O1 Steel - History and Properties

Larrin

Larrin

Knifemaker / Craftsman / Service Provider
Joined
Jan 17, 2004
Messages
4,970
Excellent work on your excellent blog. I love the micro photographs. Polished and reflective microscopy is a hobby of mine as well, of the mineralogical variant.
 
Nice write up.

Short preview: O1 kiiinda sucks a little.

I like it enough in my 2 Hinderers though :thumbsup:
 
The late Brian Lyttle said that O1 was one of the most under rated steels and when the heat treat was done properly, it was a pretty remarkable blade steel. As I remember, he had made a knife and gave it to a guy to field test it, didn't tell him what it was made of but wanted him to see how it performed. He came back amazed at the keenness and edge holding ability of the knife after his hunting trip and said it had to be one of the new super steels. The fellow was quite surprised to find out that it was plain old O1 tool steel.

I think we can sometimes over look things like 01 since it is a pretty old steel compared to all the new kids on the block.

G2
 
Gary W. Graley said:
The late Brian Lyttle said that O1 was one of the most under rated steels and when the heat treat was done properly, it was a pretty remarkable blade steel. As I remember, he had made a knife and gave it to a guy to field test it, didn't tell him what it was made of but wanted him to see how it performed. He came back amazed at the keenness and edge holding ability of the knife after his hunting trip and said it had to be one of the new super steels. The fellow was quite surprised to find out that it was plain old O1 tool steel.

I think we can sometimes over look things like 01 since it is a pretty old steel compared to all the new kids on the block.

G2
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It would definitely be a winner in the “keenness” department. If given a nice thin edge it would probably be pretty impressive.
 
uraninite said:
Excellent work on your excellent blog. I love the micro photographs. Polished and reflective microscopy is a hobby of mine as well, of the mineralogical variant.
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I wish I had enough time to do more.
 
it's really a bit of a mystery; how o1 could show such poor toughness results... esp when you compare it to 52100

http://www.zknives.com/knives/steels/steelgraph.php?nm=o1,52100

is the big difference for toughness the Mn amount? (o1 has quite a bit more)
or maybe 52100 is so much tougher because it's lower in P and S? (ie, cleaner steel)?

I know it's probably both, but the difference still seems really big (52100 is 300% tougher at 61 hrc)
O1-vs-low-alloy-toughness-8-22.jpg
 
thank you again for pointing that out, steel has such complex subtleties, but very simple on the surface..., the microscopic world of stuff that is built from the apex element in our sun (and nearly all stars) continues to inspire ; )

and yet, the tiny drop in carbon in 8670 makes it blast both of those in terms of toughness, despite having only 0.5% chrome
http://www.zknives.com/knives/steels/steelgraph.php?nm=o1,52100,8670
...
(that last bit is not meant to argue your point, of course, since it's all true)
 
I agree with plate martensite roles in reducing toughness. However 1095 & O1 data (in graph) above don't aligned with other steels.

CruforgeV has same 0.5Cr% as O1 however the graph/data shows it is 200% tougher than O1. Obviously cfv samples received good ht protocol, where results are closely reflect toughness level appropriate to 52100 ht.

26C3 has 0.3%Cr is ~100% tougher than O1. Also 25c3 has quite a bit more carbon% than O1, which would be more likely putting more carbon in solution, i.e. more likely to produce higher percentage plate martensite. You've an article on how to ht this steel to produce good result. Again, this result reflect toughness level appropriate to carbide volume of this steel relative to 52100.

Prediction/expectation (with good ht) 1095 & O1 toughness should be +- 10 ft-lbs relative to 52100. Their results are outside of expected the range, IMO - 1095&O1 data are bad.

Larrin said:
The high Cr drops carbon in solution making plate martensite less likely. That is one potential mechanism. I explained that more here: https://knifesteelnerds.com/2019/01/28/history-and-properties-of-52100-steel/
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bluntcut said:
Prediction/expectation (with good ht) 1095 & O1 toughness should be +- 10 ft-lbs relative to 52100. Their results are outside of expected the range, IMO - 1095&O1 data are bad.
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The toughness results for 1095 and O1 line up with other sources. If you think you can heat treat it better please send me some specimens.
 
You've pondered about this toughness disparity in your article and many have asked similar questions about this. So perhaps need to increase statistical confident by having more data points by repeat sampling 1095 & O1 using same ht, plus maybe DET and or Tempering Annealed protocols. Toughness data from you and others (participants) are well appreciated.

My participation has been refrained because BCMW ht is proprietary, so data can not be validate/repeatable by others thereby its value limited to 'instances'/'existence'. Otoh if you are willing to add data from 'undisclosed ht protocol' to your collection/study, please let us know.

Larrin said:
The toughness results for 1095 and O1 line up with other sources. If you think you can heat treat it better please send me some specimens.
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There are questions about why certain steels seem to perform poorly despite characteristics that would seem to point to better performance. However, we haven’t had many samples that contradicted previously published data, unless the data was already conflicting or incomplete. 1095 and O1 have been tested with relatively poor toughness by many.

Testing more heat treatments, steels, etc. is going to happen. It’s only limited by the number of people willing to contribute. I only test samples which are provided with a processing history.
 
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bluntcut's ht, while technically proprietary is not something he keeps secret, there are huge threads about it on bf...
the tldr; it's a variation on mar-quenching with a really slow temp drop over a long period of time

it would be great if he submitted a bunch of different steel samples to match Larrin Larrin requirements on toughness testing
 
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