HT'ing Alabama Damascus

K

Ken H>

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Hello all, I've got a carving knife profiled using a billet of Alabama Damascus I purchased at Blade this year. Just now getting around to making the wife her carving knife. I've looked all over the Alabama Damascus website and can not find any HT'ing info. I do remember getting a pamphlet at the time, but that's paper and it got lost. I read on their website the composition is:
Material = (4) layers 5160, (3) layers 203E, (3) layers 52100, (3) layers 15N20 folded 5 times for 416 layer damascus
Click to expand...
I was surprised at using 4 difference alloys - doesn't seem like those alloys really go together for a pattern welded steel, and 203E is a low carbon alloy for pressure vessels.

Based on the 4 layers of 5160 I would expect to heat in oven to about 1525ºF for 10 minutes or so (or does it need longer for carbon to get fully soaked?), then quench in 125ºF canola oil (only oil I've got).

Does Alabama Damascus benefit from normalizing? Heat to 1575ºF and allow to air cool?

I've read Alabama Damascus has a tendency to warp on quench, so I'm concerned about this long thin blade. 1" wide, .100" thick and tapered to .060" at tip and is 14" long. Would quenching for 10 (longer? Less?) seconds in oil, then clamping between aluminum plates help prevent warp?

Lot of questions here, but as I've researched HT'ing today I'm more confused than ever.

Thanks to all for any help,

Ken H>
 
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I've used Alabama Damascus in the past. So here's my experience.

1. Thermal cycle 1600, 1500 then 1400.

2. Austentize 1475 hold for a few minutes then quench in 120 degree canola.

3. Temper as per 15N20 specs. Around 375 degrees depending on your hardness goal.

4. Test your edge after tempering, and bump the temperature up if its too chippy.

5. My first heat treat I did not thermal cycle, and the blade bent like a banana. I went back and thermal cycled, then hardened it again and the blade stayed straight.


Good luck!
 
I've heard that it is best to heat treat damascus steel to the specs of the highest carbon content steel, which in this case would be the 52100. That being said, what Shane laid out in the post above is excellent. I might be tempted to normalize a bit hotter myself, 1650°F, then cycle down. 1475°F for at least 10 minutes, into the canola.
 
The four steels are to get four different color stripes due to the differences in the alloy ingredients. The layers of the alloy ingredients stays striated in the order they are layered.

The individual steels' carbon content, however, gets pretty much evened out in the manufacturing process (carbon diffusion). In this particular mix billet, it probably ends up around .60% ( 180+0+300+225/12=58.75).

I would HT as a hypoeutectiod steel, and use the specs for 5160.
1525F for five to ten minutes and quench in canola or Parks AAA. Temper at 400F for an hour twice.
If it was forged, then the normalization cycles at 1600/1500/1400F would be good to do.
 
The billet I used warped even after multiple cycles. Even after straightening in the temper, it would move back crooked. After a tip from Brad Stallsmith of Peters Heat Treat, I ended up using a propane torch to add a little heat, maybe 250-300 degrees or so, then bent it straight. It stayed.

As far as hardening, the other guys are right on.

For a long thin piece like you describe, I'd think the plates might be helpful as you suggested.
 
Thanks to all for comments - Stacy, since damascus is forged in making, would that not require normalization? Since this blade is so long 'n thin I only profiled, no bevels yet hoping that will help prevent warping.

Shane, thanks for the detailed instructions, sounds like everyone is pretty much in agreement so I'll go with what ya'll say. I hope to HT later today. Even if it doesn't "need" normalizing, going thru the normalizing shouldn't hurt anything - should it? Might even help to prevent warping?

Jason, Samauri - thanks for your input also. I think I'll quench in oil, then after 10 seconds or so, (it should be past the nose then?) then clamp between plates in hopes of no warp. My quench tank is a vertical tank about 6" sq, so I'll have a wire thru a hole in tang, then go into oil tip first with some up 'n down movement during the 10 second quench. OR - should I hold longer than 10 seconds?

Stacy? Others for comments please.

Ken H>
 
I think you're on the right track. Good call on grinding post-heat treat, that ought to help with the warping. The ones that gave me such fits were HT after grinding, and had tapered tangs and thin blades.
 
Every piece of steel you pick up has been forged - either at the mill for making flat/round stock, or in manufacture of damascus. It has also usually been normalized before you get it.
The damascus you get from Alabama has had thermal cycles to anneal it and remove stresses. If you have doubts about how well it is normalized, do a series of cycles.

As to warp and twist in damascus.... it is twisted, disrupted, and manipulated on several planes while being forged and patterned. Even with normalization, the different steel layers may have different thermal properties, and will contract and expand at different rates/amounts during heating and cooling. Straightening at 300-400F after fully tempering the blade is a normal part of the process.

Quenching and clamping between plates on damascus while it drops below Mf may only slightly help. It will more likely just trap stresses that will release later during temper and/or when finishing and warp the blade. Best to let the stresses go where they want during HT and straighten after the second temper.
 
