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Old 03-02-2017, 12:07 AM
Doug Lester Doug Lester is offline
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Join Date: Sep 2006
Location: Decatur, IL
Posts: 2,612
Not all that much to go on. I know that you said that it is a chrome/vanadium alloy but we don't know the percentages or how much carbon it has in it so it's still pretty much mystery metal. Depending on how much chromium the alloy has in it it could be oil quenching or air quenching.

It's a little pointless to discuss temperatures with a gas forge. I do have a thermocouple on one of my forges that I can use to throttle the gas back so that I heat up my blades a little slower and don't overheat the thin parts as I try to get the thick parts up to temperature but it's no where like having a regulated high temperature oven to work with. The best that I can tell you for your level of experience is to take the blade up to where it will no longer attract a magnet and then get it a very little brighter and try to hold it at that brightness for about 5 minutes. That's assuming that you have done the primary grinding. I would then let it cool in still air.

After that check the edge with a file. If the file skates across the edge without digging in then the steel was air hardening and you will be ready to temper and do your final grinding. If the file bites into the edge then the steel is oil hardening. You won't have wasted you efforts though; you will have normalized the blade. An important step.

If that is the case repeat the heating of the blade as before and quench in something like canola oi at about 130?. Personally, I don't like to move the blade in the quenchant. I just put it in point first and hold it there until it's cool enough to hold in your hand. Some will bob the blade up and down a little or cut it back and forth in the oil. Never move the blade side to side.

After the steels cools I would scrub the oil off with hot soapy water and put it directly in a preheated oven at 400?-425? for two one hour cycles

Proceed to your secondary grind and put a rough edge on the blade. If you don't have a Rockwell hardness tester, or access to one, you can test the strength of the edge by trying to drive the blade though some bailing wire or something like a 1/16" brass rod. Hopefully there will be little deformation in the edge. If you have a little have circle that looks like it has chipped out then you need to grind the chip away and re-temper the blade about 25? hotter than you did the last time.

If the little half circle in the edge looks like to tore and folded then the temper is too soft and you will have to repeat the hardening cycle again and temper the blade about 25? lower.

Good luck,
Doug


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