The knife-steel snobs are pushing the market for trendy pocket knives (and Japenese style kitchen knives) farther and farther out the hardness scale. Is this a good thing? I like sharpening my Buck pocket knives and Henckel kitchen knives cuz it's a snap. Takes about 6 strokes on a sharpening steel or 5 minutes on the Sharpmaker. They have never shown any tendency towards brittleness (well there was that one incident with the hammer but let's not go there). What's your opinion on this hardness trend? Fad or functional?
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>>60 hardness
- Thread starter matt321
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Functional, you'll spend as much or less time sharpening the steel overall. It may take a little longer to set the bevels, but you do it less often. I have a preference for the way I want a steel to fail depending on use, but I still want over 55 Rc, not under
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http://www.buckknives.com/technical_steel.php
I know that it may seem illogical, but extra hardness does not necessarily translate to a steel being harder to sharpen. The Buck Knive's information posted at the above URL states that S30V with a hardness of Rc 59.5 to 61 is easier to sharpen than BG42 (Rc 61-62) or 154CM (Rc 60-61). They rate S30V as being equal in ease of resharpening to 420HC and 420J2 (Rc 56-58).
I am not an expert. However, I would have to say that the above information does come from a reliable source.
I know that it may seem illogical, but extra hardness does not necessarily translate to a steel being harder to sharpen. The Buck Knive's information posted at the above URL states that S30V with a hardness of Rc 59.5 to 61 is easier to sharpen than BG42 (Rc 61-62) or 154CM (Rc 60-61). They rate S30V as being equal in ease of resharpening to 420HC and 420J2 (Rc 56-58).
I am not an expert. However, I would have to say that the above information does come from a reliable source.
Well seeing that your sharpening stones are still well above these hardness values, there are no real problems. The burden of sharpening has more to do with how much material you have to remove - what is the stock thickness and how is the knife ground. Kitchen knives for example are usually quite thin at the edge and easy to sharpen irregardless of hardness. Too soft a steel can be a lot harder to sharpen than a comparatively hard one as it tends to form a large burr and misalign the edge. Hard steel are then again harder to regrind or reprofile, since then you always have to remove a lot of steel.
Few knives, IMO, need be below 58 HRc. I'd really like to see thinner ground knives hardened over 60, if the toughness curves allow.
Few knives, IMO, need be below 58 HRc. I'd really like to see thinner ground knives hardened over 60, if the toughness curves allow.
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Knifes are cutting instrments and in my opinnon should be harder than most are manufactured, Most of my knifes are 61-62 cpm3v s30v and d2. I started using DMT bench diamond stones years ago so sharping is not a problem with hard blades. If I need a chopper I will use a chopper axe etc. I like sharp knifes that hold their edge. If a knife is soft enough to be a chopping or hacking tool it can not also be a fine cutting tool. I carry one knife cpm3v, with me that is a utility knife that is used for everthing in a pinch, it is 59-60 rc. One big advantage of higher hardness with some steel such as 3V,A2 S30V is that you can reduce the micro bevel down to 12-15 degrees, if you limit it to cutting tasks that do not require a great deal of pressure. You will have an outstanding cutting edge with the reduced angle and the harder steel will tolorate that angle better.
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I agree with Leon Pugh. To me a knife is a KNIFE! It's not a sword, machete, axe, hatchet, tomahawk etc. I use a knife to cut. I use an axe or hatchet to chop.
I like a knife that will hold an edge well, and cut like a razor. I especially like A-2 and D-2 hardened to RC 59-60 or harder
I like a knife that will hold an edge well, and cut like a razor. I especially like A-2 and D-2 hardened to RC 59-60 or harder
Cliff Stamp
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The actual fad is the "golden rule" of 60 HRC. Many of the steels which are so hardened are actually at their most brittle there as it puts them in an embrittlement region. This is simply because of lack of materials knowledge and salesmen pushing propoganda. It somehow became law that 60 HRC was some ideal goal regardless of the steel. Generally ease of sharpening isn't a concern with a high hardness, in many cases the knife will get easier to sharpen beause there is less of an issue with burrs.
