Aged steel cuts better??? You are kidding, right?

[Gadgetaholic]

Testing Reveals the Older Some Knives Are, the Better They Cut.

I can believe that.

The assertion by the writer is that some knives that he tested 1-4 years earlier were now cutting 3 to 10 times better....because they have "aged".

Wait, what? 3 to 10 times better? I thought we would be talking 1 to 10 percent better! How bad could a new knife be that it could be cutting 10 times better a few years later? Upon reading this my bullshit meter went off!

I have bought a new knife and after sharpening it I found that it cut 10x better - if we are talking blunt vs sharp then I could see something in it. But just from ageing the steel? I seriously doubt it!

 

[Rick]

Complete bunk. It's embarrasing that a national magazine would print that. Nobody can remember how a knife cut years ago well enough to make a comparison. That is even if the edge were in exactlyl the same condition - never sharpened and never used. It reminds me of the audiophiles who believe they can hear connecting cables. This is a good example of what is known as the "placebo effect."

I suppose it is all done in the name of entertainment.

Not to get too far afield, but sonic differences in audio cable are often clearly audible (and measurable) in high resolution audio systems. Resistance, capacitance, inductance, conductance, velocity of propagation, RFI and EMI radiation and absorption, mechanical resonance, strand interaction, high filtering, reflections, electrical resonance, dissipation factors, envelope delay, phase distortion, harmonic distortion, structural return loss, corrosion, cross-talk, bridge-tap, and the interaction of these and a hundred other things are all factors that affect the "sound" of audio cables. But of course, you've actually listened for yourself in a sufficiently high-rez system, right?

 

[Nomad333]

It reminds me of the audiophiles who believe they can hear connecting cables. This is a good example of what is known as the "placebo effect."

Honestly, I'm no audiophile (I do love music) but I can usually tell if someone is moving the cables of my sounds, or if the plug is shifted.

 

[cotdt]

This won't account for cutting 3-10x better, but over time retained austenite can convert to fresh martensite which would theoretically improve edge holding but also make the blade more brittle. Blades with a lot of retained austenite often have rolling issues, even when they rockwell test just fine.

Sharpening away the first section of the edge may help too, that region might be decarburized during the heat treat.

By the end of the day, who knows? We don't know how the blades were heat treated. All I know is that if a blade was heat treated correctly it won't have these issues.

 

[puukkoman]

Maybe factory sharpening compromised the heat treat on the cutting edge, and years of use and sharpenings got him down to properly hardened steel.

Just my WAG.

Chris

Beat me to it; that was going to be my wild-ass-guess also.

 

[jayinhk]

Maybe he never got around to sharpening them until it was time for this test and the factory edges sucked. Maybe the new edge geometry was much better than the old geometry. Who knows? His technique could have improved over time too.

 

[KnifeHead]

Over coffee, T.Bose just told me that he is going to put a Viagra in every packet of steel he heat treats. This'll make it better, right?

 

[VCM3]

Over coffee, T.Bose just told me that he is going to put a Viagra in every packet of steel he heat treats. This'll make it better, right?

Tell him though,you gotta be careful,folders may stay open,for more than 8 hours.

 

[Lazydog1]

Now what to do?
Bury my knives in dung or pack 'em away with a little blue pill in every box?
Thing is, my wife won't let me bring dung nor viagra into the house...so problem solved.
....and who needs self-opening folders anyway....

<<Guys - best read I've had in a long time!>>

 

[cziv]

-1 for "aged" belly dancers :thumbdn:

Dissolve one (1) Viagara in warm water, soak blade for 45 minutes. Results - super hard, diamond-cutting hard, blade steel.

 

[woody d]

"if folder stays open for more than 4 hours CALL EVERYONE YOU KNOW AND TELL THEM ABOUT IT"

 

[eKretz]

Ok, guys, there are some valid points being discounted here, as well as some wild claims that make no sense whatsoever. As for the original author and article, no clue on what that guy is thinking. If the guy didn't use the exact same rope that he used in the first test, along with the exact same sharpening stones and sharpen the blade to the exact same angle, the entire premise is bunk.

