Cracked blades

F

Forged For Combat

Joined
Nov 15, 2011
Messages
12
Hey everyone, I'm new to the forum and i have a question. I just started making knives a few months ago, and lately I've had some blades crack. I've noticed cracks parallel to the blade edge. I'm noticing them after the heat treat, when I'm starting to sharpen the blade. I'm using 1095 Hi carbon steel from Jantz knife supply, 3/16 in thick, quinched in 30w motor oil. Any suggestions? Or help would be great.
 
Hey everyone, I'm new to the forum and i have a question. I just started making knives a few months ago, and lately I've had some blades crack. I've noticed cracks parallel to the blade edge. I'm noticing them after the heat treat, when I'm starting to sharpen the blade. I'm using 1095 Hi carbon steel from Jantz knife supply, 3/16 in thick, quinched in 30w motor oil. Any suggestions? Or help would be great.
 
MOOving_on.png


This thread should be MOOved to the Shop Talk - BladeSmith Q&A forum
 
I was just gonna suggest that the OP post this in Shop Talk instead of general discussion.
 
heres what i use.

1095
slow heat to 1475 , soak for 4 to 5 min bigger blade , smaller blades 3 to 4 min.
Oil should be 130 to 140f. Park#50
Temp @450 2 times for 2 hours at a time, with cool-down between
vern
 
I'm told that 1095 is a difficult steel to HT properly. I would guess that you're not using the right oil, and the oil isn't at the right temperature. Canola oil is commonly recommended, but you'll want to search around in the knifemakers shop talk forum to get the exact temperature. Or, you can do what I do and send your knives to Darrin Sanders for heat treat. He did a great job with my 1095 blades.
 
How thin are your edges? You might have it too thin before HT. Should leave it about .020-.030 before HT. Also you might want to look into getting a quench oil, as motor oil will not harden the shallow hardening steels. Or you could switch to 5160 or 1084.
 
Additionally, are you forging these blades or using purely stock removal? Forging brings in some other variables that could contribute to your problems.
 
Probably overheated and too slow of oil.1095 requires a very fast quench.
Stan
 
I merged this thread with the other of the same name - Double thread.
 
Last edited:
Do a quick polish (800 to 1000 grit) on a small portion of your next blade and before heat treat soak it in vinegar for 10 minutes, then rinse it, rinse it with alcohol, and air dry it. Look at it under magnification and if you see fine parallel lines runnning about where you were getting cracks you might have carbide segregation banding ( a real problem with Admiral's 1095 and Jantz might be getting their 1095 from Admiral) this would only be made worse by overheating and not using the proper oil. Read Kevin Cashen's stickey on working with the three steel types, pay particular attention to the section on hypereutechtoid steels (1095 IS a hypereutechtoid steel)

You are probably getting serious pearlite precipitation in the motor oil because there is no way that motor oil is going to cool your steel fast enough to get in under the "pearlite nose" portion of the TTT curve, and that alone will give you a seriously brittle knife, all of the other things listed are just adding cars to your trainwreck.
how are you heating your blades? how are you controlling your austenizing temperature?

My suggestions:
Buy some 1084 from Aldo (www.njsteelbaron.com)
buy a gallon or two of canola oil until you can afford a real quenching oil and recycle your used 30 weight oil in an environmentally safe manner
preheat your canola to 130 degrees f

READ THE BLOODY STICKIES THAT IS WHAT THEY ARE THERE FOR!

Welcome to Bladeforums, I'm here all week (try the fish)

-Page
 
All of the above, plus preheat the tempering oven before hand and then after quench RUN to the tempering oven!
 
But if you run, make sure you are cleaning the oil off the knife before your put it in the oven or your wife will be very angry after about 15 minutes!
 
Aldo Bruno said:
Sounds like you may have had the experience:)

Page, be nice.
Click to expand...

Please read the stickies. There is a lot of really really really great information there that will help you avoid a lot of problems in your knifemaking career

-Page
 
You must log in or register to reply here.
Back
Top