually the cladding is shorter than the core, so that would recreate a difference in resonance, difference tend to decrease the overall quality of sound created.

in the vibrations and dampening side, austenitic, ferritic, and martensitic steels all have different dampening coefficients. The differences in dampening coefficients will all affect vibration transmission and propagation. Not to mention the boundaries between the cladding and core steel will act as natural dampening. stainless steels will exhibit better damping due to magneto-mechanical effects according to Lazan,B.J. & Goodman,L.E., "Effect of Material and Slip Damping on Resonance Behavior", 1956, ASME, Shock and Vibration Instrumentation, pp.55-74.

unfortunately, dampening is one of those black holes in engineering and its really tough to find reliable data, so take what i just said with a few lbs of salt, i may or may not be right.

in short, I am fairly certain that mono steel knifes will "feel" better than clad, but its more about the ability of the user to discern the differences in feel.

 

[JohnnyChance]

Not debating/doubting your theory on modulus, but have you compared cutting with a laser and a clad gyuto side by side? I have, as have others. I certainly notice a big difference in tactile feel and prefer the feel of a mono laser for most tasks.

Why does laser keep being using a synonym for mono steel blade in this thread? I have and used fat mono steel blades; and have and used very thin clad blades.

Maybe you just prefer the cutting feel of a thin knife? There are plenty of thin clad knives out there; Carter, Devin, Shigefusa (some), Kochi, etc. I'll take any of those over a wippy little mono blade from Sakai city.

 

[Sarge]

A question for those who do feel a difference and those who don't. What type of cuts do you make the most? Do you pre-dominately push cut? Or do you mostly rock chop? Or some other type. I exclusively push cut, with either a forward or slightly backward motion depending on the food, (I haven't rock chopped in years).

The point I'm getting at is push cutting the difference in feel and feedback is very obvious (at least to me) now having stopped rock chopping before I picked up a cladded knife. I haven't tested this to see if it makes a difference in feeling, and I don't care enough to conduct one. Any-dang-way perhaps the difference in technique is the reason some feel and notice the difference where others do not?

I'm guessing that for rock chopping the difference is less obvious but I could be very wrong

 

[tk59]

Tell you what. I have a bunch gyutos, several of which are stainless clad, some lasers in each category. I'll see if I can find a couple of pros that are willing to dice an onion with each, blindfolded and see if they can guess which are cladded. My money is on no one discerning a difference. I find the most important factors in feel is the weight of the knife and the sharpening job.

 

[WillC]

That brings the term "harmonics" nicely into my sphere of understanding. Hit it with a hammer , excellent tip, people have told me dodgy anvils don't ring, makes sense with the older ones where the face is welded onto a wrought body.

one thought to consider is that the slightest flaw in the weld with San-Mai will act as a harmonic dampener.

a good way to check a bar of damascus for solid welds is to hold it lightly 1/3 from the end and lightly "ring" the end of the bar with a hammer. It should produce a clear bell like tone with no rattle and a good bit of sustain.

if it's a dull thunk or the ring pans out quickly then there is a bad weld in the bar somewhere.

the same concept would apply to San-Mai construction

 

[JohnnyChance]

Tell you what. I have a bunch gyutos, several of which are stainless clad, some lasers in each category. I'll see if I can find a couple of pros that are willing to dice an onion with each, blindfolded and see if they can guess which is cladded. My money is on no one discerning a difference. I find the most important factors in feel is the weight of the knife and the sharpening job.

Good idea. There are too many variables in addition to blade construction. Most san mai blades use a core that is not offered in monosteel blades. And if they are, they are from different manufacturers. Different handle construction, different methods of attaching handles, materials in the handle and blade, grind/geometry/thickness would all affect feedback (and maybe more so) than mono v. clad.

 

[mpukas]

Why does laser keep being using a synonym for mono steel blade in this thread? I have and used fat mono steel blades; and have and used very thin clad blades.

Maybe you just prefer the cutting feel of a thin knife? There are plenty of thin clad knives out there; Carter, Devin, Shigefusa (some), Kochi, etc. I'll take any of those over a wippy little mono blade from Sakai city.

