D2 - Your thoughts

JTknives

JTknives

Joined
Jun 11, 2006
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I have always heard that D2 takes a pore edge and holds it forever. But i finished a knife i made from D2 and it sharpened easy and has one of the sharpest edges i have seen. Its a full flat grind down to between .004 and .005 on the edge with a nice polish. It was not as easy to grind as say W2 or 5160 but it was not bad enough for me to not like it or have a hard time. I am really impressed with this steel so far and might switch to using it mostly for my smaller drop points. I was just wondering what your thoughts are on D2 and how you heat treat it or why you like or dis like it
 
I use D-2 a good bit for EDC sized knives. I don't have any problem sharpening it and like the edge I get from my fine grit diamond stones. It does hold an edge very well from my experience in slicing type uses. I haven't used it for any chopping or batoning because of the large carbides it has. Paul Bos does my heat treating. Living in a coastal environment, rust really is a factor for most of my customers, and though it isn't technically stainless and will rust without proper care, it is a huge improvement in that area over lower alloyed tool steels and simple carbon steels. It is a pain to hand sand and I don't like the finish you get with it at higher grits, say over 600.


Todd
 
I love that it stays sharp, it keeps cutting even when dull. I hate that it eats my abrasives..

Emre
 
I have been using D2 on some of my blades for about 7 years now. Before I started using it I had a maker who had been using it for, I think he said over 25 yrs., tell me that the edge retention and ease of grinding would vary according to who it was bought from. I have tried many suppliers and I have found that to be very true. I recently bought some CPMD2 and am in the process of grinding some blades from it. I will be interested in finding out how it compares. I like the way it grinds.
 
One of my favorite steels. One of the very best working steels IMO. It's not loved by the microscopic level polished edge guys -- but they're not actually using their knives for real world cutting anyway. And I'd call it "stainless enough".

I tend to judge steels by the difficulty of sharpening versus edge holding -- some steels are a bitch to sharpen, yet hardly do better than a decent production ATS34 blade. D2 really hits a sweet spot on that in my experience -- not at all bad to sharpen compared to some - actually rather easy to do with a decent diamond hone followed by a fine ceramic - yet cuts and cuts and cuts. Thinning out an edge is not so much fun, but that's the case with most high alloy steels (and really, if you're delivering a custom knife, you should already have the edge geometry set up correctly, so the customer shouldn't need to bother).

As far as toughness, although Crucible was careful to avoid comparisons, or put it into hard numbers, if you poke around enough, you'll find a chart that shows that S30V and D2 have basically the same level of toughness (and this is their standard grade D2, not the CPM D2)
 
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I can't speak much for gross toughness (I don't use knives in ways that breaks blades) but the kind of toughness I see is what happens if you use your knife to deburr parts, or trim gates off of moldings, or (gasp) hammer through a wire or something. In these applications, properly heat treated D2 is way more durable than any stainless I've ever used. Ever cut a nail with S30V? And it is "stainless enough". I've run it through the dish washer without issue.

Then, there is the beer bottle test. Cut open a case of beer, accidently bump a bottle, what happens to the edge? D2 does great. Perhaps not as good as a nice simple high carbon such as W2 - but way better than stainless.

And it keeps cutting even after it is blunt. I use it in non serrated steak knives - the toothy edge just keeps cutting, even after blunting on the porcelain.

The thing about D2 is it has a terrible tendency to retain too much austenite when tempered low which leads to poor fine edge stability. And when tempered high you get a combination of carbides and carbon lean martensite that do not lend themselves to good edge stability. I've done a lot of testing of D2, and I've had Paul do some for me and I have a Dozier. I have come to the conclusion that the very best D2 is frozen to -100 as a part of an uninterrupted quench and double tempered around 450-475 for a hardness around 61-62. This minimizes RA and maximizes free chrome, which gives it good edge stability and corrosion resistance. No snap temper. Paul uses a snap temper and it shows. He and I discussed it and he mentioned he might change his process, though I'm not sure if that is his "standard" HT or not.

A rapid quench maximizes hardness and free chrome and minimizes RA. A slow oil quench is ideal, but plate quench is good too. Most "atmosphere" quenches aren't very fast. I have been told that quenching out of tempering rather than the normal air cool (a bizarre thing to me) will reduce its tendency to be brittle in cold weather.

I like thin (.010-.015) hollow grinds and 13 deg per side for an excellent slicer with tenacious edge retention in a wide variety of applications from caping a deer to industrial cutting. I do not find it difficult to achieve a hair whittling edge with it. D2 is my favorite steel.
 
When I first started I used D2 left overs from our scrap cutters. The HT directions i sent with the blades was the same that we used on our D2 punches...

Two step preheat at 1200 and 1550 F
Austinize at 1800 to 1875 F for a minimun of 30 minutes
Nitrogen quench
pre temper at 300 to 325 F for 1 hour
return to nitrogen and stabolize at -100 to -120 F for 2 hours minimum, let it come up to room temp
temper at 400 to 450 F
60 to 62 Rc

This worked well on our punches that were match metal and designed to punch out plastic lids, cups, plates..millions of them a day 7 days a week. This process also worked very well on the knife blades i sent.
 
Interestingly, from what little I've learned from Bob Dozier's comments, his process with D2 involves three temper cycles and he does *not* use a cryo cycle. If I remember correctly, he said that he prefers for D2 to retain a small amount of austenite (I'll have to dig around for the details -- but remember that this is from a while back out of my less than totally perfect memory).
 
