D2

seved

seved

Well-Known Member
Is there anyone with experience of D2. I wonder if there is worth it to normalise it and at wich temp if so. I will make two test knives and see if i can get it sharp and not brake. I have heard so many say that it hold a bad edge forever.So i must test it.:D

Seved
 
Last edited:
Seved,

D2 is an air hardening steel. Normalizing would be a bad idea I think. It should be hardened at1875 degrees F and quenched in air (or oil) then tempered twice at 450 degrees F for two hours each. Let cool between tempers in still air. This should get you a Rc hardness of about58 and it will hold that edge for a long time. It is my preference for a nearly stainless blade. It is tough but can be broken if you're in a destructive mood.

It's only drawback over carbon steel is that it is a little hard to resharpen without equipment. All this is my opinion. Others will surely disagree
 
Thanks Gary B. :D. I wonder if i heat it to the lower temp and quench it. I get a little finer structure.

Seved
 
To refine the grain by heat treating you must austinize and then quench. Austinizing at the lowest temperature needed is always a plus because the rate of grain growth is more dependant on temperature than time. If you are going to forge it you will have to get it hotter than most steels and, from my reference materials, not forge it under an orange color. D2 is rather red hard but Hrisoulas said nothing about it being red short like O1 can be. Being that D2 is air quenching, you are pretty much restricted to multiple quenches to refine grain by heat treating.

Doug Lester
 
Doug Lester said:
To refine the grain by heat treating you must austinize and then quench. Austinizing at the lowest temperature needed is always a plus because the rate of grain growth is more dependant on temperature than time. If you are going to forge it you will have to get it hotter than most steels and, from my reference materials, not forge it under an orange color. D2 is rather red hard but Hrisoulas said nothing about it being red short like O1 can be. Being that D2 is air quenching, you are pretty much restricted to multiple quenches to refine grain by heat treating.

Doug Lester
Click to expand...

Yes austinize at lowest possible temp must be the best, the problem maybe is that it not get as hard as i want. What means with redhard. How do mean multiple quenches.

Thanks bubba-san. great links :D

Seved
 
Red hard means that the steel retains more hardness when glowing hot when compared to others that are "softer". Multiple quenching means just that, to quench multiple times in succession, usually not more than three times however. It uses the characteristic that when steel crystals, really iron crystals, change phases back and forth new crystals will form on the borders of the existing crystals in a smaller size.

Doug Lester
 
D2 isn't the best steel for forging. It can be done - but you can also teach a pig to sing... If you're not prepared to address what happens to the microstructure after forging heats, you're probably not going to make a great blade this way.

If you're not prepared to address retained austenite - this is not a good material for a knife blade. Hence it's reputation for taking a lousy edge and holding it forever. A 20% RA blade with big chunks of carbide will have an edge that chips and rolls, yet be difficult to sharpen. Simpler steels will outperform it if you do not address the RA.

Unless you have forged it, or previously heat treated it, D2 will not need to be normalized. This high carbide steel still maintain a grain size around 10, which is considered fine grained (though other knife steels can achieve much finer) all the way up to nearly 2000F. So don't worry about grain growth in this steel during it's first heat. IF, for whatever reason you want to reaustenitize it - watch out, grain can grow to a size 4 or worse during a second heat. HSS is this way also. And annealing and normalizing to repair it takes special equipment and techniques that you're going to want to avoid. So don't multiple quench D2

I believe the best way to heat treat it is to use a moderate temp (1850, this will free up enough carbon for a carbon rich martensite, without overdoing it and creating excessive RA), soak for 30-45 min, plate or slow oil quench (the rapid quench reduce RA and increases free chromium) and continue that quench as an uninterrupted trip all the way down to Mf, which is around -100 F (go get some dry ice for this). Then temper at about 450 for a Rockwell hardness around 62. This steel, with this heat treat, has outperformed anything I have ever tested for a thin slicer with an acute edge angle of about 25 deg included.

Then, it will take a sharp edge and hold it reasonably well, and maintain a working sharpness a very long time in many different material, and it will tolerate abuse such as cutting metal that would ruin a stainless steel edge.
 
Nathan The Machinist said:
D2 isn't the best steel for forging. It can be done - but you can also teach a pig to sing... If you're not prepared to address what happens to the microstructure after forging heats, you're probably not going to make a great blade this way.

If you're not prepared to address retained austenite - this is not a good material for a knife blade. Hence it's reputation for taking a lousy edge and holding it forever. A 20% RA blade with big chunks of carbide will have an edge that chips and rolls, yet be difficult to sharpen. Simpler steels will outperform it if you do not address the RA.

Unless you have forged it, or previously heat treated it, D2 will not need to be normalized. This high carbide steel still maintain a grain size around 10, which is considered fine grained (though other knife steels can achieve much finer) all the way up to nearly 2000F. So don't worry about grain growth in this steel during it's first heat. IF, for whatever reason you want to reaustenitize it - watch out, grain can grow to a size 4 or worse during a second heat. HSS is this way also. And annealing and normalizing to repair it takes special equipment and techniques that you're going to want to avoid. So don't multiple quench D2

I believe the best way to heat treat it is to use a moderate temp (1850, this will free up enough carbon for a carbon rich martensite, without overdoing it and creating excessive RA), soak for 30-45 min, plate or slow oil quench (the rapid quench reduce RA and increases free chromium) and continue that quench as an uninterrupted trip all the way down to Mf, which is around -100 F (go get some dry ice for this). Then temper at about 450 for a Rockwell hardness around 62. This steel, with this heat treat, has outperformed anything I have ever tested for a thin slicer with an acute edge angle of about 25 deg included.

Then, it will take a sharp edge and hold it reasonably well, and maintain a working sharpness a very long time in many different material, and it will tolerate abuse such as cutting metal that would ruin a stainless steel edge.
Click to expand...

Thank you Nathan The Machinist. That was realy helpfull. I will try it. I will order some D2 from sheffild knifemakingsupply next time. I am very exited about it:D.

Thank you Doug Lester i see what you mean. 2thumbs.

Great links again bubba-san2thumbs

Seved
 
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