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Thread: S30V : H1 : 8Cr13MoV on plywood with acute edge profiles

  1. #1
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    S30V : H1 : 8Cr13MoV on plywood with acute edge profiles


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    Small Sebenza, Pacific Salt and Bryd Meadowlark, all blades were reprofiled flat to the primary grinds, this left primary grind edges of 5.8, 6.5, and 6.3 degrees respectively. The blades were then hand sharpened on waterstones to a fine polish (mainly to check ease of resharpening) and then a 20 degree micro-bevel applied to a fine polish with a Sharpmaker using a Jeff Clarks's burr removal method.

    I wanted this to be a rougher sort of test meaning not making an attempt to be overly quantitative could a difference be readily seen in the blades. Considering the massive difference in the steels and the price this would seem to be likely. The main criteria to judge performance was the ability to cut paper. There were three main benchmarks :

    1) push cut at 90
    2) push cut at 45
    3) slice at 45

    There were three runs of cutting performed on the plywood, which was 3/8" thick, 2" long cuts made 1/16"-1/32" deep. A total of 310 cuts were made and the sharpness was checked every 10*2^n cuts. Before each round the micro-bevel was completely cut off, any damage was removed with a x-coarse waterstone and the bevel reset.

    All blades started off easily doing a push cut at 90, in general the Sebenza was sharper than the Pacific Salt which was sharper than the Meadowlark in terms of smoothness of cut. The differences were small but they could easily be felt. It could be noticed when shaving as well.

    During the first round heavy force was applied (75 lbs) so the cuts were fast, the Sebenza chipped out heavily during the first ten slices and lost a piece of the edge a millimeter deep. I continued with it up to 150 cuts and by that time it had several visible pieces out of the edge and the entire edge was distorted.

    The Pacific Salt and Meadowlark lost the 90 degree push cutting ability after 10 cuts, but kept the ability to push cut at 45 until 150 cuts and after 310 slices could still do the 45 degree slice easily. The Meadowlark was ahead of the Pacific Salt but they were very close, I checked it on light cotton and the Pacific Salt was 21 (11) % more degraded, just barely on the point of significance (the cotton was the average of all three rounds).

    For the next round the force was backed way off, less than half of full, the Sebenza still took severe damage after the first ten cuts and the edge was visbly distorted. Checked under magnification the microbevel had cracked off from 1/2 to 3/4 width (0.15 mm wide), in the contact region. No more cutting was attempted with it. The other two knives went right to 310 cuts with the same behavior as before.

    For the final round very light force was used (15 lbs), the Sebenza now did the first ten cuts with no damage, however after the next 20 cuts it was chipped out to less than half its micro-bevel. In the places not chipped it was still able to push cut at 90 so was sharper than the other blades. After another 40 cuts the Sebenza just lost the push cutting ability at 90 but in some sections the micro-bevel was again just cracked off in places. Cutting was suspended with it again.

    The performance of the Meadowlark and Pacific Salt was consistent in the final run. What was interesting is that it made no difference to those blades if the force was 75 lbs or 15 lbs, they looked exactly the same at the end. After 310 cuts most of the micro-bevel would be removed on both blades, however in this state, due to the thin nature of the primary edge, they could still readily slice newsprint, so most would consider them still sharp.

    As a final check, I micro-beveled the Pacific Salt and Meadowlark with micro-bevels taking twice as many passes on the fine rods (20 per side) to thicken the bevels to see if that made any difference, I didn't see how it would, but it never hurts to check. It made no difference at all. They blunted exactly the same. The complete sharpening process was :

    -reset edge on x-coarse SiC waterstone
    -polish on 800,1000, 4000, natural chinese waterstone
    -10 passes per side at 20 degrees on medium Sharpmaker
    -deburr at 30 degrees per side, 2 passes on fine ceramics
    -hone edge at ten passes per side on fine ceramics at 20

    Note while the primary edge bevels were very acute (around six degrees) due to hand sharpening there was a convexity to the bevels so they increased in angle towards the very edge. The actual edge bevel in the last 1/8" was 10.0 (5), 10.5 (4), and 10.3 (5) for the small Sebenza, Meadowlark and Pacific Salt respectively.

    The performance is interesting for several reasons, first that H1 can match 8Cr13MoV which means I need another reference point, is H1 high or the other low. I need to run VG-10 on the plywood and see what happen to it, and then maybe M2, D2 and other tool steels.

