Forged blade chips

J

jimbowie7

Joined
Mar 13, 2005
Messages
90
Hi,

Forged my first knife today from O1, the edge is kinda thin, it's a good slicer -but I chopped for a while at a dried eucalyptus tree trunk and the blade chipped out along the edge. It's razor sharp -but for some reason can't use it to hack at dried hardwood.

Any ideas?

P.S. I tempered it at 350 degrees F for two hours.

Thanks.
 
With O1 you should go at least 400F if not up to 425F

At 350F the O1 blade is too hard and will chip like that. I'd use 350F on a hunting blade made of 5160....because of its lower carbon content.

Throw that blade back in the oven at 425f for a couple hrs and you'll see better results.....you'll see that the blade will show a nice straw yellow color after that.

Greg C
 
I'll jump in and give my vote for a higher temp also.

My neighbor has been my knife tester for several years. He works heating and A.C.

He USES a knife for a hammer, screwdriver, drill, bottle opener and lastly a knife.

I made up a bunch of BS knives out of 0-1. I started with a 350 temper on his first one, and ended up at 425 on the last one he got. He's still using the last one for over a year.
 
O-1 is my new favorite steel. My newest knife has been put through the wringer with days of chopping, can slicing, bottle splitting, cardboard dismemberment, etc....i took a while and put a really nice polished edge on it until it was beyond shaving sharp and popping hair above the skin, and it is still shaving without anything but a light strop after the tin cans....

I have already ordered a length of 18" 1/4" thick O-1 that will compose a nice competition-size cutter I plan to work on over the winter...for some reason Ive never had a HT on 1084 or 1095 instill this kind of edge, even though my HT methods are nearly identical.
 
It worked on one blade.

The other one's weird. The front half of the blade is fine, sharp as hell, but the rear half just keeps chipping when I try to touch it up with a Sharpmaker or chop wood -it seems like the edge is too brittle. ie. half of the knife is fine, the other half sucks. Shards of metal come off the edge when sharpened with a Sharpmaker.

Could I have overheated it or underheated it prior to quench? What happens if you overheat and get too much grain growth -will the edge chip out when you try to sharpen it with ceramic rods? Since it's O1 can I try the heat-treat again?
 
You might try tempering agian at just a little higher temp.
If you over heat before quench, should not be a prob, unless you soaked it or went real hot, usually the tip will over heat before the back half. Anyway if the higher tempering doesn't work, you can heat treat 01 again. Ever hear of multiple quenchs, 01 is an alot like 52100. Sounds like the edge is still way to hard on the back half of the blade.
 
Thanks for the reply Don.

I tried tempering at 450 for 2 hours and it still chips.

What happens if you leave it above critical temp for too long? Does this weaken the edge? Maybe I should quench it again...
 
Above critical for too long grows large grain in the steel which makes it weak, quenching again would refine the grain and may be all that is needed. You could quench two more times if you want, but watch the heat and do not over heat.
 
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