CPM 154cm heat treating nightmare

H

Houser USA

Joined
Nov 3, 2013
Messages
7
While I'm fairly new to knife making, this is my second time heat treating CPM 154 after I completed my profiling. The major difference this time, the blade was grossly distorted, and it snapped in half while in the furnace? My pyrometer read no more than 2030, but the furnace looked to me MUCH hotter. What kind of heat would cause that?? The first three knives prior to that came through with flying colors. Did my pyrometer malfunction??? Not a pleasant time !
 
i have used alot of cpm154 but have never had that happen (a little warping if i ground a bit more to one side or way to thin) but never to the point it woudl crack. im not even sure how that coudl have happened in the kiln. are you sure it was cpm154? i had a bit of misslabled steel a while back and ran some W2 at 2000f. plate quenched and ground fine sept seemed softer then the cpm154 broke a tip on one of the blades and saw the grain was shot all to hell. thought that the kiln over fired till i went back and tested all the blades and remembered i used 2 different sheets of steel for the batch.
 
Hi Butch…yes, I checked the shipment and package of the steel. The three previous knives I went great. One dagger, one K-bar style, and one filet knife. For them I heated to 1500 for 10 min, then increased the furnace to 2030 for 20 min. Oil quenched and sandwiched between two pieces of dry ice (since I don’t have access to liquid nitrogen), then soaked at 400 for 4 hours. They came out great…
This has me baffled, so I’m going to give it another go in a few days after I find some way to test my pyrometer.
 
Maybe this is over simplifying, but would some cones for testing in a ceramic kiln work? Frank
 
Temp-stix and temp-cones are excellent ways of checking that all is well with your PID and thermocouple.
 
Ok..my mistake not being clear enough on my equipment.
I’m using a NC knifemaker forge from NC tools. This little rocket has 2 burners and is capable of forging demascus. So, at first I was just using 1095 and 01 steel. This was easy because I simply brought up to temp, held and did the magnet test. Now with the CPM 154, I purchased a pyrometer with a probe that I put next to the center and as close to the side as possible. By using the gas regulatory I was able to keep things as close to possible needed for heat treating the CPM 154. I’ve done this now on 3 other knives and things went smoothly, this time the furnace was obviously very hot by the amount of UV light kicking up, but the pyrometer only read around 2000. I hope this is a mater of my lack of experience with heat treating, and not knowing my furnace good enough just yet.
Can you use the cones in a gas furnace as well? I know this set up is not ideal, but for now it’s all I have.
Thank you for any input.
 
you can use slow oil
i woudl be more worried at this point about the heating of the blade and if the blade is in foil or not to protect it
 
You answered your own question. It just is not a ideal way to go about heat treating CPM154 . Your temps are all over the place in that forge. CPM154 is expensive and if it were me I just wouldn't chance such a fine steel to that method.
 
I've made some 440c knives that are well used and loved that were heat treated in a forge, I built a little stainless box to put inside the forge cavity, and kept putting chips of wood in there. I'm very familiar with the forge and the blades seem to be fine but.....I sure don't recommend it if you have ANY other furnace to use.

If you're going to do that, it's VERY important to have a reducing rather than oxidizing atmosphere in that forge- something venturi forges aren't that great with, IIRC.
You have to have a tongue of yellow flame coming out the door, in other words, or there's just way too much free O2 for this stunt to work.
 
You would save yourself the time and headache by just sending your blades out for heat treating. CPM154 is air hardening steel but needs to be in an oxygen free atmosphere.

Even though it worked the first time something is still not correct because you were not able to replicate your results.
 
Thank you everyone for the advice. I'm going to give it a go once again since I enjoy the challenge !
 
well good luck but a higher alloy steels are better done in a kiln or salt pot. in a forge it will always be hit or miss due to the temps needed and the hold times required
 
You must log in or register to reply here.
Back
Top