15N20 plate quenching question.

[P. McKinley]

I've been working on a small project for a repeat customer and I'm looking for some guidance on the process of plate quenching these blades.

First, I have never tried plate quenching. But, the other week I spent $8.00 at the local scrap yard on a 3' x 1' section of aluminum plate in anticipation of this need. I cut the plate into four equal sized pieces, cleaned them up, and devised a crude clamping system. Now I think I'm ready to give this a shot.

The blades I'm working on are rather thin(ok, very thin) 15N20 given to me by my friend Rick Marchand.

In a recent thread Stacy(Bladesmith) advised "....austenitize at 1500F for 10 minutes and quench in medium oil. I pull from the oil after 10 seconds and place in quench plates. When cooled to room temp, I immediately temper at 375F".

Would this advice hold true for the blades I'm working on?

Thank you,

-Peter

 

[fast14riot]

Hard to see the dimension, but looks like its about 0.060" thick? I would just straight plate quench that. I have a knife by my bud DanCo that is 15N20 in that thickness and plate quenched (no oil). It's holding up great.


-Xander

 

[mete]

The problem is that the plate quenching is good only for AIR hardening steel !! The quench rate is too slow for other steels .
If you're doing Stacy's method the oil may very well get the 15N20 past the pearlite nose and the slower plate quench part brings it down slowly to minimize warping. Depending on the alloy and thickness that might work.Try it and let us know.

 

[P. McKinley]

Thanks guys.

My intention with the plates was merely to minimize the chance of warping, not necessarily used for the full quench process. I plan on quenching in canola(all I have) for an 8 or 10-count, then clamp between the plates.
I'm doing the heat treat this evening. I'll post the results.

 

[fast14riot]

The problem is that the plate quenching is good only for AIR hardening steel !! The quench rate is too slow for other steels .
If you're doing Stacy's method the oil may very well get the 15N20 past the pearlite nose and the slower plate quench part brings it down slowly to minimize warping. Depending on the alloy and thickness that might work.Try it and let us know.

Yes, in normal thickness blade steel, air hardening alloys are plate quenched, but this stuff is thin and can be brought past the nose with plates. My bud DanCo did exactly this with testing both ways, and I have a knife by him that is thin 15n20 and plate quenched and is holding up exactly as expected. He did do destruction testing to see the grain as well.

Also, other makers have quenched simple oil hardening steels in thin sections with plates to good success. I personally wouldn't plate quench anything over 0.100" if it was an air hardening steel.


-Xander

 

[BluntCut MetalWorks]

My intention with the plates was merely to minimize the chance of warping, not necessarily used for the full quench process. I plan on quenching in canola(all I have) for an 8 or 10-count, then clamp between the plates.
I'm doing the heat treat this evening. I'll post the results.

a newb imo

8 seconds in canola could be way too long for a blade with 0.06" thick. Winged on my rusty math http://en.wikipedia.org/wiki/Heat_equation and some of my recent canola quenches, I think 2 to 2.5 seconds might works better before clamp to plates. Well, if the blade is not evaporate/smoke oil when pull out, then the oil part was too long. on other hand, blade on fire = not long enough.

 

[Daniel Fairly Knives]

Well, if the blade is not evaporate/smoke oil when pull out, then the oil part was too long. on other hand, blade on fire = not long enough.

That is my general rule when oil to plate quenching thin 15n20.

The last time I did 15n20 heat treat I did 10 knives in .049." I had one warp a hair and went to the plates too slow after the quench and it snapped. Other than that I have great luck with the process. Before I started using the plates it was easy to lose one to warp, I heat treat outside and once the wind picked up and just curled a Chef's knife.

Good luck! The knives look great.

 

[P. McKinley]

I think 2 to 2.5 seconds might works better before clamp to plates.

Bluntcut - I was hoping someone would comment on my quench time... it seemed to long to me for that thin stock. Your advice seems more suitable.

Thank you.

-Peter

 

[P. McKinley]

Heat treat went just fine. I quenched for a 2-count in canola, then immediately clamped between the plates. No warp. At this point I haven't done any edge testing so the final verdict is yet to be in, but so far I quite happy. I'll grind bevels today and do a bit of testing, then assemble this thing.

Rick gave me this steel hinting that it would make a wonderful fillet knife blade... and I'm sure it will. He gave me a second piece which is destined for that purpose, but this first piece was calling out to be used for a mini.

Thanks for the help folks.

-Peter

edit to add: Rick, clear out your PM box!!