    Secondly what happened to S30V, the performance was so lopsided it wasn't even in the same class, the damage with the other two blades was much less extensive even after much more cutting with much more force, many to one in both aspects. I need to check this with other S30V blades.

    No plywood on hand currently though.

    -Cliff
    Last edited by Cliff Stamp; 02-11-2006 at 01:06 PM.

  2. #2
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    Gads, S30V looks like its chipping a bit?

    Annoying to see it again, is all I can say (write).

    CRK uses a lower RC, right? Wonder what Spyderco's heat treat will do.

  3. #3
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    Interesing Cliff.

    I enjoy reading your reviews. they are very educating.

    I just bought a s30v native and put it to some light cutting tests. I plan on edcing it for a while, to see how well it's edge retention is, and how well it cuts rope on the lobster boat. I did find that there was a tiny burr or blunting of about a millimeter of edge near the ricasso, when paring a .5L water bottle into a slinky. The edge damage occured fairly early in the cut, which was continuous for the length of the bottle. I noticed it hanging up when I used that portion of the blade, and at first thought it was glue or paper from the bottle's wrapper, but inspecting it closer, it was edge damage.

    I have another s30v native I am going to try, to see if that was a problem inherent to s30v (I am new to this steel) or simply caused by a defective blade.

    Peter

  4. #4
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    Very interesting! Thanks for the effort, this is good information.

    JD

  5. #5
    I wonder if there is an edge angle with S30V below which a steep performance drop occurs. Maybe, below 10 deg or so, the Vanadium carbides simply break out of the edge?

    Also wonder what hardness does at these thin edge profiles.The Meadowlark is run pretty hard (about 61 Rc IIRC), and the Pacific is in the range of 65 Rc, while CRK is running their S30V in the range of 57-58 Rc or so? That a BIG difference. Maybe the edge buckles first and then tears of, because it is already deformed?

  6. #6
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    I am really glad you like doing these test Cliff. The information is very interesting. Thanks

  7. #7
    I'm still trying to get a handle on S30V. I've had some severe chipping problems and some mild problems and some knives in that steel with no chipping. Some people seem to have trouble with it and some not.

    Could it be that it's tricky to grind the final edge without overheating the steel and making it brittle or creating minor cracks? Sometimes the grinder gets it right and sometimes not? It's hard to believe that Crucible is turning out that many bad batches of steel.

    The small chipping looks like sculpted clam shell chips -- like the cavities left from chipping an arrowhead out of flint, only much smaller. The severe chips seem to be caused by a crack running straight up into the edge and a chunk then falling out.

  8. #8
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    the chipping problem of S30V has been discussed before. I guess we can't have it all right? but why use a small sebenza? please send it to me and i'll give you a Spyderco in S30V !

  9. #9
    Thanx for the input Cliff. Appreciate.

    I have found that there is a considerable difference is differents steel's ability to survive a very thin edge. I believe its chemistry more than grain size. I'm sure heat treat also has more to do with it than is imagined.

    Right at that point where the edge and material meet in force, the ability of the molecules to "stick together" no matter what, is the target of study.

    Your views?

    sal

  10. #10
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    Quote Originally Posted by HoB
    I wonder if there is an edge angle with S30V below which a steep performance drop occurs. Maybe, below 10 deg or so, the Vanadium carbides simply break out of the edge?
    I would expect carbide size to be a limiting factor, but it should not be vanadium carbides because they are very small in size and a much smaller volume fraction of the steel. It depends of course on how you heat treat it, specifically the austenizing temperature, as you can put all of the chromium into solution if you want to.

    I also would find it hard to believe that it is a carbide issue here because this should effect the level of sharpness and this knife consistently ranks among the top sharpness when I measure it and gets there very easily. It is odd because CPM steels are supposed to have a finer carbide size and better distribution.

    The performance of the knives was surprising, I didn't intend at first to use the Sebenza, I was looking at the H1 data I had and realized I needed more edge holding so did some cardboard and then used the plywood because it makes an interesting comment on edge holding in general as it depends on different properties.

    I really leaned into the Meadowlark and Salt on a few test trials later including powering them through some knots, I could not generate the macroscopic damage. This doesn't surprise me because in general while many would consider these profiles to be thin, they are quite robust to what I have on some knives.

