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High-Performance Blades Sharing ideas for getting the most out of our steel.

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  #1  
Old 10-13-2002, 09:48 PM
Jason Cutter Jason Cutter is offline
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Working with D-2

Here's a new question on what is probably an old thread.

I've worked with D-2 before and find it somewhat slow to work, especially since I generally use O-1 carbon steel. On both I rough grind to about 75% of the final grind and then true up the surfaces and get the final finish after heat treat. That last 25% on D-2 is HARD. Nonetheless, I do like the performance of D-2. I don't get any warpage with the sizes I use.

How close to final grind can you get with D-2 b4 heat treat ?
Is there a risk of warpage if the sections are thinner ?
What have you guys found to be the "sweet spot" for hardness?
(I'm told its about 60-61HRC.)
Has anyone had problems with brittleness with D-2 given the high hardness counts ?
I know it makes an awesome cutting tool but what about toughness ?

A few questions there but I want to build a 6inch hidden tang drop-point hunter with 5/32inch stock D-2. It'll be a lot bigger than the 2-1/2inch blade neck knife I previously made. So before I invest time and money ...

Thanks and cheers.


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  #2  
Old 10-14-2002, 11:40 PM
Brett Bennett Brett Bennett is offline
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Jason,

As long as you are heat treating in a relatively oxygen-free environment, you can nearly finish the blade prior to HT. You can accomplish this by wrapping your blade in stainless foil.
There is always an increased risk of warpage with thinner sections, but I haven't had any problems going to roughly 0.020-0.025 prior to HT.
You are correct to choose 60-61 RC. The reason is that the hardness (RC) to toughness relationship can be exhibited in a bell curve fashion, as opposed to the typical linear fashion of most steels in the hardness range we use. D-2 is actually tougher in the 60-61 RC range than it is a few points higher or lower.
D-2 isn't the toughest steel, but if HTed properly, it will do well for the size of blade you are wanting to make.


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  #3  
Old 10-15-2002, 06:08 PM
george tichbour george tichbour is offline
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I had problems with warpage once upon a time but I found that most of it went away when I began to check the blades for straightness before heat treating. In my rush to heat treat I wasn't making sure that any warpage caused by grinding was eliminated.


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  #4  
Old 10-15-2002, 06:32 PM
Jason Cutter Jason Cutter is offline
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Thumbs up D2

Thanks heaps, Brett & George,
I guess it confirms my feelings. D-2 is top notch material. I still tend to ascribe to the general hard = brittle idea. I do all my own differential heat treat on carbon steel - O-1, 1095, 1084, L6 but I send my high alloy steels to a professional firm locally who are well-known for their affiliation with knifemakers. They will set up their oven just to do your one knife at no extra cost ! For some reason, the local standard for non-knife use of D-2 is 58-59HRC but they are more than happy to temper to 60-61HRC.

For those in Australia / New Zealand, I strongly suggest Hills Heat Treatment in Bayswater, Victoria 3152, Australia (03-97626233) for professional heat treatment. The folks there are experienced and thoroughly knowledgeable about knives. You just can't surprise them. They handle everything from straight carbon steel to particulate metallurgy steels and will happily accommodate your specific needs at very reasonably cost.

I'll make up the "bigger" knife in D-2 and use my standard 20-degree semi-convexed edge on it. From all the feedback so far, that should have no troubles with durability. If there are any problems I'll let you know, but it all looks good to start.

Thanks again.


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  #5  
Old 10-18-2002, 11:45 AM
Jerry Hossom Jerry Hossom is offline
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Just to add to what Geoege said on "warpage", I learned just a couple years ago that what I was calling "warpage" was in fact bending that was the result of my leaning into the blade on the grinding wheel. Since I grind all my blades pretty thin, and taper the tangs very thin, I was actually bending them in the grinding process. If I took the time to straighten the blades before they went off to heat treat, they tended to "warp" less.

D2 is good steel. It does tend to be a little coarse grained though, and is thus more difficult to get to a very fine edge and it just won't take a very good finish unless you take some extra time to get there.


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  #6  
Old 10-19-2002, 02:06 AM
Jan Dox Jan Dox is offline
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I had my first batch of stainless blades suffer from this bending too. I checked straightness after grinding but not anymore after hand sanding (sometimes without solid support) . And when you're in a hurry to get several blades ready to ship to a prof. heat-treater it hurts afterwards when you need to put on handle scales.
D2 is tough, doesn't take a fine finish easy but makes fine blades .
Bob Dozier tempers his D2 three times for two hours.( so I'm told)
and gets great performance.(no sub-zero quench).(If I'm wrong on Bob's tempering cyles here, someone please correct me)

Jan
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  #7  
Old 10-20-2002, 06:55 PM
Jason Cutter Jason Cutter is offline
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Thumbs up D-2 rocks

Many thanks for the feedback,

I am a pedantic (not necessarily skilled) grinder. I use a el-cheapo 36inch grinder which sits in the wrong position but I've done all my grinding, ever, on this machine. I always get the blades straight and do a lot of jumping, yelling and gnashing of teeth of if the blades then bend for whatever reason. In fact the blades that warp are my carbon steel blades which I heat treat myself. Thats why I only 75% grind prior to heat treat, especially on thin stock, eg.- 1/8inch and under. on my 3/32inch stock for kitchen knives, I don't even start grinding until after heat treat.

