D2 Soak Time

Randy Wirtz

Randy Wirtz

Joined
Feb 29, 2016
Messages
20
I’ve been working with D2 fairly consistently of late and have been getting some decent results thus far. This is primarily because of the tremendous insight I’ve received from many on this forum.

With 3/16”- 5/16” thick material, I’ve been soaking the D2 for 30-40 minutes @ 1850-1900°F. Recently I’ve worked with some D2 that is 3/32” thick. It seems that the soak time for this thinner material should be considerably less.

I would appreciate any insights on this topic. Thanks
 
Hold the work piece at the hardening temperature until it is completely and uniformly heated. D2 is an air hardening steel and will develop hardness on cooling in still air. So yes it should take less time, if you can see the color of the piece is completely uniform it's done.
 
SteelJunkee said:
Hold the work piece at the hardening temperature until it is completely and uniformly heated. D2 is an air hardening steel and will develop hardness on cooling in still air. So yes it should take less time, if you can see the color of the piece is completely uniform it's done.
Click to expand...

Unfortunately, I can't see the color because the blade is inside a stainless steel foil pouch.
 
SteelJunkee said:
Hold the work piece at the hardening temperature until it is completely and uniformly heated. D2 is an air hardening steel and will develop hardness on cooling in still air. So yes it should take less time, if you can see the color of the piece is completely uniform it's done.
Click to expand...
I don t think that this is good advice ....D2 need soaking time
 
That is too bad because, the fact that you let it soak a bit longer does not change anything except the waste of energy. I would like to help more but this is dependent of the oven used, you could do a test without the pouch and leave it a little longer with the pouch afterward to be on the safe side.
 
The steel requires time at temperature to dissolve carbides. The only difference in time with thickness comes from time to heat through.
 
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Larrin said:
The steel requires time at temperature to dissolve carbides. The only difference in time with thickness comes from time to heat through.
Click to expand...

How would you proceed with thin pieces like those the OP is talking about ? i honestly don't think the 25 min per cm thick rule apply in this case ? because he is talking about 2.38 mm and this would result in a 6 min bath ? it does depend on how much time the bath takes to heat up tho.
 
SteelJunkee said:
Hold the work piece at the hardening temperature until it is completely and uniformly heated. D2 is an air hardening steel and will develop hardness on cooling in still air. So yes it should take less time, if you can see the color of the piece is completely uniform it's done.
Click to expand...

This is wrong
 
SteelJunkee said:
Hold the work piece at the hardening temperature until it is completely and uniformly heated. D2 is an air hardening steel and will develop hardness on cooling in still air. So yes it should take less time, if you can see the color of the piece is completely uniform it's done.
Click to expand...

Unfortunately, I can't see the color because the blade is inside a stainless steel foil pouch.
Nathan the Machinist said:
This is wrong
Click to expand...


I've done a handful of the 3/32" thick D2 with a 30 minute soak at 1850 and the results are good. I was thinking that there was the possibility that I could be over doing it a bit.
 
SteelJunkee said:
Ok. Then humbly.... Elaborate.
Click to expand...



This is inaccurate and terrible advice:

SteelJunkee said:
Hold the work piece at the hardening temperature until it is completely and uniformly heated. D2 is an air hardening steel and will develop hardness on cooling in still air. So yes it should take less time, if you can see the color of the piece is completely uniform it's done.
Click to expand...

I'm sorry, I'm not trying to be adversarial but it's a problem when someone comes in here and states bad information as fact like this. That sort of wrong information is one of the reasons people sometimes have trouble with steels like D2.

It almost doesn't matter how long it takes to become "completely and uniformly heated". Knives are thin, it takes a few minutes, it's almost just a rounding error compared to the soak time it needs due to carbides. What matters is the time it takes to dissolve the carbides and for the carbon to equalize. Almost all steel is supplied in a spheroidized condition meaning it is going to need to a soak a while but D2, with it's large carbides and carbon content, is an extreme example of that. D2 that is quenched once it reaches temp would be hopelessly bad. Soaked for 10-15 minutes once at temp, would still be wildly under soaked and won't perform. It will be like chunky peanut butter. However, with the large vanadium content pinning the grain and moderate austenitizing temperature you could probably soak it for hours without a problem.

People become confused when they take heat treat protocols designed for stamping tools that are going to soak for hours and try to apply it to a thin knife blade. Yes, it still takes time for the material to reach temperature equilibrium, but in something as thin as a knife blade that time is dwarfed by the amount of time that it needs to soak at temp. 30 minutes at temp is a good time for D2.
​
 
SteelJunkee said:
Ok. Then humbly.... Elaborate.
Click to expand...

Before you reply. your answer should be.

