New Steel – Crucible S45VN

[Larrin]

Crucible and Niagara have just announced a new stainless powder metallurgy steel – S45VN. I was able to get a bar of it early to do a range of experiments on it including hardness, corrosion resistance, and toughness. I have a recommendation on how to best heat treat it too. How does it compare to the existing stainless knife steels? https://knifesteelnerds.com/2019/11/01/crucible-s45vn-steel/

 

[M1k3]

Thanks for another interesting read!

 

[rob]

Good read, thanks Larrin.

 

[Interapid101]

Great article. Couple questions:
1. What's the story behind the addition of nitrogen in S30V, but no mention of it in the datasheet?
2. You have optimized heat treats/tempering for several steels with conditions that are significantly different from the recommendations in datasheets, and S45VN is another example. Why is this? Do the steel companies not perform as exhaustive of an analysis as you do? If so, why not? One would assume that they would better characterize their materials before putting them on the market.

 

[Larrin]

Great article. Couple questions:
1. What's the story behind the addition of nitrogen in S30V, but no mention of it in the datasheet?
2. You have optimized heat treats/tempering for several steels with conditions that are significantly different from the recommendations in datasheets, and S45VN is another example. Why is this? Do the steel companies not perform as exhaustive of an analysis as you do? If so, why not? One would assume that they would better characterize their materials before putting them on the market.

1. Not sure. They also regularly omit Mn and Si from the datasheet even though those are always added in some amount. Apparently they decided not to list it. Now since the nitrogen addition is a major change and there is excitement about "nitrogen steels" they are now listing it.
2. I wouldn't say that my recommended heat treatments are vastly different than datasheets. In some cases they are different than the accepted standard used by knifemakers but are more similar to datasheets, like 52100 for example. Knifemakers often use 1475°F while the datasheets typically say 1500-1550°F. The optimal properties ended up being 1500-1525°F in our testing.
It is true that in many cases manufacturers do not perform extensive comparisons between different heat treatment variables. Or their goals for an optimal heat treatment are different than mine. The QA for heat treating by knife manufacturers and professional heat treaters, for example, is typically rockwell hardness. So they design their heat treatments around getting the most consistent hardness. My goal is to have the best balance of hardness and toughness, without excessive retained austenite. If I had the money and time I would do a full comparison against corrosion resistance and edge retention as well.
The recommended heat treatment for S45VN was unchanged from S30V and S35VN, and I don't think that was because they did a large number of tests and just happened to land on the exact same recommendation.

 

[inferno]

Great article. Couple questions:
1. What's the story behind the addition of nitrogen in S30V, but no mention of it in the datasheet?
2. You have optimized heat treats/tempering for several steels with conditions that are significantly different from the recommendations in datasheets, and S45VN is another example. Why is this? Do the steel companies not perform as exhaustive of an analysis as you do? If so, why not? One would assume that they would better characterize their materials before putting them on the market.

1 its probably there to make it more stain resistant. and/or as C substitute.
2 of course they make extensive tests. but if can "read between the lines" you can go way outside these recommended temperatures and times to get other results. many times the recommended processes are more aimed at getting repeatable results in mass production than people pushing the stuff to the max potential (and what that max potential is could be very different for your and my intended use).

i mean spyderco don't plate quench for instance. if you know what i mean. then there is also the economy aspect of using higher temps and similar. higher heat cost more money. and it goes on and on and on.

 

[inferno]

i'm reading the article as we speak. looks like they made a stainless s30v

did you try cryo after first temper too larrin? the RA seems kinda high at 3-6% even after nitro. i wonder what the RA was as quenched at 2050... like 40-50% or so?

 

[Larrin]

i'm reading the article as we speak. looks like they made a stainless s30v

did you try cryo after first temper too larrin? the RA seems kinda high at 3-6% even after nitro. i wonder what the RA was as quenched at 2050... like 40-50% or so?

I would describe 3-6% as quite low for stainless steels. It's very difficult to get rid of the last few percent even with cryo. High temperature tempering is a little better at eliminating it but I don't like tempering in that range, especially for stainless steels as it reduces corrosion resistance. Up to 15% RA is probably fine for most applications.

 

[inferno]

also another thing with the recommended HT specs. many times blades are HTed in big 1,5x1,5x1,5m vacuum ovens, and they put the blades in a kind of cubical shaped cage with hundreds or even thousands of blades and they do them all at the same time.

now its completely impossible to get all these blades at the same temp. i guess the difference in temperature in a big oven like that could be 50 or even 100 deg C from coldest spot to hottest. and then it makes sense to provide specs that will make them all kinda similar anyway. that what i'm thinking at least.

 

[inferno]

did you try to make any actual knife out of the new steel? is it a b1tch to sharpen with all that V/Nb?

 

[inferno]

ok read it all. good work larrin! i wonder how the toughness would have been with a high temp tempering. 1ft/lb?
not really impressed with the toughness. i guess its the price you pay.

does it have a pronounced secondary hardening peak?? looks like it might at least.

