Blade Steels

Cliff Stamp said:
It forms chromium carbide and thus the chromium is no longer "free" in the steel and thus can not form the passive chromium oxide layer to protect the steel. This is why high carbon stainless steels in general are far less corrosion resistant than low carbon stainless steels of similar other alloy content.

-Cliff
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Well, yea, but there are stainlesses with elements added that tie up carbon before Cr gets a chance. There are also steels with very low carbon, 316L and 304L, less than 0.05% and these will rust quickly in certain environments.
 
And melting steel is like cooking soup and not any soup tastes exactly like the other but mostly.
 
S30V is an excellent steel for folders. I love D2 in small fixed blades. Both steels have to be heat treated properlly and to a high enough Rc of course.
 
me2 said:
Well, yea, but there are stainlesses with elements added that tie up carbon before Cr gets a chance. There are also steels with very low carbon, 316L and 304L, less than 0.05% and these will rust quickly in certain environments.
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Indeed, there are many elements which effect corrosion resistance both indirectly and directly. There are formulas to estimate pitting resistance based on elemental composition.

-Cliff
 
amw308 said:
This is off topic, but could somebody explain the meaning of life to me?:D
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Indeed:
Try and be nice to people, avoid eating fat, read a good book every now and then, get some walking in, and try and live together in peace and harmony with people of all creeds and nations.
 
It's all about m4 if you can find someone who wants to spend that long grinding . Those who say INFI is better than M4 I'd love to see a side by side, but from what the knife cutting competitions are showing M4 is dominant in its edge holding ability. I really doubt either posseses corrosion resistance edge that would be noticable. S30v and such are soooo last year =P I am of course kidding to some extent. Some steels are well suited to a single purpose and the sharpest thing around is still obsidian in a single flake (they still make scalpels for delicate surgery out of it). Still M4 is able to become scary sharp, hold the edge, not chip, break or shatter and has corrosion resistance. Besides ease of sharpening, I cant see a type of knife it would not be well suited towards. EDIT: for some reason I was thinking M4 was a stainless wich it is not. Guess for corrosion resistance it wouldnt be up there. Still with a blade coating this steel has everything else one could want.
 
Cliff Stamp said:
Indeed, there are many elements which effect corrosion resistance both indirectly and directly. There are formulas to estimate pitting resistance based on elemental composition.

-Cliff
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Cool. Where? ASM?

Who is making knives out of M4? Alvin Johnson has been pushing M2 for years, but M4 is a new one on me, at least for knives. Are they grinding the M4 hardened like Alvin recommends for M2, or are they sending it out/hardening it themselves? I've read some horror stories about annealed M2 grinding similar to hardened O1.
 
S30V, BG-42, VG10, ATS-34 and 440C = all seem to work the same for me. Blade length, shape, thickness and grind are the prevailing factors dictating my knife choice for a task. For fixed blades, I've had good luck with 52100, 5160 and 01 - strong and tough. The British bushcraft design with the single large bevel has proven to be optimal for most of my requirements. For chopping, I use a GB axe.
 
me2 said:
Cool. Where? ASM?
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Yes, these forumla's exist for most properties, Ms, and calculations can even be made to predict carbide type/volume which are very accurate.

Who is making knives out of M4?
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Crucible is pushing it as a large blade steel.

Are they grinding the M4 hardened like Alvin recommends for M2, or are they sending it out/hardening it themselves?
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It is hardened to common knife hardness, similar to Benchmades use of M2.

-Cliff
 
M4 has a normal RC range when hardened of 62-64 Rc but it is best to underharden it at 59-61 Rc to increase its toughness. Gayle Bradley, Warren Osborn, Jerry Halfrich and Tom Overeynder are all making knives in it. I did just realize that its not a stainless however but was corrected to find out it is easy to sharpen (seems odd considering its supposed to be a real bear to grind). Crucible says the 4% vanadium sets it apart from other steels in the tool class and that they sell more M4 than S30V or 154CM. The ballance of toughness and wear resistance is supposed to be second to none. I would say that M4 with duracote or another simmilar coating may be "the blade steel" for the moment at least. I'm waiting to try some out and see just how bad it hogs belts.
 
thombrogan said:
Oh, well, then S7 tempered to about RC57 with a standard heat treatment and M2 hardened to about RC65 with standard heat treatment are the best.
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Dang it, Thom, you always beat me to the punch. I was going to say there is no best, except S7 (S5 is prolly better, but i've never been able to find any) and M4 (M2, whatever). I have always wanted to see how a knife made of A9 would perform... The stuff looks good on paper, but paper can be deceiving... It seems like with technology such as it is, someone should be able to come up with a blade that is as hard as diamonds, tougher than titanium and lighter than helium. Ok, maybe light as lithium; floating knives could be dangerous...
 
hara-kiri-yogi said:
Dang it, Thom, you always beat me to the punch. I was going to say there is no best, except S7 (S5 is prolly better, but i've never been able to find any) and M4 (M2, whatever). I have always wanted to see how a knife made of A9 would perform... The stuff looks good on paper, but paper can be deceiving... It seems like with technology such as it is, someone should be able to come up with a blade that is as hard as diamonds, tougher than titanium and lighter than helium. Ok, maybe light as lithium; floating knives could be dangerous...
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I think you can get S5 in round bar from Crucible.
 
I just had a small knife made for me out of M4 by Justin Gingrich of Ranger Knives. I'm really happy with it so far (I have only had it a few weeks). Just to give fair warning, though, the stuff is really expensive. And i have heard that the corrosion resistance of M2 and M4 is very low, like on par with L6. Fortunately corrosion resistance is practically a non-issue for me.
 
The steels made for sharpness, like the AUS6 and the Sandvik 13C26. Could be made very sharp with good edge retention and decent corrosion resistance. S30V underhardened is nice as well, otherwise it tends to chip.

//Jay
 
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