School me on 52100

H

Hesparus

Joined
Oct 31, 2004
Messages
1,442
Hi Everyone,

I'm going to be buying some 52100 from Aldo very soon. It will primarily be for kitchen knives, but I will also do some EDC blades and probably some outdoors knives. I will be doing stock reduction and having my HT done at Peter's. Is there anything I need to know about using this steel before I get started?

Thanks,
Chris
 
If you are having your HT done at Peters, you shouldn't have too much in-house to worry about. It acts like a normal high carbon steel for grinding. You may want to consider RC's above 60 for kitchen knives- 62 Rc, with a good thin edge, will be quite tough still for a chef knife edge. Especially compared to VG-10 or something.

I don't know to what extent Peters will be able to prevent or correct warpage- so I don't know how thin you ought to grind blades before HT with them. Maybe send them a smaller blade or two, 6" or 7" santoku or chef, ground down to .020 at the edge and see how those do. If they come back warped, maybe go to .030 before HT. Grind 'em down thinner at the end with sharp ceramic belts at low speeds. The 984 Cubitrons are reputed to do well staying sharp at lower speeds, I bought a couple last time and so far they are very good.
 
I routinely send blades (including three in 52100 a few months ago, and several blades in various steels that were quite thin overall) to Peters, ground all the way down to .015" at the edge, and have yet to have a warpage problem. Any thinner than that, it gets kinda dicey... but it doesn't matter much because .015" is basically ready to sharpen up and go to town.

I didn't have any trouble grinding or drilling Aldo's 52100. It was nicely annealed, and very clean. Ask him to surface grind the mill scale off for you - it only costs a few bucks and saves a fair amount of time. I think you'll like working with it, and cutting with it :)
 
Thanks for the advise, guys! RC62 is about what I was planning on for my kitchen knives. If I wanted to go higher than that, what's the upper useable limit for 52100? What hardness would you shoot for on EDC or hard use knives? What edge thickness would you go for on these knives?

- Chris
 
I think 62Rc is about the max. I had mine done to 58Rc for toughness (they were tactical knives)... it's still fairly wear-resistant. I grind my edges to about .015" on pretty much everything... maybe a little thinner on kitchen stuff. I let the steel selection/HT, and in some cases final edge angle deal with any toughness/chipping issues. It's pretty surprising how thin you can grind good steel to make it really cut well, and still have durability pretty darn similar to thicker edges.

Here's Latrobe's datasheet on their version.
 
Personally, 60 Rc ish with a variable temper for hard use, with an edge more like .015 before sharpening.

For a really hard use knife, FFG to an edge thickness of .040 or so, then convex the edge down to .015ish. Draw the back to gray blue, and the tip to purple.
 
Chris, or kitchen knives you probably want to look at Kevin Cashen's website to get the numbers for austenizing 52100 below the "saturation line" Kevin did some in salt at 1475, which is 50 or more degrees below the normal temp used to making bearings and then oil quenched it. That gave an as quenched hardness as high as 67!!!!!!
 
Hesparus, that is what I mean.

67 is screaming hard. I recall that from Kevin as well, wish I had heat control that good.
 
But you can still specify the austenizing temp, can't you? You may not going to get quite that hard in a fluidized bed setup, but it will still be hard, have fine grain and carbide structure and probably without a lot of RA.
Hesparus said:
Thanks!
JDM61: I've read that, but it's moot since I'm outsourcing my HT.

- Chris
Click to expand...
 
Hesparus said:
I hadn't thought of that — I guess I can check.
Click to expand...

I think Joe is raising very good questions. I'm tellin' ya bro, call Brad and ask him. He probably knows more about this than all of us put together, and there's a very good chance he's dealt with this application before. Plus, he's a lot of fun to talk with :)
 
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