BCMW's ht chopping impact tests

Hardened the last W2 blade in this experimental batch - got as quenched hardness around 67-67.5rc. Cleaned up and found free of any sort of cracks. I will use Honduran Rosewood for temp 7" long handle. Stronger and shorter handle would minimize tang torquing. I probably, will soften the tang using a torch, so I can perform chopping tests using the handle.

Untempered edge geometry for testing will be about the same - 0.02" BET, 15dps.
 
Luong, loving the mods to the Jest design from the original.

Microchipping of the 67 RC W2 looking like not bad for the factors involved.
 
Thanks, Martin. The handle feels nice in hand.

I agree, those chips are quite small in a light chop tests. After look through the video a few times, I wonder if the polluted chopping stump plays any roles with those chips. I found that stump while ago on the beach and have been used to chop cinder-block and other harsh stuff. I will try to factor out (eliminate) the chopping surface out in the future tests. Unless I chop at harsh or harsher stuff :)
HeavyHanded said:
Luong, loving the mods to the Jest design from the original.

Microchipping of the 67 RC W2 looking like not bad for the factors involved.
Click to expand...
 
Why test an untempered blade? You can temper the blade without losing much, if any hardness. But the stress relief seems critically important.

What does testing a knife that has only been partially heat treated tell you?
 
Excellent question :thumbup:

Weakness/stresses/high-strained-dislocation/etc in the matrix will be present in the matrix at as-quenched/untempered; tempered; spring-tempered; sub-critical annealed with degrees/amplitude of stress go from high to low respectively. Tempering is a process of relief/relax/precipitate/diffusive/etc - essential obscuring/alleviating/etc the matrix inherent attributes.

I knew this early on but was prudent enough to avoided test untempered matrix because that would be the same as throw test blades away - for certain, that would be the case if I try early on.

If we treat tempering as a bandage, fair to ask - what is THE perfect size?

RX-79G said:
Why test an untempered blade? You can temper the blade without losing much, if any hardness. But the stress relief seems critically important.

What does testing a knife that has only been partially heat treated tell you?
Click to expand...
 
bluntcut said:
Excellent question :thumbup:

Weakness/stresses/high-strained-dislocation/etc in the matrix will be present in the matrix at as-quenched/untempered; tempered; spring-tempered; sub-critical annealed with degrees/amplitude of stress go from high to low respectively. Tempering is a process of relief/relax/precipitate/diffusive/etc - essential obscuring/alleviating/etc the matrix inherent attributes.

I knew this early on but was prudent enough to avoided test untempered matrix because that would be the same as throw test blades away - for certain, that would be the case if I try early on.

If we treat tempering as a bandage, fair to ask - what is THE perfect size?
Click to expand...

So in other words you wanted any imperfections inherent in the blade to be unable to hide behind the temper?
 
bluntcut said:
Excellent question :thumbup:

Weakness/stresses/high-strained-dislocation/etc in the matrix will be present in the matrix at as-quenched/untempered; tempered; spring-tempered; sub-critical annealed with degrees/amplitude of stress go from high to low respectively. Tempering is a process of relief/relax/precipitate/diffusive/etc - essential obscuring/alleviating/etc the matrix inherent attributes.

I knew this early on but was prudent enough to avoided test untempered matrix because that would be the same as throw test blades away - for certain, that would be the case if I try early on.

If we treat tempering as a bandage, fair to ask - what is THE perfect size?
Click to expand...

That's a strange perspective. Quenching is a violent disturbance in the steel structure that is induced to freeze the metal in a particular state. Tempering just fixes some of that damage.

That doesn't seem much different than testing edge stability after hot grinding the edge. You aren't testing the steel, you're testing what you've temporarily done to the steel.


The reason this doesn't make sense to me is that you may produce a blade that - as quenched - is much more fragile than a blade made of something like an air cooled steel, like A2. But after tempering your blade may actually be more ductile than the A2 is after tempering. The pre-temper comparison didn't provide any data on how the final blades would behave.
 
I think he's saying that to get the highest hardness you need to have a blade that's almost perfect right out of the quench.

And the stresses that tempering is meant to fix won't ever go away, they'll just be mitigated through stress relieving tempering cycles. If he can get a blade that passes his tests in an untempered state with only minor issues, then he can focus on what failed prior to tempering. Once those issues are fixed then tempering will only make the blade stronger without the inherent imperfections that may have been present but covered up because of the temper cycles.

Basically bringing the faults of the steel out without trying to hide them.

It's like inbreeding and line breeding dogs. You inbreed and line breed to bring the faults out so you can cull the puppies with the faults and re-breed the dogs without them. Given several generations, the faults will have all surfaced and have been culled out leaving a very homogenous line that performs how the breeder desires.

