What steel will hold a 25 degree inclusive edge the best?

I would like to put in my half cents worth of sharpening knowledge.

I have a love and hate relationship with s30v, I love the way it performs for me, but setting the right edge is very difficult for me.

One thing that I have learned from manufacturers such as Spyderco is that many of them intentionally put really small angles on their grinds so that when we come back and sharpen it to a higher angle, the secondary bevel is pushed back a bit so that cutting is very smooth.

Personally I see no need to have anything thinner than 30 degrees. I usually put a 30 degree secondary bevel on my knife and come back at 40 degrees and what I have found is that I get a hair popping sharpness that lasts a very long time (especially in s30v).

I know that I EVERYONE has their own opinion on this but it works well for me. Also I am referring to my PM2 and 940 as s30v references.
 
Regarding edge angle, if I carried a knife for cutting only, it would look much different in terms of edge geometry. In this case, I can make a good case for going lower than 15 degrees per side/30 inclusive, and have even run chopping knives at less than 30 degrees inclusive. However, my work/daily carry knives get used for scraping, cutting, scoring, light prying (staples and such), some batonning, (I cut some bamboo skewers today using that method) and even digging. Such a thin geometry wouldn't last long with any of the sideways activities like scraping.
 
Winguy, there's a pretty informative thread about this very thing in the general knife discussion forum. Some knowledgeable guys are advocating for some specific steels. You might find it interesting.



winguy7 said:
I've been edc'n a para 2 in s30v for a year now with this edge, and I'm sick of touching it up after every use. It folds or chips after one light use. As far as I'm concerned s30v is a glorified letter opener. Now I know some people like it and I respect their opinions, it just doesn't fit my bill. Problem is good steel is expensive, and I'm looking for user experience with brands/knives/steels that will not roll or chip with light use at a more acute angle. I like my knives dam sharp, and I'd like one that stays that way at least for a little bit. I have a nice but small collection and don't mind buying a double if it will fit my needs, I just cant afford to play around with them. So does any steel manage to hold that angle well? I am talking light use here. Mostly used for cutting green or dead branches, with rope occasionally. My thoughts would be spydie manix 2 in s110v, or something in m4 or 204p. Also m390 is a strong consideration. What are you're opinions?
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Winguy,

In all seriousness, I've had the same problem with S30V in several different knives. It was bad enough that now I won't even consider a knife if it's S30V. I've had really good luck with CPM M4 (Gayle Bradley), CPM 3V (lots of knives), and D2 (both Queen and Dozier). For me, the harder, the better, but I'm not rough on my knives. The Manix 2 in S110V is a great performer also.
 
S30V is fussy about how it's heat treated. Done poorly, it's chippy. But when it's done right, S30V is an excellent steel -- tough, highly wear resistant and not chippy at all. In another thread Jerry Hossom says it needs a fast quench. I don't know about that personally, but I do know that I've had a couple horrible S30V blades and some extremely good S30V blades.
 
Twindog said:
S30V is fussy about how it's heat treated. Done poorly, it's chippy. But when it's done right, S30V is an excellent steel -- tough, highly wear resistant and not chippy at all. In another thread Jerry Hossom says it needs a fast quench. I don't know about that personally, but I do know that I've had a couple horrible S30V blades and some extremely good S30V blades.
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I can agree with that, whole-heartedly. At one time, I'd have never believed S30V could or would take or hold a finer edge. But heat treat is everything, and a fast quench is apparently what limits grain growth in steel; that limits or minimizes issues created by bulkier grain, like reduced toughness (making it chippy) and difficulty in getting the steel to take a fine edge in the first place. I have knives from Chris Reeve (Sebenza) and Kershaw (Leek) with outstanding edges, and no issues with chipping at all. I have another one, from another (unnamed) maker that I've never been able to keep as fine an edge on, no matter what I've done to it; it gets to a certain 'sharpness', then degrades very quickly in cutting cardboard, seemingly as if the fine edge just 'crumbles' off.

BTW, all the above would apply to other steels as well; but the mistakes seem much more easily noticed in the bad examples of some steels, like S30V. Even 1095 can run the gamut, from horrid to amazing, depending on heat treat.


David
 
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Obsessed with Edges said:
BTW, all the above would apply to other steels as well; but the mistakes seem much more easily noticed in the bad examples of some steels, like S30V. Even 1095 can run the gamut, from horrid to amazing, depending on heat treat.

David
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I fully agree with your post, especially the portion I quoted. My issue is this - I've never yet had a D2 blade with a bad heat treatment (as far as I can tell), same goes for 3V. But I've never yet had a good blade with S30V - of course I haven't bought one in a long time - over 5 years, probably longer. They might have gotten better with it, but after half a dozen stinkers (including some big-name ones), I'm just not willing to risk my money any more. Especially when there are other steels with better edge retention and (apparently) much easier or consistent heat treats.

To the OP I would also say this. Determine what your cutting needs are. Do you want stainless, or do you not care? If you are looking at cutting abrasive materials with no scraping or pounding, then look and see what steels can be finished at or above 62 HRC. Generally, the higher the hardness, the stronger the steel, and the thinner you can take the grind. I think that you can really see a difference when you get above 63.

