Re: Steel Hardness In Production Knives August 07, 2019 03:30PM |
Admin Registered: 5 years ago Posts: 5,679 |
Quote
It would be interesting to see kinives M390/20CV/204p compared to each other to see how much the HRC changes their edge retention, what is ideal, and what we can expect from a production HT. If M390/20CV/204p is only going to give S30V/S35VN results, it might be better for companies to go with using S90V to get better performance if the can't get M390/20CV/204p to cut better than ELMAX, since M390/20CV/204p have a similar carbide percentage (although different types of carbides) as S90V
Re: Steel Hardness In Production Knives August 17, 2019 09:42AM |
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Re: Steel Hardness In Production Knives August 24, 2019 08:53PM |
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Re: Steel Hardness In Production Knives August 28, 2019 07:19PM |
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Re: Steel Hardness In Production Knives September 01, 2019 05:28PM |
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Re: Steel Hardness In Production Knives September 17, 2019 05:50PM |
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Re: Steel Hardness In Production Knives September 18, 2019 03:56AM |
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Re: Steel Hardness In Production Knives September 24, 2019 08:24PM |
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Re: Steel Hardness In Production Knives September 25, 2019 06:15AM |
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Re: Steel Hardness In Production Knives September 25, 2019 07:10AM |
Registered: 4 years ago Posts: 282 |
M390 is more wear resistant than S30V due to higher carbide content.Quote
cabraljr
Except black Spyder that's S30V at 61 Rc, in a range over 60 Rc M390 seems wrong and contradicts the rule of higher Rc better wear resistance, but I think is not!
We have to keep in mind that up some threshold, say 60 Rc, lower Rc freed C to form more carbides, so you have more wear resistance.
CATRA only measure wear resistance with perfect vertical loads without side loads or torsion like we humans do.
This made perfect plausible that after certain threshold lower Rc shows better wear resistance simple because there are more V chromium enriched carbides with much higher hardness than the matrix that resists more to direct wear and not having to face plastic deformation do to lateral loads ( here matrix hardness is important ).
Despite my poor english this make sense to you?
Re: Steel Hardness In Production Knives September 25, 2019 09:11AM |
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Re: Steel Hardness In Production Knives September 25, 2019 09:37AM |
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Re: Steel Hardness In Production Knives September 25, 2019 10:20AM |
Registered: 4 years ago Posts: 282 |
That's been shown a million times. Why would anyone argue about it? I've shown data about it in my CATRA articles as well.Quote
jasonstone20
There are three things that are trying to be proven with these tests:
1. Higher HRC can contribute to higher edge retention, and can be shown when using the same steel, edge bevel angle, and edge finish
Re: Steel Hardness In Production Knives September 25, 2019 10:23AM |
Registered: 4 years ago Posts: 282 |
M390 has around 15-20% better slicing edge retention than S30V at equivalent hardness. I don't understand the "more C available from the matrix to form carbides" though. Carbon in the matrix contributes to hardness. The remaining carbon is tied up in carbides.Quote
cabraljr
Thanks Larrin, I know that.
What I want to tell is that excluding S30V knife that's not in the same ballpark of the other 3 knives exactly in this aspect ( carbide volume ) the possible explanation for lower Rc knives showing higher performance in CATRA test ( above certain threshold - 60 Rc - ) is more C available from the matrix to form more carbides.
What are you think about this?
Thank you for your prompt response.
Re: Steel Hardness In Production Knives September 25, 2019 10:23AM |
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Re: Steel Hardness In Production Knives September 25, 2019 11:23AM |
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Re: Steel Hardness In Production Knives September 25, 2019 11:42AM |
Registered: 4 years ago Posts: 282 |
OK that can happen if using a lower austenitizing temperature. However, if tempering down to a lower hardness you get the formation of very tiny tempering carbides that don't really contribute to wear resistance much. When thinking practically the effect of hardness is usually greatest for a given steel. The bigger effect would be composition. For example, using your 0.55% carbon, that leaves 0.9% carbon for carbide formation in S30V vs 1.35% carbon in M390.Quote
cabraljr
Hehehehe, I can't express myself in english.
