Blade steels - what's wrong with improvement?

[thombrogan]

Thanks, Zvi!

That explains my fetish for those sorts of steels even more in line with my professed bigotry against high vanadium/molybdenum steels because the tungsten is forming less carbides. A steel using an appreciable amount of tungsten, such as 1.3355 with 19% per weight would probably not be the droid I'm looking for and make me say "Save me, CPM-M4! Save me, Oprah Winfrey!"

 

[james terrio]

That explains my fetish for those sorts of steels even more in line with my professed bigotry against high vanadium/molybdenum steels because the tungsten is forming less carbides.

I don't understand the logic there. If you don't want carbides, why have W in cutlery steel at all? It doesn't do a whole lot else other than raise red-hardness (essentially resists heat) and that's very important for drill bits and mills, but it doesn't matter in knife blades. Tungsten's grain-limiting properties are a little unclear to me, but I'm reasonably certain it's not any better at it than vanadium.

Vanadium on the other hand, in small doses is very helpful in preventing grain growth during HT even in very simple steels, whether you want enough to form carbides or not. (for instance Aldo at NJSB has "his" 1084 made with just a touch of V specifically for that purpose). And if you do want carbides, V forms much harder, more uniform ones* much more efficiently.

Surely there's a reason so many steel manufacturers have shifted more and more away from W in tool steels and towards vanadium instead for several decades...

* it's my understanding that W2C are relatively difficult to form and therefore rare in knife steels as we typically treat them.

 

[thombrogan]

I don't understand the logic there. If you don't want carbides, why have W in cutlery steel at all?

Great question! Until this morning, I had thought that the tungsten in some of my favorite steels (Blue #2 in particular) was giving the steel an easily sharpened and relatively long lasting edge (though it's not like I'd been having edge retention problems with AEB-L or White #2). It might still be doing something wicked groovy and favorable, just it's unlikely doing so as a carbide.

Vanadium on the other hand, in small doses is very helpful in preventing grain growth during HT even in very simple steels, whether you want enough to form carbides or not. (for instance Aldo at NJSB has "his" 1084 made with just a touch of V specifically for that purpose).

It's also in Blue 'super,' 1.2552, and O7 and even AUS-6 and Krupp 1.4116 and in levels that suggest grain refinement. I don't think it's in CPM-S35VN or CPM-S110V for that purpose (I think it's in CPM-S110V so I can resharpen a recurve with a diamond hone after cutting sod without blacking out and wetting myself - a lesson VG-10 could learn).

And if you do want carbides, V forms much harder, more uniform ones* much more efficiently.

I only want teeny carbides like the ones found in the 10XX steels and the martensitic stainless strips steels (12C27, 13C26 et al). I want the martensite to bear-hug the carbides at edge angles that suggest T-Rex sized arms. A T-Rex has the leverage to give a harder bear hug to Urkel than to Louie Anderson - even if Louie Anderson was covered in a boron carbide coating and Urkel was covered in butter.

Surely there's a reason so many steel manufacturers have shifted more and more away from W in tool steels and towards vanadium instead for several decades...

Many complex alloys have both, some complex alloys have neither. It could be the supply of tungsten relative to vanadium has shifted over the past several decades and the metallurgists formulating these steels are creating a whole gamut ranging from "better than anything else existing before this moment for this range of tasks" to "it's either this or you're having a sad Christmas."

I believe I'm guilty of making an 'ad hoc ergo proctor hoc' error here. The appearance of large carbide steels in popular non-kitchen cutlery (not just the ones with 3-15% vanadium per weight) seemed to appear at the same time as the annoying cutting/toughness dichotomy. That's the one where the end user says "this knife is too thick for easy cutting" and is told by fans of the knife (rarely ever directly by its maker) "the knife needs to be a little thicker than you wanted so it can stand up to hard use." The first person decides to use the knife harder and it breaks (not unexpected with ATS-34 through ZDP-189) and is then scolded by those same fans of the blade with a "Duh! < facepalm /> Knives are for cutting."

edited to add:
There's a neat layman description of what tungsten does for steels at Azom and, while it's not nearly nerdy 'nuff, it does show that the behaviors of this sinfully sweet poison are dose dependent (just like carbon or molybdenum or chromium or...).