    So I had no concerns about them in general on the plywood, I do that with thinner knives anyway, and have used the Salt aggressively with that profile for months, similar with the Meadowlark but generally keep the Sebenza for lighter work, mainly so I will always have one razor sharp knife at all times, I EDC it.

    I may sacrifice it shortly anyway since it can't hold the necessary profile for light work and still have a decent scope of work and I want to see how a nice integral holds up under heavy batoning and finally rigged up a weight drop impact testor using a 25 lbs lead weight so I'll get some info out of it anyway.

    I also may have it rehardened, I need to discuss it with Crucible and Wilson because the edge is way thinner than you would normally have on a knife to be hardened.

    Maybe the edge buckles first and then tears of, because it is already deformed?
    Yes that is what I assume, the actual level of impacts is low, the speed on the latter cuts was slow so this is definately a low yield problem. I'll try it with the Delica/Endura once they get back from the passarounds. In general, impact toughness isn't an issue on cutting, that is more for chopping. Unless of course you are cutting at massive speed and plow into something hard.

    Quote Originally Posted by Twindog
    Could it be that it's tricky to grind the final edge without overheating the steel and making it brittle or creating minor cracks?
    It does have a much lower machinabiilty and maybe people are leaning into the steel more to compensate, that is an interesting point. It could also explain why people are often solving the problem with sharpening.

    It's hard to believe that Crucible is turning out that many bad batches of steel.
    One thing which needs to be factored into the equation in regards to interpreting performance reports is that the actual raw number of people using knives and discussing them in detail is MASSIVE now compared to what it used to be, this may be skewing the failure rates somewhat.

    However I have talked to people who have seen extreme defect percentages, often 3-4 blades with problems from different makers, some even got replacements which were also defective in the same way. I have even handled then personally and verified it for myself at times. It is too bad that S90V wasn't more widespread used because it would have made an interesting point of comparison.

    Quote Originally Posted by Sal Glesser
    I have found that there is a considerable difference is differents steel's ability to survive a very thin edge. I believe its chemistry more than grain size. I'm sure heat treat also has more to do with it than is imagined.
    Yes, the problem here is that we are often guessing at unknowns, even knowing the hardness doesn't tell you much beyond a gross estimate. You can effect the structure by how you quench (oil vs air) how far you quench (room vs cold) how hot it is soaked and how it is tempered and how often. You can easily end up at the same HRC point and have two massively different steels.

    To compound the problem you have to ask is this representative of even that manufacturers version of the steel let alone the optimal performance of that steel in general. I have other S30V blades so it would be informative to do it with them. The above are very low profiles though, it will take some work to replicate them on the other profiles.

    Glad everyone else found it useful, I literally have boxes full of notebooks of this type of information.

    -Cliff
    Last edited by Cliff Stamp; 02-04-2006 at 11:11 PM.

  11. #11
    Thanks for testing. Everytime I read one of your reviews I come up with a dozen questions. I'm wondering how the various CPM steel types stack up against each other, and curious about VG-10 (the cobalt king of steels) results.

    Comparison of CPM versus 440-C and 154CM Stainless:

    Carbon Manganese Silicon Chromium Molybdenum Vanadium
    440 C 1.20 1.00 1.00 18.00 0.75 0.00
    154 CM 1.02 0.60 0.25 14.00 4.00 0.00

    CPM 3V 0.80 0.50 0.90 5.23 1.30 9.75
    CPM 10V 2.46 - - 7.50 1.30 2.75
    CPM S60V (440V) 2.30 - - 14.00 1.00 9.00
    CPM S90V (420V) 2.15 0.40 0.40 17.00 0.40 5.50
    CPM S30V 1.45 0.40 0.40 14.00 2.00 4.00
    Last edited by DGG; 02-07-2006 at 04:19 PM.

  12. #12
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    Quote Originally Posted by DGG
    Everytime I read one of your reviews I come up with a dozen questions.
    Ideal experiments answer some questions and pose more which induce more experiments. Unless you are just trying to trivially verify something, you are ideally looked to be confused, you can't learn anything otherwise.

    You raise a number of interesting comparisons, 3V vs 10V/15V, which is more important the toughness of 3V or the insane wear resistance and higher hardness of the 10V/15V, similar with S30V vs S90V/S125V.