Heat Treating D2 tool Steel

To begin... wrap the piece in stainless steel tool wrap and leave an extra two inches on each end of the package (This will be for handling purposes). The foil should be double crimped around the edges. Note: be careful to not tear or puncture the wrap!


Once wrapped place in the furnace and heat to 1850F. Upon reaching this temperature immediately begin timing the soak for 15 to 20 minutes. (Soak time is the amount of time the steel is held at the desired temperature; which in this case is 1850 degrees Fahrenheit)

Note: soak times will very depending on steel thickness. See formula at the bottom of page.

When the soak time is complete, very carefully remove the entire package, and place it on a wire rack allowing it to air cool. Once the piece reaches 125F begin the temper process. To temper the piece remove it from the foil wrapper and place it back into the furnace at 950F allowing it to soak for 2 hours. Then remove the piece and allow it to cool to room temperature.

Tip: Open the oven door and let it be cooling to 950F while the piece is cooling to 125F.

To begin the second temper place the piece back in the furnace and soak for 2 hours this time at 900F. Once this step is complete remove the piece and allow it to cool. It should now be approx hardness 58-60 RC.

Tip: The piece can be placed in dry ice for an hour this will add some stability and a little extra hardness.

Note: Pre quench soak times can very to some degree. However, commonly one can figure about 1 hour of soak at hardening temperature per inch of steel thickness
i.e:
1 inch = 1hour

1/2 inch = 30mins

1/4 inch = 15mins

1/8inch = 7.5mins

So it should be a 7.96 minutes bath or.... until the piece is uniformly heated to desire temperature it`s not time but uniformity in matter so in my opinion this should soak half an hour. Please correct me if i`m wrong again.
 
Have you used that heat treat on D2 before?
 
SteelJunkee said:
Before you reply. your answer should be.

Heat Treating D2 tool Steel

To begin... wrap the piece in stainless steel tool wrap and leave an extra two inches on each end of the package (This will be for handling purposes). The foil should be double crimped around the edges. Note: be careful to not tear or puncture the wrap!


Once wrapped place in the furnace and heat to 1850F. Upon reaching this temperature immediately begin timing the soak for 15 to 20 minutes. (Soak time is the amount of time the steel is held at the desired temperature; which in this case is 1850 degrees Fahrenheit)

Note: soak times will very depending on steel thickness. See formula at the bottom of page.

When the soak time is complete, very carefully remove the entire package, and place it on a wire rack allowing it to air cool. Once the piece reaches 125F begin the temper process. To temper the piece remove it from the foil wrapper and place it back into the furnace at 950F allowing it to soak for 2 hours. Then remove the piece and allow it to cool to room temperature.

Tip: Open the oven door and let it be cooling to 950F while the piece is cooling to 125F.

To begin the second temper place the piece back in the furnace and soak for 2 hours this time at 900F. Once this step is complete remove the piece and allow it to cool. It should now be approx hardness 58-60 RC.

Tip: The piece can be placed in dry ice for an hour this will add some stability and a little extra hardness.

Note: Pre quench soak times can very to some degree. However, commonly one can figure about 1 hour of soak at hardening temperature per inch of steel thickness
i.e:
1 inch = 1hour

1/2 inch = 30mins

1/4 inch = 15mins

1/8inch = 7.5mins

So it should be a 7.96 minutes bath or.... until the piece is uniformly heated to desire temperature it`s not time but uniformity in matter so in my opinion this should soak half an hour. Please correct me if i`m wrong again.
Click to expand...
Nathan already explained why you are wrong. Larren has written some nice articles that are available and would probably help to understand how it all works if you are interested.
Hopefully you can understand that dogmatic answers with incorrect information perhaps came across a trolling and brought out some curt answers. If you did want a discussion about the theory behind their answers it might be best to start a new thread since it's off topic for the OP.
 
^ not just wrong. That HT, that appears copied and pasted from somewhere, has temper before cryo (from 125?) and uses the secondary hardening hump. It's an old version of the "takes a crappy edge and holds it forever" HT that most folks don't use for knives. Works fine for tool and die, but not great for knives due to edge stability issues. Which makes me wonder...

We don't need people, who don't make knives, giving (bad) advice to others (who do make knives) how to make knives. I'm sorry to dump on a new member here, but that kind of thing isn't good for the forum, but that's what it looks like to me.

Seriously, I'm not trying to be an A hole here, but it seems like it needed to be addressed.




edit to add: to the OP, if your stock is much thinner than you usually use, you might shorten your time to get to temp a few minutes but your time at temp doesn't change. In practice you probably don't need to change anything. Disregard any nonsense about quenching D2 once it reaches temp. That's unhelpful misinformation.
 
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Thank you all for contributing to this discussion. Nathan, I particularly appreciate your insight into D2. I have learned a ton from your past posts on this material. Hopefully this thread will be helpful to others. Once again, thanks all.
 
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