 

[shqxk]

Surely there's a reason so many steel manufacturers have shifted more and more away from W in tool steels and towards vanadium instead for several decades...

Some the best performance cutlery steel does contain W, to name a few M4, PD1, M390, K390.

 

[Gator97]

I suspect It's more for hardeability that for cabide forming, given the amounts W can forms.
Plus, in steels high on Chromium Vanadium positively affects(increases) chromium carbide hardness as well, and refines the same. W or Nb provide no such effect, at least according to the paper I've read.

 

[Ankerson]

I suspect It's more for hardeability that for cabide forming, given the amounts W can forms.
Plus, in steels high on Chromium Vanadium positively affects(increases) chromium carbide hardness as well, and refines the same. W or Nb provide no such effect, at least according to the paper I've read.

Pretty much like the difference between K294 and K390 for example.

They dropped the V content to 9% and added 1% W.

And Dropped the Chromium Content from 5.2% to 4.15%

Also Added 2% Cobalt and upped the Molybdenum from 1.3% to 3.75%.

And a few other minor changes in an effort to make K390 slightly tougher than K294 while still having about the same wear resistance.

I tested the K390 Mule and put it through some pretty rough treatment and it held up well, at 15 DPS and .026" behind the edge, and at 63-64 RC.

I use it quite often for cutting cardboard up to 1/2" thick and haven't seen any problems with it so far.

 

[sodak]

Ok, I'm going to try and break this down, because I don't understand your point.

I believe I'm guilty of making an 'ad hoc ergo proctor hoc' error here. The appearance of large carbide steels in popular non-kitchen cutlery (not just the ones with 3-15% vanadium per weight) seemed to appear at the same time as the annoying cutting/toughness dichotomy. That's the one where the end user says "this knife is too thick for easy cutting"

Why would a user say that the knife is too thick? All of my high carbide knives that I've handled are quite thin. For examply, the Spyderco Southfork in S90V. My customs in S110V and K390 are both less than 0.01 inches behind the edge. All are extremely durable and wicked cutters.

and is told by fans of the knife (rarely ever directly by its maker) "the knife needs to be a little thicker than you wanted so it can stand up to hard use."

I have never heard this. I have some Fehrmans in CPM 3V that are thinner behind the edge precisely because 3V is so tough, they can get away with being thinner and still be more than strong enough for great chopping. Thinner than 52100, for example, and that's a low alloy steel that I really like as well.

The first person decides to use the knife harder and it breaks (not unexpected with ATS-34 through ZDP-189) and is then scolded by those same fans of the blade with a "Duh! < facepalm /> Knives are for cutting."

Again, where has this happened, or is this just another strawman? I have ZDP knives thinned by Tom Krein at less than 0.005 inches behind the edge, and they have held up fine. Better than some others I've had him thin, although I suspect this has more to do with hardness than carbide volume. I'm finding that knives that are above 62HRC seem to profit more from thinning than knives at 57 HRC.

 

[Gator97]

Pretty much like the difference between K294 and K390 for example.
...

Well, at least some of the science matched real life huh I do need some of that K390 for experimenting...

 

[thombrogan]

Ok, I'm going to try and break this down, because I don't understand your point.

Sounds good to me.

Why would a user say that the knife is too thick?

A user would say a knife is too thick because its blade isn't thin enough for efficient cutting. Back in the late 1990s and early 2000s, low saber-flat ground and low saber hollow ground knives; often made of ATS-34 or 154CM with a small and growing number of knives moving over to S60V and later S30V; were the norm.

