Heat treating 154 cm

bladegrinder

Well-Known Member
I just recently switched from 440-C to 154 cm. after searching around for heat treat info I decided I'd try this, the blade was foil wraped,placed in room temp. oven and brought to 1400 deg. I let it soak for 10 min. and brought it up to 1950 deg. and soaked for 15 min.
it was then quenched with 1" thick aluminum plates,a few minuites later after cooled it was placed in another oven at 400 deg. for 2 hours, cooled then placed back in at 400 for another 2 hours. the next day I had it rockwell tested on a certified tester and it came out at 57-58.
that was a heart breaker,I was aiming for 59-60.
I'm hoping someone here with experiance heat treating 154 CM can tell me where I went wrong,
what I should do, and can this blade be saved ?
 
Your procedure is fine except for a couple of things. I always double wrap my blades because I find they come out cleaner but this isn't really necessary. If you will go to a sub-zero quench or liquid nitrogen quench immediately after removing from the plates and foil you will gain another point or so. If you don't have a dewar or access to liquid nitrogen you can do a sub-zero quench by using dry ice and denatured alcohol or dry ice and acetone. If you use the dry ice method you only need a 30 minute soak before you temper. If you do a full cryo you should soak for 8-12 hours. Then you temper as normal. Another tip on tempering is to do the first temper at 350 and move the temp up 25 degrees at a time until you get to your target hardness. I hope this makes sense and helps. If you try it let me know how it works out.
 
Thanks Darrin, I was hoping to get 58-59 or even 60 with out having to do a sub zero quench. if I can get to this point I plan on using CPM 154. what kind of results would I get if I tempered at a higher temp.? according to Crucibles data at 900-950 deg. it would come out around 58-59, that looks like it would raise the hardness but how else could that temp. affect the performance of the blade?
 
To get the most from CPM 154 a sub-zero or cryo is a must. This is what is required to convert the retained Austenite into Martensite. Your only other choice is to live with the RA and temper at a lower temp.. I have no personal experience with secondary hardening at high tempering temps.. I have a friend who swears by it but have heard other people say that it causes embrittlement/chipping issues. Do a test blade and see what happens. Please keep me/us posted on your testing and results. I just thought of one other thing. You may wanna increase your final soak @ 1950 to 30 min. instead of 15. Just keep experimenting but only change one variable at a time until you get the results you want.
 
Your procedure is fine except for a couple of things. I always double wrap my blades because I find they come out cleaner but this isn't really necessary. If you will go to a sub-zero quench or liquid nitrogen quench immediately after removing from the plates and foil you will gain another point or so. If you don't have a dewar or access to liquid nitrogen you can do a sub-zero quench by using dry ice and denatured alcohol or dry ice and acetone. If you use the dry ice method you only need a 30 minute soak before you temper. If you do a full cryo you should soak for 8-12 hours. Then you temper as normal. Another tip on tempering is to do the first temper at 350 and move the temp up 25 degrees at a time until you get to your target hardness. I hope this makes sense and helps. If you try it let me know how it works out.

Right on!
 
Secondary hardening occurs from the precipitation of chromium carbides and molybdenum carbides and from conversion of retained austenite from the higher tempering temperature followed by cooling. Retained austenite conversion is good, as is the precipitation of carbides for high temperature applications, for which 154cm is designed. However, secondary hardening is known to cause a loss of corrosion resistance and a loss of toughness in hardenable, martensitic stainless steels. If you dont have acess to cryo or cold treatment, the higher tempering range may be a good option, but you need to determine if the loss of corrosion resistance and toughness will compromise the performance of the blades.
 
I have been heat treating 154cm for about 25 years now.
Got this formula from D'Holder
Foil rap Blades
Heat to 1500
Hold for 30 Min.
Raise to 1975
Hold for 20 min
Take out of oven and let sit until you can hold package
Remove from package
Put back in Oven at 900
Hold for one hour
Remove from oven let sit until cool
I then put them in a Stainless steel pan,Cover with dry Ice and cover Dry Ice with Acetone
Let sit until all Dry Ice is Gone
Put back in Oven at 925 to 950 for 1 hour
I RC test every blade and get between 61 and 63 all the time
Hope this helps.
 
Back
Top