I've just done 6 blades from RWL-34 a particulate metallurgy version of ATS-34 from Sweden, in various shapes and tapers. The thickness on all was just over 1/8inch after taking the skin off. I ground to 99% of the final grind and applied a 400grit satin hand rub (identical to a final "selling" finish). In the heat treat, none of the blades warped, all came back with no scale, with a barely light yellow tempering colour with a finalo Rockwell of 59.

I was very happy with the result. The blades will only require an edge applied and a refinishing with 400grit hand rubbing. I'm anticipating the same from D-2 as soon as I get more in. I'd been only going as far as a 75% rough grind previously and was eating up my belts grinding hardened D-2.

Obviously the skill of the heat treater is crucial. This mob - Hills Heat Treatment in Bayswater, Victoria (Australia) is top notch and they cater especially to knifemakers. They do cryogenic treatments as well. All their work on high-alloyed steel appears to be in vacuum chambers, which accounts for their consistent results and the "pretty" steel after all the work.

I know about working with D-2. Because I want to make high-performance working knives (Dozier-worshipper, etc.) the final finish doesn't worry me too much. It just needs to be clean, crisp and consistent. On another thread, I'm researching protective blade coatings which may make an extremely fine final finish a redundancy. The very fine micron finishes will still need a nice hand rub nonetheless.

I'll stop rattling on. Thanks again. Top stuff.

Cheers.


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  #8  
Old 12-04-2002, 04:25 PM
Gene Gene is offline
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Question Heat treating D-2?

Gentlemen knifemakers!

I dearly hope I don't look as stupid as I really am, posting this question here, but I've searched the forum for a couple of hours, and haven't found these answers anywhere.

So I'm gonna' HAVE to give 'em a shot!

I'm just finishing a 12" blade Persian Fighting Knife, by stock reduction, out of D-2. And I lost the last two blades I sent off for "mail order" heat treating. So I figured I'd just jolly well build my own little Propane forge and start teaching myself how to do my own heat treating - starting with this blade.

Yeah, I know, I can hear you already, "dumb!". But I just put way too much of my twilight years in my knife blades, just to throw them in my bottom dresser drawer! And apparently some of the mass heat treaters, who carge only $35 or whatever, just cannot (and I am not blaming them at all!) take the time to watch each individual blade, and jerk it out and straighten it in the nick of time, if it bends. They'd have to charge five times as much to be able to render that kind of individual service!

But I'm getting conflicting recommendation on heat treating D-2.

1. Should I preheat thoroughly at 1400/1500F - hold for 30 minutes - raise to 1850F until uniformly heated - soak for 45 - 60 minutes. Temper at 400F for one hour, two times. Or is that wrong?

2. Do I just let the blade cool off by itself after the 1850? And let it cool off by itself after the two 400F sessions?

3. Or do I "blow" cool it?

4. In a Propane forge, do I HAVE to wrap the blade? I'd a whole lot prefer to be able to see it while it's heating, to see whether it's bending, for example!

5. And Sheffield supply house says, "to minimize surface decarburization, use salt bath, controlled atmosphere furnace or pack harden. So,
(a) Do I need the salt bath? And
(b) What does "pack harden" mean?

6. But, simultaneously, Sheffield also says, "Quench in still air or dry air blast. Do they mean IN ADDITION to the salt bath and pack hardening, or do they mean IN LIEU of the salt bath and/or pack hardening?

7. Are those "temperature Crayons", sold by reliable dealers, any good at all?

I can't tell you how much I would appreciate your help here!

I just now, at age 71, finished my first knife, a gorgeous ("I" think!) California Bowie, and you can see a few little shots of it AND the Persian Fighter on my new little web site http://www.copperheadknives.com.

And I'll be posting some professional photos there shortly. But I would NEVER, EVER, HAVE BEEN ABLE TO MAKE THESE KNIVES IF IT WERE NOT FOR THE GREAT HELP I RECEIVED FROM YOU GUYS on CKD! THANK YOU, THANK YOU, THANK YOU!

I might add, I'd love to hear from any of you directly at my home email, if you want to gab about knives in general!