All of my high carbide knives that I've handled are quite thin. For examply, the Spyderco Southfork in S90V. My customs in S110V and K390 are both less than 0.01 inches behind the edge. All are extremely durable and wicked cutters.

That's all kind of recent, though, isn't it? I think Phil was one of the first; along with Reeve; to use some of these steels, but he was relatively unknown to the typical Benchmade, Spyderco, or Buck user posting on the internet back in the early 2000s.

I have never heard this.

Again, where has this happened, or is this just another strawman?

I remember it happening to noss4 when he'd put knives marketed as "hard use" or "tough" through their paces and I remember it happening to Dr. Stamp.

I have ZDP knives thinned by Tom Krein at less than 0.005 inches behind the edge, and they have held up fine.

You just asked me why would a user say a knife is too thick and now you're mentioning having enlisted Tom Krein to thin out your blades. If you were seeking revenge for my confusing comments, you owe me more, but that was a great first volley.

Better than some others I've had him thin, although I suspect this has more to do with hardness than carbide volume.
I'm finding that knives that are above 62HRC seem to profit more from thinning than knives at 57 HRC.

Have found that, too. Sharpened a Benchmade 921 Switchback to what the lines on my EdgePro Apex said was about 12° per side (but the huge, Scandi-looking new primary grind I made suggested otherwise) and it was a good looking, but floppy knife. On the advice of a friend, I begged Phil Wilson to reharden the steel for me and - voila! - it stands at attention and sharpens so much better. Of course, then I ruined its looks applying a convex grind, but the point was I agree with you that overall hardness seems to make thinly ground blades be themselves and spread joy regardless of carbide volume and final edge apex.

 

[Ankerson]

Well, at least some of the science matched real life huh I do need some of that K390 for experimenting...

I don't know, haven't has any issues with K294 or K390 so i can't really say.

 

[lakerol]

If h2 is actually smaller than h1, i.e. the material pulls away from the edge as it is cut by the apex, the force goes to zero before the edge bevel is even in the material:

W= (K/2)*tan(a)*h2

Now in both of these equations take note that apex angle is rendered via trigonometry to a ration of thickness:height and then multiplied by the height of either the cut or the edge itself such that the effect of the angle is reduced to THICKNESS. And this makes sense because "angle" is simply a convenient way of describing the space between two lines, i.e. thickness. THIS is why thickness is the most important factor per physics/math.

That second equation, which I assume is for less flexible materials, seems to require a 52% increase in work needed going from 10 to 15 degrees per side (tan(15)/tan(10)).

 

[sodak]

A user would say a knife is too thick because its blade isn't thin enough for efficient cutting. Back in the late 1990s and early 2000s, low saber-flat ground and low saber hollow ground knives; often made of ATS-34 or 154CM with a small and growing number of knives moving over to S60V and later S30V; were the norm.

I must have missed that trend. I tend to ignore things that I'm not interested in, and these grinds don't interest me.

That's all kind of recent, though, isn't it? I think Phil was one of the first; along with Reeve; to use some of these steels, but he was relatively unknown to the typical Benchmade, Spyderco, or Buck user posting on the internet back in the early 2000s.

No, Phil and Dozier have been well known for a while now, probably Dozier longer. I started getting interested in Phil when I heard of him here on this forum, probably 2003 or so. Perhaps you are right about non-forumites, though. Buck's edge 2000 was back in 2000, and it made quite a splash then. Perhaps they can receive partial credit for helping cutting knives get thinned out.

You just asked me why would a user say a knife is too thick and now you're mentioning having enlisted Tom Krein to thin out your blades. If you were seeking revenge for my confusing comments, you owe me more, but that was a great first volley.

Nope. All the knives that Krein has done for me were thin to start with. I just wanted to take it to an extreme, and he was willing to do it.

http://i137.photobucket.com/albums/q203/sodak_photos/inventory/p1010011-1.jpg
http://i137.photobucket.com/albums/q203/sodak_photos/inventory/p1010017-1.jpg

All of my thicker knives such as Busse, Cold Steel, etc, I thin out on my EP or belt sander. I have found that the thicker ones weren't related to alloy, but rather perceived function, i.e., chopping. Most of them are much thicker than they need to be, but I understand that the manufacturer is probably trying to avoid warranty work due to abuse.

