PM2 in S90V or 15V?

[DeadboxHero]

Larrin’s toughness rankings are not Rc defined. 15V and S90V have similar toughness. The BBB 15V is run around 65 while most makers do S90V around 60-62. S90V at 61 is tougher than 15V at 65. See the graphs here (toughness graph of stainless steels has S90V and toughness graph of tool steels has 15V):

S90V and S125V Knife Steel - History, Properties, and How to Heat Treat - Knife Steel Nerds

S90V and S125V have the highest edge retention of any available stainless knife steels. What is the steel's history? How to heat treat?

knifesteelnerds.com

Impact toughness does not translate directly to Edge Stability.

The BBB 15V was not directly measured in Dr Larrin's charpy impact testing since it is a proprietary heat treatment.

Strength is an important factor not just bulk properties with HRC and Impact testing alone.

With the same grind and edge geometry under the same task/force the s90V will yield/deform sooner and stop working with cutting/slicing.

Can't strop out that edge deformation either, it has to be re-cut/re-apexed. So it's the same effect as a chowdered up edge.

 

[lambertiana]

Impact toughness does not translate directly to Edge Stability.

The BBB 15V was not directly measured in Dr Larrin's charpy impact testing since it is a proprietary heat treatment.

Strength is an important factor not just bulk properties with HRC and Impact testing alone.

With the same grind and edge geometry under the same task/force the s90V will yield/deform sooner and stop working with cutting/slicing.

Can't strop out that edge deformation either, it has to be re-cut/re-apexed. So it's the same effect as a chowdered up edge.

Is this comparison based on both steels at the same Rc? Or is it comparing BBB 15V at 65 with a standard heat treat S90V at 61? I’d love to see the experimental data for this comparison.

 

[lambertiana]

Impact toughness does not translate directly to Edge Stability.

The BBB 15V was not directly measured in Dr Larrin's charpy impact testing since it is a proprietary heat treatment.

Strength is an important factor not just bulk properties with HRC and Impact testing alone.

With the same grind and edge geometry under the same task/force the s90V will yield/deform sooner and stop working with cutting/slicing.

Can't strop out that edge deformation either, it has to be re-cut/re-apexed. So it's the same effect as a chowdered up edge.

I'm really curious what this edge deformation looks like. Would you care to share microscope pictures of it, along with the Rc of the S90V and 15V blades involved, and who did the heat treat on the S90V?

 

[Don M]

The BBB 15V was not directly measured in Dr Larrin's charpy impact testing since it is a proprietary heat treatment.

You have the data. Please share it and enlighten us. Many claims have been made that your heat treat is better than typical heat treat for 15V. Since there's no "regular" 15V for people to compare, it's impossible to verify the claims, which makes them unsubstantiated claims. This could be settled quite easily.

 

[lambertiana]

For the many of you that have both Spyderco S90V and Spyderco 15V, which do you consider less chippy? I've got all the Larrin Thomas charts downloaded and compared the two on paper. I see the difference in corrosion resistance, edge holding and toughness. However, if you're only judging how chippy it is in use and during sharpening, which one do you prefer or consider best?

I just did a comparison test at home with a 15V PM3 LW, S90V N5 LW, and K390 Delica. As in previous tests, I wanted to simulate typical use for me, not just the single medium tests such as what you see with CATRA. For this, I used cardboard (large produce boxes from the grocery store), plastic (gallon ice cream buckets and gallon milk jugs), wood (well seasoned cedar), and 5/16" sisal rope. I did it in repeating rounds - three cuts in each medium with each knife, then start over again for another set. I ended up doing about 40 sets of cutting with each knife, which is more cutting than I do in a year of normal use. I favor tests like this because they not only show overall performance in a broad range of media, they also introduce something that is probably lacking in the tightly controlled testing, namely random side loading.

All three knives have the same blade length; the PM3 and N5 have the same blade thickness, while the Delica has a thinner blade stock. The 15V PM3 was sharpened by Shawn (BBB) and had a very nice edge at the start. The other two were sharpened by me on a 40/28 CBN stone followed by 1u diamond strop. The 15V PM3 started this with a better edge, but all three were shaving cleanly at the start.

