Heat Treat/Cryo CPM154

J

John R. Fraps

Joined
Mar 10, 2000
Messages
1,146
Hi All,
Got a question.
Recently got some CPM154 in 3/32" thickness.
Was recently talking with a fine maker I respect who is really "high" on CPM154.
He successfully attains 59-60 Rc by heating at 1950 F for 30 minutes and 2-2 hour draws at 400F....and no Cryogenic Chill.
Crucible doesn't have tech sheets on CPM154 online but does have tech sheets on 154CM which state that cryo is desireable BUT "Thin sections can be successfully quenched in forced air and will obtain results to those in the table above.

Is the thought that that the CPM process distirbutes the carbides so more evenly and the steel would perform so well without cryo freeze that cryo freeze espc on thinner pieces (like blades under .10") isn't required and aren't noticeably enhanced by cryo.

Thoughts are appreciated.
Thank-You
 
i tested both ways and can say i did not like the small window not cryo left for RC 60 (i was getting 59) not bad but temper can be tricky because of the quick drop off of hardness
i ll look again but i think im running cpm154 at soak 1545 7 min ramp 2000 30 min plate quench then right into the Ln over night and then tempering at like 450 i think 2x 2hours
all kilns are different so you have to play with it
the thing i like about cryo of cpm154 is the trempering curve after quench from 2000 it stays between 60 and 61 from something like 450-1000 as per crucible i dont temper blades in the range of 800-1100
just my .02
butch
 
Like similar steels CPM154 lends itself to plate quenching very nicely. Cryo should get you 1-2 Rc points higher hardness.This is usually found by those using similar steels such as S30V. If there is any difference CPM154 between 154cm and CPM154 it should be that CPM154 should require shorter soak times .That is because the carbides are smaller and evenly distributed.The benefit of cryo is due to the retained austenite and that is there because of the chemistry regardless of the carbide size.
 
John, I have been working some with CPM 154 and it is very nice to heat treat. At this point I have not been able to see any increase in hardness in the cryo cycle. With other steels especially 154CM there is a difference that can be detected with a hardness tester. Does this mean there is no benefit? Hard to say since there is no way to see retained austentite with out laboratory equipment. I still do the cryo cycle mostly for insurance. PHIL
 
John, I should add some more info on CPM154. I have tried a 30 min soak at 1950, 2000 and 2030 furnace temp. With a cryo cycle in LN2 for 2 hours and 2 tempers for one hour each at 400 I get a finshed hardness of 59, 60 and 61/62 respectfully. This steel acts more like S30V than 154CM.

So far 61 seems like the best overall hardness.. for toughness and edge holding balance.. PHIL
 
bl, preheat at 1500
ramp to 1950, 2000 0r 2030
air quench in front of a fan to RT
direct to LN2 for 2 hrs
temper 2 times at 400 for 1 hr each
final grind and finish and retemper at 375 to remove residuial stress.

By the way Turco works fine with this steel even up to 2030 F. Say good bye to the foil hassle. PHIL
 
Phillip, I think K&G may have it now. I got my original supply from him but the price went way up so he stopped carrying it for a while. The supply I have now I got direct from the manufacturer, Ken at K&G gave the contact number for the supplier. This was about 3 years ago. I had to buy 5 gallons ($250) since that is the only size container approved for shipment now. If you strike out with Ken give me an e mail. PHIL
 
I have read that Turco gets very corrosive above 1800°F or so. I lost a batch of S30V blades I hardened at 2000°F a few years ago-they were all deeply pitted and corroded. I noticed a lot of pitting on D2 blades done at 1870°F, too. I haven't used it on anything that hardens above Carbon steel temps since. I bought mine from K&G ~ 2002. I still have a little left.
 
Steve, Turco works fine at up to 2040 furnance temp. It does not work on the high Vanadium steels because vanadium is very reactive at high tempertures. At least that is the explanation I got from a metalurgist. It works fine on CPM 154, 154CM, AEB-L ( I just tried this one yesterday). I haven't tried it on D2, don't use that one at all anymore. Turco as you know has a learning curve for application, and I have paid my dues with it. I get no pitting and as the blade cools it just flakes off leving a nice clean surface. If anyone wants to know my method I will be glad to post it. PHIL
 
I guess Turco won't work for me then; i want to use it for M4, which has a lot of vanadium. :(
 
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