Stacy - thanks for the info, I didn't know if Alabama Damascus would normalize before selling or not.... BUT - considering what you posted, I didn't do the normalize, just held at 1525 for 8 minutes, quenched in 125ºF canola oil. From quench it's about 62 Rc. I do have a tad of a warp in the tang, so now have in tempering oven at 375ºF for an hour. I'll take it out then to check warp. I did clamp in plates, but not sure that did anything.... good anyway. I had a bit of tang sticking out because the knife is longer than my plates and that's where I got the warp. Oh well. As Stacy says, just a part of working with damascus:)

I think I'll work the blade after the 2nd temper at 375ºF, then after bevels are finished, I'll see if I think it's going to be too chippy. For just carving - I don't think it will be. Anything from 58 to 60Rc will be just fine with me.

Thanks again to all for the help 'n guidance,

Ken H>
 
Ken I remember emailing the guys at Alabama Damascus and they suggested doing a normalizing cycle.
 
Shane - "NOW" you tell me to do a normalize:) Well, I'd planned to but was concerned about how much scale would build up on the blade with that many cycles of heating. I should have took a small scrape piece and ran a practice run to see just how much scale would have built up. Oh well - I coat the blade good with powdered borax. Heat blade a bit while sprinkling borax powder on blade. This allows the borax to melt on blade forming a glass coat over blade. I've had good luck with this method for a single heat/quench cycle.

It's been a LONG time since I've fooled with carbon steel much. For the last couple of years I've only used SS, of which 99% has been Sandvik SS - 14C28N - Love that stuff! It's hard (Impossible) to find in thin thickness of less than .098", so for paring/fillet type knives I'll use 12C27 or AEB-L and those do work good.

I've got the blade out of temper now and it's pretty straight. I'll go from there with grinding bevels tomorrow. I've got to glue up handles, the wife wants ebony/mammoth ivory spacer/spalted wood handle. I'll use a white spacer between scale and tang. Tomorrow my white dye should be sure to color the epoxy for gluing up scales. Also have to finish a mosaic pin for the front. She who must be obeyed wants it to match the layout of this handle of her chef's knife. The spalted wood will be different.

Inside_Handle-s_zpsnir2t8rl.jpg


Thanks again to all for the help

Ken H>
 
I just received 3 billets of Alabama Damascus. Heat treat went well with no warpage.

Their instructions say- Heat to 1550 for at least two minutes, then quench in a quick oil.

Drawback at 350 for two hours, once or twice. Your choice depending on how hard you want it. Mine came out at 61 - 62.
 
Ken,
What SWMBO wants .... SWMBO gets. ( pronounced swambo for the uninformed)

Not many people still remember Rumpole of the Bailey anymore. I have a stack of VCs and a few DVDs of the shows.




Shane, like I said, if there has been any extreme work, or forging, a normalization will help. IIRC, Brad ( or Lacy?) told me they run the steel through a normalization and annealing process.


In full disclosure, I don't use Alabama Damascus anymore. I have had too many problems with delamination and cold shut pockets. If Don and I got half of the bars we purchased flaw free we thought we were lucky. Yes, Lacy replaced them, but it became a waste of time and abrasives for a 50% success rate. I now use mostly Delbert Ealy's damascus. It is much more expensive, but I have yet to grind into a pocket or have it open up or blister during HT.
 
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SWMBO? Hmmm, I had to look up "Rumpole of the Bailey" for I'd never heard of that series. Sounds like a good series - Dr Who of the old Tom Baker era of Dr Who was my family's stable TV for Sat night back in late 1980's. "She Who Must Be Obeyed" was something I used a few yrs ago..... because following it makes for a happy marriage {g}

Sad to say, I had a small delamination in the butt of tang on this blade - not much, ground most of it out. BUT - that does give me question if there are other places that are hid in the blade somewhere? Stacy - do you think using 4 different alloy mixes are part of the reason for these bad places?

Ken H>
 
No, I think it is the HUGE billet sizes and speed they make the billets at. You can call Lacy and tell him you had a de-lam, and he will send a replacement bar. A close up photo in the email will help.
One problem I have had is when the blade looks fine, but the delam is in the layers below the surface. During Heating and when the quench comes, the void blows up as a big blister ... with no repair possible. Afyter hours of grinding and sanding, tossing knives in the trash bin gets old fast.
 
Stacy, I know that 15N20 is not as "imcompatible" with true deep hardening steels as say L6 and W2 would be, but could the slight difference in hardening"speed" between the 15N20 and the 52100 and 5160 be a factor in warpage or do you think that it is just stress?
 
You are missing the point.
There is no 15N20 in the billet anymore
There is no 52100 in the billet anymore
There is non 5160 in the billet anymore.

What you have is a bar of steel with a carbon content of around .60% and 416 strata of alloying that has varying amounts of chromium and nickel. These strata are .0003" each.
The layers may have slightly different mechanical properties, but at that thinness there will be no warping from cooling rate differences. The warp comes from the layering more than what is in the layers.
 
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