How hard to make CPM154 and S35VN

R

rockfishbrewery

Joined
Jan 24, 2012
Messages
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Hello,

I plan on making two paring knives of the below spec. One using CPM154, and the other using S35VN. I'm essentially testing both steels to see which one I like better.

overall Length = ~8in
Blade Length = 4in
Steel thickness = .060in
Steel type = One knife in CPM154, and one in S35VN
Hardness = Unknown yet

My question is as follows:

  • How hard should I make the CPM154 blade, and the S35VN blade? Since they're going to be paring knives, they're not going to get slammed against a cutting board. Therefore, I would like to make them as hard as I can for maximum edge retention.

Thanks in advance for any input you may have.
 
Yes, 60/61 works well. But if you test them at the same hardness, you won't really discover anything surprising. They will both do well.

Here is what I would suggest you do:
Make the CPM-154 blade Rc61, and make the S35VN blade Rc62 . Test them side-by-side, doing a variety of kitchen cutting tasks, rope cuts, and cardboard cuts. After each cut, slice up a sheet of printer paper with each blade. Note if the knife starts dulling and/or snags, and examine the edges with a 10X magnifier or scope after each test. look for micro-chipping, rolling, dulling/rounding etc. You will discover that the S35VN has the same toughness at Rc62 as CPM-154 at Rc61, and thus the edge last longer between sharpenings.

In have found that CPM-154 is optimal at Rc61 and CPM-S35VN is optimal at Rc62. Be advised that this degree of superiority isn't going to show a 50% increase, but careful testing should show that S35VN will hold up at higher hardness, and thus has longer edge retention.


Do your own tests, and post what you find.

BTW, to do this test in the full and proper way, you wold make three knives in each steel, and harden them at Rc60,61,62. This would tell at what point the blade chipped, rolled, etc. The simplified test above eliminates that discovery and does the final testing. If you are a purist, or doubt the hardness ratings, do all six blades.
 
Thanks all for the insight, I will be sure to post the results.

My test scenarios aren't quite as extreme as Bladsmith's. My plan is to use both for day-to-day tasks in my kitchen, and evaluate the following after ~2 months:

1) Edge retention
2) Compare stain resistance
3) Ease of sharpening
4) Workability of the steel
 
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