Is H1 work hardening a myth?

[zenheretic]

When H1 first came out we were told it work hardens and thus over time would require less visits to the sharpener. Now after years away I come back and people keep posting that is a myth (on a different forum).

So did new information come out since I've been away or are those folk as ignorant about that as they are about so much else from the classic days?

[yablanowitz]

Ignorance is bliss, and those people are happy. Ask the military survival training people about the Aqua Salt. They're why it was reintroduced and why it now comes with black DLC. They had found out how good it was after it was well seasoned, i.e. sharpened enough to work harden to a level approaching the serrated edges.

[sal]

Hi Zen,

This is one of those areas that make edge-ology so interesting. While we do know that processing the material does increase the hardness, these are all mechanical processes. There is no empirical evidence to support that hand sharpening will work harden the edge of a plain edge H1 blade. There are numerous personal accounts that do substantiate the claim.

sal

[JT]

Imho, and really just imho, my most used H1, the Pe Tasman Salt, really keeps it edge for longer periods after all these years. No scientific data to back it up, it's just the way it feels to me.

[Evil D]

Well, I can't understand how removing metal is supposed to make the metal underneath it harder, but just because I don't understand it that doesn't mean it isn't happening. If that were the case then I don't see why we don't just regrind every H1 blade we have and skip the middle man. If cutting serrations makes for a harder edge, then why doesn't cutting a PE bevel have the same effect? If we regrind a blade, does that also add to the work hardening? Is this something we can exploit? If "work hardening" is a simple matter of stock removal, can we just start with a 10mm thick slab of H1 and grind it down into a 3mm PE blade and end up with amazing performance?

[sal]

The material is also compressed from an original 7mm down to the desired thickness. This is not removing metal, but is does add to the work hardening.

Bending a paper clip back and forth work hardens the clip until it is hard enough to break.

sal

[Saxconnection]

The material is also compressed from an original 7mm down to the desired thickness. This is not removing metal, but is does add to the work hardening.

Bending a paper clip back and forth work hardens the clip until it is hard enough to break.

sal

Wow! That is quite a difference! How does that compare to other steels? I mainly just cut them, I'm slightly ignorant as to how they're processed as stock.

[SF Native]

My recollection from engineering school is that work hardening happens when the material is plastically deformed (meaning it doesn't come back to its original shape). Serrations should qualify. Sharpening a plain edge is more of a gray area. More aggressive sharpening might be an advantage with H1. Working up a burr and then taking it off, might do it.

[seber]

Any compression that is done will happen before heat treat. Subsequent heat treat will then wipe out any effect of that operation. Stock removal during sharpening could indeed harden the worked steel. That is the steel that is removed. I can't prove anything either way, but unless someone does an actual scientific test I will have to believe the hardening effect is in the believers' head.

[sal]

Hi Seber,

Welcome to our forum.

H1 is not heat treated.

sal

[chuck_roxas45]

It makes sense that a material work hardens when compressive force is applied but how much compression is really imparted with hand sharpening? Once again the butt dyno effect?

[bdblue]

The material is also compressed from an original 7mm down to the desired thickness. This is not removing metal, but is does add to the work hardening.
Bending a paper clip back and forth work hardens the clip until it is hard enough to break.

For normal carbon steel, plastic deformation leads to work hardening. Pull on a tension specimen past yield into its plastic zone and then before it fractures it will work harden and increase in strength. (This is visible in a normal stress-strain curve.) I don't know how H1 steel works in this regards. Grinding away material to create bevels and serrations is different and I don't know how it would lead to work hardening, or at least other than right on the very surface. The example you gave, bending a paper clip, is an example of normal steel that goes past yield in bending and work hardens to the point of fracture.

I'll try to link to a stress-strain curve on the net:


This brings up an interesting question- does forging improve a metal through work hardening? I suppose the answer should be yes, but in the context of knifemaking the next step is heat treatment so I suppose the heat treatment goes beyond the point of the forging and the end result is the same whether you start with forged steel or not.

[Bushminer]

Suspect H1 is not really a steel (Iron -carbon alloy with the carbon jammed in the crystal lattice) and doesn't necessarily behave like one.

My understanding is that sufficient alloys are added to remove all the carbon from the iron and tie it up as carbides. This gives the corrosion resistance. Nitrogen is added (jammed in the crystal strucure) to replace the dislocation locking effect in the iron. Tis could give different behaviour

An example of non standard behaviour with extreme work hardening is Hadfield steel (magnalloy 13%manganese 1%carbon) as used in mining and earth moving equipment.

[PayneTrain]

Yeah, I don't think the work hardening of H1 is a myth, it's just misunderstood. As has been pretty well explained here, work hardening requires strain. Sharpening, especially hand sharpening, should not provide enough stress to lead to work hardening. If you're pushing that hard to sharpen, I think you're doing it wrong!

I may certainly be missing something, but I really don't believe that H1 gets harder the more you sharpen it, at least not as a function of sharpening it. Perhaps the steel is harder in the middle due to work hardening during production? Perhaps it's just the thicker stock leading to stronger edges? Perhaps it's purely subjective and it's not actually any different?

[clovisc]

I have a SE Pacific I've been using hard for over 10 years. It has become an absolute beast!

[sal]

Hi Bushminer,

Welcome to our forum.

What is the advantage of Hadfield steel in the mining industry?

sal

[Doc Dan]

Here is an interesting read on that stuff:
https://en.wikipedia.org/wiki/Mangalloy

[sal]

Thanx Doc,

good stiff.

sal

[ChrisinHove]

It makes sense that a material work hardens when compressive force is applied but how much compression is really imparted with hand sharpening? Once again the butt dyno effect?

I recall Cliff Stamp remarking that the use of the sharpmaker corner in sharpening could deform and weaken the edge in some circumstances.

I guess that deformation could have a positive effect on H1?

[ThePeacent]

Well, I can only contribute in saying that my newer Tasman (1 year) does not seem to hold its edge like the much more beat up and resharpened one from 9 years ago.



It's just my experience after using them almost daily an alternating between both from time to time. This one feels like holds an edge for a couple days more before I have to sharpen



but I cannot give accurate data about that, the black one still has to be beaten quite a bit to get up there!