Tempered too far. Fixable???

[happycat]

I heat treated two knives last night and things didn't go quite as I had hoped. I'm using 1095, and heating with a torch to a nice bright red/orange (i've done test samples until I know the right color. It's so subjective to describe it.) I then quench in olive oil. After cleaning up the blades to get rid of the oil, I heat them in my oven at 450 until they turn light to dark straw which (I'm told) puts me somewhere in the 60 range (rockwell). Well last night I got wrapped up in my email while the knives were cooking and thry are in the "full vermillion to peacock range with some blue on the edge ( which acording to my chart puts me in the mid 50's

My question is this: Can I simply re-heat treat and re-temper? Or are these doomed to be on the soft side? HELP!!
HappyCat

 

[Ed Caffrey]

You can give it another try, as long as the edges were left a little thick (about the thickness of a nickel/quarter), if you have a magnet laying around, us it to test for critical temp as you heat, you will be surprised at the color difference when the magnet lets go, vs what you thought it should be. Your eyes will sometimes trick you, but the magnet will never lie. When you temper, pre-heat your oven, and let it cycle a couple of times before putting the blades in. When heated with a torch/quenched, 1095 will perform very well in the high 50s RC. When you get into the 60s with 1095, depending on grind style, you are likely to wind up with edges that will chip. Just the nature of the beast.
http://www.mtn-webtech.com/~caffrey

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Ed Caffrey
"The Montana Bladesmith"




[This message has been edited by Ed Caffrey (edited 31 August 1999).]