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gull wing
07-18-2011, 09:27 AM
I will buy a HT oven, right now saving enough scratch to get one.
In the meantime, I'm studying and asking dumb questions.:
154CM "We temper twice at 500 deg for two hours each time"
1. AFTER THE FIRST TEMPER - Do you take the blade out of the oven and reach room temp then do the second temper?
2. or Do the tempers back to back, that is, program two identical Segments, and not take the blades out of the oven?

I hope this is clear to you.

James Terrio
07-18-2011, 09:38 AM
1. AFTER THE FIRST TEMPER - Do you take the blade out of the oven and reach room temp then do the second temper?

Yes. You can leave the oven at temp, it won't take very long for the blade to cool between cycles. You can even put it in the freezer to save time.

Dan Pierson
07-18-2011, 10:36 AM
Or water quench the blade between tempers.

gull wing
07-18-2011, 01:57 PM
Thank You!
All right then, easy enough. That will be fast.

kevin - the professor
07-18-2011, 09:36 PM
water quench. Retained austenite will become untempered martensite during first temper, and you want to temper this remaining martensite. Quenching in cold water will help to get as much as possible of the martensite formed. It is for this reason that some steels benefit from cry treatments, at least supposedly. I am only really up on heat treating 1075, 1095, w1, and w2. 1080 and 1084 treat just like 1075, I just don't use them much. Damascus with 1075 or w2 and 15n20, but 15n20 treats like 1075. So, I can only really speak for the simple steels just at or above eutectoid. For them, temper twice. Some people do 3. If you are polishing to show a hamon, which is why I use the steels I do, you can get away with one temper after dif heat treat, but I usually do 2 anyway. Just not above 400F and not more an 45 mins each to keep from fading the hamon.

kc