    The angle is critical here as well, if you go obtuse enough the edge won't chip or roll no matter what the steel however the more metal on the edge the lower the cutting ability.

    -Cliff

  13. #13
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    Forumite Roman Landes did a testing of fine edges on differnt steel grades a few years ago. There he was noticing, that the amount of carbides in S60V was responsible for the large break outs at the very edge.

    I guess, PM technology is the right way for high allooys, but less filled with carbide formers would be a solution. Like PM 154CM wich will be close to the swedish RWL34 could show better results compared to S30V.

    8X15Cr. should be compared to AUS8, because they are pretty close in composition. Good time for comparing an CRKT AUS8 to an "super hard" Benchmade red class.

  14. #14
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    Quote Originally Posted by Blop
    Forumite Roman Landes did a testing of fine edges on differnt steel grades a few years ago. There he was noticing, that the amount of carbides in S60V was responsible for the large break outs at the very edge.
    Yes, Alvin tested this on his custom knives a *long* time ago on D2 and Bos hardened ATS-34. You simply can't grind them really fine, the edge falls apart. However the grinds he was using was far thinner than the above, which I consider actually fairly robust (for the Salt and Meadowlark). I have knives with final edge profiles the same as the primary grinds in the above.

    I guess, PM technology is the right way for high allooys, but less filled with carbide formers would be a solution. Like PM 154CM wich will be close to the swedish RWL34 could show better results compared to S30V.
    It depends on what you are cutting and how and the edge profile. I ran the Sebenza vs the Meadowlark on cardboard with the same profiles in the above with the edges micro-beveled at 15 degrees and the Sebenza had much better slicing edge retention, push cutting was similar (seeing the influence of wear resistance vs hardness respectively).

    The main point of the above is that edge retention does not equal wear resistance, this has been discussed on rec.knives for more than ten years, it was well known before I started reading and still yet you read statements in Crucibles data sheets that S60V has better edge retention for knifemakers because of the wear resistance vs other steels.

    This simply isn't true. Edge retention depends as well on strength and toughness (and corrosion resistance) Alvin coined the term "edge stability" for this awhile ago. What difference does it make if the edge resists wear if it just deforms/breaks off. If you have to reduce 440V/S60V to 56 HRC so it doesn't chip it simply won't compare well to steels 4-6 points harder in terms of deformation.

    There simply isn't very much data out there on the new cutlery steels, especially the CPM stainless, I would like to see the performance with a maximal secondary hardening. Yes, the impact toughness is decreased but who cares they are not chopping tools, you want strength and fine carbides for maximal cutting performance.

    The problem is these steels are *expensive* you really can't expect a maker to buy a few dozen billets and run multiple blanks through various cycles and see what turns up - that is a *massive* cost due to time and materials, not to mention that you could be actually selling knives during that time.

    Phil Wilson does a lot of it even then though, taking steels over a variety of temping temperatures and examining how the edge retention fares and then picking the best compromise of strength and toughness.

    8X15Cr. should be compared to AUS8, because they are pretty close in composition. Good time for comparing an CRKT AUS8 to an "super hard" Benchmade red class.
    I think it would be interesting to do an edge retention comparison of 440A vs 440C with both at 60/61 HRC and see which one has better edge retention on hemp, carpet, wood (pine/phywood), with edges at 15/10/5 degrees. Or even something like AEB-L vs S30V on the same.

    Then of course you blow them all away with the right tool steel.

    -Cliff

  15. #15
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    I always read these threads and think to myself:

    "what does any of this have to do with the steel if we can't find out the exact heat treat process of those blades"

    You can take something like simple 1095 and make a blade that will chop 2x4s all day, still shave hair, and bend to 90 degrees without breaking. Another maker with different HT process might have a blade that chips out during chopping, wont hold that edge, and snaps easilly due to grain growth by overheating.

    Is there any way to get the HT process for these knives, to see the differences? I dont think any knife of any decent quality, should ever blunt while corkscrew cutting a plastic bottle.

    In the end, steel is just steel unless its treated right. Magic mixes of exotic alloys are only and will only ever be as good as they have been heat treated.

    Assuming perfect heat treat on a knife coming off a production line might be too big of an assumption to make....