Forget S30V. What I meant is M390 or other high carbon steels at 62 Rc for example, has a given amount of C in the matrix to achieve this hardness. Let's say hypothetically 0.55% C.
At lower hardness, let's say 60 Rc some of that C is no more embedded in the matrix and form more carbides, in other words, lower Rc require less C in the matrix let's say 0.50%, so 0.05% is free to form more carbides and with more carbides more wear resistance.
Thank you again for your patience.
Re: Steel Hardness In Production Knives September 25, 2019 12:51PM |
Registered: 7 years ago Posts: 68 |
Re: Steel Hardness In Production Knives September 25, 2019 01:55PM |
Registered: 4 years ago Posts: 282 |
My ability to write in any language other than English is still non-existent so I am completely reliant on the bilingual talents of others.Quote
cabraljr
Larrin, thank you very much for detailed explanation and although I can't write in english I can read quite well and once more I learn from you.
Re: Steel Hardness In Production Knives September 25, 2019 09:26PM |
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Re: Steel Hardness In Production Knives September 25, 2019 10:18PM |
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Re: Steel Hardness In Production Knives September 26, 2019 05:55AM |
Registered: 4 years ago Posts: 282 |
So many arguments over nothing.Quote
jasonstone20
Larrin,
That's the issue. A few knife makers, knife sellers and knife reviewers challenged that very fact. Some by claiming that a HTC test is difficult for a properly trained person to execute accurately, some claiming that a production HT'd blade is softer or harder at the pivot areas where the testing is mainly done, some claimed that HRC had little or no impact on edge retention, others that none of the cutting tests mattered before because it was cutting done by hand, not CATRA, and still others claiming that M390 is always superior in cutting tests to S30V and S35VN. So Alchemy1/Clint raised the money to have the CATRA testing done, and guess who didn't contribute on dime? That's right, not one of the naysayers.
Re: Steel Hardness In Production Knives September 26, 2019 07:52PM |
Registered: 5 years ago Posts: 437 |
Hi,
Re: Steel Hardness In Production Knives September 27, 2019 12:43PM |
Registered: 4 years ago Posts: 282 |
I wouldn't use that equation for tests in other laboratories. It is good for relative comparisons (the trends with steel, hardness, and edge angle are likely extremely similar), but when predicting CATRA values from other testers there are definitely differences. I don't know if that is due to the standard test knives that are thick behind the edge from the dataset I had, or differences in sharpening, testing procedure, different CATRA testers, etc. For example even in my first article where I proposed that equation I showed that it predicted the trend of the Bohler-Uddeholm CATRA results well but the numbers were not the same even when I tried to compensate with edge angle. [knifesteelnerds.com]Quote
ShaperAndMower
Hi,
I find it curious how the recorded tcc is consistently higher than Larrins calculated tcc for 20CV
recorded ( 626.0 + 707.7 + 784.7 )/3 = 706.13333
calculated ( 527.6 + 574.0 + 542.4 )/3 = 548
Re: Steel Hardness In Production Knives September 27, 2019 06:42PM |
Registered: 5 years ago Posts: 437 |
Quote
Larrin
I wouldn't use that equation for tests in other laboratories. It is good for relative comparisons (the trends with steel, hardness, and edge angle are likely extremely similar), but when predicting CATRA values from other testers there are definitely differences. I don't know if that is due to the standard test knives that are thick behind the edge from the dataset I had, or differences in sharpening, testing procedure, different CATRA testers, etc. For example even in my first article where I proposed that equation I showed that it predicted the trend of the Bohler-Uddeholm CATRA results well but the numbers were not the same even when I tried to compensate with edge angle. [knifesteelnerds.com]
Re: Steel Hardness In Production Knives October 08, 2019 10:20PM |
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Re: Steel Hardness In Production Knives October 12, 2019 10:14AM |
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Re: Steel Hardness In Production Knives October 13, 2019 07:26PM |
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Re: Steel Hardness In Production Knives October 14, 2019 07:59PM |
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Interesting,
Re: Steel Hardness In Production Knives October 15, 2019 05:22AM |
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