Have found that, too. Sharpened a Benchmade 921 Switchback to what the lines on my EdgePro Apex said was about 12° per side (but the huge, Scandi-looking new primary grind I made suggested otherwise) and it was a good looking, but floppy knife. On the advice of a friend, I begged Phil Wilson to reharden the steel for me and - voila! - it stands at attention and sharpens so much better. Of course, then I ruined its looks applying a convex grind, but the point was I agree with you that overall hardness seems to make thinly ground blades be themselves and spread joy regardless of carbide volume and final edge apex.

Exactly. I also have a Caly 3 in VG10, and thinning it really didn't help, it's too soft. I'll need to get it rehardened or use it for a letter opener. The edge tends to roll, but that's my fault, and I'm ok with it, now I know. The regular Caly 3's are superb, this was an experiment that just didn't work out.

 

[thombrogan]

I must have missed that trend. I tend to ignore things that I'm not interested in, and these grinds don't interest me.

Your inner-ninja must be better at hiding than mine.

No, Phil and Dozier have been well known for a while now, probably Dozier longer.

Dozier and his heat-treatment of D2 has been well-known well before the internets - especially to everyone with an A. G. Russell catalog, but, somehow, his thin grinds weren't mentioned in the folding knife forums - just that his heat-treatment was the stuff of legend.

Another grinder of thin blades is David Boye, but he's barely been able to make a dent in the tactical folder market.

I started getting interested in Phil when I heard of him here on this forum, probably 2003 or so. Perhaps you are right about non-forumites, though. Buck's edge 2000 was back in 2000, and it made quite a splash then. Perhaps they can receive partial credit for helping cutting knives get thinned out.

That actually squares in with my late 90's/early 00's timeline and CPM-S30V's appearance as a commercial knife steel around 2,002 or so.

Nope. All the knives that Krein has done for me were thin to start with. I just wanted to take it to an extreme, and he was willing to do it.

http://i137.photobucket.com/albums/q203/sodak_photos/inventory/p1010011-1.jpg
http://i137.photobucket.com/albums/q203/sodak_photos/inventory/p1010017-1.jpg

I think morrowj had a Caly3 regrind from Tom like that. Only with the CF/ZDP version. My neighbor has what used to be my VG-10 Caly 3. It was too chunky. Speaking of which, Mel Pardue and Doug Ritter might be thin, but that Griptillian RSK was fat, fat, fat. If you pulled back the Axis Lock to let the blade swing or flick open, marble-sized beads of sweat would roll from its thumbstuds and its stopbar would have the most asthmatic wheeze.

I had the Pardue-only version for a long time. Saber ground 440C, comfortable Noryl GTX scales, and was as well-made as any folding pocketknife I've ever used. It could cut pretty good for what I was used to at the time, but it mostly sat on the sofa drinking margaritas and watching anything from Golan Globus ("Otello" starring Placido Domingo, a bunch of Sho Kosugi flicks, "Breaking," and "Breaking 2: Electric Bugaloo" for instance). Fat, fat, fat. Tried stropping the edge and it caused a flabberlanche.

Knives exist to help us get or stay fat - not the other way around.

Incoherent rambling aside, it really is a nice knife and your D2 RSK/Kreinified version looks even better.

All of my thicker knives such as Busse, Cold Steel, etc, I thin out on my EP or belt sander. I have found that the thicker ones weren't related to alloy, but rather perceived function, i.e., chopping. Most of them are much thicker than they need to be, but I understand that the manufacturer is probably trying to avoid warranty work due to abuse.

A lot of those types of knives have full or nearly full tangs. Maybe it was also for overall balance without adding costs for extra labor or more thorough CNC programming, too?