I wonder why the do new versions of s30v. why not make something completely different instead. maybe 0,8-1%C and half that V, or no V at all, and 1-2% or so Nb instead. it feels like they're beating a dead horse.
........................

i also have an unrelated question. have you done any tests on 15n20 and 80crv2? i think those would be interesting since they can be easily done by hobbyists. and as far as i can see 15n20 is quite popular on BF. i think there would be much interest in these 2 alloys. any way good work!

 

[Larrin]

also another thing with the recommended HT specs. many times blades are HTed in big 1,5x1,5x1,5m vacuum ovens, and they put the blades in a kind of cubical shaped cage with hundreds or even thousands of blades and they do them all at the same time.

now its completely impossible to get all these blades at the same temp. i guess the difference in temperature in a big oven like that could be 50 or even 100 deg C from coldest spot to hottest. and then it makes sense to provide specs that will make them all kinda similar anyway. that what i'm thinking at least.

I haven't seen any measurements of the temperature variation within those furnaces, but there is definitely going to be some. Some have more comfort in sending their knives to a "professional" but there are advantages to doing heat treating in a small furnace in small batches.

 

[Larrin]

did you try to make any actual knife out of the new steel? is it a b1tch to sharpen with all that V/Nb?

I did not make a knife from it. But I have had an S30V folder for years and it isn't all that difficult to sharpen. Maybe for giving it a high polish it is more difficult.

 

[Larrin]

ok read it all. good work larrin! i wonder how the toughness would have been with a high temp tempering. 1ft/lb?
not really impressed with the toughness. i guess its the price you pay.

does it have a pronounced secondary hardening peak?? looks like it might at least.

I wonder why the do new versions of s30v. why not make something completely different instead. maybe 0,8-1%C and half that V, or no V at all, and 1-2% or so Nb instead. it feels like they're beating a dead horse.
........................

i also have an unrelated question. have you done any tests on 15n20 and 80crv2? i think those would be interesting since they can be easily done by hobbyists. and as far as i can see 15n20 is quite popular on BF. i think there would be much interest in these 2 alloys. any way good work!

The high tempering temperature would have slightly worse toughness, not 1 ft-lb. The 2% Mo definitely gives it some secondary hardening. The datasheet lists hardness from a 1000°F temper. I didn't look at that range since it doesn't interest me.

There are definitely other interesting composition ranges to look at. Hopefully we will convince them to explore in other areas. Crucible no longer has R&D since their bankruptcy in 2009.

 

[inferno]

I haven't seen any measurements of the temperature variation within those furnaces, but there is definitely going to be some. Some have more comfort in sending their knives to a "professional" but there are advantages to doing heat treating in a small furnace in small batches.

i saw a vid from one of the big german kitchen knife manufacturers and they had one of those big ones. must have been 1000 blades going in at at once. on a cage.

 

[inferno]

There are definitely other interesting composition ranges to look at. Hopefully we will convince them to explore in other areas. Crucible no longer has R&D since their bankruptcy in 2009.

you could be their RD department for the knife division! make them an offer they can't refuse...

 

[K813zra]

Thanks for posting. I'll have to read it a few times, as per usual, to get the most out of it but I will enjoy that.

 

[Interapid101]

1. Not sure. They also regularly omit Mn and Si from the datasheet even though those are always added in some amount. Apparently they decided not to list it. Now since the nitrogen addition is a major change and there is excitement about "nitrogen steels" they are now listing it.
2. I wouldn't say that my recommended heat treatments are vastly different than datasheets. In some cases they are different than the accepted standard used by knifemakers but are more similar to datasheets, like 52100 for example. Knifemakers often use 1475°F while the datasheets typically say 1500-1550°F. The optimal properties ended up being 1500-1525°F in our testing.
It is true that in many cases manufacturers do not perform extensive comparisons between different heat treatment variables. Or their goals for an optimal heat treatment are different than mine. The QA for heat treating by knife manufacturers and professional heat treaters, for example, is typically rockwell hardness. So they design their heat treatments around getting the most consistent hardness. My goal is to have the best balance of hardness and toughness, without excessive retained austenite. If I had the money and time I would do a full comparison against corrosion resistance and edge retention as well.
The recommended heat treatment for S45VN was unchanged from S30V and S35VN, and I don't think that was because they did a large number of tests and just happened to land on the exact same recommendation.

Thanks for the breakdown!

 

[bahamaroot]

Another great article Larrin. As a fan of and owning knives in both s30v and s35vn, this was a very interesting read for me.

 

[inferno]

there is basically no user noticable difference between s30v, s35v and s45v. just so you know. it would be microscopic at most. and i'd say its highly uncertain even machines could detect it.

 

[Deadboxhero]

there is basically no user noticable difference between s30v, s35v and s45v. just so you know. it would be microscopic at most. and i'd say its highly uncertain even machines could detect it.

Nah, they have differences that can be quantified in controlled cut testing. They have different options with HT in hardness and microstructures, etc. Sharpeners could detects small nuances in how the edge comes up.


There are pictures in the article that show differences between them.