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View Full Version : damascus..to wrap or not to wrap



J S Machine
07-07-2011, 01:46 PM
I think my trouble with getting the proper hardness out of the damascus I have worked with may be in the method I am heat treating it. I work in a toolroom, so we wrap our steel in stainless foil.

I have done my few pieces of damascus this way, and I think the issue may be that I am not quenching fast enough. I have to remove the package from the oven, cut the foil, and dip it into the oil. This can take up to a minute.

I've never really had to deal with scale before, but I think I may try just putting the part in the oven bare, and when its time to come out go straight for the oil. probably less than 5 seconds this way.

Could foil be my problem?

joe levy
07-07-2011, 02:15 PM
I think it would work better to leave it out of the foil. I don't do a lot of oil quench but never have wrapped it in the foil. I use mostly air quench and always wrap those.

Rudy Joly
07-07-2011, 02:18 PM
If you're taking that long with 10x steels you SHOULD reevaluate your method. If scale is the problem, maybe try a coating like Turco. One minute is at least 50 seconds too long with most steels.

Rudy

Josh Dabney
07-07-2011, 02:47 PM
I was wondering if this was STAINLESS damascus after reading your WIP update this morning.

Oil quenching steels are not going to respond with a foil wrap because by the time you remove the blade from the foil it's under critical temp. and thus will not harden. This will especially hold true in a thin cross section like your slippie blade.

I think a typical procedure for carbon steel folder blades is to leave a little extra meat on the blade for HT. Drill your pivot hole undersize BEFORE HT then surface grind and ream the pivot hole AFTER HT. At least that's how I'd go about it.

On a blade that small I'd probably just profile and drill the pivot hole then HT. This will leave plenty of steel for removing decarb and getting the blade both flat and straight.

-Josh

J S Machine
07-07-2011, 03:20 PM
I haven't heat treated the balde yet Josh, just trying to get some stuff straight before I do. I will do it in the morning without foil wrap. I bet bthat was the problem on the few others I have done. I never could seem to get them above about 45 Rc.

Josh Dabney
07-07-2011, 03:33 PM
That would certainly give you trouble.

I'm not very experienced with folders having only made 2 (and one was stainless)- BUT I've heard others say that especially on something thin like a folder blade even the tongs will act as a heat sink and cool that part of the blade enough to prevent the back of the blade from hardening properly.

IIRC it was suggested to use a piece of wire (like a coat hanger) through the pivot hole and bent into a circle so to quench you grab the wire with the tongs instead of grabbing directly on the blade.

Good luck with it ! -Josh

P.S. The WIP is comming along nicely !

EdCaffreyMS
07-07-2011, 05:36 PM
My strong suspicion is that the foil, and the time consumption to remove it, is the problem. As a general rule, most oil quench steels require that you get from critical temp, to less than 400F, in 6 seconds or less to achieve full hardening. It's nearly impossible to achieve that using foil.

J S Machine
07-08-2011, 07:03 AM
That would certainly give you trouble.

I'm not very experienced with folders having only made 2 (and one was stainless)- BUT I've heard others say that especially on something thin like a folder blade even the tongs will act as a heat sink and cool that part of the blade enough to prevent the back of the blade from hardening properly.

IIRC it was suggested to use a piece of wire (like a coat hanger) through the pivot hole and bent into a circle so to quench you grab the wire with the tongs instead of grabbing directly on the blade.

Good luck with it ! -Josh

P.S. The WIP is comming along nicely !

Great advice Josh. Makes perfect sense. I never even thought of the fact that the tongs probably suck the heat out of the blade. I will use the wire method and do it like that.


My strong suspicion is that the foil, and the time consumption to remove it, is the problem. As a general rule, most oil quench steels require that you get from critical temp, to less than 400F, in 6 seconds or less to achieve full hardening. It's nearly impossible to achieve that using foil.

Ed, I'm almost sure this was the problem all along. I don't have much experience with oil or water quenching stuff. We wrap everything in foil, and I guess the purpose of that is to keep the scale off of our parts. when we pull them out of the oven, we unwrap them and let them air cool. But we are talking about air hardening steels too - A2, D2, S7..

The only steel I have had much oil quenching experience with is 01, which we consider a cheaper steel and we sometimes make misc parts out of it. I have never had a problem with it hardening though, and if I recall correctly we wrapped it too.

I will try to heat treat the part, open the oven, pull it out with a piece of wire and go directly into the oil. All new to me, but whatever works..

Still not sure what kind of oil I'm going into either. I'll find out about that. Whatever it is, it's very thin, almost like water.

J S Machine
07-08-2011, 07:39 AM
The quench oil is nitriding oil.

GHEzell
07-08-2011, 02:19 PM
Instead of a foil wrap you could try an anti-scale compound, the results should be the same, except for a hard blade...