15N20 steel toughness

[Larrin]

There was a discussion recently about the toughness of 15N20. I tested that along with some other stuff. I have an article and a video.

Article: https://knifesteelnerds.com/2023/03/22/how-to-heat-treat-nickel-knife-steels-15n20-8670-l6/

 

[Crag the Brewer]

haha, I know what I am watching tonight after work...... I hope 15n20 is favorable, I know I love it.
Thanks!

 

[DanF]

Your tests bear out my real-world experiences with 15N20.
Did not understand why my kitchen knives at 60-62 outperformed the 63+ knives. Now I know.
Thanks Larrin.

 

[DevinT]

Good stuff Larrin. Lots of useful information in there.

Hoss

 

[Ken H>]

Another GREAT article from Larrin - thank you.

 

[velegski]

Well Done! Thanks for sharing your knowledge

 

[JoeBusic]

Larrin Are Si and Ni compatible to achieve even greater toughness?

 

[Larrin]

Larrin Are Si and Ni compatible to achieve even greater toughness?

At least one study found that silicon additions only contribute to better toughness at higher tempering temperatures, which might be less desirable for knife steels. I cited it here: https://knifesteelnerds.com/2018/10/22/silicon-additions-for-improving-steel-toughness/

That said, S5 (2% Si) has been tested to have very high toughness. And to more directly answer the question, 300M is a steel with both high Ni and Si, it is 4340 plus 1.6% Si.

 

[JoeBusic]

At least one study found that silicon additions only contribute to better toughness at higher tempering temperatures, which might be less desirable for knife steels. I cited it here: https://knifesteelnerds.com/2018/10/22/silicon-additions-for-improving-steel-toughness/

That said, S5 (2% Si) has been tested to have very high toughness. And to more directly answer the question, 300M is a steel with both high Ni and Si, it is 4340 plus 1.6% Si.

Can you have an assumption of hardness and toughness of Bohlers K600? Composition in the screenshot. And is it possible to add that much Ni to 420HC to get more toughness without sacrificing hardness?

 

[hugofeynman]

Can you have an assumption of hardness and toughness of Bohlers K600? Composition in the screenshot. And is it possible to add that much Ni to 420HC to get more toughness without sacrificing hardness?View attachment 2129306

Hardness is in the 54hrc range after temper. I have some big choppers made in this steel. Toughness only Larrin and/or tests can answer, but it’s quite high.

 

[JoeBusic]

Hardness is in the 54hrc range after temper. I have some big choppers made in this steel. Toughness only Larrin and/or tests can answer, but it’s quite high.

Can it be pushed to 57-58 HRC?

 

[hugofeynman]

If you temper it at 100C, I think so, but you probably will loose a lot of toughness.

 

[Larrin]

Can you have an assumption of hardness and toughness of Bohlers K600? Composition in the screenshot. And is it possible to add that much Ni to 420HC to get more toughness without sacrificing hardness?View attachment 2129306

Adding 4% nickel to 420HC would definitely limit its max hardness.

 

[hugofeynman]

Can you have an assumption of hardness and toughness of Bohlers K600? Composition in the screenshot. And is it possible to add that much Ni to 420HC to get more toughness without sacrificing hardness?View attachment 2129306

https://www.bohler-edelstahl.com/app/uploads/sites/92/2021/09/productdb/api/k600_en.pdf

Look at that table from Bohler. k320 is S7 steel, so k600 is much tougher.

 

[JoeBusic]

https://www.bohler-edelstahl.com/app/uploads/sites/92/2021/09/productdb/api/k600_en.pdf

Look at that table from Bohler. k320 is S7 steel, so k600 is much tougher.

Pity it's soft for knives.