How does s90v have higher wear resistance than k390?

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yepimonfire

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They both have the same amount of Vanadium but s90v has a softer matrix hardness than k390 by a pretty significant amount (59-60hrc vs 64-66hrc), Larrin's TCC rankings put s90v far above k390 and in actual use I've found it definitely outperforms k390 (provided I don't do something crazy like cut metal wire). Anybody who knows more than I do care to chime in as to why it has higher wear resistance?
 
For one Larrin's CARTA tests were done with S90V at 61.7 and K390 at 62.6, pretty close in hardness, but for another wear resistance is mostly controlled by volume and type/hardness of carbides. S90V has higher volume of carbides, so it is more wear resistant than K390 at similar hardness. For K390 to get close to S90V it would need to be at 66 HRC or higher.
 
Agreed on carbide volume. Both steels have 9% vanadium, but S90V has 14% chromium compared to K390's 4%. So I'm guessing S90V has a lot of chromium carbide or vanadium-enriched chromium carbide adding to its carbide total.
 
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Delta-v said:
Agreed on carbide volume. Both steels have 9% vanadium, but S90V has 14% chromium compared to K390's 4%. So I'm guessing S90V has a lot of chromium carbide or vanadium-enriched chromium carbide adding to its carbide total.
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The total weight of elements is not equal to the actual volume of carbide type present inside the steel.

9% wt V does not equal 9% Vol. V carbide.
 
yepimonfire said:
They both have the same amount of Vanadium but s90v has a softer matrix hardness than k390 by a pretty significant amount (59-60hrc vs 64-66hrc), Larrin's TCC rankings put s90v far above k390 and in actual use I've found it definitely outperforms k390 (provided I don't do something crazy like cut metal wire). Anybody who knows more than I do care to chime in as to why it has higher wear resistance?
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Probably depends on the heat treatment balde angle etc. My understanding as an intenet ninja is that s90v is easier to get the heat treatment right on. So like, if spyderco was making both of them, then maybe?
 
I have Peters' take the S90V to 61.5-62 HRC and it performs very well. The old thinking hat S90V could "only" be taken to 60 HRC was proven false.
 
And I'm guessing the Chromium carbides make up the difference between both of these two steels?

ace said:
For one Larrin's CARTA tests were done with S90V at 61.7 and K390 at 62.6, pretty close in hardness, but for another wear resistance is mostly controlled by volume and type/hardness of carbides. S90V has higher volume of carbides, so it is more wear resistant than K390 at similar hardness. For K390 to get close to S90V it would need to be at 66 HRC or higher.
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I never noticed that! That's very hard S90V and very soft K390... You just blew my mind a bit haha
 
minimag03 said:
And I'm guessing the Chromium carbides make up the difference between both of these two steels?


I never noticed that! That's very hard S90V and very soft K390... You just blew my mind a bit haha
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Well, to test steel correctly you need to have as many variables as possible same. For example, geometry makes a huge difference, so testing knives with different geometry and different steel is somewhat useless. This is why knives in Larrin's tests have the same geometry and he tries to get the hardness as close as possible among different steels. This way the steels themselves can be tested in a meaningful way.

S90V has larger volume of carbides, which specific types in what proportion I don't remember, but it is most likely in the article somewhere. Even softer chromium carbides are significantly harder than the harder steel matrix this is why steels like m390 for example have relatively high wear resistance with mostly chromium carbides.
 
Larrin said:
The K390 datasheet says 58-64 Rc is recommended. The internet’s opinion on what is “very soft” is getting pretty extreme.
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I'm not saying you did anything wrong. I appreciate your work and own both of your books. I was just surprised by both of those HRCs since most production knife companies don't normally run either of those steels in that range, at least to my knowledge.
 
minimag03 said:
I'm not saying you did anything wrong. I appreciate your work and own both of your books. I was just surprised by both of those HRCs since most production knife companies don't normally run either of those steels in that range, at least to my knowledge.
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Hardness choices from production knife companies can be mysterious sometimes. Both of those steels are relatively rare in production knives though.
 
All I know is, when I need an atom...I'm calling "strong atom" and not his weakling sidekick. I have a call in to van der Waals in the great beyond as we speak.


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