You're right - I wasn't intended to use laser as synonomous for mono. I do prefer the feel of cutting w/ a thin knife. I'd really like to try a thin clad knife, because I also like the sturdiness and heft of a clad blade. Trying to find the sweet spot.

 

[Lucretia]

For simplicity's sake, let's treat the blade as a cantilever beam, and assume cladding is perfectly welded.

The natural (resonant) frequency of a cantilever beam is going to be affected by the steel used (modulus of elasticity and density) and the geometry of the blade (thickness, height, length). The natural frequency will be proportional to:

the square root of
(
( (Modulus of Elasticity) x (Thickness of blade) x (Height of blade CUBED) )

divided by

( (Mass) x (Length of blade CUBED) )
)


The modulus of elasticity doesn't vary that much between steels, regardless of heat treat. Say in the range of 10%, which only will affect the natural frequency by about 5%. Mass also doesn't vary much with different steels, and is also a linear component of the equation.

Changes in height and length have more drastic effects because they are multiplied on top of themselves. Change the height or length of the blade by 10%, and your natural frequency is going to change on the order of 13-15%.

Since blades are thin relative to their height and length, a "small" change can actually be a fairly large change on a percentage basis. Go from a 1 mm blade to a 2 mm blade, and you've increased your resonant frequency by around 40%.

While there may be some damping due to material differences, geometry has a more significant effect on the dynamic response of the blade. Unless you're comparing blades that are exactly the same, you're looking at apples and oranges.

That said, if you don't have good physical connection between your layers, you've built a low-pass filter. If I remember correctly, a good bolted connection is only good for transmitting frequencies up to about 400 Hz--well within the audible range, as well as something that can be felt. Welds with voids will filter out higher frequencies in a similar manner to bolted connections--not at the same frequency, but they'll behave similarly--making something sound dead when you hit it with a hammer.

 

[Eamon Burke]

Wow! I missed a good thread.

I have read some literature on the perception of feel, and its mostly comprised of sound and touch. In the golfing world, forged clubs from 1018 steel are regarded to have the best feel, while stainless steels or multimaterial construction are usually described as feeling harsh or disconnected. Also, Mizuno golf uses harmonics (sound) to fine tune the feel of the clubs, where its usually accepted that sound in golf matters more to feel than forge or cast.

Good thing here is that the knife is a simple geometry, which is a quasi cantilever beam, so I am going to approximate with the simple equations. we would be talking about resonance, which is most affected by length and spring constant(or elasticity modulus ). While I might be stretching a bit, but usually the cladding is shorter than the core, so that would recreate a difference in resonance, difference tend to decrease the overall quality of sound created.

in the vibrations and dampening side, austenitic, ferritic, and martensitic steels all have different dampening coefficients. The differences in dampening coefficients will all affect vibration transmission and propagation. Not to mention the boundaries between the cladding and core steel will act as natural dampening. stainless steels will exhibit better damping due to magneto-mechanical effects according to Lazan,B.J. & Goodman,L.E., "Effect of Material and Slip Damping on Resonance Behavior", 1956, ASME, Shock and Vibration Instrumentation, pp.55-74.

unfortunately, dampening is one of those black holes in engineering and its really tough to find reliable data, so take what i just said with a few lbs of salt, i may or may not be right.

in short, I am fairly certain that mono steel knifes will "feel" better than clad, but its more about the ability of the user to discern the differences in feel.

I agree with this, except that your conclusion seems to assert that the feel is better if you are more sensitive to feel, rather than what the information asserts, which is that "feel" is more likely a perceptual satisfaction created by noise. I can get in on this. I think a lot of "feel" on stones is sonic, for the same reasons.


Larrin, your chart shows the difference in elastic modulus for 3 kinds of steel, and it would seem that if the difference between Carbon Steel and Nickel Steel is greater than the difference between Carbon Steel and Cro-Mo steels(which would be stainless cladding, since 13% Cr defines stainless). So it would follow that if the difference in elastic modulus was causing this polarizing "deadness" in feel, then all of the Damascus blades should be even MORE dead feeling, than clad since the difference in modulus is greater.