  16. #16
    I would be very interested in seeing how zdp189 compared with the s30v in terms of chipping and edge retention. Any chance of getting a zdp blade?

  17. #17
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    Quote Originally Posted by TikTock
    "what does any of this have to do with the steel if we can't find out the exact heat treat process of those blades"
    Can you use this work to judge all S30V, no. Can you use it to judge the optimal performance of S30V, no. I can of course use it to judge what I can and can not do with this Sebenza, and unless Reeve tells me it is defective I know how Sebenza's in general will behave and similar for the other knives.

    As for the obtaining the heat treatment, just ask Reeve, or take one, crack it in half and from the primary carbide volume fraction, grain size, secondary carbide precipitation level and hardness, you should be able to figure out the heat treatment.

    I have a blade in ZDP-189, that would be an informative comparison. Generally there are few problems reported with ZDP-189, even though it is fairly hard, but it is being pushed as a cutting steel whereas S30V was promoted for heavy use tacticals and there is much more of it being used.

    -Cliff

  18. #18
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    Quote Originally Posted by outofgum
    I would be very interested in seeing how zdp189 compared with the s30v in terms of chipping and edge retention.
    Calypso Jr, primary edge reground to 7.2 (8) degrees per side, micro-bevel applied with 5 passes per side on medium rods, 10 passes per side on fine, 2 passes per side to deburr at 30, then ten pass per side to reset edge. Initial performance was 0.25 (2) cm on 200 g loaded cotton (easily shaves, catches hair above the skin, etc.).

    Three runs were performed, same as with other knives, the average performance was extremely high, it took 150 cuts for the Calypso Jr. to lose the ability to push cut on a 90, and it just barely did so, even a tiny angle, 10-20 degrees allowed a push cut. It still shaved on a slice after 310 cuts with little pressure.

    Under magnification the edge was only slightly damaged after 310 cuts, the damage ranged from 1/4 - 3/4 of the edge bevel and was less than 5% of the edge even in the worst places, in no regions was the entire micro bevel removed. By eye there was just a glint of light reflecting in a couple of places each round.

    The cotton score was 0.89 (6) after the cutting, this is sharper than a lot of knives NIB. The runs were also a little less than optimal because I didn't reset the edges completely each time with the 200 grit SiC hone, I just gave them a light cleaning on 800 AO and redid the microbevel, so it wasn't fresh steel each time.

    Even then, on one of the rounds the knife went to 310 cuts and *still* push cut the newsprint. If I had been as careful with this sharpening as with the last ones I have no doubt it would have done this easily with each round. Note the primary angle is also lower and I didn't set the micro-bevel as heavy either, only 5 passes per side on the medium.

    After the final run I did twently full force cuts where I didn't whittle off shavings, I cut right through the plywood from one side to the other, taking off 1/8"+ strips. This had no macroscopic effect on the edge at all, and no significant further degredation under 10x mag.

    http://i7.photobucket.com/albums/y26...jr_plywood.jpg

    I also forgot to mention in the above, the ergonomics were very different. The Byrd was uncomfortable when heavy force was used, I would want to use a glove for the full 310 cuts. The Sebenza was better than the Salt but not significantly, I would not want a glove for either. The Calypso Jr. handled very well, comfortable during the cutting.

    -Cliff

  19. #19
    Quote Originally Posted by Cliff Stamp
    Calypso Jr, primary edge reground to 7.2 (8) degrees per side, micro-bevel applied with 5 passes per side on medium rods, 10 passes per side on fine, 2 passes per side to deburr at 30, then ten pass per side to reset edge. <snip>
    Thanks Cliff. That's a very interesting result, and it seems like ZDP-189 is the cat's meow when it comes to stainless steels. I had initially some problems with chipping, but no problems since I resharpened my Calypso Jr.

    I actually think these tests are among the most interesting I've read so far. They sort of confirm my suspicion that S30V is very variable in performance, much more than some people would have us believe. I'd quite like to see a few more, for instance with VG-10, a steel I like very much, and good toolsteels like M2.

    Hans

  20. #20
    Thank you for the (really quick) calypso zdp review. There haven't been too many hard use tests and this confirms the lack of brittleness and excellent edge holding of zdp. It seems like a laminated blade isn't necessary, and gives me more confidence in the unlaminated full zdp delica that should be out soon.

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