In order to do that testing to find faults rather than testing to advertise for sale is necessary. I get what he's doing.
 
:thumbup::thumbup: Spot on, thanks, bodog!
bodog said:
I think he's saying that to get the highest hardness you need to have a blade that's almost perfect right out of the quench.

And the stresses that tempering is meant to fix won't ever go away, they'll just be mitigated through stress relieving tempering cycles. If he can get a blade that passes his tests in an untempered state with only minor issues, then he can focus on what failed prior to tempering. Once those issues are fixed then tempering will only make the blade stronger without the inherent imperfections that may have been present but covered up because of the temper cycles.

Basically bringing the faults of the steel out without trying to hide them.

It's like inbreeding and line breeding dogs. You inbreed and line breed to bring the faults out so you can cull the puppies with the faults and re-breed the dogs without them. Given several generations, the faults will have all surfaced and have been culled out leaving a very homogenous line that performs how the breeder desires.

In order to do that testing to find faults rather than testing to advertise for sale is necessary. I get what he's doing.
Click to expand...

There were
3/1 59 views 67.5rc light choppings video
3/2 26 views on 68rc untempered video
3/3 20 views on untempered video (post #64)

Along with closeup images of aftermath edge.

Thanks for watching them & posted comments. My apology, all 3 BCMW videos & 2 images are no longer available.

bodog said:
Ballsy Luong, especially at 68 RC +/-. And to video it and present it to the public is even ballsier!
Click to expand...

It calls out-of-the-box thinking... if the matrix is close to perfect out of quenched, deduce as - tempering is degrading the matrix, right? Ah but that is ridiculous because there is no such untempered matrix can withstand harsh impacts - well, we could agree to disagree on this one:cool:
RX-79G said:
That's a strange perspective. Quenching is a violent disturbance in the steel structure that is induced to freeze the metal in a particular state. Tempering just fixes some of that damage.

That doesn't seem much different than testing edge stability after hot grinding the edge. You aren't testing the steel, you're testing what you've temporarily done to the steel.


The reason this doesn't make sense to me is that you may produce a blade that - as quenched - is much more fragile than a blade made of something like an air cooled steel, like A2. But after tempering your blade may actually be more ductile than the A2 is after tempering. The pre-temper comparison didn't provide any data on how the final blades would behave.
Click to expand...
 
bluntcut said:
:thumbup::thumbup: Spot on, thanks, bodog!


There were
3/1 59 views 67.5rc light choppings video
3/2 26 views on 68rc untempered video
3/3 20 views on untempered video (post #64)

Along with closeup images of aftermath edge.

Thanks for watching them & posted comments. My apology, all 3 BCMW videos & 2 images are no longer available.



It calls out-of-the-box thinking... if the matrix is close to perfect out of quenched, deduce as - tempering is degrading the matrix, right? Ah but that is ridiculous because there is no such untempered matrix can withstand harsh impacts - well, we could agree to disagree on this one:cool:
Click to expand...

If an untempered matrix can withstand impacts, that's great. The one you posted does not, and it is generally believed to that no glass-hard steel is good for impacts. I could decide that infants make the best drivers, but the testing process isn't going to be much fun because of all the car crashes.


But the specific idea that tempering "hides" imperfections is, I think, bogus. Tempering relieves the stresses that the steel will attempt to relieve on its own if you give it long enough. Immediately post quench is the most unnatural state - the recent violent crystallization of the blade steel was humongously traumatic. The flaws that are there are there for a reason, and they aren't there because there was something wrong with the steel or the process - they are part of the process. Time and temperature restore the natural balance to the steel.


Aside from that, who actually believes any glass hard piece of steel, flawed or perfect, isn't going to break when you hit it hard? Even if the OP has come up with a dramatic increase in toughness at high levels of hardness, the toughness is still going to be much, much lower than the same steel at 60 Hrc.
 
Those have seen my latest video & image before I deleted them, feel free to chime in. Did the untempered blade shatter into pieces like glass when hard chops into granite rock?

Agree to disagree about untempered matrix - shall we?

btw - 65.5rc W2 0.325" thick chopper went through many chopping tests (most woods + a few copper wire) - no problem. It seems tougher than 67+rc blades. Poor penetration due to wedging. I probably will harden the 5/32" 52100 chopper to ~65rc and test it. I will try to make & post a video of thick w2 & thin 52100 choppers in harsh chops against seasoned woods.

RX-79G said:
If an untempered matrix can withstand impacts, that's great. The one you posted does not, and it is generally believed to that no glass-hard steel is good for impacts. I could decide that infants make the best drivers, but the testing process isn't going to be much fun because of all the car crashes.


