Hand Tools

Subject:
see the end of my statement..
Response To:
toughness not necessary? ()

David Weaver
...anything that can charpy notch at 10 ft lbs or so is fine for woodworking tools.

White steel, which generally makes the best performing chisels in any kind of tests has less than 10 ft lbs of toughness.

52100 has drastically more toughness and fares poorly in my tests - a foil starts to form when it begins to deform and then the foil remains and seems to help propagate more damage. Even when the steel is relatively hard .

I'm curious as to whether or not it's so tough that can just be used barely tempered (but the hardness would be so high that almost nobody would like it).

In terms of snapping untempered samples, 52100 is far harder to break off in the vise than a tempered commercial file. It's nutty. It's more or less the toughness version of 3V, but with the potential to go much harder. At "normal" hardness, the toughness is a detriment.

When you get into the really coarse carbide steels with high volumes, those tend to not hold a fine edge well, and are described in the knife community as "good for a coarse edge". Their notch toughness values are also very low (4-5). CPM Rex, which is at the top of the list for edge retention is coarse and has a notch toughness of 2.

D2 (non cpm) has a notch toughness of about 5 (at a normal hardness). It also has a reputation for not holding a fine edge, though some of that may be due to carbide coarseness (the two are probably related, but coarseness isn't the only factor for toughness. O1 is at least as fine as 52100, but it's less tough. It almost certainly makes a better chisel because of it, something I can test down the road, too).

Avoiding deformation, though, is more important than being able to tolerate it by deflecting (into a deformation) without breaking.

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