Thread: Charnley Forest steel types

So my buddy was asking me if a charnley forest stone would cut A2 and other powder steels? He is a knife and woodworking guy. I don't know much about steel types so figured someone here may be able to educate me on the answer to this.

A2 yes since it's only a high carbon steel.

Powdered steels it depends. It almost feels like a baited question because steel alloys in so many ways, and a few adjustments in the forging process can create steels with very different properties.

Carbon steel at <60 rockwell hardness then the CF should be able to deal with it.

Carbide steel with a >60 rockwell hardness you may find the silica just can't do anything to the metal. It depends on what they have alloyed into the steel, and how much free carbon was available, And what temps the metal was forged at. Vanadium 15V steels when made and hardened correctly can have a hardness of over 80 rockwell. You'd need something far harder than silica to abrade that, like silicon carbide, CBN, or diamonds. It's variable because when the correct forge conditions are not met you can still have a steel with the correct vanadium content, but the free carbon did not react and form carbides.... So the metal content is there but it's not a carbide steel.

Tools and knives are often made in non-carbide steels. The added alloy metals are there for other properties like corrosion resistance, or to improve toughness. A knife that is too hard to sharpen, and brittle is no good in a lot of applications. There are exceptions to this, and some very brittle but also very hard steels are used for cutting, but generally this is expected when you are cutting equally hard materials like other metals and you can control impact so as not to damage your carbide steel cutting faces.

The only real way to know what will sharpen what when exotic alloys are used is to ask the manufacturer. If there hardening beyond 60, and using something exotic to sharpen on, then CF probably won't work. On the other hand if there using water stones to sharpen with aluminium oxide abrasives then CF may well work.

Pretty much the prior information is correct. BUT... keep in mind that a CF stone is not really for cutting steel. its use with razors is really best suited to final polishing. Which it will do an admirable job on. There are very few razors out there with a hardness over 60-62 A good noviculite stone will work well imo.

I have had excellent results on my Brian Brown razor, which I am under the impression to be in the 60+ range.

The Charnley forest stone will work on A2 steel even if correctly hardened, but don't expect to use an 1k stone or sandpaper, jump on the Charnley and expect it to work. But it will abrade steel.
Iceni, there is no steel that reaches 80 RC hardness.
https://www.crucible.com/eselector/p...s/cpm15vp.html It's optimal RC hardness is at about 63.
There is a difference between "Vanadium carbide is 80RC hard" and "steel is 80RC hard". Ceramic knives have a lower RC hardness value.
The presence of "exotic" carbides in steel don't change it's hardness but other characteristics, wear resistance for this case. A Charnley won't be able to abrade that steel but not because of its hardness, it will be because of it's wear resistance. And because Vanadium carbides are a pain in general. No matter what you do, you can't achieve the hardness above 67RC on any steel, quenched in water, and around 65RC quenched in oil. There is no steel that can harden up to 80RC.
There are the famous Iwasaki tamahagane kamisori, I don't know what they did but they managed to achieve that 65-67RC hardness. At that point, no natural stone can wear them, not Japanese stones, no coticules, you have to use synthetic stones, or wear your naturals a lot more compared to a classic western made razor, to see a small difference.

Originally Posted by Vasilis

There are the famous Iwasaki tamahagane kamisori, I don't know what they did but they managed to achieve that 65-67RC hardness. At that point, no natural stone can wear them, not Japanese stones, no coticules, you have to use synthetic stones, or wear your naturals a lot more compared to a classic western made razor, to see a small difference.

I am not sure that is correct. I have to check because I honed my Iwasaki Tamahagane several years a go and can't remember what I used on it. I find it hard to believe they will not hone on Jnats though.
Off to test...

Originally Posted by mainaman

I am not sure that is correct. I have to check because I honed my Iwasaki Tamahagane several years a go and can't remember what I used on it. I find it hard to believe they will not hone on Jnats though.
Off to test...

A follow up, I refreshed my Iwasaki Tamahagane on a J-Nat and it worked very well. I remember that initial bevel set up was a bit challenging but now that the bevel is set the razor is easy to handle. I will add that there were other Japanese razors that I have honed that were tougher to get right on Jnats compared to the Iwasaki.