I was looking at Crucible's heat treat data for CPM 154 (link) and could not figure out the recipe I needed for a slip joint that I'm going to make. If I want to keep 5 points of hardness difference between the blade and the back spring (to prevent galling) I can easily do it with 1900F and no cryo (blade 59Rc and the back spring 54Rc). If I want to convert any retained austenite I need to sub zero quench, but can not find a tempering temp to use to get the back spring down to 54Rc. For knife blade thickness, is 1 hour soak time still the correct time to be used? Thanks in advance.
CPM 154 heat treat question
- Thread starter KDX
- Start date
EdCaffreyMS
"The Montana Bladesmith"
If it were me, I would rethink what I use for the spring. Most stainless steel, and especially any of the CPM steels are not like carbon/alloy steels..... they need to be at a fairly specific "target" hardness, and are not good candidates for trying to make softer through tempering. There are a number of things that can/may occur if these steels are used outside the recommended hardness range. One thing in particular with many of the CPM steels is the secondary hardening curve..... chances are good that if you try to temper it at a higher temp, hoping to achieve a "spring temper", you're likely going to get just the opposite, because you'll get into that secondary hardening curve.
This is one of those knifemaker "give-n-take" situations...... if you insist on using CPM154 for the spring, be prepared to have/deal with the issues it presents. On the other side, if you choose a material that would work better for/as a spring, its not going to be CPM154, and it will create other issues to deal with. The "give-n-take" aspect is essentially up to you..... one way or the other you're likely going to have to give up something, in order to gain something else. The trick is figuring out what YOU feel are the best options for YOU, and the current knife you are building.
This is one of those knifemaker "give-n-take" situations...... if you insist on using CPM154 for the spring, be prepared to have/deal with the issues it presents. On the other side, if you choose a material that would work better for/as a spring, its not going to be CPM154, and it will create other issues to deal with. The "give-n-take" aspect is essentially up to you..... one way or the other you're likely going to have to give up something, in order to gain something else. The trick is figuring out what YOU feel are the best options for YOU, and the current knife you are building.