Then thin the edge down as far as possible until you start seeing rolling or chipping. Then put a small microbevel on that edge, and you have an extremely optimized cutter. You can always thicken a thin edge if necessary with a microbevel or repeated sharpenings, and you will never look back. Personally, if I had to start all over again, I'd go with CPM 10V above 64 or CPM S110V above 63. M390/K294/K390 are great also.

You haven't lived until you have a knife out of one of these steels that's under 0.010 (got a couple at 0.005) inches at the edge. The cutting is just unreal, effortless, a joy to use. And you'll look at the knife in amusement because you realize that you cannot remember the last time you sharpened it. They really are that good.

As always, YMMV.
 
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Quenching speed (different from cooling speed) doesn't affect grain size. It does however affect carbide size and amount. Cooling as quickly as possible is a good idea, as long as cracking and undue distortion/warping can be avoided. Remember that the standard form for steel, or the way steel wants to exist, at room temperature is just ferrite and carbides. A slow air cool might allow too many carbides too form and allow existing ones to grow unduly large. Plate quenching or calling a quench oil supplier and asking for the slowest they have will avoid this if it is a problem. If it is or not is up to a variety of factors. Also, FWIW, I've not found grain size to be a large factor in the sharpness of an edge. Any really sharp edge is smaller than the grains in all but a very few cases, like friction forged D2.

Sodak, if you have any blades left, try some M2 with a 5 dps edge with just a tiny microbevel at 12-15 dps (degrees per side). I'm talking about a microbevel less than 0.001" thick at the top. The high hardness and moderate carbide volume should be something to behold for daily cutting. You could try the other steels, but the higher carbide volume might need to use a higher angle, maybe 20 dps or so. I'm flat grinding one of my hollow ground knives now to about 4 dps and will add a 10-15 dps microbevel after I'm done. It's an experiment to be sure, but if successful in AUS-8, M2 should work as well.
 
Regarding effects of quench rate on grain size (whether carbides are affected similarly or not), this info below touches on what I'd read elsewhere, i.e. grain continues to grow until cooled below a certain temperature (by quench, at least in part, as explained below); therefore the method of quench and rate of cooling affects how large grain will get. That's what I was trying to get across earlier.

Quoted from: http://www.heattreatconsortium.com/TechPro/HeatTreatChemistry.htm#Glossary
"The hardness, brittleness, ductility, and grain size of a steel is a result of the heating and cooling method that is used in the Heat Treat Cycle.

When steel is heated above the Transformation Temperature to form Austenite, and then quenched very rapidly it will most often transform into Martensite. It will be hard, strong and have a small grain size, but will also be brittle.

When steel is heated above the Transformation Temperature to form Austenite, and then cooled very slowly, it will transform into Ferrite, Pearlite and Cementite. This structure is comparatively softer, less strong, more ductile, and has a larger grain size.

The ideal properties for heat treated steel is hardness, strength, ductility and small grain size."
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Also, from the same site ( http://www.heattreatconsortium.com/TechPro/HeatTreatChemistry.htm#Grain ):
"Grain Size

As molten metal cools, it aligns itself in to a precise regular structure that is called Unit Cells (bcc, fcc, bct). As the Cells form, they combine to form "Nucleation Sites". This process continues in all three dimensions, forming "Colonies" of Unit Cells. When the boundaries of the Colonies touch each other, a "Grain" or "Grain Boundary" is formed. In general, the slower the cooling rate, the fewer the Nucleation Sites and therefore the larger the Colonies or the larger the Grain Size. Conversely, the faster the cooling rate the more Nucleations Sites and the smaller the Grain Size. The Grain Size effects the mechanical properties of the steel.

The smaller the Grain Size (cooled fast) the greater the strength. The larger the Grain Size (cooled slowly) the more ductile it is. Therefore, a part is cooled according to the desired property."
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David
 
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I feel as though we've started this discussion before? While the linked article is generally correct, it covers a huge range of conditions in a very short amount of text.

Based on this being a knife forum, and the general form for steel in knives is martensite, I'm assuming there is a quenching speed fast enough to form martensite without allowing, or at least minimizing, the formation of other phases, such as pearlite or bainite. This is why I differentiated between quenching speed (with the implication of martensite) vs. cooling speed (which is generic and varies depending on what you want the heat treatment to do).

If the steel is cooling from liquid, or if it was austenized then cooled to form pearlite or bainite, the grains will indeed depend on the cooling rate, at least in part, as there are other factors. Slower cooling rates mean fewer nuclei to start grains, and they will be further apart and grow until they meet. Voila, larger grains, though for bainite, that's not exactly how it works.

