Dealing with D2

JTknives

JTknives

Joined
Jun 11, 2006
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Now that my oven is done my first project is to anneal a bunch of D2 planer blades I have. Thy are 26" long and .160 thick and about 1.25" wide or more. For me it's worth the effort to figure out these blades becaus I have something like 200+lbs of this stuff. Thy are made by Wisconsin Knife Works and thy call there alloy "Karbo Krome™ D-2" so it's D2 but exact makeup is unknown. I have read that some times re heat treating D2 that has been heat treated in the past can be problematic and have huge grain growth. My plan is to batch anneal these but want to make sure I do it right. Right now I got 9 of these in the oven and I'm running a test annealing program. I had it ramp up to 1600° and set for 1hr then cool to 1000° at a rate of 40°/hr. Once it hits 1000° it's cooling at the rate the oven looses heat. So any advice in working with this stuff and am I on the right track with annealing. Thanks guys
 
I think 20 per hour might be more typical.

You'll still probably want to sphereoidize afterwards.
 
Does D2 have a special sphereoidize process. I have been doing some research into proper sphereoiding but can't find anything referring to D2. And half the things I come across seam kinda vague in any detail.
 
JT, I tried to do a little surfing to figure out ideal D2 anneal. I think the "Heat to 1650F, hold one hour, cool to 1000F at a 40°F rate" accomplishes a lamellar anneal...not really sure. However, if you have a martensite structure, then "temper" at 1200F for an hour or two, I think that might work. What temp to use, that I don't know. Probably the austentizing temp....but please don't take my word for anything dealing with D2. I haven't messed with it/researched it much at all. Just trying to help a little. Maybe not helping at all, I'm afraid!
 
Yeah I don't know how to go about it. I tried doing research and did not come up with much besides the heat to 1600 and cool at x rate to 1000. Hoping to catch Nathan again so I can pick his brain.
 
I pulled the 9 blades out of the oven yesterday after there annealing and besides being dark and covered in oxide thy look rather good. Thy seam quite soft now and easily take a set when flexed. My plan is to do a hand full of mules to pass out for testing to see how my heat treating system works. But the plan is heat to 1750° and do and oil or plate quench. Then slowly ramp to around 1500-1550deg then up to 1800°. Then soak for around 30 min and oil quench or plate quench, then right into a dry ice bath for 1/2-1hr. Next would be a 400-425° temper. So that's the plan at least we will see how it goes.
 
me2 said:
Could it be easier to work the blades as is?
Click to expand...

this is how I made all of my first 20-30 knives... I used to work at a sawmill and got them from the scrap bin. two big problems with doing them like this was that they are HARD!!! I didn't know about Rockwell tests or anything back then and never had one checked but they were a little brittle at whatever HRC they came at back in those days, and they were a bear to sharpen in the field from the guys I sold/gave them to, so that's one thing.. and of course drilling and finishing them is pretty labour intensive when they are hard. Wish I could help more, but it can be done.
 
You can get spheroidized structure by starting out with martensite , then temper at 1200F for 2hours .This is referred to as "sub critical anneal ". Easier to do , avoids scale, decarb, and of course will let you drill holes in the tang etc.
 
Hum I never thought of that 1200° temper. But how's that work when I go to re heat treat the steel.
 
Not sure if this helps, but this is what one of my books Tool Steels 4th Edition by Roberts and Cary ASM: "anneal at 1600 - 1650F; the cooling rate should not exceed 50F/h to 1000F.". . ."If lower hardness than those obtainable with the procedure described above are desired, cooling slowly from 1600-1650F down to 1000F, followed by reheating to 1400-1450F, and slow cooling to room temperature may be effective. In certain instances, the following isothermal annealing cycle may result in a saving of time:
1. Heat to 1650F, hold for 2h at temp
2. Cool to 1425F and hold at this temp for 4-6h
3. Air cool
To ensure minimum distortion on hardening, a stress-relief anneal at 1200-1300F is recommended after rough machining and before final finish machining." pp 530-531.
 
weo said:
Not sure if this helps, but this is what one of my books Tool Steels 4th Edition by Roberts and Cary ASM: "anneal at 1600 - 1650F; the cooling rate should not exceed 50F/h to 1000F.". . ."If lower hardness than those obtainable with the procedure described above are desired, cooling slowly from 1600-1650F down to 1000F, followed by reheating to 1400-1450F, and slow cooling to room temperature may be effective. In certain instances, the following isothermal annealing cycle may result in a saving of time:
1. Heat to 1650F, hold for 2h at temp
2. Cool to 1425F and hold at this temp for 4-6h
3. Air cool
To ensure minimum distortion on hardening, a stress-relief anneal at 1200-1300F is recommended after rough machining and before final finish machining." pp 530-531.
Click to expand...

Indeed, this is the traditional anneal cited in tool steel books. I "think" this is a lamellar anneal, however. As I mentioned in the previous reply (Mete actually gave that spheroidize anneal recommendation on another forum for D2), starting with a martensitic structure, and then "tempering" that for 2 hours at 1200°F will spheroidize it, which is preferred over a lamellar anneal. I think of lamellar annealing as sheets on top of each other. Some hard, some soft. Whereas a spheroidized annealing will not form "sheets", but rather balls of carbide in a soft matrix, easily machinable. It also has advantages, mentioned in Mete's post above, as well as being in a state that is ready to harden.
 
Yes, if you have martensite, you can just hold at about 1200 (I always go for 1225 or 1250, but I am anal) for a couple of hours.

If you do not have martensite, then heat to 1350, hold for at least one hour, and then let cool slowly (no more than 40F per hour) until below 900F.

Sometimes, paradoxically, it is easier to harden and then to temper to get the softest possible structure.
 
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