Exactly. I also have a Caly 3 in VG10, and thinning it really didn't help, it's too soft. I'll need to get it rehardened or use it for a letter opener. The edge tends to roll, but that's my fault, and I'm ok with it, now I know. The regular Caly 3's are superb, this was an experiment that just didn't work out.

After it's already ground very thin, I'd worry that it's more prone to warp when being rehardened.

 

[chiral.grolim]

I shouldn't post again (supposed to give up BF for Lent) but...

That second equation, which I assume is for less flexible materials, seems to require ONLY a 52% increase in work needed going from 10 to 15 degrees per side (tan(15)/tan(10)).

I inserted a word into your post. Keep in mind that tan(10) presents a 102% increase over tan(5) while tan(15) is ONLY 52% greater than tan(10). On a relative scale, that advantage is minimal if h2 is minimal. The advantage between 5-degrees per side (10 inclusive) gets smaller as you climb to 45-dps (468% increase over 10-dps). The graph of Y=tan(X) is non-linear.

Furthermore, the ratio ignores the reality of precision measurement, or rather a lack thereof. Work is measured in Joules of energy, and while there may be easy to detect a difference between 10 Joules and 100 Joules, it is harder to detect a difference between 1 and 10 Joules, even harder between 0.1 and 1 Joules, each a 10X difference. For reference, it takes 1 Joule of work to lift 1 apple (~0.1kg) 1 meter. Are you sufficiently sensitive to the difference in weight that you could tell if you were lifting 1/10 of that apple vs. 1/100? Keep in mind that your finger might be heavier than 10g. If you used 2 knives, each 0.010" thick at the shoulder, one 10-dps the other 15-dps and had to make a cut 0.020" deep (height of the 15-dps bevel) with this equation, i posit that you could not tell the difference between them because the level of energy required to make the cut may be less than your ability to detect and the difference is ONLY 50% higher for the 15-dps.

And again, that is only IF you can achieve and maintain a true 10-dps which, according to professionals and professors even on razor-blades, can be challenging if the steel is insufficiently hard or you have poor technique sharpening. If it is NOT so hard to achieve or difficult to maintain, Go for it! :thumbup: Just know that if the edge chips or rolls, depending on how deep the damage goes you don't necessarily need to re-profile the edge to a higher angle, just put a slightly higher angle on the very edge, i.e. a microbevel, and you may see a substantial jump in durability.

It'd be interesting to know who you are, your 1st post being to this thread and in response to that single post that is actually pretty off topic...

 

[me2]

See the thread started in Maintenance, Tinkering, and Embellishment. It's beyond this thread.

 

[moffatik]

i must admit your reference table is well laid out containing the best knives in the market. kudos for such a good ob

 

[ursamajor]

They are cool. But in production knives, early runs can have HT issues. There is something to be said about a company that keeps a narrow focus on blade steels in production knives, as they settle in, refine their process, and put out a great product at a great price.

Think Buck and the amazing job they do with 420HC

 

[Kwon Kwang]

I see we have a zombie thread.

My opinion on this is simple: in use, the noticeable differences in performance between steels suitable for blades is minimal at best (while people like us might notice, the average user is a lot less likely to), and past a certain price point there is a nosedive in the price to performance ratio. Newer steels are going to be more expensive because they're new and popular. Yes, it is certainly a flavor-of-the-week matter.

Don't believe me? Brian Evans sells his midtech S35VN Companions at $84 USD a pop. Other companies such as Kizer sell Ti framelocks in "super steels" for not much more. These steels aren't super expensive because they're super performers, they're super expensive because of market forces. The high price is a part of the marketing, and I think that's actually part of why people buy knives in these steels. They want to feel some degree of exclusivity when they buy a certain knife.

Classic and "plain" steels like 420HC and 1095 might sound boring in comparison, but they're classic for a reason. The price to performance ratio is sky high, and steels like S30V aren't far off because they aren't the flavor of the week anymore.