However, when martensite is the intended outcome, the maximum temperature during austenization and the time held there is the determining factor for the coarseness/fineness of the martensite, again among other things. The martensite size will be limited by the austenite grain size at the time of quenching. There isn't enough time for it to get bigger as the temperature goes down before martensite forms, as illustrated by this video. Notice the grains (dark outlines at the very beginning) don't move as the steel cools.

https://www.youtube.com/watch?v=OQ5lVjYssko

This is one of my favorite videos. The little lines that appear are the martensite lathes forming. Notice they do not cross the grain boundaries, thus, the austenite grain size determines the limit for the coarseness of the martensite.
 
me2 said:
Sodak, if you have any blades left, try some M2 with a 5 dps edge with just a tiny microbevel at 12-15 dps (degrees per side). I'm talking about a microbevel less than 0.001" thick at the top. The high hardness and moderate carbide volume should be something to behold for daily cutting. You could try the other steels, but the higher carbide volume might need to use a higher angle, maybe 20 dps or so. I'm flat grinding one of my hollow ground knives now to about 4 dps and will add a 10-15 dps microbevel after I'm done. It's an experiment to be sure, but if successful in AUS-8, M2 should work as well.
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I'll give it a try, thanks!
 
OP you should be discussing your needs with a custom maker.

I have no trouble with durability on my s90v southfork , and it is at precisely 12.5 dps. I use it for an edc , camp knife whatever... Its been batoned through small branches in an attempt to try and make it fail.

However if you are that hard on knives discuss Vanadis 4 Extra with someone like Dan Keffeler. It can be ran all the way up to 64rc I believe ,however with the correct HT at about 62 rc its durability can actually be insane. See some of Dan Keffelers videos for some examples. I still have some sample pieces i need to return to him..
 
I still don't see 4V in the kinds of tests that V4E can sail through. Everyone says that 4V is the same as V4E but man, some of the stuff V4E can do is pretty outstanding. You'd think with 4V being more available than V4E that if it was really the same then there'd be the same kinds of torture tests and the same glowing outcomes. Makes me wonder if there's something special about the specific composition and production process of V4E that makes it truly shine.
 
bodog said:
I still don't see 4V in the kinds of tests that V4E can sail through. Everyone says that 4V is the same as V4E but man, some of the stuff V4E can do is pretty outstanding. You'd think with 4V being more available than V4E that if it was really the same then there'd be the same kinds of torture tests and the same glowing outcomes. Makes me wonder if there's something special about the specific composition and production process of V4E that makes it truly shine.
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V4E and 4V are VERY close to each other in alloy content....

There is some makers who are working with 4V and it can be taken into the 63-64 range, I have a knife here for testing in 4V that is .010" behind the edge and 63 HRC.... So we will see how it does....
 
I've seen the content of the steels and that's why I'm so intrigued. From BRK to Big Chris have made knives in 4V. I haven't heard much other than it's a quality steel.

Then I see the stuff from Knife Research, Fred Haakosen (sp?), and especially Dan Keffeler and it's, according to what's been shown, absolutely outstanding. Seriously amazing. You'd think that there'd be similar stuff said about 4V.

Now, I guess it could be that KR, FH, and DH had optimal heat treating services performed whereas BRK and Big Chris haven't, but I don't know. There aren't many negative reports from the latter two.

All I know is that Dan Keffeler has a cozy relationship with Peters and probably has his stuff treated for free and they probably take work from him a little more seriously than others, but that wouldn't explain KR and FH knives doing such absolutely crazy things.

Hell, I can't even find a custom maker that can finish a knife in V4E, let alone get ahold of it to test it myself. I don't honestly trust Zero Tolerance to do it right, so that kind of tears me in two. Go with the ZT and quite possibly be disappointed with the results or go with ZT and be overwhelmed with such a fantastic steel. I personally think ZT will leave the grind too thick, leave the steel too soft, and overcharge for what they produce.
 
bodog said:
I've seen the content of the steels and that's why I'm so intrigued. From BRK to Big Chris have made knives in 4V. I haven't heard much other than it's a quality steel.

Then I see the stuff from Knife Research, Fred Haakosen (sp?), and especially Dan Keffeler and it's, according to what's been shown, absolutely outstanding. Seriously amazing. You'd think that there'd be similar stuff said about 4V.

Now, I guess it could be that KR, FH, and DH had optimal heat treating services performed whereas BRK and Big Chris haven't, but I don't know. There aren't many negative reports from the latter two.

All I know is that Dan Keffeler has a cozy relationship with Peters and probably has his stuff treated for free and they probably take work from him a little more seriously than others, but that wouldn't explain KR and FH knives doing such absolutely crazy things.

Hell, I can't even find a custom maker that can finish a knife in V4E, let alone get ahold of it to test it myself. I don't honestly trust Zero Tolerance to do it right, so that kind of tears me in two. Go with the ZT and quite possibly be disappointed with the results or go with ZT and be overwhelmed with such a fantastic steel. I personally think ZT will leave the grind too thick, leave the steel too soft, and overcharge for what they produce.
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Nothing wrong with 4V. :)

Should have another one coming to run in 4V for another data point.....
 
Well, I hope that you can get a V4E knife with a heat treated by someone who knows what they're doing to compare head to head. It'd be interesting.
 
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