Hi RJ,
Tell more? Sure love to. (I really like reading up on other people's tests.)
After I replaced the bricks in the door, I did a set of CM154 blades using the 'normal' procedure and soaked at 1950 for 20 minutes. However after tempering to 500 the hardness was 56! I knew something had changed.
All that to say, I'm listing my oven settings, but I think you should subtract 30 to 50 degrees.
Plus I just list the information for blocks #1 and #2 (there were many others).
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>> What were your soak times at temp?
#1 was 1970 for 45 minutes (blade in cool oven, slow ramp to temp to boot, 4 hours total oven time).
#2 was 2000 for 23 minutes (Blade in at 1500 and fast ramp)
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>> Were you freezing before or after the first temper?
These two samples went straight to the LN.
BTW there was another sample done exactly like #1, but had a snap temper for 1/2 hour at 300. It was not as brittle!!! Maybe had some of bainite?
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>> I see you tempered at 1000F. Is this the temperature you use for your knives, or was that just to check the furnace?
No not what I normally use on knives (usually 400-500). I was just testing with the temps on the Crucible data sheets.
I know Paul Bos uses the high temp tempering cycle. Maybe I'll start.
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>> Please tell us more about the tempering cycle on #2, the one that bent.
Not sure what to add. Let's see.
I did one test immediately after quench, while it was warm: 63.
One test after I chilled it in the freezer: 63
LN for 1/2 hour: 63
LN for 1 hour: 63
Ln for 15 hours: 63
400 for 1 hour: 62
500 for 1 hour: 60
600 for 1 hour: 59
1000 for 1 hour: 60
The first 2 tempers were in the toaster oven with a good themometer. The second 2 where in the heattreating oven, so maybe the temp was a little less?
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Results of all the testing showed slow ramp and extra soak times didn't really have an effect. Crucible lists equalizing at 1400 degrees. However, 1/8" steel probably doesn't need it.
Steve
PS I'm still wondering why the LN didn't raise the hardness.
