Talk to me about no cryo heat treat.

Judging by the two images alone,
It seems to me that we have take an expensive piece of PM steel with uniform an evenly distributed carbides and by the process of deep freeze cooling, as part of the quench cycle, turned it into a piece of conventionally manufactured D2, which has been made more brittle due to the removal of retained austenite, more difficult to sharpen and with a weaker edge, unless we are targeting a toothy serrated edge.
 
Way-Barney said:
Judging by the two images alone,
It seems to me that we have take an expensive piece of PM steel with uniform an evenly distributed carbides and by the process of deep freeze cooling, as part of the quench cycle, turned it into a piece of conventionally manufactured D2, which has been made more brittle due to the removal of retained austenite, more difficult to sharpen and with a weaker edge, unless we are targeting a toothy serrated edge.
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That is incorrect.
 
DevinT said:
I think I'm going to write a book entitled “The cheap lazy bastard’s guide to heat treating”.

Hoss
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I only use simple steels, and ht in a kiln(with a thermocouple and baffle). So this entire thread doesn't really apply to me; however, it's fun to read anyway. This is a book I would definitely buy.
 
Way-Barney said:
I prefer the structure in the top image, those carbides at the bottom are huge and I did not realize that deep freeze cooling led to such grain growth.
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Micrographs can be very confusing to those who don't look at them every day. I just enjoy them as artwork ... Sometimes I see a little horse or the face of Lincoln?
Those two images are the same scale but the etch shows things differently. It is like taking a photo of two similar size girls at the beach, one in a blue bikini and one in a red bikini. If the sun is behind the blue girl and in front of the red girl, they will look different. It would be wrong to say that one had bigger boobs or darker skin.

What I see in the two images is the same amount of Chromium Carbides, but #2 has more Martensite and very little Retained Austenite.
 
Way-Barney said:
Judging by the two images alone,
It seems to me that we have take an expensive piece of PM steel with uniform an evenly distributed carbides and by the process of deep freeze cooling, as part of the quench cycle, turned it into a piece of conventionally manufactured D2, which has been made more brittle due to the removal of retained austenite, more difficult to sharpen and with a weaker edge, unless we are targeting a toothy serrated edge.
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Is it the same steel before and after cryo? No mention of it.
 
An interesting paper on "D" series tool steels given Cryogenic treatment, Lacking in detail regarding specific temperatures etc. Comments on D3 having a better response than D2 with lower RA, look worth investigation. Sadly lacking numbers.
 

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DevinT said:
I think I'm going to write a book entitled “The cheap lazy bastard’s guide to heat treating”.

Hoss
Click to expand...
It’s not so much that usually. I used to be able to buy ln2 for 50 bucks to fill my 10l deware. Now it’s 100 dollars. And since I moved farther from town, it’s even harder to get it. I work all week, and they are closed on weekends. So I’ve been experimenting with no cryo on my choice of steels. And I can only see a very small difference if at all. It comes down to testing, and of course convenience! I can’t take time off work to run to air gas. So I did have to change my choice of steels. And I do use a lot of high tempering these days. I wouldn’t say that’s a lazier way of heat treating. It’s just what I have to do! Some steels work just fine with high temper and no cryo. Some need cryo for the best performance. I do prefer cryo, even with a high temper. Because they just seem to gain more! But it’s not necessarily worth it for me! So convenient yes, lazy, no!!
 
Peter's heat treatment does offer cryogenic services with their heat treatment. I think if one is doing in-house heat treatment the processing should meet or exceed what is available from a heat treat service.

There is a hidden cost to in-house heat treatment in time, equipment, maintenance, knowledge and experience.

It should only be done if a maker is interested in the subject and is able and willing to meet or exceed services that are on the market.

Otherwise, limited time and resources should be spent in different areas.
 
DeadboxHero said:
Peter's heat treatment does offer cryogenic services with their heat treatment. I think if one is doing in-house heat treatment the processing should meet or exceed what is available from a heat treat service.

There is a hidden cost to in-house heat treatment in time, equipment, maintenance, knowledge and experience.

It should only be done if a maker is interested in the subject and is able and willing to meet or exceed services that are on the market.

Otherwise, limited time and resources should be spent in different areas.
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But only if the actual cryo increases performance. Some alloys don’t get much of an increase. Even some of these medium alloy tool steels. I do prefer cryo. But from the testing I’ve done on the steels I use, the results are negligible! Then again I’m not into the super high alloy steels some people use! Ease of field sharpening and toughness are a priority for me !
After all the years I’ve spent out hunting and all my wilderness pack trips and elk hunts, Some longer than most people would ever think of doing. I’m pretty content with these medium alloy steels. I’m definitely not saying you get a better blade without cryo.


But I do have more testing to do. I’m talking extended field trips while hunting. If I can draw my tags this year, I will definitely be making a couple side by side blades to test on elk! And I tested a lot of A8 blades on several elk, deer and oryx this last year with phenomenal results! I will be trying a few with and without cryo, low and high temper! So in other words, tailor your blades and steel choices to your convenience and capabilities!
 
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