A-2 Hardness

G

gshamr

Joined
Jan 18, 2002
Messages
178
I finally have enough money and have ordered a Sugar Creek knife oven because mailing mulitple large knives to be heat treated gets really expensive.

I have multiple large knives ground out of A-2 that I will be heat treating. A few of them have blades over 15". (I bought a lot of this from flatground.com a couple years ago when they had a sale on A-2)

My question is whether 60 RC is the best to shoot for on really large knives. I understand that it is supposed to be the peak point for A2 impact resisitance and had knives hardened by Paul Bos to 60 RC. The reaon I ask is that some factory makers of A-2 hard use knives a lower RC of 57 or 58. What is the purpose of this? Am I confusing impact resistance with something else? Thanks.

I want to specify that these are hobby knives only for my personal use.

Gerry Hamrick
Snohomish, WA
 
There's a toughness peak at 500 F which will give you 60 HRc, so that's where you go !
 
Ok, thanks. I thought it might be for people using their knives a prybars or to dig with. I'm going to head for 60 rc then. I appreciate the info.:)
 
http://www.bucorp.com/files/aisi_a2.pdf

The site above is the data sheet for A2 from Uddeholm Steel. It has the most detailed info on A2 heat treatment I have found. I have been using it since 2001. I shoot for HRC 60, harden at 1750. I do soak for 45 minutes which is a few more than the specs. I do three tempers for two hours each 400°, 450° then test and go to 500° for the third if needed to get HRC 60.
 
Last edited:
I realy like A-2 steel and I always bring the oven up 1500 F put the foil wraped blade in the oven let it woak for 10 to 15 minutes then ramp the oven up to 1775 F and let the blade soak for 20 minutes or so then I plate quench and temper it at 500 F twice for 2 hours each and they always seem very tough and good edge holders.
 
Last edited:
The Charpy impact strength is a measure of transverse toughness of the steel, A2 peaks at 41 lbs at 55 and 60 HRC and drops off in between.
At HRC 58 the Charpy C -notch test for A2 drops to between 29 and 33 lbs (per Crucible Data Sheet).
 
Last edited:
what ever works,,, they make all kinds i just try to snap the tips off,, my edges are not a question,,,, just my real world observation,,, and my opinion
 
Steve Hayden said:
The Charpy impact strength is a measure of transverse toughness of the steel, A2 peaks at 41 lbs at 55 and 60 HRC and drops off in between.
At HRC 58 the Charpy C -notch test for A2 drops to between 29 and 33 lbs (per Crucible Data Sheet).
Click to expand...

.






.
do your thing,, I'm sure your Data is accurate,, I just know what works for me on Knives,,
 
Are impact toughness and resistance to breakage due to bending measured the same way? Maybe I'm confused but I don't see how something being used as a prybar has anything to do with impact.
 
There is a significant difference between transverse and longitudinal impact. Transverse is the problem.Check Crucible's CPM steels and you'll see that the steel making method greatly improves transverse impact strength !!
 
While we're on the subject of A2, how thin can the edge of a knife be ground before hardening? Does the air hardening allow it to be ground to less than 0.02" before hardening without warping or cracking?
 
It can,, I leave about .035. Usually,, there abouts but you can go lower,, I leave more up by the tip, like .080 or more the last 1/2 inch of blade or so,,
 
me2 said:
While we're on the subject of A2, how thin can the edge of a knife be ground before hardening? Does the air hardening allow it to be ground to less than 0.02" before hardening without warping or cracking?
Click to expand...

I think the warping all depends on how you ground the blade in the first place prior to heat treatment and how thin the knife itself is at the max thickness and overall length of the blade itself. Blades for instance ground out of 1/4" stock at around 10" overall most likely will not warp, where as something in the 15" length and over will likely warp a little...no big...just straighten with a vise. What i have noticed with A2 is that you can still straighten it even if it falls below 400'F :eek: and it won't crack or chip !
 
You must log in or register to reply here.
Back
Top