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Thread: Stainless san mai, core steel testing.......

  1. #31
    Senior Member zitangy's Avatar
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    Quote Originally Posted by WillC View Post
    Yep lets see. I expect the D2 and 3v will be chalk and cheese. Its fun to play in these extremes to learn. Yeah the main concern is the D2 will not be terribly stable on a very thin edge due to larger carbides. Although the grain looks fine would need a micrograph to show up the large undissolved carbides. So I'm hoping I have pulled off something with my moderate HT in not going for extreme hardness and multiple temper cycles, cryo, all this should help reduce the larger carbides and give a more even distribution, but we will see.
    I have just found an excellent source for samples of many Bohler and latrobe steels, so more testing to come over future months. Obviously the pm steels get expensive so will be done gradually.
    Hi Will,

    Dont know enough abt steel..

    reading metallurgy .. quite hard for me to absorb. Based on the above, you are attempting to get the best out pf the steel ( mono steel) in terms of performance and edge retention.

    A possibility could be folding the 2 different type of steel each excelling in the specific criteria and making a solid damascus of it provided that they both have the same HT treatment process/ criteria with less priority on how the contrasting damascus would look like.. .. a thought inspired by your early piece where by the damascus was not so contrasting.

    In terms of percentage increase of edge retention, are you expecting a significant jump?

    Have fun.

  2. #32
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    Yes damascus of the right choice can give a nice toothy nature and excellent edge stability. Old school damascus of 1080/15n20 does offer a nice toothy edge, especially if all the weld cross the edge like in a W's based pattern like feather.

    This is just me taking opportunity to test some different and more complex steels to offer another option or two eventually in san mai. It also gives me an introduction to welding a few different steels. This might come to play in damascus work later, its all good learning, and while I'm learning about the steels I'm also learning the critical measures to welding them together and how to treat them after forging.

    But for now its just to offer some new options in san mai and have an opportunity to test them.

    With regard to wear resistance, yeah there will always be a big leap as you add wear resistant alloys or more carbon but its going to be at the expense of something else. So its about finding a balance for me. Having said that I will have to try one of the super wear resistant steels eventually, like 10V, or a more moderate one like rex cpm M4, just so I can try it.

  3. #33
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    Quote Originally Posted by WillC View Post
    Thats the baby, great film
    Scrubbers!

    Thanks for the answer Will, your contributions here are most awesome.

  4. #34
    WillC's Avatar
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    So many classic lines

    Due to small tool breakage I got to get the two samples together for a weekend of abuse.
    One all rounder petty gyuto profile and another Pettysuki style. Both ground double bevel, coves, and taken as thin as normal at this stage. That is they have not been hand finished yet, so they would go a bit further after that. But they are relatively thin on the edge for sure. Here are the sample blades.




    And some geometry and bevel shots. The blades sharpened very easily. I set the bevels on 400 grit, and took them to 5000 with a brief strop. Anymore would be wasted, they push cut hairs nicely. No issues with sharpening at all. The bevels I set at 15 degrees per side.








    They are basically like a knife which as been thinned as far as it will go, after a couple of sharpenings, so just about the best place in terms of thinness vs edge retention.

    Will see what it takes to chip or distort the edge over the weekend and see what it takes to break a tip etc.

    So far a flex test on very thin edge towards the tip was very promising. The edge flexed a long way and returned. I was expecting to see damage to be honest on such a thin edge, judging from what I saw with my test piece, so that is a very nice surprise. I will push one to destruction at some point over the weekend, will see what happens in normal use and fair tests first.

    One thing to consider is that my core may have lost a tiny percentage of carbon, I did not use a carbon barrier or see the need as the start materials were very thick so I doubt it would be much and lets face it D2 has plenty to spare so it could only improve things. Plus a little carbon escaping is very pretty on a well finished blade.

    So far neither showing any sighs of distortion of chipping so actually looking good.

    The nature and feel of the edge is toothy. Even polished it really sticks in a nail, a nice edge for food at the moment I have to say.
    Will give a full report and updates and some horror damage abuse shots over the weekend.

    Yes I used damascus cladding for test blades, not very clever, but I think we will get a couple of nice knives out of these even if they may be a mill or two shorter after some abuse.


    And......... for laters.....

    Cpm 3v core san mai cooling in the furnace.

  5. #35
    WillC's Avatar
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    So far I have been abusing the Pettysuki in a most un kitchen knife like way, to establish the parameters of the steel.

    I cut through a steel can on a polished thin edge, this was expected to destroy the edge in someway, it was done with very little care. The edge rolled towards the thinest part towards the tip. Damage was very minimal however and any hint of ripple to the edge was removed on a *400 stone.

    I jabbed the tip in my board and bent the tip around to destruction. The thinest part on the end stayed bent, on bending it back the other way it came away. No more than 2mm was lost.

