15n20 score

R

Rob!

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Feb 9, 2000
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I just scored a bunch of old saw blades. Several pieces of bandsaw blade that are over 12" between the teeth. It has teeth on both sides and measures about .085 thick. I cut one of those big honkin' teeth off and cleaned it up a bit. It rockwells at between 42 - 45 about an inch behind the tips. It also files without too much trouble.

The others are circular blades - most also .085 but one that is more like .130.

I've seen the information on Dan's site about Bandsaw blade stel and it is very useful - though it took me a long time to find that thread that used to be so convenient.

The mill foreman tells me both are 15N20 - and at this point I have no reason to doubt him.

I was wondering if anyone has a link to heat treat tables and data that would show a range of hardnesses and responses?

I have enough of it that it would be worth testing some samples I guess by trial and error on small pieces. I was thinking of putting it in a BIG foil envelope - with someting to eat up the O2 - heating it to 1475 or so and then ramping it down about 50 degrees per hour as per crucibles L6 (champalloy). If I pretty much stuff the oven, it will easily be worth the long cycle. Then again - at RHC 45 does it really need annealing? ONe of the reasons I'm looking for data

Thoughts?

Rob!
 
WOW! 73 views without an answer. Well, I've got some in the oven now - 9 test pieces - 3 in foil will be plate quenched after 15 min - 3 will be oil quenched at 10 min - and 3 will be oil quenched at 20 minutes. The oil ones are turco coated. All will be at 1500 deg - because that fits in all the range of all the types Dan references.

Presuming they harden, the pieces will be tempered at different temps to get an idea of tempering response.

RHC tests along the way. I'll keep you posted.

Hmmmm... I wonder if the nickle steel will heat blue???? :confused:

Rob!
 
Please do keep us informed! I have a guy who works a sawmill getting me some pieces of commercial bandsaw blade about 9" between the teeth. I'm not sure about thickness. I was thinking more of damascus but will see what it is when I get it.

Sorry I can't provide answers,I have the same questions!!
 
Well they're out of the oven.

Plate quench came out at 42, 45 and 51. OK, so this is not an air quenching steel. A guy can hope right? :o

10 minutes at 1500 with turco came out at 61.5, 62 and 62 out of the old tranny fluid quench.

20 minutes at 1500 with turco was a little harder to clean up but gave similar results 61.5, 61, 62.

Next step is to temper, but it will be a few hours before the oven cools down enough.

More later.

Rob!
 
Hi Rob, Hate to comment because I don't really know, but I've used a little 15n20 that I've had on hand to make a couple of slip joints. Blade and back spring seem to respond like simple carbon steels (1075 based on searches).
Good luck, Craig
 
Craig

Comment anytime. Interesting proposition. I looked up 1075 on a couple charts and it is supposed to be about RHC65 out of quench. The RHC 62 that I'm getting may suggest a closer relationship to 1065 behaviour. :confused:

I think I'm going to try tempering at 275, 325 and 375 and see what spits out.
 
Always hard to say about saw blade steel until you get an analysis. I would suggest a higher temper. Start at 350 then 400 and 425.I do L-6 at 425.
L-6 is an oil quenching steel. Use Heatbath AAA or similar quenchant.Also make sure there is a sufficient volume of oil.Turco will do fine, no need for foil and such.1450-1475 is all you need.
Stacy
 
Good call Stacy

Just took the first couple out of temper (single temper for now). 375 for 2 hours.

The one that was at 1500 for 10 minutes comes out at RHC 60 over and over.

The one that was at 1500 for 20 minutes gives 59 - 60 depending on where I hit it.

----------------

I've put the next set in already for 325 - but the third set will be going in at 425.

Rob!

Then I have to figure the spring temper for back springs. :rolleyes:
 
With six of the bandsaw pieces and 5 of the circular, I have some trimming work ahead of me.

obs.jpg

Rob!
 
Next couple out of temper (325 degrees) and no surprises there. Both pieces RHC 61 all over. Very little tempering so probably of limited use - except maybe as a flash temper range. The next couple are in at Stacy's preferred 425. (though we still aren't sure it's the same steel) and I'm expecting something in the 58 range.

Anyone got a good guess for spring temper testing? 650 sound a fair guess?

Rob!
 
...and the ones at 425 are out - 58.5 - 59. I suspect that will leave me with using 375 for small folders and 425 for fixed blade knives. I now have a set in at 650 to see if that gets me near a spring temper.

Rob!
 
Way to go. Testing is the only thing that will give you results with mystery steel.Your results seem in line with L-6.
Stacy
 
Sounds like some good places to start when I get ahold of some.:thumbup: Thanks for sharing your results!!!:cool:

Randy
 
And the results (readers digest version)

Harden - Preheat oven to 1500 - turco blades and soak 10 minutes at temp. Quench in Oil - I got RHC 62 +/-

Temper 2 hours (twice) (I only did once for these tests)

375 - RHC 59-60
425 - RHC 58-59
650 - RHC 54 - should be good for backsprings with a tough steel like this.

Stacey - you are right that it looks close to L6. It is also close to the 15N20 Dan describes on his site.

I've read a lot of threads about how the only thing these steels share is use in bandsaw blades. There are some obvious alloying differences. Seems they aren't that far apart for heat treat though. I'd still like to see manufacturer specs or TTT chart for 15N20 if anyone has them.

Thanks for all the input everyone.

Rob!
 
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