Cutting that darned 15n20

[rhrocker]

No matter how much I think I've annealed the 15n20, it still takes the teeth off of my bandsaw blades. Is there a trick, or just simply use a cut-off saw?

[mete]

are you work hardening the steel as you cut it ?

[rhrocker]

Humm....I could be. The billet is already made of 15n20 and 1084, then was brought to non-mag and then put in vermiculite overnight. Next day I was able to cut about 1/4 way through the bar, and then that was it, no more teeth. Could that be work hardening Mete?
BTW, your avatar is exactly what I've always though you might look like <G>.

[Burke]

RH, try bringing it up to just below non magnetic and hold it for a time then cool slowly

[Alan L]

A good bandsaw blade makes all the difference in the world, too. I used to use the cheap ones, and they'd do fine with everything except 15n20, and then I got the same results you did, i.e. a shower of broken teeth.

Got a Lenox Diemaster 2 blade about two years ago, and it's still going strong.

[rhrocker]

Thanks guys, I'll look into all of this. I figure I can't be the only one having problems cutting this stuff.

[Ray Rogers]

I also make billets of 15N20 and 1084. I heat them to near forging temps (beyond non-mag) and pack them in wood ash for 24 hours or more. After that, they cut like butter. BTW, I also use the Diemaster blades....

[Cal Ganshorn]

Originally Posted by rhrocker

No matter how much I think I've annealed the 15n20, it still takes the teeth off of my bandsaw blades. Is there a trick, or just simply use a cut-off saw?

I never anneal my billets just let them air cool. You have to use a bimetal saw blade, the cheap saw blades will last about 30 seconds.
The part that I find it tough cutting through is the scale. I grind it off where I want to make the cut and it adds considerable life to the blade.
15N20 as it comes from the factory is about Rc 45 I believe the last time I checked.
I had about 1000 lbs of it sheared into 1 inch strips and it sure it hard stuff to cut,especially the 1/8 inch stuff.
To cut forged billets I have gone to a chop saw, it is a lot more economical.

[mete]

Robert , my new avatar is what I look like when I see someone HT'ing a complex steel like S30V the same as he would do 1080 !!

[deker]

Robert,

What I've taken to doing in my billets is running Kevin Cashen's approximation of a speroidize anneal.

- Heat to critical
- Quench
- Temper @ 1275 for 1 hour

Works like a charm.

-d

[mete]

That's a subcritical anneal which gives you finer spheres of carbide.

[Mike Turner]

Just a question here Robert, what is the TPI on your blade??? I know lots of folks that try and cut real thin stuff with the wrong blade and it will strip the teeth off in a hurry. I use a 20-24 bi-metal blade when I am cutting 15N20.

[rhrocker]

Originally Posted by mete

Robert , my new avatar is what I look like when I see someone HT'ing a complex steel like S30V the same as he would do 1080 !!

I hear you!! That's a good one Mete

[rhrocker]

Mike, I currently have a 3/4" 14 TPI blade, and it's an el cheapo. A friend of mine gave me 8 brand new ones a while back. I think I now know why.
Anyway, I solved my problem this way. First, I don't think I had been annealing the billet as good as I could have been. So this time I did the ol trick of leaving the billet in the forge when I was finished, closed up the openings, and left it for the night. Secondly, I took some extra time getting the scale off of the billet. To bad a blade can't be made from scale, I swear that's the toughest stuff I know of. I used a 7" right angle grinder with a 50 grit blade and it made quick work of the scale. I decided not to use the bandsaw, but instead used my abrasive cut-off saw, and it went through that billet like butter (well, not quite, but better than the first time).
So, plenty of annealing, a good cleaing of the scale, and either abrasive cutting, or possibly even a bandsaw with the correct # of teeth.
Thanks guys for the help!