It would seem that if the information you related is reliable(which I assume it is, since YOU presented it), then the "elastic modulus theory" appears dead, leaving only faulty lamination or observer bias; I feel it is the latter. If pleasant tonality and steel quality were related, we'd be making knives out of tuning forks instead of bastard files.

IME, "feel" has a lot more to do with weight and cutting efficiency. My Yanagiba(AS) will slice through salmon pinbones without me noticing they are there.

 

[DevinT]

The reason that cladded blades feel different is because there is size change after heat treatment in steels causing tension between layers. Steels with the greater amount of carbon in them will grow to a greater amount than steels with less carbon. This is why the Japanese cold forge their blades, to relieve the tension between layers.

Some steels grow quite a lot after hardening, and tempering releives some of this size change but not all. There is always some tension between layers forge welded together. Cladded blades will be stiffer than mono steel blades because of the tension.

Hoss

 

[JohnnyChance]

The reason that cladded blades feel different is because there is size change after heat treatment in steels causing tension between layers. Steels with the greater amount of carbon in them will grow to a greater amount than steels with less carbon. This is why the Japanese cold forge their blades, to relieve the tension between layers.

Some steels grow quite a lot after hardening, and tempering releives some of this size change but not all. There is always some tension between layers forge welded together. Cladded blades will be stiffer than mono steel blades because of the tension.

Hoss

You should have come along earlier and saved us 6 pages!

Thanks Devin.

 

[Delbert Ealy]

The reason that cladded blades feel different is because there is size change after heat treatment in steels causing tension between layers. Steels with the greater amount of carbon in them will grow to a greater amount than steels with less carbon. This is why the Japanese cold forge their blades, to relieve the tension between layers.

Some steels grow quite a lot after hardening, and tempering releives some of this size change but not all. There is always some tension between layers forge welded together. Cladded blades will be stiffer than mono steel blades because of the tension.

Hoss

Devin,
With the cladding that is normally used(a 300 series stainless) the cladding acts more like a non-ferrous metal than steel and the rules for hardening those are very different than for steel. The "cold forging" will harden the cladding(adding stress) rather than relieving it.
Del

 

[DevinT]

Del,

Most are using 403, 410, 416 etc. The Japanese cold forge before heat treating and any stress is relieved during HT. It does cause some hardening but it also causes the cladding to grow and during HT the core catches up with the growth of the cladding.

The Japanese claim that the cold forging is for grain refinement, which it does.

Hoss

 

[Eamon Burke]

Dang it, hoss, do you have to know everything? We were having a perfectly valid bullshyte session.

 

[Delbert Ealy]

Devin,
With the way you worded it "after heat treatment in steels causing tension between layers.............cold forge their blades, to relieve the tension between layers." it sounded to me like you meant they cold forge after heat treatment.
Are you sure they are using 400 series, because if they are then there should be some activity like Bill Burke gets on his blades. The Cramer I had on loan for a bit was clad with a 300 series and that is what I based my above statement on. Them using 300 series stainless would also explain some people feeling a difference in the clad blades over monosteel blades.
Thanks,
Del

 

[DevinT]

Del,

Size change happens because of HT. Most steels expand when hardened and shrink a little when tempered but still have a net gain. All damascus (pattern welded) and clad materials have some tension after HT. That is the point here.

The Japanese use low carbon 400 series martensitic steel for cladding.

Hoss

 

[Delbert Ealy]

Just checking out carters site and that was 410 clad, so I guess I was wrong about that, I am surprised that there is no activity in his blades, maybe they use a thin nickel layer to avoid it.
Devin, I know about the size changes during heat treat, I have seen clad blades blown apart because of the streeses of heat treat, with the primary steels I choose to work with, and the style of knives I make, it just isn't much of an issue. O-1 is one of the most stable as far as size goes of all the tools steels.
Del