154cm heat treat question


Hello everyone, I have a question about 154cm, I'm making a slipjoint after heat treat and tempering, I noticed it was less magnetic, so much so that it would not secure to the surface grinder chuck, this is my first time using 154cm. is this normal? my recipe ramp to 1450 for 10 min, ramp to 1950 hold for 45 mins, tempered twice at 400.

thanks for any advice
Did you do any sort of cryo? I believe I read somewhere that CPM154 can have around 30% retained austenite after heat treat without cryo. It’s about the only reason I can come up with.
Thansk for the reply, I didnt the odd thing the springs are magnetic only difference is the temper. is it possible to quench to fast? everything came out just like it went in bright and shiny
Well, like any steel you can certainly quench too fast. Faster quench rates will generally result in a little lower retained austenite, but a much higher risk of cracks. Plate quenching between aluminum plates is the way to go. Knowing that there was no cryo, I’m going to guess that you have high retained austenite in the blade. The spring may have cooled at a faster rate, resulting in lower RA. If you don’t have a means to cryo, you can try to use the higher tempering temperatures as these will generally help convert the remaining RA. Chances are though, if it’s been some time since you heat treated it, the RA has stabilized and will not convert to martensite well. If that is the problem, all you can do is redo the heat treat at this point. I wouldn’t recommend finishing the blade in its current state. It will be more prone to breaking, and won’t really hold up well for cutting. 154 is a little tricky to heat treat, but it is an excellent steel when done properly.
Also, did you temper the spring at the same 400 degrees? If you tempered that at a higher temp that could be why that part is magnetic but the blade isn’t so much. Higher tempering temps convert RA
I do quench with aluminum plates in a milling vise I use a drill to close the vise quick. I tempered the spring at 1100 and the blade at 400, what do you suggest for temper since I don't cryo?
Ok that’s why the spring is magnetic then. Makes sense. I really don’t know what to suggest for a high temp temper, I do cryo and lower temps, and haven’t done any research on higher temps.
can i reheat treat the blade of do i need to start over?
I would say you could after annealing it first. For AEB-L, you would foil wrap and soak at 1350 for 12 hours to anneal. I haven’t found anything on 154cm.
In Larrin Thomas’ knife engineering book, he recommends 1900 for 20 minutes then plate quench if not using cryo for 154cm.