A2 blades split down the middle at the butt end after heat treat

S

SamaraVolk

Joined
Apr 17, 2014
Messages
93
I heat treated a batch of A2 blades (4) and used a dry ice cryo. I was grinding one of the blades (post heat treat bare hands) and happened to notice the handle. Looking at the butt end, the knife is split in half. I checked the other 3 blades and noticed 1 other one with this problem. My guess is that I placed the blades in dry ice (with alcohol) and it thermal shocked the knives. They did make a strange "creaking" noise when I immersed them. I did not notice the cracks after the process though. Could it have happened later? Possibly during grinding? I plan on changing my process so I add the knives to the dry ice with no liquid, wait a half hour or so, then add the alcohol.
 
I've never posted a pic. It is not as intuitive as I hoped. Once I figure it out I'll post one.
 
I'm on Instagram as cold.war.steel if you want to see a pic. I have no idea how to post one here
 
SamaraVolk said:
I'm on Instagram as cold.war.steel if you want to see a pic. I have no idea how to post one here
Click to expand...

Here ;)
ngUu8B5.jpg
 
Woah! :eek: Looks like delamination, but it's mono steel...never seen a split like that.

~Chip
 
I purchased the A2 from NJ Steel Baron. 2 knives had this happen to it. Both from the same bar
 
I know from working at a tool and die shop that A2 is an air hardening steel, its one of the primary steels we use that being said however we usually heat treat bigger blocks of steel so you may not want to cryo.
 
Last edited:
I've made a couple hundred knives from A2, and have never seen that. I'd definitely be inclined to say there was something wrong with that bar
 
We have had that problem come up a couple times over the years on Shop talk. In all cases, the problem was the steel. Steel can be damaged longitudinally in rolling. Too cold on one side ( or a cooled off roller) and it splits down the middle as the colder/harder side tries to no move and the softer/hotter side does. It may get closed up tight in subsequent hot rolling, but the crack never goes away. In the stress of HT and cryo, it pops apart.
Contact Aldo and see if he has had a problem. Even if he says he had no reports of any problems, he should replace the steel.
 
Thanks guys. I'll contact Aldo. I slow ramped to 1450 and held it for 30 minutes. I ramped to 1775 and held it for 45 minutes. I dry ice cryo'd for 8 hours and tempered twice.
 
I've had this happen with S7 years ago although mine split while drilling prior to heat treating. It can happen at the mill while rolling the steel as Stacy mentioned. I'm sure Aldo will replace it.
Scott
 
SamaraVolk said:
The A2 is from NJ Steel Baron.
Click to expand...

The steel was sold to you by NJ Steel Baron. I was wondering if you knew who's steel is was. In my opinion there is either a significant stringer down the middle of that bar (does happen) or it was rolled improperly. In either case I think something went wrong during the manufacturing process of that material and I was trying to get a feel who's it was. Aldo didn't screw that material up, but he may be selling Precision Marshall steel which is advertised as made in USA but is actually processed in the USA and the material is imported. I've had issues with them before and started using Latrobe for my A2, which I have sourced through Aldo in the past, but there are many different flavors of A2 and I'm curious to know what flavor you used that did this. Thanks.
 
You must log in or register to reply here.
Back
Top