What when wrong with my heat treatment?

Thanks Sunshadow, but I don't think I will be heat treating it again. Is there anything I can do to straighten out the tip?
 
Keith_H said:
Thanks Sunshadow, but I don't think I will be heat treating it again. Is there anything I can do to straighten out the tip?
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To try to fix this one you would have to anneal, straighten, normlize, remove your decarb, and re-heat treat. You don't want to hear this, but you've just ad a learning experience. This one should join the dreaded pile under the bench, you will be better served by starting fresh with a clean piece of steel. You will spend a lot less time and frustration.

sorry
-Page
P.S. I still occaisionally end up with 'one for the pile' . In 25 years I have built up quite a pile, I learned a long time ago that it's not worth the aggravation once things get to a certain point
 
For the oil the temperature should be between 90 and 140 F to measure that I used one of those cooking thermometer for meats, I stick the needle in the oil and read the temperature, if it's not warm enough I heat up another piece of steel an drop it in. As for the oven, you could invest in one of those toaster ovens they're very cheap new, check on craigslist they might have a couple used for even cheaper, there's always ppl moving that need to get rid of their stuff. Or buy a thermometer that can be put in the oven.

This is for the oil:
http://www.chefsresource.com/proaccurate-instant-read-cooking-thermometer-cdn.html

This is for the oven:
http://www.chefsresource.com/masuth.html

Hope this helps

Dario
 
As for the oil, the last time I heat treated this I had a candy thermometer in the oil and had a few chunks of steel with the blade to throw in. The problem is is that by the time that you open the door to throw warm the oil, the oven loses 300 degrees. I dropped some metal in there but the oil only went up 10 degrees :( Then it takes another ten minutes to get it up to heat again. I am positive that if I had the right equipment I could do a perfect heat treatment. One thing I did learn is that a piece of 500 degree metal would warm the oil better that 1500 degree metal.

As for starting fresh, I have to send this knife for the Christmas gift exchange. I filed out all the bevels so I have invested too much time in this to chuck it.
 
To warm the oil, I use a hot plate and the oil is in a large stainless steel pot. I tried heating the oil by dropping in hot chunks of steel once, and found it way too slow and inaccurate (for my very limited patience/attention span). Be sure and stir the oil to equalize the temp throughout.

--nathan
 
What i use to heat my oil.... http://www.walmart.com/catalog/product.do?product_id=7788888&findingMethod=rr

A cheapo 25$ GE roaster oven with removable internal tray. That and i have a long stem meat thermometer that goes from 40 to 300 that i sit in the oil to know when it's at temp. On the GE roaster oven i've got i need to set the 'temp' on the outside to a little over 200 to get 120 degree oil. (i've got 2 gallons of oil in my pan)
 
Keith_H said:
As for starting fresh, I have to send this knife for the Christmas gift exchange. I filed out all the bevels so I have invested too much time in this to chuck it.
Click to expand...

good luck. Don't try to bend your blade in hardened-tempered state. it will crack before it bends. you will need to anneal it before attempting to straighten it, then normalize it after straightening it, then grind off your decarb, then re heat treat it, finish grind it etc.

good luck, take pictures
-Page
 
I know what went wrong. After referring to colour charts, I have found that the temperature of the oven was 200-300 degrees colder than what the kiln said it was. Therefore, what said 1200 was a grey colour which would be around 900, and what said 1500 was around 1300 degrees, or a dull red.
 
Don't be too quick to judge by colour. It is affected greatly by ambient lighting and individual preception. The technique is useful, but only with significant experience.
It wouldn't surprise me to see a thermocouple out by 50 or even 100 degrees, but I would expect it's death before it was out by 300 :confused:

How about testing with a magnet before relying too much on colour?

Rob!
 
I didn't think I would need a magnet if the temperature was correct. My teacher said that the colour was a little dark for heat treatment. The light was moderately dim, does 1200 degrees come out grey? I tempered it at 400 degrees for half an hour and it had no colour.
 
Keith_H said:
I didn't think I would need a magnet if the temperature was correct. My teacher said that the colour was a little dark for heat treatment. The light was moderately dim, does 1200 degrees come out grey? I tempered it at 400 degrees for half an hour and it had no colour.
Click to expand...

A magnet will tell you when you have reached curie point 1414-1416 farenheit very reliably. that is too cold for heat treating O-1, read the specs. use the magnet to ballpark your pyrometer.

-Page
 
You could set the oven for 1450 and soak a piece of steel (not your knife) for a few minutes then remove and quickly check with a magnet. If it sticks go to 1475 and try again, keep going up by 25f. Once it does NOT stick you will know your oven is close to 1415. Then add 50-75f and you should be close to the correct temperature for hardening your knife.
 
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