The story about engine blocks being buried or left sitting in bulk in a field or warehouse is completely legit however. Many manufacturers did this in the past with their iron castings, and some still do something similar today. It doesn't have anything to do with hardness, it has to do with stress relief and the way that cast iron tends to settle/move to minimal stress state over time. I have never heard of this being done with steel castings, however.

Now...as we come to the soul-stealing part, I think we all understand that this has to be true, since it is documented that knives have soul-stealing abilities in several movies and videogames, and we all know that Hollyweird is never wrong!

 

[Hawkings]

I am no expert by a long shot... but I was talking with a maker about something similar the other day.

I think it is possible.... but it does not have so much to do with the "aging" as it does with the sharpening.

Of course it would depend on the steel, heat treat, tempering, was it forged,.... a bunch of things.

But, say a knife was forged a bit to "hot"..... some carbon is "burned out".... more so on the thinner part down toward the edge.

Say heat treat is a bit on the "hot" side..... a very slight bit more carbon may be "burned out"..... especially on the thinner edge.

When the knife is finished, you can get it sharp...... but it mat not hold an edge real good. However, with repeated sharpening it gets to where it should be as far as edge retention goes.
Was it because it aged?...... Probably not.

Most likely it was because with repeated sharpening you get past the part of the edge that was ever so slightly lacking in carbon and get to a bit thicker part of the blade that contain the correct amount of carbon.

At least that was how it was presented to me and made perfect sense.

I think we all remember when the rittergrip came out and lots of people had problems with the edge micro chipping on paper and other things, This went away after a few sharpenings (Mine was like this)

 

[C.S. Graves]

But work hardening could come into play here.

I've read about work hardening occurring with scythe blades whose edges are repeatedly peened over years of use. The claim is that the hardness is slightly increased with peening. Then again, I've heard some metallurgist-types claim such a phenomenon is buncombe.

 

[PayetteRucker]

Not sure if it's been suggested already but a good patina could be the answer. On some steels a nice even patina, the kind you acquire over time, can harden the surface of the steel. If the edge hasn't been sharpened in a while it could be the results of the surface patina hardening the edge.

 

[mete]

Scythe blades can be sharpened with a stone but also by hammering. The blades are fairly low carbon and you can thin the edge and harden it by hammering .You can still buy small anvils and hammers for this operation !! This was a method often used in ancient times to harden and sharpen iron and also bronze blades.Anyone who tells you different is a jerk !!!

Patina is nothing more than a thin oxide coating and will not make much difference in blade performance.

Retained austenite transformation, decarburization, and initial grinding damage would have influence !!

 

[C.S. Graves]

Scythe blades can be sharpened with a stone but also by hammering. The blades are fairly low carbon and you can thin the edge and harden it by hammering .You can still buy small anvils and hammers for this operation !! This was a method often used in ancient times to harden and sharpen iron and also bronze blades.Anyone who tells you different is a jerk !!!

Actually got a scythe peening anvil myself... it ain't an easy process! But is there really something to the "work hardening" thing? How does it work? The concept of thinning of the edge to help produce a sharper edge is easy enough to grasp, but as per hardening, I wondered if the steel just doesn't get displaced instead of, I dunno, compressed.

Not that people are going to be peening their knives on a regular basis. </tangent>

 

[mete]

It has to be a soft steel to work. A butcher's steel does a similar thing and of course that works on the softer steels not the harder ones.
Technically hammering produces dislocations in the steel which strengthens it. I don't mention dislocations in my comments in the Knife Maker's Section because it is too technical for most. But one of the resons martensite is strong is that it's got lots of dislocations !!

 

[Karda]

What i was referring to is that the act of Using and burnishing a blade edge over time could effectively "work harden" the edge to an extent that it may make the knife cut slightly better. Wether or not it would make it 3-10 X better remains subjective though.

 

[wally@ferguson]

Work hardening (cold forging) is different that constant temperature aging.

Tool and die makers who made their own gauges and 1-2-3 blocks woud bury them in the backyard for a minimum of 6 months before the final micron grind. It was all about metal stabilization.