D2 Question

J

J.D.

Joined
Feb 12, 2006
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342
I am going to try some D2, and in looking at the data sheets on composition, I have found that Crucible and Latrobe do not have Cabalt, but the D2 that Amtek Tool sells has 1.00 of Cobalt. Amtek Tool has a good price on flat ground tool steels, but what effect will the Cobalt have?
Thanks for any help. Dale
 
Very good question... I would guess the addition of that much cobalt would help a lot with wear resistance and maybe with corrosion resistance too. Amtek has S7 with a different recipe too, very attractive with enough vanadium for grain refinement and up to 1% Si which should make it even tougher... but the Si content is random! I'd like to hear some experienced users comment.
 
D5 is D2 with 3% Cobalt... so I am guessing the properties will be in between D2 and D5. D5 heat treats the same but has higher hot hardness.
 
Based upon the way cobalt works in some HSS, I'd guess higher hot hardness at the expense of toughness. 1% isn't a lot for cobalt (I don't think it is a carbide former), some steels get 10% or more, so the difference would probably be modest.
 
Thanks to all who responded. The price seems very good to me, so I guess I will try it, but I would hate to loose much in the way of toughness, as I understand it, D2 is not known for its toughness anyway.
Thanks, Dale
 
J.D. said:
Thanks to all who responded. The price seems very good to me, so I guess I will try it, but I would hate to loose much in the way of toughness, as I understand it, D2 is not known for its toughness anyway.
Thanks, Dale
Click to expand...

You can increase the toughness of D2 if you do a grain refinement cycle.
 
J.D. said:
cotdt, what is the procedure to do a grain refinement for D2?
Dale
Click to expand...

d2grainrefinement925104.jpg


Heat treating D2 from annealled stock gives you a fracture grain size of 9, you can get it much finer by quenching first at 925-980° C, and a 2nd quench at 1030-1040° C.
 
No doubt that is interesting. But who actually uses that sort of HT recipe? Asking a honest question, not trolling...
 
gixxer said:
No doubt that is interesting. But who actually uses that sort of HT recipe? Asking a honest question, not trolling...
Click to expand...

No one that I know of, though some makers have their own proprietary heat treats for D2 that they don't share.

I've tried grain refinement for D2 as well as certain other steels, and it does work. When you break them the cross section is white smooth and very sparkley, especially under the microscope. Keep in mind that with finer grain size you need a faster quench though, like oil or quench plates.
 
So lemme break this down. I heat to the lower end of the temp window then quench (plate in my case), then immediately go back into the heat to the higher end of the temp window, soak, quench, then temper and press on with business?

Is 1030C right at the edge of almost too hot for the steel?
 
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gixxer said:
So lemme break this down. I heat to the lower end of the temp window then quench (plate in my case), then immediately go back into the heat to the higher end of the temp window, soak, quench, then temper and press on with business?
Click to expand...

Yeah exactly. Although I also do cryo after the final quench to minimize the retained austenite.

You can do 1010°C which is typical for D2, I just use a slightly higher austenization temp because I do a cryo step so retained austenite isn't a problem for me.
 
Sounds like something to experiment with, cook one and smack it with the hammer.
 
Is D2 not annealed when we buy it in flat ground stock? And if it is, and you do stock removal, why anneal before heat treating? If you grind slow, and don't get the blade hot enough to change the color, is it even nessacery to normalize? Just asking, because I want to do it the right way, and don't know. All of this is about to change my mind on
D2.
Dale
 
J.D. said:
Is D2 not annealed when we buy it in flat ground stock? And if it is, and you do stock removal, why anneal before heat treating? If you grind slow, and don't get the blade hot enough to change the color, is it even nessacery to normalize? Just asking, because I want to do it the right way, and don't know. All of this is about to change my mind on
D2.
Dale
Click to expand...

Dale,
at that thread you may read that the process was all wrong, the procedure was a mistake etc.. I was confused because the steel firm (Bohler) where I bought my D2 stock was not recommending normalizing and I wasn't aware of stress relieving procedure. Therefore I decided to anneal those blades. But I was not sure about it, also I mis-programmed the kiln. So after all, the almost all worst heat treating scenario was actually happened. Long high heat soak, very slow cooling etc. The steel at that condition was unusable.

So I took valuable guidance from here and found a decent solution. Which was answering also your question above :
cotdt, what is the procedure to do a grain refinement for D2?
Dale
Click to expand...

So I thought you could use that info. Yes I know, you don't need to anneal stock removal blades, but if someone has a brittle D2 or any other high alloy steel in hand, via my foolish experience they can refine the grain and carbide distribution.
 
Interesting thread. For some reason I always thought normalizing, and multiple heat cycles for grain refinement was something that could only be done with carbon (non-stainless) steels.

Is this something that could be applied to other stainless steels as well (154cm, 13c26, etc) or does it only work with D2 because it's semi-stainless?
Would it be worth trying on CPM-D2 or would do little since their particle metallurgy already results in a consistent, refined grain structure.
 
cotdt said:
Heat treating D2 from annealled stock gives you a fracture grain size of 9, you can get it much finer by quenching first at 925-980° C, and a 2nd quench at 1030-1040° C.
Click to expand...

It's my understanding that Bob Dozier does something similar in his D2 heat treat process. This is just my understanding cobbled together from a few things he's said about heat treating D2 in general - YMMV.
 
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