I want to like 52100... but..

[Troop]

Thank you, Ed. I understand what you mean now.:thumbup:

 

[Mike Krall]

The small amount of precipitated carbides in O1 during cryo won't bring it anywhere near the carbide volume of D2. The wear resistance numbers are bogus.

Larrin,

Is there anything about the .pdf "69_knives" put up that is sound... is it just the wear chart being impossible?

Mike

 

[69_knives]

Ed, your info and experience is greatly appreciated. Thank you.

 

[Mike Krall]

Here is what I do:
3 post forging quenches, from critical inroom temp texaco type A oil, 35 seconds a quench.
2 flash and one full normalize - critical to room temp - 70 f. then to the freezer overnight.
3 annealing heats 988 f. for 2 hours, slow up in the Paragon - slow cool to room temp then to the freezer overninght.
Grind the blade oversize, polish to 220 grit.
Differentially harden harden 3 times - let the blades cool to room temp in the oil, then in the freezer overnight - 3 days.
Temper 3 times, in the Paragon cool, to 388 f, for 2 hours, cool to room temp in the Paragon, then back to the freezer over night each cycle.
Blades Rockwell 60 - 61, but will scratch a 62 Rockwell steel.
Photomicrographs reveal no measurable retained autenite in hardened zone.
Grain size 14 and finer.

For best results you have to set the table for this system to work, high rate of reduction by forging, low temp forging - 1625 f top temp. Many thermal cycles.
and the three post forging quenches are very significant - very uniform grain and no blade warp.

We have found that when blades crack in heat treat (52100 and 5160) it is usually due to forging too hot - overheating - or faults in the steel. I have not had a blade crack using quality steel for over 15 years.

We have found that while vanadium = fine grain it also reduces toughness significantly.

Troop - Joe knows what he is doing, a good man to listen to.

We have found that if Cryo. results in a significant difference in performance, you need to modify what went before to be more in harmony with your steel and make up the difference that way for the performance qualities we like to see in a blade.

Ed, would you say what temp. your "critical" is and/or how determined, both for the "post forging quenches" and "differentially harden 3 times", please.

Also, in "differentially harden 3 times", I assume Texaco A and is it room-temp. as in "post forging quenches", or... ???

Mike

 

[Ed Fowler]

We use a magnet to predict critical temp.
Post forging quenches are in Texaco type A at room temp or maybe a little higher with the oil temp raising due to the heat of the blades on the first and subsequent quenches. Always for at least 35 seconds.
Hardening quenches are in Texaco Type A at 165 f.

 

[Larrin]

Larrin,

Is there anything about the .pdf "69_knives" put up that is sound... is it just the wear chart being impossible?

Mike

I didn't read it. It looks more legitimate than most articles/advertisements with similar charts.

 

[cotdt]

The small amount of precipitated carbides in O1 during cryo won't bring it anywhere near the carbide volume of D2. The wear resistance numbers are bogus.

I'm more interested in how they could possibly come up with such numbers.