Gene
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  #9  
Old 12-04-2002, 07:24 PM
Jerry Hossom Jerry Hossom is offline
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D2 is an air hardening steel so it doesn't need a salt bath. The best solution though is Paul Bos. I think he charges $12 for a single blade, and maybe a couple $ more for big ones, but he'll treat it like he ground it himself and will NEVER send you back a warped blade EVER! All my blades warp. I know, I used to do it myself. They can be straightened though and that's what Paul does.


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  #10  
Old 12-05-2002, 10:32 AM
Gene Gene is offline
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Talking Heat treating D-2

Thank you very much, Jerry!

And your recommendation on Paul Bos is extremely encouraging indeed!

But - I'd still love to know the answer to my 7 questions above - if anyone knows the answers.

AND ALSO, now today I notice some guys recommend Cryo treat for D-2, and others don't. And I'd dearly love to get the skinny on that also!

Thank you again, very much!

Gene
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  #11  
Old 12-05-2002, 01:25 PM
Jerry Hossom Jerry Hossom is offline
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1. You really don't need to preheat, but it's like chicken soup. It doesn't hurt. You only need to hold the steel at heat for 10-15 minutes. The times in the manuals are for thicker sections. Tempering twice at 400F should give you about Rc61-62.

2. Yes, though you want it to cool itself as quickly as possible after the hardening. Cool airflow works.

3. Blow hard (joking), but not from one side. You need both side to cool evenly. A fan running the length of the blade is OK. When the steel is just cool enough to handle is the time you want to straighten out the warp. It's pretty maleable and you can fix your problems there.

4. D2 hardens at 1825-1875F, and you'll need toolwrap or something else to protect it or the steel will decarburize.

5. See 4

6. See 2 & 3

7. Dunno. Most folks do this in temperature controlled ovens with a thermocouple.

71 is no excuse!


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  #12  
Old 12-05-2002, 02:03 PM
LYNN DRURY LYNN DRURY is offline
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D-2

I USE ATS-34 AND D-2. WHEN I PULL THEM FROM
THE OVEN I PUT THE KNIFE BETWEEN TWO PIECES
OF HEAVY FLAT STEEL AND HAVE NEVER HAD ONE
TO WARP. IT HOLDS THEM FLAT AND PULLS THE HEAT
OUT FAST.


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  #13  
Old 12-05-2002, 02:17 PM
Jerry Hossom Jerry Hossom is offline
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Yep, Lynn's suggestion is a good one. Lots of folks are using quench plates these days for some of the newer steels like S30V and CPM-3V. Air quench just doesn't get it done for them, and a fast quench benefits all air hardening steels IMHO.


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  #14  
Old 12-05-2002, 05:28 PM
Gene Gene is offline
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Talking Heat treating D-2

Thank you very much Jerry and Lynn!

But Jerry, shhhhhhhhhhhhhh - when you're BORN just cold stupid, clumsy, and dumb like I was, you'd be surprised how many folks you can fool just by telling them you're 71! And in two more months I can use the old "72" excuse for a whole year! And folks'll feel sorry for me. DON'T blow my cover!

But I DEARLY DO appreciate your and Lynn's detailed replies!

And I'm tryin' to put together a little vertical propane forge - just for heat treating my D-2 blades. And, if it works out, I'll just stick with D-2 for the rest of my knives. If I don't get it done in time, I'll try Paul Bos, by all means. EVERYBODY ONLY says nice things about him!

Thank you so very much!

Gene
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  #15  
Old 12-06-2002, 02:45 AM
Gene Gene is offline
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Question Heat Treating D-2

Me again Lynn and Jerry -

I'm up at 2 am, still worryin' about this darned heat treating! I surely am glad I don't HAVE to make knives for a living - it'd drive me nuts and I'd starve to death. But I love every second I'm in my shop or just turning a new blade over in my hand. Ha ha I even show off my new blades to my wife about every hour or so! But she never tires of talking with me about the blades.

But, on second thought, I don't think bolting my blades between to big chunks of steel would stop warping - because of my distal taper. I parabolically (?) distal taper my blades from the guard area to the tip of the blade, so I don't think that wouldn't work for me.

Also, do any of you know anything about this 'NEW" TURCO PRETREAT SOLUTION from www.knifeandgun.com? Is it supposed to take the place of HEAT TREATING FOIL WRAP. It would surely be nice to do away with the wrap, if possible! (And how do you enter a hyperlink here in this forum?).

But I see, in the latest BLADE, an ad by a knifemaker who says he heat AND CRYO treats his own D-2 blades (and I've emailed him). So when - after heat treating and tempering - does the Cryo come in? Do you have to go immediately from tempering into Cryo? Or can you finish the heat treating and mail the blade off for Cryogenic treatment. How cold and how long? Or can I just forget about Cryo with D-2?

Okay, maybe I can go back to sleep now. . . .

THANK YOU VERY, VERY MUCH GUYS!

Gene
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