    Some edge further edge deformation tests, I hacked badly and while deliberately twisting the knife out of the wood through a 2 x 2 inch piece of wood. It took a while with a petty with no handle But there was no edge deformation whatsoever, intact the knife still cleanly shaved arm hair though was duller to the touch on the central part used for the hacking.

    Brass rod test once again, edge shows a very acceptable amount of flex, pushed to destruction and with considerable effort the edge distorts on a thin edge rather than chipping. I have not managed to chip the blade yet.

    So what does all that tell me, well , Im happy with the HT and the steel at around hrc 60/61, any more hardness than that and any less care during the prep and ht would lead to those little cemi circle half mill chips on a thin edge. I think the HT has made this steel stable enough on a very thin edge if required and it excels where the edge is just a fraction thicker.

    It gets no where near as fine a sharp edge as a fine grained steel like 01, it has teeth and bite from the off however, so this is as hoped and expected from nature of the steel.

    On edge retention. Hard to say, I will comment more on this tomorrow. But from these test it will handle some very heavy tasks even abuse and still make fine cuts.

    I will try the other blade on a pile of food tomorrow.

    Working out what to cook, I might get some chickens to deck with it for paprika chicken and a pile of veg and tomatoes for before and after test. Any other ideas or requests let me know within reason and bearing in mind a big test will keep me in dinner for a week

  6. #36
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    Right, just processed some dinner, with the more petty shaped one. I've worked up a fair appetite
    Quick strop and straight off into tomatoes so I can see how the edge feels. It push cuts and slices acceptably, sticks once on the skin. Feels nice in onions especially on horizontal cuts, and slicing. Felt a bit aggressive on push cut on onion. Carrots and leeks feels great and Peppers no matter if they are skin side up. So for all the veg prep it works and actually feels very nice through some tougher stuff and slicing. Then the chicken, it has a relatively thin edge for a knife to be pushed and sliced through bone, it really excels at this task. Made very very light work of the chicken indeed and I have the feeling it could have down it all day.
    Back to tomato and it cuts exactly the same, push cuts but doesn't feel great as before. No damage whatsoever to the edge, quick strop and good as new.







    So in conclusion for D2, yes with the right heat treat I can get a decent all round kitchen knife out of it. But there are better steels for that purpose, it just does not get as super fine sharp enough to give satisfaction on push cuts.
    But for tough stuff this steel with this HT I really like. I think I would like to consider this steel for hard use boning knives, that can turn its hand to finer stuff where required. It really excels over carbon in offering confidence going through bone etc on an edge which you would think too fine for that purpose.

  7. #37
    Senior Member zitangy's Avatar
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    Quote Originally Posted by WillC View Post
    So in conclusion for D2, yes with the right heat treat I can get a decent all round kitchen knife out of it. But there are better steels for that purpose, it just does not get as super fine sharp enough to give satisfaction on push cuts.
    Hi Will,

    Interesting observation..

    Push Cuts. Being superfine sharp may not have direct relation to ability to do a satisfying Push cut.

    I have problems with push cuts on paper with my sharpening and I do not quite understand as to why it can do a pull cut beautifully and not the opposite ( push cut) when doing paper testing. In real life application I do not see much of a problem as a push cut exerts more pressure on the item being cut.

    One of the main reasons I suspect is the angle of the striations in relation to the edge or it cld be that there is more pressure on the item being cut and hence the feel is not the same.

    I could be wrong on these two points.

    Thanks for posting the WIPs.

    RGds
    d

  8. #38
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    Push cuts in tissue paper is a good one beyond thin rizla paper..........certainly not all steels are capable of being sharpened to that fine an edge. Or the hanging hair test. Damascus is a mistake for the edge of a straight razor, there is no way I would make a razor from D2 either
    Once you have ruled out the variations, angle, level of polish on the edge, etc....you realise its a steel thing.
    01 I can get sharp enough to push cut tissue paper as can 14c28n. Larrin has put up some excellent micrographs of the edges of cpm 154 vs aeb-l. A steel with larger carbides, won't be able to take as small a radius edge as a fine carbide steel.
    Its a feel thing really, but the result is D2 feels different in food than 01. Its subtle but there. And in some cases it gives some advantage in slicing and cutting through bone.

  9. #39
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    That pettysuki looks like a cracker Will. If it ever fancies a short trip to Bristol for further testing...

  10. #40
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    Tim it could be really handy to have an individual near by for quick second opinions. Do please shoot me a pm with your details and usage. I actually get over to bristol quite allot, I have friends in the area.
    These two, as are damascus and i'm happy with them, I will finish and sell in the next couple of week to help balance costs.
    I have another plain stainless clad blank in D2 core I would like to be a Garsuki, I enjoyed this on chicken so much,
    I think that would be a cool knife to use D2 for as would Atso Deba and Hankotsu was another idea. I have other steels to try too though.
    Then there are the two in cpm 3v core. These will be medium size Gyuto, 220mm ish.

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