Heat treating CPMS30-V

[KenH]

I've read the spec sheet - Seems pretty straight forward, but I do have a question.... or two.

The spec sheet says to pre-heat to 1550-1600F and equalize. Then to heat to 2,000F (for max hardness) for 15-30 minutes.

I would expect to set the oven to heat full speed to 1550F, then hold.... for how long to stabilize? I've read 30 minutes to stabilize - does it really need that long? Seems like as slow as these ovens heat up the blade would be fairly well "stabilized" by the time the oven reached 1500-1600F. Isn't that stabilizing - hold until the item is fully even temperature thru-out the blade?

Then full speed ramp up to 1950F and hold for 30 minutes. I'll then pull blade from oven and clamp between quench plates and cool.

I have a Kershaw 1670 with a 420HC blade that I've never been very impressed with. I'd like to make a new blade from S30V and see how that works. For this blade, I'd expect 450F temper for 2 hrs for a Rc around 60 or so? Dunk in a bucket of dry ice & alcohol mixture for.... How long? Then back in tempering oven for another 2 hr at 450F.

Does this sound like a decent plan? I've never used this stuff before and just wish to give it an honest trial. How long to equalize? Is there any advantage in holding at 2,000F for 30 minutes rather than 15 minutes? I read if using 1950F, hold for 30 minutes, but if using 2,000F plus, then 10 to 15 minutes is plenty. comments?

I've watched a couple of youtube videos on taking the 1670 apart, doesn't "seem" too hard. Comments on my idea? Too much? Anything special I should look for?

Thanks for any comments or suggestions.

Ken H>

 

[Knifemaker.ca]

You are exactly right about equalizing. Knife thickness pieces in an electric kiln are pretty much 'equalized' all the way. Most of my programs have a 5 minute equalize - mostly because some like it - and it meets the test of "do no harm". I use the 1950 schedule - mostly because my comfort zone is not good at the outer edge. Cryo has it's best effect if done as a continuation of the quench - before any tempers. I do cryo before the first temper (stainless only) and the only blade I ever had a crack in turned out to be a faulty billet from Crucible Service Centers. I have no idea how many blades I've heat treated, but lets just say over 10,000.

So, my suggestion would be 5 minute equalize - 1950 - 30 to 45 minutes - plate quench - cryo (dry ice and alcohol is fine) - double temper at 400 x 2hrs for 60/61 or 450 for 59/60. Remember S30V gets it's edge retention from the vanadium carbides so it doesn't have to be silly hard - and may be easier to sharpen if a little softer.

 

[KenH]

Thank you for the input Rob - I like the idea of 5 minutes equalize. That will give me a chance to use that setpro controller for something other than a simple 1 step ramp up. I think I'll go for the 59/60 Rc - that would work just fine. That's what I normally get from my 14C28N blades and it works good there.

I've never used the cryo step before, the Sandvik steels work pretty good without it, but are said to benefit from cryo. I think I'll try to get a few blades ready and find some dry ice. If I've got 5 or 6 blades, that's not too bad cost per blade.

Thanks again for input Rob,

Ken H>