-Cliff
I'm not Cliff, but I've been following his work, as well as posted discussions with Alvin Johnson, Phil Wilson and a couple of other knife makers who try for higher hardness. Phils work with the listed stainless steels at >60 is interesting and promising, although I cant afford his work. A2 at ~64 seems a good bet, but I dont know anyone who's tried it. It looks like the tempering temperature is more important than the actual hardness. David Boye recommends 62.5 Rc for A2 in his book. With a subzero quench he says 1-2 more hardness points can be gained without a loss of toughness. The tempering temperature agrees with the toughness peaks from Cliff's site, which I believe come from ASM. Alvin seems to like M2 at the second hardness peak of 1000 degree temper for a hardness of ~65, although he says you have to be careful. Check with Phil for D2 at 61 - 62 Rc. I can attest that 1095, quenched, frozen to -5, and double tempered at 325 F is a lot tougher than I would have expected. Alvin gets a hardness of 66 Rc. I dont know how hard mine was, but the kiridashi I made took a piece out of my garage floor with a slight ding in the tip, with and included angle of ~20 on a chisel ground tip. It would also cut steel wire (for tying reinforcing steel) at that angle without gross damage, just dulled. I have for about 3 years now believed that sharpening has much more to do with geometry than steel. The knife that took the longest for me to sharpen was a Cold Steel Safekeeper in AUS 8. Reprofiling took nearly 2.5 hours on a water cooled 12" stone turning at about 100 rpm. I'm interested to see how a Cold Steel Scalper type knife in 1095 at that hardness would work. I have some left and may give it a try if I can figure out how to HT it with my current equipment, or pay for it if its not over $20. I also have a Nicholson file blade that needs to be given the same treatment, ~ 3" long.
Cliff Stamp
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Generally, most steels tend to peak in properties close to their maximum hardness, if this hardness doesn't have the desired range of properties usually another steel is a better solution than drawing the steel for many reasons.
For example lets assume you take D2 and you find that when it is hard it tends to chip so you draw it back until it doesn't. However you have now made it weaker and the edge will roll and dent much easier than a steel which is inhernently tougher and can be run harder.
So what did you achieve, the knife is now more expensive because you have all that high carbide to pay for and grind and heat treat all of which requires more money and you have a softer blade which is weaker and becomes difficult to sharpen because it burrs easy.
Most of the high carbide stainless is actually difficult to get above 60 HRC simply because most of the carbon is tied up in the chromium carbides so you are limited to generally at most 61/62 HRC, some of them can be pushed slightly futher, BG-42 can reach 64, and of course ZDP-189 can reach 67 HRC.
Almost every aspect of knife performance is that way, the steel just allows you to craft a more optimal geometry however if this isn't actually done then a "lesser" steel with a more optimal grind can easy offer better performance. That is why I would recommend in general before paying a significant amount for a knife to get at least a working knowledge of how geometry influences performance and how to so optomize your knives. Anyone who takes the time to refine the blade on a 15$ Byrd to the exact cutting they do will have it easily outperform a $450 custom with the stock edge in the vast majority of cases.
-Cliff
I can speak to differences in the same steel. I have a folder in S30V. It was originally hardened to 57 HRC. I had that verified. Then, I had it re-hardened to 60.5. And again verified.
Night and day. Not even close to being the same knife. At 57, absolutely horrible edge holding, the edge would roll and dull worse than soft AUS 8A. At 60.5, it rivals some of my best (Dozier D2) knives at holding it's edge in abrasive media (cardboard and dirty carpet). It also doesn't roll and dull very easily any more, thanks to being stronger (because it's harder). And I don't particularly like S30V.
What conclusions? Pick the steel, there is definitely a sweet spot to aim for. Hit it, and if the steel, heat treat, and geometry are what you want in your application, you'll love it. If not, you'll think the steel or the knife is lousy.
Night and day. Not even close to being the same knife. At 57, absolutely horrible edge holding, the edge would roll and dull worse than soft AUS 8A. At 60.5, it rivals some of my best (Dozier D2) knives at holding it's edge in abrasive media (cardboard and dirty carpet). It also doesn't roll and dull very easily any more, thanks to being stronger (because it's harder). And I don't particularly like S30V.
What conclusions? Pick the steel, there is definitely a sweet spot to aim for. Hit it, and if the steel, heat treat, and geometry are what you want in your application, you'll love it. If not, you'll think the steel or the knife is lousy.
I have an experience that mirrors Sodak's - but I have come to slightly different conclusions.
1) Pick your knifemaker / reference person
2) Discuss your usage patterns, sharpening skills, blades/shapes you have experience with, budget, time to delivery.
3) Take their recommendation on the on the steel , geometry, and ergonomic shape that is the best fit for you. This may point you to a manufacturer or custom blade maker - or back to do more research.
The most difficult choice is in deciding who you will align yourself with - then - being patient enough to save for the product(s) that will fill the need.
IMO
MAT
1) Pick your knifemaker / reference person
2) Discuss your usage patterns, sharpening skills, blades/shapes you have experience with, budget, time to delivery.
3) Take their recommendation on the on the steel , geometry, and ergonomic shape that is the best fit for you. This may point you to a manufacturer or custom blade maker - or back to do more research.
The most difficult choice is in deciding who you will align yourself with - then - being patient enough to save for the product(s) that will fill the need.
IMO
MAT