We had a load of magnetic parts in our vacuum furnace run part way through the "burn out" cycle before the operator realized his mistake and shut it down. Then he ran the proper anneal cycle. These parts are either 8% or 12% chrome core alloys from Carpenter. Our normal anneal is 1450 F for 2-4 hours, they got up about 2000 F in the burnout cycle. The parts look OK and are meeting the hardness spec. I'm getting some critical dimensions measured.
Carpenter has this to say about heat treatment:
Due to its relatively low chromium content, Chrome Core (8)(12)-FM alloy will
form austenite if heated to too high a temperature, and some hardening
will occur if the austentized part is rapidly cooled. Consequently the best
heat treatment for improved soft magnetic properties is to subcritically
anneal.
So did the overheating do anything permanent that the subsequent anneal can't reverse?
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
Carpenter has this to say about heat treatment:
Due to its relatively low chromium content, Chrome Core (8)(12)-FM alloy will
form austenite if heated to too high a temperature, and some hardening
will occur if the austentized part is rapidly cooled. Consequently the best
heat treatment for improved soft magnetic properties is to subcritically
anneal.
So did the overheating do anything permanent that the subsequent anneal can't reverse?
----------------------------------------
The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.