Rockwell Testing of Blades

M

M. Johnwell

Joined
Jan 8, 2015
Messages
315
I see people asking about the hardness of various knives all the time, I just thought it would be nice to have a compilation of any blades which I or any of you have tested.

My results come from Wilson hardness testers in the metrology lab or heat treating lab at my college and I will update this list as I test more knives. The ones in the metrology lab is dead on according to the test samples. The one on the heat treating lab reads approximately 1.5 points low on a 62.9 RC test block. I will denote those readings with an *, and add the estimated actual hardness in parentheses afterwards so you can take the information however you wish.

Spyderco
Stretch (superblue)—64.5
Manix 2 (4v)—64
Urban (k390)—61* (62.5)
Mantra (m4)—62
Pm2 (m4)—60.5

Kizer
4401C (s35vn)—58-59 (two tests)

Steel Will
Modus (m390)—57.5* (59) tested in metrology lab at 58 three times

Benchmade
Mini Ritter (m390)—57—(retested at 59)

Buck
285 bantam (420hc)—57-57.5 (took two samples)
112 (1980’s 420hc)—54

Victornox
SAK (unknown steel) 53-54 (took two samples)

William Henry
E10-3 (m390)—59* (60.5)
 
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Mo2 said:
Are you taking and average of 3-5 tests? Generally that's how it's done. For example the directions in the aims hrc tester says to try 5 times and take an average of that.

Also here's some from Ankersons tests.

https://www.bladeforums.com/threads...ed-on-edge-retention-cutting-5-8-rope.793481/
Click to expand...

I usually only take one or two tests per knife. I know it’s not technically proper, but I carry all of my knives (and some of them are my friends’ knives) and I don’t really want them to look like Swiss cheese after I’m done.
 
M. Johnwell said:
I usually only take one or two tests per knife. I know it’s not technically proper, but I carry all of my knives (and some of them are my friends’ knives) and I don’t really want them to look like Swiss cheese after I’m done.
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fair enough. Not sure if the numbers could be off because of that but it's great anyways. Thank you.
 
Mo2 said:
fair enough. Not sure if the numbers could be off because of that but it's great anyways. Thank you.
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You’re welcome!

If there’s any that you’d like me to retest, I’d be happy to. Assuming they’re my knives and the honeymoon period/any resale value has worn off, I’d be willing to test them again.
 
M. Johnwell said:
You’re welcome!

If there’s any that you’d like me to retest, I’d be happy to. Assuming they’re my knives and the honeymoon period/any resale value has worn off, I’d be willing to test them again.
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I am surprised the Benchmade m390 was so low.
 
Lapedog said:
I am surprised the Benchmade m390 was so low.
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I was too. It was an early Mini Ritter and they were known to run a little soft. Using and sharpening it feels kind of like VG-10, and it dulls pretty quickly, so I don’t think it’s completely off, but I might check it.
 
M. Johnwell said:
I usually only take one or two tests per knife. I know it’s not technically proper, but I carry all of my knives (and some of them are my friends’ knives) and I don’t really want them to look like Swiss cheese after I’m done.
Click to expand...

I can appreciate that...I hadn't thought about multiple dimples... :)
Your data may or may not be spot on, but probably close enuf to be in the proper region. thank you.
 
I just retested the benchmade, originally it was tested at 57, today I took two samples in the metrology lab and got 59 both times. I will edit my original post.

LG&M said:
Would it be possible to test a Leatherman, SAK,Mora,Kabar,Buck.
Thank you.
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I should be able to test a SAK, leatherman, and buck pretty easily.
 
Are you sure that the knives are thick enough for regular hardness testing? I seem to remember that Rockwell C testing requires samples that are fairly thick. If the sample is too thin, the test isn't accurate.

I can't immediately think of a way to put a knife blade in a microhardness tester, but if that were possible, I'd trust the results more.

If I really wanted a thorough understanding of knife blade hardness, I'd have to do destructive testing. I'd cut the blades perpendicular to the edges and mount samples. I'd then do microhardness surveys from the edge to the spine. The results would be in Vicker's or something like that, but I'd convert those results to Rockwell C for publication.
 
WftRight said:
Are you sure that the knives are thick enough for regular hardness testing? I seem to remember that Rockwell C testing requires samples that are fairly thick. If the sample is too thin, the test isn't accurate.

I can't immediately think of a way to put a knife blade in a microhardness tester, but if that were possible, I'd trust the results more.

If I really wanted a thorough understanding of knife blade hardness, I'd have to do destructive testing. I'd cut the blades perpendicular to the edges and mount samples. I'd then do microhardness surveys from the edge to the spine. The results would be in Vicker's or something like that, but I'd convert those results to Rockwell C for publication.
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Well tell you do it its just a pipe dream.
 
WftRight said:
Are you sure that the knives are thick enough for regular hardness testing? I seem to remember that Rockwell C testing requires samples that are fairly thick. If the sample is too thin, the test isn't accurate.

I can't immediately think of a way to put a knife blade in a microhardness tester, but if that were possible, I'd trust the results more.

If I really wanted a thorough understanding of knife blade hardness, I'd have to do destructive testing. I'd cut the blades perpendicular to the edges and mount samples. I'd then do microhardness surveys from the edge to the spine. The results would be in Vicker's or something like that, but I'd convert those results to Rockwell C for publication.
Click to expand...

http://www.auto-met.com/Rockwell_hardness_tester/Minimum_Thickness.htm

According to this chart, I only need around .030” of thickness for the hardnesses that I’d be finding in knife blades. The only one I tested that could be incorrect based on this information would be the superblue since it’s a clad steel and I had to test it pretty close to the edge.

I also always try to test the hardness on the flat of the blades so that the angled surface doesn’t throw off the results. (Once again, not possible with the superblue stretch since it is clad)
 
Those are thinner than I remember, but they may have done more testing since my days in the lab. I may have just forgotten the required thicknesses. One point is that you need to use the thickness for the lowest hardness that might be there. If you test something that softer, you might get a false high that makes you think that you are hard enough to have enough thickness. Thanks for the link.
 
WftRight said:
Are you sure that the knives are thick enough for regular hardness testing?
Click to expand...

Most knives are thick enough for a valid test.

I used to have access to the metallurgy lab at work. I did a bunch of testing under the watchful eye of the senior metallurgist. He never raised an issue with my sample thickness. He did warn me that the top and bottom of the area being measured had to be parallel and that they had to be perpendicular to the indenter. The sample area had to be large enough that the indenter was at least 1/8" away from the edge. For a lot of blades, that limits the measurement area to the tang. Some of the companies who make traditional pocket knives soften the tangs so that they can crink the blades and so that they can impression stamp them. Those are marked "anealed" in the comment section.
PLNIbo5.jpg
 
I have in my collections a few knives made of hard wootz (very small crystals, not similar to typical wootz pattern). I had these knives in blank forms, I got them directly from one of Russian wootz-smiths - without handles (I made myself). It gave me opportunity to check the steel hardness without leaving marks on blade. I checked the hardness of the part under handle (full-tang). In the institute of metallurgy (heattreatment institute) I made a test and got the result 66-66.5 HRC. This is the hardness knife in my collection and despite of such high HRC it is still very flexible.
 
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