Effect of Cryo on Toughness

That was a good read! Some of it was a little over my head!! Thanks Larrin
 
I've also found that many of the "review" articles are no more trustworthy than the research it reviews.
 
Hey, Larrin Larrin , why on Fig 2 is H13 the less tough of those 4 steels? I would expect it to be the toughest, or at least the second toughest (behind S7, if H13 is out of its comfort zone (mid 40’s hrc)). Is this because the steels are all hardened to the same hrc value (high 50’s) and at this value H13 has embrittlement problems (way out of its comfort zone, at least)? Or should I read the paper (at least) more two times?
 
Another doubt, Larrin Larrin . “Tool steels are known for their relatively poor toughness”? Compared to structural steel, Maraging, Aermet and Shock resistant steels, correct?
 
hugofeynman said:
Another doubt, Larrin Larrin . “Tool steels are known for their relatively poor toughness”? Compared to structural steel, Maraging, Aermet and Shock resistant steels, correct?
Click to expand...
Compared to other steels, like the ones you mentioned, though also more broadly basically any other type of steel and many metals:
TME-vs-carbon.jpg
 
hugofeynman said:
Hey, Larrin Larrin , why on Fig 2 is H13 the less tough of those 4 steels? I would expect it to be the toughest, or at least the second toughest (behind S7, if H13 is out of its comfort zone (mid 40’s hrc)). Is this because the steels are all hardened to the same hrc value (high 50’s) and at this value H13 has embrittlement problems (way out of its comfort zone, at least)? Or should I read the paper (at least) more two times?
Click to expand...
Wow I didn't even notice. According to both Crucible and Carpenter H13 should be more than 5x tougher that they measured. Maybe another reason not to trust these cryo studies.
http://www.crucible.com/PDFs/DataSheets2010/dsNuDieVH13v12010.pdf
https://cartech.ides.com/datasheet.aspx?i=102&E=122&FMT=PRINT
 
Is it a question of cryo studies ? There are lots of people who know nothing about cryo. Finding info is a nightmare!. my personal experience with impact studies often showed a big difference in theory vs reality . me, I tend to take the info along with a maybe !
 
After reading many of these cryo studies, yes I have a hard time trusting them.
 
Fun to read and I feel like I understand most of it. But I'm wondering this...this indicates a .40 increase in toughness in D2. What does this translate into real world usability you know? I've seen firsthand a W2 knife heat treated and tempered with an oxy acetylene torch cleanly cut a rolling paper, chop through 5 pieces of seasoned oak as thick as a human leg, then come back and cleanly cut a rolling paper again...no edge deformation.

Is it wishful thinking at some point? I have sent a few blades out of more complicated steels like 3V and even some AEB-L and they have been cryo'd so I'm not saying I don't do it myself just wondering if anyone has ever done anything like side by side hemp rope slices to compare the two.

Thanks for posting this and opening up the discussion.
 
Shaw Blades said:
Fun to read and I feel like I understand most of it. But I'm wondering this...this indicates a .40 increase in toughness in D2. What does this translate into real world usability you know? I've seen firsthand a W2 knife heat treated and tempered with an oxy acetylene torch cleanly cut a rolling paper, chop through 5 pieces of seasoned oak as thick as a human leg, then come back and cleanly cut a rolling paper again...no edge deformation.
Click to expand...
It wouldn't make a difference. Especially since the tasks you are describing will be largely controlled by design, edge geometry, and sharpness.
 
When I first started to try and understand cryo and what it does for knife steels, I came across charts that claimed an enormous increase in wear resistance with steels that were cryo'd vs non cryo. I recall O1 (it may have been 52100) had a 400% increase in wear resistance. That's 4 times the wear resistance. I find that highly doubtful. Theoretically, it would take me 4 times as long to put a hand rubbed finish on a cryo 52100 blade vs non cryo, when in reality, there is no discernible difference. A lot of that "research", as it turns out, was funded by companies heavily vested in cryo processing. Getting real world data, especially for knife steels, is still in it's infancy.

Larrin, thank you for taking the time you put into researching these topics for us!
 
To add to the discussion, I think Larrin’s tests in z-wear with similar hardness, cryo/non cryo, low temper, and high temper is the best dataset listed. To complete the picture, we need to see what the trade offs, if any, in wear resistance or edge stability are. My personal experience is that the cryo/low temper knives I’ve made have a finer edge, and hold that fine edge longer. I suspect the high temper samples will hold a working edge longer, but I never let my knives get that dull.
 
What kind of test could we do to shed a bit more light on this? My big plan is to be exploring some higher alloy tool steels. I'm kinda thinking this might take me little while. It would be nice to have some structure to be looking build off of.
 
You must log in or register to reply here.
Back
Top