New micrographs of 42 knife steels

Interesting stuff Larrin, thanks for the post, and all the hard work!
 
Cool. So we are still stuck trying to explain some of the results with the weird "mid range outliers" like CFV, 52100 and CPM 154. I will be interesting to see how plain old 154CM/ATS34 does compared to comparable ingot stainless steels.
 
jdm61 said:
Cool. So we are still stuck trying to explain some of the results with the weird "mid range outliers" like CFV, 52100 and CPM 154. I will be interesting to see how plain old 154CM/ATS34 does compared to comparable ingot stainless steels.
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I don’t think I would call 52100 and CruForgeV outliers. 1095/O1 are lower than expected based on their carbide structures, though not inconsistent with old toughness studies of them. 52100 and CruForgeV are more in line with what you would expect based on their carbides.
 
Yeah. I was a bit surprised by the 1095 and O1, especially when seeing that leaving the 1095 "soft" had pretty much no effect. Not surprised so much the 52100. As CFV was pretty much a custom/one-off smelt (definitely one-off in hindsight) what do you think would happen good, bad or otherwise, if you added say an 8670 amount of nickel to that blend?
Larrin said:
I don’t think I would call 52100 and CruForgeV outliers. 1095/O1 are lower than expected based on their carbide structures, though not inconsistent with old toughness studies of them. 52100 and CruForgeV are more in line with what you would expect based on their carbides.
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Just about everything I know about nickel I put in the Why Cold Steel is Brittle article. I would like to see some more toughness comparisons between steels with different nickel additions. If it is a universal improvement to toughness I don’t know why it isn’t used more often.
 
You have probity gone over this, but I was wondering for a long time why they didn't use nickel in martensitic stainless steels and I finally read somewhere that it just doesn't work the same, but I don't recall why. Any insight on that?
Larrin said:
Just about everything I know about nickel I put in the Why Cold Steel is Brittle article. I would like to see some more toughness comparisons between steels with different nickel additions. If it is a universal improvement to toughness I don’t know why it isn’t used more often.
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Nickel is used in 414 and 431 but they are low carbon martensitic stainless steels. Nickel was also added to a no longer in production non-stainless that had 0.8% C and 11% Cr. The main reason it isn’t used is because retained austenite is often the limiting factor for hardness in stainless steels and nickel is an “austenite stabilizer.” It could be done but the composition would have to be carefully balanced.
 
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Larrin said:
Nickel is used in 416 and 431 but they are low carbon martensitic stainless steels. Nickel was also added to a no longer in production non-stainless that had 0.8% C and 11% Cr. The main reason it isn’t used is because retained austenite is often the limiting factor for hardness in stainless steels and nickel is an “austenite stabilizer.” It could be done but the composition would have to be carefully balanced.
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I think you mean 414 stainless has nickel.

Hoss
 
WOW, you've been busy!!
Another great article, thank you.
I've always been frustrated (until now!) by the various magnifications and selection of micrographs I could turn up online. This is really valuable work.
 
This is the best article yet! (At least for my interests.) Our home brew heat treats are resulting in consistent structures and carbides. I’m looking forward to more of these images of the different heat treats.
 
After receiving permission from Larrin, I thought I would post a few more micrographs of Cru Forge V that aren't all that widely circulated. I am pretty sure these came directly from Crucible. The edge is ~62HRC and the spine is ~52HRC. Hardness readings were taken from the center line of the knife blade in Knoop, and converted to Rockwell C. (Note that 0.001" is equivalent to 25.4 microns, so these are very close to the same magnification as Larrin's collection. I have the same photos in 0.0001"/2.54 micron if interested)....

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Larrin said:
Nickel is used in 414 and 431 but they are low carbon martensitic stainless steels. Nickel was also added to a no longer in production non-stainless that had 0.8% C and 11% Cr. The main reason it isn’t used is because retained austenite is often the limiting factor for hardness in stainless steels and nickel is an “austenite stabilizer.” It could be done but the composition would have to be carefully balanced.
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I did a reverse alloy search on matweb for ferrous materials with nickel, high carbon, and high chromium. I noticed that some 440C and 440A variants can have (optional) nickel. Do you know if it's common for nickel to be present in those?
 
Nick Dunham said:
I did a reverse alloy search on matweb for ferrous materials with nickel, high carbon, and high chromium. I noticed that some 440C and 440A variants can have (optional) nickel. Do you know if it's common for nickel to be present in those?
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If they have any nickel it will be in very small amounts. Nickel is avoided in tool steels and martensitic stainless steels because it makes them very sluggish. They become almost impossible to anneal and other weird things happen.

Hoss
 
I just think it's funny how some of the oldest steel is the toughest, even today.
8670 for plain carbon and aeb-l for stainless - and both are amazingly inexpensive

it's about time to test out how a thin aeb-l machete works out - anyone ever do one?
 
Nick Dunham said:
I did a reverse alloy search on matweb for ferrous materials with nickel, high carbon, and high chromium. I noticed that some 440C and 440A variants can have (optional) nickel. Do you know if it's common for nickel to be present in those?
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The nickel is allowed because it is often present in scrap steel and is not easily removed.
 
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