A couple questions on my CPM154 process

Grayzer86 · Dec 21, 2016

Hey guys, I just have a couple questions about my CPM154 heat treat process. I am in a bit of a bind because i didnt realize i was out of 1084, 80CrV2 etc, and only have a stick of 154 left, and a bunch of AEB-L. I traded a couple items for a future knife, and didnt realize that the guy meant future as in by christmas so he could give it to a buddy of his. I havent heat treated any 154 myself before but i do have an Evenheat KF22.5 and 309 foil etc. First question i need to ask is that since i dont have aluminum plates yet, would i get away with steel plates for doing one single knife? The steel plates i have available are 18x5x.40. The blade stock is .125 thick. With a good stream of compressed air, would this be acceptable for this knife only?

Second Question is if my heat treat process looks ok. This is what i have worked out.

-Wrap blade in 309 foil with a puff of talc in the pouch to stop sticking
-place blades in kiln
-ramp to 1450 and hold 10 minutes
-ramp to 1925 and hold 30 minutes
-Plate quench (if my plates are even usable)
-Cryo (may have to be dry ice at this point)
-temper 375 for around 60HRC and 400 for 59HRC

Thanks in advance, I really appreciate anything anyone can offer here

mete · Dec 21, 2016

Cryo implies -300 F , the temperature of Liquid Nitrogen .It reduces RA but also permits formation of small eta carbides .Cryo should be done immediately and held about 6 hours .When it gets to room temperature ,temper as wanted which will temper the larger carbides and permit formation of the eta carbides also.
Sub-zero treatment implies -100 F which only reduces RA.

A very nice blade steel !

Grayzer86 · Dec 21, 2016

Thank you Mete. I am aware of the temp and function differences between real Cryo and a dry ice and acetone bath (or the other liquids used). I didn't mean to use the words interchangeably, just that i would like to do cryo, however i may be stuck with dry ice at this point. Do you think the available steel plates i mentioned for quench, when combined with compressed air, would be sufficient for one blade? If they wont work at all, i could likely get steel thicker if i headed out to my friends metal yard, but that involves a lot of digging since we have 26 inches of snow right now. He said he has no aluminum over 3/16 plate right now.

SBuzek · Dec 21, 2016

My numbers in my kiln
wrap
place in kiln and ramp to 1250 hold 15 min
ramp to 1650 hold 15 min
ramp to 1980 and hold 30 min.
quench (the steel plates will work)
i do cryo but you can do the dry ice step at this point
temper 2 times at 425 for 2 hours to get Rc 60-61

Grayzer86 · Dec 21, 2016

Thanks a bunch Stan. I increased my temp to 1950 and my hold time to 40 minutes. First crack at stainless steels and a plate quench but it sure is nice with no smoke, flames, and scale all over.

Matt Rochester · Dec 21, 2016

I go 1400 then place blades in for 10 mins. Ramp to 1950 and soak for 30. Plate quench and forced air. Subzero and temper twice at 525 gives me 61. I'm not sure about the steel plates. You can oil quench or even air cool. With air cool you may lose a point or 2 on hardness.

shqxk · Dec 22, 2016

Warm veg oil quench will give you maximum hardness. I have oil quench pre ground air hardening steel with no problem many time

duurza · Dec 22, 2016

Do you have a TTT for this steel? If not, do you know at which time and temperature is the pearlite nose?

Aluminum has a thermal conductivity 4x that of iron at room temperature which would mean that steel would be significantly slower at drawing the heat out. This value actually decreases for iron as the temperature rises. I haven't found enough info on aluminum to know how it would behave.

EDIT: According to http://www.efunda.com/materials/elements/TC_Table.cfm?Element_ID=Al , the thermal conductivity stays relative high even as the temperature rises. Also, the heat capacity rises but still stays relative the same as temperature rises http://www.efunda.com/materials/elements/HC_Table.cfm?Element_ID=Al . In essence, if you use steel plates, they would act as a heat resistor compared to aluminum. If there is no concern for warping, air cooling should be more effective in the long run. I can do some simulations for you if you give me dimensions and any info on a TTT or a couple of important points from it.