So what's the deal with S390? Possible competitor for K390?

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PlumasDePan

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Jul 21, 2020
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I see that a lot of Russian knifemakers are using them.

It seems to be able to have get high hrc and keep a good thoughness

Do any of you guys have any experience with the steel?
 
I wouldn't necessarily compare it to K390. It is a high speed steel similar to T15. In terms of steels you may have heard of it would be more similar to Rex 86, Z-Max, Maxamet, or HAP 72, though with somewhat lower carbon. Bohler has their own version of the higher carbon steels called S290. You can read about that general class of high speed steels here: https://knifesteelnerds.com/2019/12...ed-steels-maxamet-rex-121-and-more-explained/

In a document by Bohler they rate S390 5 stars for wear resistance along with K390 though they give K390 a higher toughness rating, probably due to the lower working hardness. https://www.bohler-edelstahl.com/ap...02/productdb/api/bw050de_kaltarbeitsstahl.pdf

CATRA testing of the higher carbon Z-Max put it above K390, at least at 70 Rc. Toughness testing of Maxamet, even at a "low" hardness of 67 Rc was still below the toughness of 10V and Vanadis 8 (similar to K390) when they are at 64-65 Rc. The reduced carbon in S390 would be expected to slightly improve toughness and to decrease edge retention. Personally I would probably prefer K390, 10V, or Vanadis 8, and those steels can also be heat treated to 66+ Rc if desired. S390 and other high speed steels are not as optimized for "cold" work like knives. But those high speed steels can have uses for very high hardness.

Edit: This document also claims K390 has a better toughness-wear resistance balance than S390: https://www.bohler-edelstahl.com/app/uploads/sites/92/2020/02/productdb/api/s000en.pdf
 
Larrin said:
I wouldn't necessarily compare it to K390. It is a high speed steel similar to T15. In terms of steels you may have heard of it would be more similar to Rex 86, Z-Max, Maxamet, or HAP 72, though with somewhat lower carbon. Bohler has their own version of the higher carbon steels called S290. You can read about that general class of high speed steels here: https://knifesteelnerds.com/2019/12...ed-steels-maxamet-rex-121-and-more-explained/

In a document by Bohler they rate S390 5 stars for wear resistance along with K390 though they give K390 a higher toughness rating, probably due to the lower working hardness. https://www.bohler-edelstahl.com/ap...02/productdb/api/bw050de_kaltarbeitsstahl.pdf

CATRA testing of the higher carbon Z-Max put it above K390, at least at 70 Rc. Toughness testing of Maxamet, even at a "low" hardness of 67 Rc was still below the toughness of 10V and Vanadis 8 (similar to K390) when they are at 64-65 Rc. The reduced carbon in S390 would be expected to slightly improve toughness and to decrease edge retention. Personally I would probably prefer K390, 10V, or Vanadis 8, and those steels can also be heat treated to 66+ Rc if desired. S390 and other high speed steels are not as optimized for "cold" work like knives. But those high speed steels can have uses for very high hardness.

Edit: This document also claims K390 has a better toughness-wear resistance balance than S390: https://www.bohler-edelstahl.com/app/uploads/sites/92/2020/02/productdb/api/s000en.pdf
Click to expand...
Thanks again larrin!
 
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