BCMW 66+rc W2 blade abusive chop tests and light chop at cryogenic temperature

BluntCut MetalWorks

BluntCut MetalWorks

Knifemaker / Craftsman / Service Provider
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Apr 28, 2012
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Instead of throw an old experimental W2 blade away. I decided to test my re-ht procedure. After hardened and few light chops into dried olive wood - it gifted me a big chip. Got to find out whether that was a precondition or my re-ht procedure has problem. Grinded & put on new edge - might as well documenting my abusive tests.

W2 1/8" thick with hardness
Prior: 63rc
New: 66+rc, 0.018" behind edge thick, 18 degrees per side

Abusive chop tests: thin metal tube, red brick, 2" thick aggregate concrete, 16d nail.

Edge after tests

MgjgBET.jpg


Thanks for watching(9m:20s video) & comments.

[video]https://youtu.be/HJpd64itaj4[/video]
 
Last edited:
After re-watched the video and re-examined the edge -> saw edge damages from chopping concrete with aggregates, which slightly more than chopped 16d nail.

fBAvPNK.jpg
 
Thanks, Chris!

Part of the edge is 30*inclusive but widest bevel is around 35-36*inclusive. Overall - as seen in video - I was surprised how well this thin edge performed/survived these harsh tests. Which mean, re-ht old blade is an option but pre-existing cracks/damages will carry forward.

Chris "Anagarika";16181488 said:
66HRC without big chip @ 30° inclusive? :eek:
Click to expand...
 
My videos sometime seem random but here is some context into cold temperature toughness

Excerpt from my post in another thread:

When optimize metallic materials for dealing with thermal contraction, keyed attributes:

1) Elemental - atomic. Opt for low temperature radius contraction. L6 counts on Ni

2) Crystal + adjacent elem. Opt for low temperature radius contraction. Many steels heavily padded with free alloys

3) Grain. Opt for smallest grain; cleanest gb and low dislocation (mis-aligned angles). Gotta be good ht

4) Inter-crystal (lattices). Opt for highest collapse coherency. Envision, Hoberman sphere as a high coherence lattices. Gotta be ludicrously good ht :p
​

1) for example Nickel can helps lower the transition temperature. So steep drop off in toughness won't happen until a colder temperature point than steels w/o high Ni%.

2) Reduce the toughness drop off rate, i.e. widen the transition temperature window.

For both 1) & 2) - once transition taken placed, their toughness will be similar to those steels without 1) & 2) attributes because of structural collapse by thermal contraction.

Perfecting 3) & 4) could make transition temperature concept inapplicable to this material. Whence its toughness only slight tapering off as temperature goes toward abs zero. I think, I made a small% progress toward this goal OR could be negative % as well :p
 
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