But the specific idea that tempering "hides" imperfections is, I think, bogus. Tempering relieves the stresses that the steel will attempt to relieve on its own if you give it long enough. Immediately post quench is the most unnatural state - the recent violent crystallization of the blade steel was humongously traumatic. The flaws that are there are there for a reason, and they aren't there because there was something wrong with the steel or the process - they are part of the process. Time and temperature restore the natural balance to the steel.


Aside from that, who actually believes any glass hard piece of steel, flawed or perfect, isn't going to break when you hit it hard? Even if the OP has come up with a dramatic increase in toughness at high levels of hardness, the toughness is still going to be much, much lower than the same steel at 60 Hrc.
Click to expand...
 
It didn't.
RX-79G said:
Since you have deleted the video, when did it shatter?
Click to expand...

Just something to look at.
yg32p61.jpg
 
Last edited:
Well, bodog has put a well thought off comment.

I'm guessing what Luong trying to do: if the matrix he envisions can be created and not shatter like glass, tempering it will make a super chopper that's both hard & tough. We're so used to have hard but not tough (chippy', or tough but not hard 'rollie', say at total value 100 (60+40 or 40+60)
His premise is if we can raise this point to 150, having both at higher value, we have better blade, perhaps 80+70 rather than 60+40.

In short, untempered perfection is even better after tempering process.
Unfortunately I didn't chance to see his 68HRC close up picture on bigger screen, so I can't tell much from that failure mode. Have to take his word that the quenched state has failure lines, thus it shattered.

Luong, please email me the full size stone & coin image;).
 
RX-79G said:
I see you'd prefer to drape this in mystery. Ciao.
Click to expand...

Well, you didn't chance to have watched the video ;).
I did, and it didn't break.

Imagine powder steel technology, if the 'glued' material holds up, then the sintered material / fused one will hold up even better.
(I read sintering on one of old article from www.balisongcollector.com. Webmaster was (is?) one of the moderator here.)
 
Last edited:
Not to go too far off track, but let's say a steel can get to 65 RC but its charpy numbers are in the low teens or even less. At 59 its chart numbers in the 80's. Well, people wouldn't want a big chopper made of this steel at 65 RC, they'd go for 59 or maybe even less.

Now if you had a steel that could hit 68 RC and is in the 30's or 40's, and through tempering it shoots up into the 40's and 50's (which is pretty decent for most knives, even big knives) at 66 RC (which is unheard of) I think most people can see the benefit of it.

Strength is good, toughness is good, but they rarely co-exist nicely. If someone could make that happen, that'd be a nice little hidden gem. People don't normally need knives that range up into 80 to 90 ft lbs range, but people do need knives that hold their apex. That's what the pursuit with steels has been for a long time.

First, find a steel that holds its apex the best. That would be a combination of strength and toughness. Once that's been figured out then account for wear resistance through carbide content. Once that's figured out, then move on to some, at least moderate, level of corrosion resistance. Once that's figured out where a knife at 66 or 67 RC can range into the 40 or 50 ft lb territory and have an 8 to 10% vanadium, tungsten, and/ or niobium content with an added 5% or more free chromium content, well, that'd be a helluva knife at any size.

I think that's what Luong is shooting for and his efforts are appreciated. If he's onto something legitimate, which I've seen a super thin blade from him at 64 RC do some fairly ridiculous things without failure, then it may change how people think about blade steels. The question that would remain is if it would be accepted, like building a car that runs on water where oil and car manufacturing companies would fight the new concept tooth and nail.

Again, I think Luong might be proven right, and him sharing his successes and failures along the way with interested parties couldn't be more appreciated.

Of course, there will be detractors along the way who say this or that isn't possible, it's snake oil and quackery, but those people aren't out there pushing into territory not explored and don't want what they believe to be interrupted. That's how it always is in any field.

There are many genius inventions and methods that have been lost in time because of these very human jealousies and bickering. But occasionally someone comes along and changes things for the better in a field they're passionate about. Time will tell if Luong is one of those people or not

Until then, he's devoting a lot of his own time and money into this pursuit. I don't have the knowledge, funding, or desire to pursue the same thing, but I am interested in his results. So I applaud him as others should, too, even if they don't believe it.

He's not asking for anyone to contribute to his endeavors. He's not asking anyone to believe him based on his word alone. When he feels like he did something well he sends a test piece or pieces out for others to try. When he feels like he's reached his goal I'm sure he'll send it out for a full scientifically rigorous test. And if that day comes I hope he gets credit.
 
Last edited:
You must log in or register to reply here.
Back
Top