Testing after heat treat

J

Joe W

Joined
May 9, 2000
Messages
59
I just tried heat treating my first four knives this past weekend. They are 1095 so I heated the edge to non-magnetic and quenched in 120 deg. 5w30 oil. Then I tempered in the oven at 400 for one hour. The blades had an even line 1/4" back from the edge. I decided to sharpen and test one before I finished them. I choped through a couple 1x4's and cut a bunch of cardboard and most of it held a razor sharp edge, even the part that did most of the choping. There are a few spots on the curve and near the tip that started to dull. Did I do something worng heat treating or is this normal? Does it get softer there because the spine is smaller?
I had them sitting on the spine in the oven. Is that right or do you just lay them flat.
Thanks, Joe
 
The best way to tell if that is "normal" would be to sharpen another one of your 1095 blades and test it the same way. One thing you can do to be sure of the temper is to buy a small oven thermometer. If the temperature of the oven is off that will affect your blade's performance. Keep your eye on the color too. It should have come out of the oven with a straw-yellow color. Clean at least one side of the blade off with 120 grit so you can see the color. My first 6 or 7 blades fell victem to the rigors of testing, sometimes destructive tests. I would not know what I do now if it was not for those broken, chipped, bent, and dulled blades.
 
Dear Joe, 1095 is a water hardening steel. You probably did not get the hardness you were capable of because you quenched in oil. The oil just does not disperse the heat as fast as water. Best of luck,,Ed
 
Here's what Engnath has to say about 1095.
"1050 to 1095 steel Brine quench from 1475 to 1500 F. hardens to RC 60 to 65. Draw immediately. Oil quench at the same temperatures for slightly lower hardness. Shallow hardening and can be done in the Japanese style with a decorative temper line."
I've had best results quenching in light oil with a fairly low temper. It cracks when water or brine quenched more often than not unless you're using refractory clay.
Joe, when you quenched your blades, did the edge touch the bottom of your quench tank? This can sometimes cause soft spots when the bubbles from the boiling oil insulate portions of the edge, causing them to cool just a little more slowly.

------------------
Oz

"Sticking feathers up your butt does not make you a chicken!"
http://www.freespeech.org/oz/
 
Oz, no the blade didn't touch the bottom. I used a crock pot to heat 3 quarts of oil, and the blade was 1 1/2" or more from the bottom and side.
I picked up an oven thermometer today so I'll check the accuracy tonight.
Thanks, Joe
 
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