Heat treat questions

[linkelric362]

I have two knives that are ready for heat treatment and i was planning on doing it in my forge. One is made out of a nicholson file and is 1/8 inch thick, the other is 1075/1080 steel and is 3/16 inch. The only problem is that im not sure what to quench them in? I have canola oil, old motor oil and i can always use water or brine. What do you guys suggest???

[thegeek574]

Canola. If in doubt, look it up. Put the phrase site:bladeforums.com after any serch terms in google and it will only show results for BF. Here is what I turned up:
https://www.google.com/search?ie=UTF...ladeforums.com

The third result down answers your question.

Also, when researching, don't expect the question to be exactly the same as yours. Often the information given will apply to more than one question.

[linkelric362]

Thanks i have been doing that and reading a lot of threads but not getting the answers i have been looking for. One other question: should i heat the canola?

[bladsmth]

Here is the bladeforums search engine. Put it in your browser bar.
http://www.google.com/cse/home?cx=01...%3Aqfobr3dlcra

Warm the canola to about 120F. You want at least a gallon. Two would be even better.

You want to stress relieve the blades before hardening,.... doing that will heat up the oil for you.
Heat the blade to non-magnetic and take out of the forge - about 1350F. Let cool in the air until it turns black ( called black heat), that is about 900F. Wait about ten seconds more and quench in the oil. Repeat again at 1350F. Then, heat up and bring to almost non-magnetic, about 1200-1250F, and let cool in the air. The steel should be stress free and the oil should be warmed.
From there, check that everything is straight and do the final hardening HT. Temper as soon as you can at 400-450F.

[Troop]

Here is the bladeforums search engine. Put it in your browser bar.
http://www.google.com/cse/home?cx=01...%3Aqfobr3dlcra

Warm the canola to about 120F. You want at least a gallon. Two would be even better.

You want to stress relieve the blades before hardening,.... doing that will heat up the oil for you.
Heat the blade to non-magnetic and take out of the forge - about 1350F. Let cool in the air until it turns black ( called black heat), that is about 900F. Wait about ten seconds more and quench in the oil. Repeat again at 1350F. Then, heat up and bring to almost non-magnetic, about 1200-1250F, and let cool in the air. The steel should be stress free and the oil should be warmed.
From there, check that everything is straight and do the final hardening HT. Temper as soon as you can at 400-450F.

Stacy, could you please explain, "metallurgically", what happens to the steel when you quench in black heat condition?
- Thank you