This knife has a excellent edge stability
I'm wondering how if would do in a dend test ? Would it shatter?
70rc 15V would fracture when exceeded yield point. This knife edge accidentally hit a 7/32" dia screw in wood and chipped ~1.5mm (visible height, removal depth maybe 1.2mm). In video, this chip is present and didn't served as a liable stress riser - otherwise, this blade would split into 2 pieces. From this behavior & my projection, if knife chops a 16d with brick/hardwood backing, edge would chip. Chip size would be inverse proportion to bevel angle and behind edge thickness.
70rc 15V has very high bending strength ~3-4GPa however bending/elastic range/angle will be ~1/3 of spring-tempered-steel, due to extra high carbide volume. So, if blade batons a 3+" dia of twisted log, when lateral bend/flex with very small bending radius (in this case) beyond elastic, then blade would snap in half. This type of baton would also be destructive even for steels with some plasticity, once yielded (set/stay-bend), strength dropped so easier to enter fracturing zone.
I will put a working/sustain edge geometry for this 15V knife/chopper - ~18-20dps, 0.020-0.025"BET. It gives 50-100% stiffer/stronger edge, which mostly for resists side/lateral flex/bend.
Chris "Anagarika";16916929 said:
I see another breakthrough. No chopper was made at 70 HRC.
:thumbup:
Luong,
You keep churning improvements, hard to keep up, even for a merely lurker/reader.
Thanks, Chris!
There probably are choppers with hardness 70+rc, however also probably mostly wall-hanger or have edge geometry of cold chisel.
Around 2 months ago, I re-hted bodog's 15V blade to 70rc. It passes my suite of pressure-cut tests. This result pushed what I thought was a ceiling of stable/usable carbide volume, 10V (~2.4-2.5%C) at that time. My recent re-hted my small cpm rex121, confirmed working edge stability at 70-72rc. Sure, sharpening was tricky at first but after a few iterations of sharpening+microscope... heheh I've a pic of rex121
From here, I can slightly flatten the apex with DMT EE (3um) to a flat fline - to erase Extra Fine jagged. Then apex EE, jaggedness will be at EE level. Use 0.25um with hardbacking to further refine but rounding a tiny bit - maybe adding a few dps convexing in 2-5um apex vicinity.
This pretty much sums up my stainless steel experiences with conventional HT, but haven't tried them all.
Getting any s*v steel on par with conventionally HT'd M4, is a giant leap.
I would be thrilled to death if my s30v blades were even close to being as stable as my m4 ones.
~64r in pressure/push cuts (low lateral) + 1-3um apex radius = S90V; 20CV/M390 would out performs M4. S30V par with M4.
~64r in impact & high lateral forces interactions + 1-3um apex radius = M4 wins easily over S*V. Aebl(class or ss with less carbon) & Niolox would be more fair for neck-to-neck comparison. Of course M4 will be a bit ahead in wear resistance area (*note: way ahead when interactions have higher draw/saw component).
Working around my yard with test blades (15dps, 0.015" BET): S30V 63rc - dulls by wear (not fracture). Ditto for 64rc 20CV & S90V. S90V has best edge retention among 3. No problem with chopping small green+dried branches, palm fronds - all soft stuff anyway. In mood of destructions, all 3 blades chipped when hard chop into Lignum Vitae Argentine. With a clear understanding of edge tool limits, we certainly can pick the right tools serve us best... Must be in pair of operational specs/requirements and tools that met specs. So if specs call for deflecting chops behind the shoulder swing while blind folded, well get a right tool for that
It would be great if there was some kind of external validation by someone who tried to replicate this HT
Bodog can hardness test his 15V blade I re-hted to 70rc for him. Also could up another level by test the blade composition - just to make sure, I didn't swapped 15V to some other steels (rex121, zdp189,...).
If someone like to hardness test & analyze steel composition of this 70rc 15V chopper - I am open to send it out for attributes verification and some performance test as well.
This 2 15V blades were CWF HT version 1.2 (advanced since published version 1.0). Also 1.2 tuned for high alloy stainless such as S90V, etc...
talking/posting to myself but hey it's for the record.
I saw on Russian Sites knives on 70rc but I have no idea which steel they use ? What is next ? Diamond is only 100rc 