Observations:

1. The 15V lost its shaving edge much faster.
2. The perceived force required to cut with the PM3 and N5 was very similar throughout the test, while the Delica required less force throughout, which I attribute to the thinner geometry.
3. At the end, the 15V blade "felt" sharper than the other two. Yeah, I know, very unscientific, but I don't have any measuring devices and after they stop shaving cleanly I can only go by how they feel using the old fashioned thumb across the edge test.
4. I don't have a microscope, but I do have a jeweler's loupe. Using the loupe I could see some very minor edge damage/microchipping on all three blades; surprisingly, I saw the most with the K390 Delica, while the PM3 and N5 were similar, with a very slight advantage to the 15V.
5. Resharpening was easy for all three, there was not enough dulling to require any real work in that regard. Four or five swipes on each side on the CBN and a few swipes on each side on the diamond strop and all three were back to hair popping sharp.

My take home lesson from this is that both 15V and S90V would suit your purposes fine. In real world use, I don't see a significant difference between them as far as chipping goes. If corrosion resistance is important for you, go with S90V. If corrosion resistance is not important, you may want to try 15V just to add it to your stable.

My hand is tired and I have a blister. I also earned an eye roll and "You're crazy" from my wife.

 

[lambertiana]

With the same grind and edge geometry under the same task/force the s90V will yield/deform sooner and stop working with cutting/slicing.

Can't strop out that edge deformation either, it has to be re-cut/re-apexed. So it's the same effect as a chowdered up edge.

You have the data. Please share it and enlighten us. Many claims have been made that your heat treat is better than typical heat treat for 15V. Since there's no "regular" 15V for people to compare, it's impossible to verify the claims, which makes them unsubstantiated claims. This could be settled quite easily.

The more I think about this the more my curiosity is piqued. First, regarding your statement about S90V vs 15V, in my recent cutting comparison, using a 15V PM3 lightweight with your edge and an S90V N5 LW with my edge (and we know what you think of my edges), I did not notice any difference in cutting ability between the two. That was over the course of a total of about 120' of cardboard, 90' of plastic, 120X cutting of a sisal rope, and a lot of whittling of seasoned cedar, which would easily approximate more than a year's use for me. Overall blade geometry of the two knives is very similar, so any difference in cutting ability would be due to the steel/heat treat. I don't have a microscope, but using a jeweler's loupe the edges looked very similar at the end. I didn't see any "chowdered" edge on the S90V blade. I would love to see images of the 15V and S90V edges after cutting that show the significant damage to the S90V edge and no damage to the 15V edge. Please include experimental data as well as geometry and heat treat data.

And I think D Don M raises a good point. We have heard many claims about the BBB heat treat, and you said that Larrin's data wasn't applicable to your heat treat. Please supply the CATRA and Charpy data to confirm this claim. I really doubt that Spyderco would commission a run of 15V using your heat treat without testing, so it is reasonable to assume that the data exists.

In social media it is common to see the tongue-in-cheek statement "Pics or it didn't happen". In science the equivalent phrase would be "data or it didn't happen" and this would not be tongue in cheek.

 

[stillshot2]

I'm getting out my popcorn

 

[DeadboxHero]

The more I think about this the more my curiosity is piqued. First, regarding your statement about S90V vs 15V, in my recent cutting comparison, using a 15V PM3 lightweight with your edge and an S90V N5 LW with my edge (and we know what you think of my edges), I did not notice any difference in cutting ability between the two. That was over the course of a total of about 120' of cardboard, 90' of plastic, 120X cutting of a sisal rope, and a lot of whittling of seasoned cedar, which would easily approximate more than a year's use for me. Overall blade geometry of the two knives is very similar, so any difference in cutting ability would be due to the steel/heat treat. I don't have a microscope, but using a jeweler's loupe the edges looked very similar at the end. I didn't see any "chowdered" edge on the S90V blade. I would love to see images of the 15V and S90V edges after cutting that show the significant damage to the S90V edge and no damage to the 15V edge. Please include experimental data as well as geometry and heat treat data.

