Hand Tools

Subject:
it'll take a very long time to know this!
Response To:
Consider fatigue as well ()

David Weaver
hah....I've read a lot about 52100. I've made a couple of plane irons the poor man's way, which is just to make sure they get to heat, go a little above by eye where they would need to go by temperature schedule (and not for long) and then quench and temper.

I understand that 52100 likes two things a whole lot if it's really going to be optimized - lots of forging to shape (which generally results in a pretty decent microstructure without much thermal cycling when the steel is water hardening or fast oil hardening like 52100), then normalization (which I don't do, at least not like a schedule normalizing. Getting to temp for me is a one to two minute thing and then not much else - not sure about the chromium and whether there's enough to have issues with temp, but chromium is problematic between 800-1400F or something, so I don't let much of anything stay in that temp range other than air cooling through it.

At any rate, I hear from the knife people that it's "almost impossible to get right without a furnace" and guess they are doing some extremely demanding testing as both of the irons that I made planed wonderfully and the edge wore uniformly - so does O1. I'll post some pictures - interestingly, while I can't see the grain in irons, I can see how fine it is by the pattern of wear in the irons. 1084 doesn't wear that long (75% of O1 maybe?), but the uniformity of the wear is no less than spectacular.

O1 and 52100 wear really nicely and then as you go up from there, things get worse (the PMs generally do OK, too - the wear looks different because their structure is different - at least from what we can see visually - and if they don't encounter anything damaging, the surface left behind is nice and bright).

As for differentiating chisel damage early vs. late - I tested what what I'll refer to as the crayon test on a japanese chisel. Several minutes of pounding in an attempt to get the chisel body warm enough to melt a crayon. That was attainable - the edge showed nothing more than burnishing, but the handle juncture (ferrule, wood, tang) didn't survive. Fortunately, the tang was fine, but the rest of the assembly took some damage from ovezealous pounding. The steel in that chisel would be regarded as not very tough, but finding the sweet spot with tempering (still very high hardness, almost too hard to get an india stone to do much) and then a little buffer edge protection and it's definitely a better performer than any commercial western chisel I've come across.

It's not better in a way that's needed, but in a way that's interesting to someone making chisels.

(the source of the battering was a large 750G metal hammer - the edge outlasted my stamina by a long shot).

I will ultimately keep (for me) at least one set of heller file, one of 52100, one of O1 and 1 of spicy white if spicy white turns out OK. A torture test could be in order then. I'm tempted to also make a set out of 1084 - it has less potential, but there's little fe carbides in excess in it so it really optimizes easily just with typical shade tree harden and temper and can get "hard enough".

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