A possibility of high strength + high toughness hardened steel?

Interesting and very good answer. I get it and 52100 would be preferable.
 
bluntcut said:
:thumbup: Excellent and loaded questions.

When testing my edges, I look for a balance point of micro-roll and mini-chip when edge encountered damaging impact. For such impact, too soft = very big roll; too hard = large crescent chip. This 'balance point' solely depend on quality of the matrix. The finer the grain and smaller carbide, the higher this balance point will be. Higher balance-point, mean higher hardness and higher toughness go together.

I think, an ideal mode of edge degradation (for non-wearing type) would be micro-roll & mini-chip because this type of damage has less depth than big roll/ripple or large chip. Say as a kid, if ask to build a high arch 3" & 10" long 1" thick bridges out of lego. Arch = bending radius. Without much hesitation, you would choose micro lego instead of those honkin' 1" thick lego, right?

Technically, this balance mode is also applicable to 'wearing' degradation type especially when carbides serve as saw teeth. So ideally, the matrix hold onto carbide as strong & tough as possible, so ideal degradation would be a release of individual carbide rather taking out a chunk of matrix along with carbide. This way, intact matrix would protect other carbides, avoiding cascading failure. In super high alloy case, well, there aren't much matrix spacing between particle/carbide, so sometime cascade (big chip) is unavoidable if the matrix can't absorb the damaging energy. With an incoming 50cal, I would rather be behind a single wall of sandbags than a single wall of bricks :p

My current ht for low Cr steels with carbon 0.9-1.2% yield similar ultra fine grain sizes. Where 52100 has slightly more & larger CrC than in W2, so it gave up tiny toughness for gain in wear resistant.
Click to expand...


I would have to agree about the balance of chipping and rolling. The worst knife to fix of any Ive beat on was actually 420hc, because it had deformed so bad the apex was probably a quarter MM thick.
 
bluntcut said:
I think 80CrV2 CharpyC falls within a narrow range of 3V - hopefully that is not a too far fetch projection. It's far cheaper for me to make another or two 80CrV2 chopper than worry about a 3V chopper with 2 halves after some test. Most likely 80CrV2 carbide size is smaller than 3V, toughness #s should be higher when grain size is the same.

So my ht version 1.0 80CrV2 chopper at 59.5rc; 0.022" edge thick - CharpyC (CC) ~60 ft.lbs. End up with large rippled edge after the test. For this pin-knotted pine chop test, obviously the combination of edge strength+tougness was less than the test load. So with added strength at 62rc but reduce toughness to 40 ft.lbs (33% less), would this combination pass the test?

My guess is No, I expect it to fail when edge thickness is less than a generous 0.03" at this hardness.

Using my latest ht, I can make 5160 or 80CrV2 tougher & stronger but it will not be as good as 52100/W2/(wimpy tough 1095)/high-carbon-low-Cr-steels. When grain size is near or below 1 micron, toughness & strength high value curves won't drastically diverge to near orthogonal until 64rc or so. My ht works well for steels with composition with less than 2.5%X. Where X is combination of Cr+other alloying elements.

btw - Infi is similar to 3V, except it only has 0.61% of Carbon+Nitrogen. Extra toughness probably will extend the Young Modulus of fracture some but strength is more important in resist edge from being steer away by pin knot. Once small part of the edge steers past a few degrees of the apex line, reaching edge failure point is very rapid after that. Lowering edge bevel angle could reduce steering but proportionally lower the impact & lateral capacity of the edge.

From your assessment/POV... is combination of high strength + high toughness hardened steel possible?
Click to expand...


According to this thread, http://www.bladeforums.com/forums/showthread.php/1067237-Toughness-Expansion-on-Charpy-C-Notch-Values

3v at 60 rockwell = CharpyC of 60, which is the same as 80crv2 at 60 rockwell according to your tests. Wouldn't that make 80crv2 just as tough as CPM-3v???
 
You must log in or register to reply here.
Back
Top