And I think D Don M raises a good point. We have heard many claims about the BBB heat treat, and you said that Larrin's data wasn't applicable to your heat treat. Please supply the CATRA and Charpy data to confirm this claim. I really doubt that Spyderco would commission a run of 15V using your heat treat without testing, so it is reasonable to assume that the data exists.

In social media it is common to see the tongue-in-cheek statement "Pics or it didn't happen". In science the equivalent phrase would be "data or it didn't happen" and this would not be tongue in cheek.

I love the enthusiasm.

I'm happy the free knife sharpening I did and the free handmade leather strop I made for you are being used and appreciated.

The Dubai chocolate I sent is also some of my favorite.

 

[lambertiana]

I love the enthusiasm.

I'm happy the free knife sharpening I did and the free handmade leather strop I made for you are being used and appreciated.

The Dubai chocolate I sent is also some of my favorite.

Yes, they are much appreciated. Especially the strop, it’s really handy.

So does this mean no more data will be forthcoming? I was hoping to expand my knowledge of different steels and how they behave in use.

 

[Seedy Lot]

You have the data. Please share it and enlighten us. Many claims have been made that your heat treat is better than typical heat treat for 15V. Since there's no "regular" 15V for people to compare, it's impossible to verify the claims, which makes them unsubstantiated claims. This could be settled quite easily.

Come on Shawn, release the files! We all want to know...

 

[Don M]

The response so far leads one to conclude that the marketing claims will remain unsubstantiated. Do the data support the claims? Based on the silence after being asked directly we may never know. Let the science talk, end the speculation.

 

[DeadboxHero]

The response so far leads one to conclude that the marketing claims will remain unsubstantiated. Do the data support the claims? Based on the silence after being asked directly we may never know. Let the science talk, end the speculation.

I appreciate the interest, I figured it was obvious Spyderco did internal testing which showed improvement and led to the collaboration.

I do not own the internal testing data; that is proprietary and property of Spyderco.

In my opinion, the ultimate test came from independent testers.

Cedric and Ada, Pavol Sandor etc who have no affiliation with me.

There testing showed improvement compared to the 15V that was already on the market.

 

[elevator man]

Spyderco doesnt even admit or release the hrc numbers for any of their steels, I doubt they're going to release in depth in house testing data. I think 15v out classes s90v in everything except not rusting. Why harp on it? Next yall are gonna be saying maxamet and Rex 121 can't hold a candle to s90v. I dont think s90v is bad, quite the contrary. But I would definitely pick 15v over it in any knife. I dont need thr corrosion resistance

 

[stillshot2]

Based on the silence after being asked directly we may never know.

Have you tried asking Sal? Though I don't think they are obligated nor likely want to release proprietary data. And I'm curious where did Spyderco make the claims their 15V is better than any other makers?

 

[lambertiana]

I appreciate the interest, I figured it was obvious Spyderco did internal testing which showed improvement and led to the collaboration.

I do not own the internal testing data; that is proprietary and property of Spyderco.

In my opinion, the ultimate test came from independent testers.

Cedric and Ada, Pavol Sandor etc who have no affiliation with me.

There testing showed improvement compared to the 15V that was already on the market.

I've been pretty much offline for the last week, so I am just now circling back to this. I understand that if Spyderco considers their data proprietary it would be difficult to share it. However, there is much to be addressed here. Just as you were willing to publicly share what you viewed as the shortcomings of my sharpening in another thread, ostensibly for educational purposes, I will likewise follow suit for educational purposes.

First, I am still waiting for the data that formed the basis of your statement that S90V would show a significant edge degradation and corresponding decline in cutting performance relative to 15V. My experience shows otherwise.

Second, to couch your argument in the findings of a youtuber like Cedric and Ada, whose testing was just as subjective as mine, does not constitute rigorous scientific evidence.

