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    WillC's Avatar
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    Some destruction testing!

    So I bought some steels form Hitachi to test in san mai.

    The idea will be to use it with my damascus as cladding and try some stainless clad too. I went for the YCS2 and blue paper 2 as they are both oil quench steels and can Ht in the same range as my damascus steels. The tempers also look good. At a 200 degree temper the clad should be about 58hrc, the core 62/63.

    I got some billets together in both steels, just to test I used en9 cladding and a layer of 75ni8 then blue paper/YCS2 core.
    They both got 3 normalizing cycles, then ht'd in the digi oven towards the lower end of the recommended temperature range. Both were tempered at 200 degrees. My thoughts are I will find what results I like best then get some hrc testing done to check all is as I assume.

    Ground them up and got them honed. I expected the blue paper core to be a pain to hone, it was very nice even at this hardness, easier than the YCS2. I like the edge off it too.

    Next I started trying to chip the edges. I could chip the edge of the YCS2 core with a lighter and considerable pressure. The chips were coming off LARGE, with a little distortion present before the chip. I couldn't chip the blue paper core with a lighter, I had to use the edge of a cast steel vice. Chips with much more limited in size, again with a little distortion present before the chip. Neither steels showed signs of microchipping in chopping tests prior to destruction I should add, so quite stable really considering the hardness.

    Next I did a bend test on each, they both got to about 50 degees before giving out in a clean break about 1/3rd of the way from the tip. I'd hoped for better with the cladding.

    Both showed a little distortion towards the break. A break though would not occur during normal kitchen use, loosing a bit off the tip would be very probable though at some point, if you dropped it in the sink or poked the tap with it. Loosing tips does seem common with 61hrc+ Japanese or custom kitchen knives?
    The grain structures are interesting, even just through a x10 Loupe, the core is visibly smaller grain to the cladding. The Blue is visibly smaller grain to the YCS2, though this could be variations in HT. Must add a microscope to the lottery shopping list

    Not very scientific yet, but just getting a taste of the steels. HRC sample tests will follow. I've made another of each and got the blue one ground, i've been using it daily for a week and it still pops hairs off my arm.

    Generally at the moment, I'm really liking the Blue, though I'll try both with a slightly higher temper and the full damascus clad. I have a feeling I will like the blue best at around hrc61/62 and the YCS2 a little lower 59/60. The blue is four times the price of the YCS2 Both are very over priced, but as a core material it could work out ok.

    Must get myself some of that V2 to try if they will sell me any.


    Blue chipping, repairable, and only possible with some serious force.

    Monster chips in the YCS2, some force or misuse required.


    YCS2 Analysis: C 1%; Si 0,5%; Mn 1,1%; Cr 0,6%, P<0,03%, S<0,003%.

    Blue Paper 2 Analysis (C = 1,1 - 1,2%, Si = 0,1 - 0,2%, Mn = 0,2 - 0,3%, Cr = 0,2 - 0,5%, W = 1,0 - 1,5%, P < 0,025%, S < 0,004%)

    To be continued.......

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    This.
    Is.
    Awesome.


  3. #3
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    Quote Originally Posted by johndoughy View Post
    This.
    Is.
    Awesome.

    +1 and yes, tip breakage (or permanent damage/deformation) is quite common regardless of steel, actually.

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    WillC's Avatar
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    So far testing in this harder range seems tip damage is more limited if you have just stabbed the tap by accident or something. With my 1085 like steel at about 58hrc, the tip would likely bend over at 90 degrees just on the end, then break off on the hones. Lossing a bit more in the end, with these only the very end seems to chip off, only 1mm or so. But stabbing a bit of wood and bending it over would result in loosing much more, but that would either be very unlucky or abuse! Whatever, the cladding isn't going to protect the tip, but it might be a little insurance on getting a blade back in several pieces at least.
    I suppose most of the hard mono-steel white or blue blades are differentially heat treated? Or drawn off on the spine.

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    Hmm. Good to know. I'm under the impression that your are correct on the differential HT but don't honestly think it has anything to do with off-setting the brittleness of knives hardened beyond 61 hrc, per se. I could be wrong.

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    WillC's Avatar
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    Got some more samples HT'd last week to break to check the grain size. Andrew suggested I try a veho usb Microscope, It works pretty well. Here are the shots from the broken samples.
    En42J

    75ni8

    Silver steel

    Blue Paper 2

    YCS 2

    01


    All test pieces had 3 normalizing cycles, then HT'd just a smidge above their lower range. All quenched in warm oil.

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    WillC's Avatar
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    I was quite let down by the silver steel on the grain examinations. I hoped it would be smaller grain than that. It does take a great edge but can be quite brittle and chippy even at 60hrc, maybe that is because of the lack of strength in the large grain structure?
    Here are two test knives I haven't destroyed. I've been throwing them at everything with a luster. Chicken, beef on the bone, hacking through lumps of wood, etc. Both have performed very well without chipping or distortion.
    The little one is Blue paper core with en9 cladding. The big Suji is damascus clad 01. They get equally as sharp, the 01 a slightly less aggressive edge. The blue is at 62 ish the 01 I have taken back to about 60hrc. It shows remarkable edge flex. I need to do some more testing with 01 as I can get it in the sizes I need for mono-steel. I'm still liking the look of the blue for a high performance damascus/clad option.

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    This is fantastic! Excellent!

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    Quote Originally Posted by WillC View Post
    I was quite let down by the silver steel on the grain examinations. I hoped it would be smaller grain than that. It does take a great edge but can be quite brittle and chippy even at 60hrc, maybe that is because of the lack of strength in the large grain structure?
    Here are two test knives I haven't destroyed. I've been throwing them at everything with a luster. Chicken, beef on the bone, hacking through lumps of wood, etc. Both have performed very well without chipping or distortion.
    The little one is Blue paper core with en9 cladding. The big Suji is damascus clad 01. They get equally as sharp, the 01 a slightly less aggressive edge. The blue is at 62 ish the 01 I have taken back to about 60hrc. It shows remarkable edge flex. I need to do some more testing with 01 as I can get it in the sizes I need for mono-steel. I'm still liking the look of the blue for a high performance damascus/clad option.
    Watcha gonna do with those testers when you're done?
    Though I could not caution all I still might warn a few; Don't raise your hand to raise no flag atop no ship of fools. - Robert Hunter

  10. #10
    WillC's Avatar
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    I'll be continuing to abuse them for a while. Neither are perfect, The petty has a slight bow to the edge, (very slight). The Suji has a couple of dirty bits on the weld line on one side, I wouldn't say flaws, just slight visual imperfections. I'll drop you a pm.

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