The blade i did comes in at around 61HRC and thats without a nitro quench. i'm guessing with the nitro quench i would gain a point or two which would alow me to up the temper temp a bit.
 
D-2 is my favorite. I would say 90% of the knives I make are D-2 and it's the most requested by my customers. I use it for skinners .010 to .015 thickness behind the edge. And for choppers and camp knives .020 + behind the edge. I have never had a problem batoning with blades made from 3/16" stock. Although I would not reccomend any prying action. I don't do cryo just the triple temper. I have sent some out to have cryo, and performance wise I personaly have'nt seen a differance.
 
be warned however!
these response are all very positive, that is because people who like d2 see your thread and want to tell you all about how great it is, people who dont care, or think it is a mediocre steel will not post
 
JBS TOOLMAKER said:
I have sent some out to have cryo, and performance wise I personaly have'nt seen a differance.
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In order for the cryo to be effective it has to be a part of the quench, it can not be added on as an after thought to a finished blade. Austenite starts to stabilize immediately.

In test knives, both at the same rockwell hardness (62) and with identical geometry and subjected to the same cuts - the difference in edge retention can be seen at an arms length. The blade that received cryo after a snap temper has visible edge damage, the blade treated as a part of the quench did not. This is due to reduced RA.

So, the purpose is not to increase hardness - it is to maximize the amount of martensite that is formed. Otherwise you have a relatively large volume of soft "stuff" mixed in which plays hell with fine edge stability. It is a moot point in a punch tool, but it is very important to a fine edge blade. The side effect is an increase in hardness. Not because the martensite is harder - but because there is more of it.

Cryo temperatures are not required to reach Mf with D2. -100 is adequate.
 
Nathan the Machinist said:
In order for the cryo to be effective it has to be a part of the quench, it can not be added on as an after thought to a finished blade. Austenite starts to stabilize immediately.

In test knives, both at the same rockwell hardness (62) and with identical geometry and subjected to the same cuts - the difference in edge retention can be seen at an arms length. The blade that received cryo after a snap temper has visible edge damage, the blade treated as a part of the quench did not. This is due to reduced RA.

So, the purpose is not to increase hardness - it is to maximize the amount of martensite that is formed. Otherwise you have a relatively large volume of soft "stuff" mixed in which plays hell with fine edge stability. It is a moot point in a punch tool, but it is very important to a fine edge blade. The side effect is an increase in hardness. Not because the martensite is harder - but because there is more of it.

Cryo temperatures are not required to reach Mf with D2. -100 is adequate.
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Nathan, I sent the knife to Paul BOS to be completely heat treated and cryo. I do understand the process and it would'nt do much good as an afterthought. I made 2 blades both skinners from same piece of barstock. They were identical. One was sent out for heat treat and cryo the other was done by me with no cryo. I put them through the same things including dressing and skinning several whitetails. This is just my opinion based on what I seen and felt while using them. Personaly I could'nt tell the differance. Both held an edge well. Cryo blade was 61 Rc. Mine was 60 Rc.
 
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Nebulae said:
be warned however!
these response are all very positive, that is because people who like d2 see your thread and want to tell you all about how great it is, people who don't care, or think it is a mediocre steel will not post
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I don't know if i agree with your statement. I think people that have an opinion will want to express it
 
Nebulae said:
be warned however!
these response are all very positive, that is because people who like d2 see your thread and want to tell you all about how great it is, people who dont care, or think it is a mediocre steel will not post
Click to expand...

It's not so much that I like D-2, I would much rather grind 1095 or even ATS-34 they're much easier to work with. I along with many makers much more experianced and well known, chose this steel for it's performance. It should be mentioned that D-2 has gotten a bad name with some people because their only experiance was with a factory made knife. :eek:
 
D2 is an excellent steel -takes and holds an edge longer than ol' reliable ATS-34/ 154 CM at the same hardness, but isn't as corrosion resistant.

Whoever said D2 takes a poor edge obviously didn't have a knife that was correctly heat treated.

The first knife I had in D2 was a production knife I purchased, it just wouldn't take an edge. However, since I started making knives and heat treating them myself -it has been one of my favorite steels. Annealed D2 is quite easy to work with. :thumbup:
 
I first handled D2 in a forged kitchen knife. At that point I fell in love with D2, this knife was so sharp it felt like it wanted to cut what ever you touched. I love my bm 710 in d2, I just put a 15deg edge on it from about 20. I would love to have a custom knife in d2. I love this steel.
 
blindviper1 said:
I first handled D2 in a forged kitchen knife. At that point I fell in love with D2, this knife was so sharp it felt like it wanted to cut what ever you touched. I love my bm 710 in d2, I just put a 15deg edge on it from about 20. I would love to have a custom knife in d2. I love this steel.
Click to expand...

Funny you should say that, I've just finished HT on 8 CPM D2 blades (5 of them chef's knives). I'm taking them out to another shop to use a Rockwell tester tomorrow. These will be my first knives out of the CPM D2 instead of just regular D2, and my first kitchen knives with it. I'm really curious to see how they handle compared to the regular stuff.

Heat treat was:

-equalized at 1100 and 1400 F for 10 min each
-soaked at 1850 F for 30-35 min
-plate quenched to hand warm
-put into cryo immediately following quench (dry ice and methyl hydrate), left in cryo for 14 hours
-removed from cryo, warmed in still air to room temp
-tempered 2 cycles for 1.5 hours each (first at 400F, second at 450F)

We'll see how they turn out:D

Have a good one,
Nathan
 
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