Third, when I finally found the google sheet with all of Pavol Sandor's data, he testing four 15V blades from Biryukov Andrey and one Spyderco PM2. As far as I can decipher the data, the Spyderco PM2 fit right in the statistical variation of the four blades from Biryukov Andrey, so it would be difficult to say which was better. Could you help me understand his data better?

 

[Seedy Lot]

There testing showed improvement compared to the 15V that was already on the market.

Was there 15v on the market before Spyderco decided to make knives in the steel?

 

[Seedy Lot]

This is an interesting read on the beginning of 15v with Spyderco. One thing that stands out is Shawn obviously had his own test data he presented to Spyderco before they decided to try the steel for themselves.

Sal, Can we get CPM 15v? - Spyderco Forums

forum.spyderco.com

 

[lambertiana]

This is an interesting read on the beginning of 15v with Spyderco. One thing that stands out is Shawn obviously had his own test data he presented to Spyderco before they decided to try the steel for themselves.

Sal, Can we get CPM 15v? - Spyderco Forums

forum.spyderco.com

There's a lot of interesting info in that thread. Shawn's HT appears to be better than what was on the Crucible datasheet. Whether it is better than other available knives in 15V is a separate question.

One thing I noticed in my testing was that the relative cutting ability (by my perception) was the same in cardboard, wood, and plastic. The 15V PM3 seemed to have a little more bite in sisal. I guess all that vanadium carbide volume pays off in some media.

 

[DeadboxHero]

Second, to couch your argument in the findings of a youtuber like Cedric and Ada, whose testing was just as subjective as mine, does not constitute rigorous scientific evidence.

It appears Pete controls for edge angle with a sharpening system and measures the amount of cuts a rope before reaching a stopping point on cutting paper.

It's more quantifiable than just sharing a subjective observation which is even more at the mercy of the eye of the beholder.


He did a cut test with a Biryukov 15V fixed blade knife in 2020.

In 2023, he did a cut test with Spyderco BBB 15V which showed a 20% improvement in cutting edge retention.

Third, when I finally found the google sheet with all of Pavol Sandor's data, he testing four 15V blades from Biryukov Andrey and one Spyderco PM2. As far as I can decipher the data, the Spyderco PM2 fit right in the statistical variation of the four blades from Biryukov Andrey, so it would be difficult to say which was better. Could you help me understand his data better?

Pavol has better control, he uses a custom, homemade, manual rope cutting device of his own design that he states follows ISO 8442-5:2004

In his testing, he also compared to the older Biryukov in 15V, He also shows the Spyderco had a 20% increase in cutting edge performance.

This is because the amount of rope cut per cutting cycle and the test forces required to cut were better with the Spyderco 15V.

Both Pete and Pavol were impressed by the results, and most importantly, they have no affiliation with me.

The Spyderco BBB Collaboration CPM 15V has been on the market since fall 2022.

So, I'm very happy to see there is still plenty of discussion and curiosity left.

Much appreciated, I am very grateful to you all.

 

[kasumi]

It appears Pete controls for edge angle with a sharpening system and measures the amount of cuts a rope before reaching a stopping point on cutting paper.

It's more quantifiable than just sharing a subjective observation which is even more at the mercy of the eye of the beholder.


He did a cut test with a Biryukov 15V fixed blade knife in 2020.

In 2023, he did a cut test with Spyderco BBB 15V which showed a 20% improvement in cutting edge retention.



Pavol has better control, he uses a custom, homemade, manual rope cutting device of his own design that he states follows ISO 8442-5:2004

In his testing, he also compared to the older Biryukov in 15V, He also shows the Spyderco had a 20% increase in cutting edge performance.

This is because the amount of rope cut per cutting cycle and the test forces required to cut were better with the Spyderco 15V.

Both Pete and Pavol were impressed by the results, and most importantly, they have no affiliation with me.

The Spyderco BBB Collaboration CPM 15V has been on the market since fall 2022.

So, I'm very happy to see there is still plenty of discussion and curiosity left.

Much appreciated, I am very grateful to you all.

Thanks for all the informative input Shawn. If you had to choose one steel for your edc knife what would that be anno 2026?