Toughness data

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ZMW
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Toughness data

#1

Post by ZMW »

There are 1 million edge retention tests and information out there, but is there any database on Steel toughness? All I can find is some info, but not a lot from Knife nerds. See below. Is this accurate? I was always told 1095 is a tough steel, but it ranks pretty low on this scale. And AEB-L is tougher then anything out there? M4 is not as high as I thought it would be. etc etc. Thoughts on these charts and steel toughness data?
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Deadboxhero
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Re: Toughness data

#2

Post by Deadboxhero »

ZMW wrote:
Mon Jun 03, 2019 12:36 pm
There are 1 million edge retention tests and information out there, but is there any database on Steel toughness? All I can find is some info, but not a lot from Knife nerds. See below. Is this accurate? I was always told 1095 is a tough steel, but it ranks pretty low on this scale. And AEB-L is tougher then anything out there? M4 is not as high as I thought it would be. etc etc. Thoughts on these charts and steel toughness data?
Those Results have been painfully complied by the Metallurgist PhD Larrin Thomas and tested on a real deal charpy impact testing machine that he has access to thanks to his profession.

The samples had to be machined down to tight tolerances with three samples tested per each HRC value to take an average from.

Each sample received a custom HT with most receiving a cryo to reduce variables from large amounts retained austenite formed

These custom makers did this work for free for the benefit of the community.

Warrin Krywko
Micheal Drinkwine
Devin Thomas
And a few others I may have missed.


The charpy test will show how much foot-pounds of impact energy the steel can handle before breaking.

So the more energy absorbed the tougher but not necessarily the end all be all since strength is also a huge factor for edge durability and there are different kinds of tougheness. It's like how wear resistance is a component of edge holding but not the sole factor in edge holding.

This data is significant because it shows the raw impact/shock toughness of these steels and how they stack up to each other.

The trend is lower carbon %wt and less carbide formers at 60-57rc will make the most impact tough, shock resistantsteel. However that doesn't mean thin geometry, strength and edge durability with super thin geometry always. One has to connect the dots with the other factors at play.

So no, 1095 is not ultra tough, there are more details about why you can read on knifesteelnerds in elaborate detail already covered there.

I'd recommend going through more of those articles to help connect the dots, lots of great information there for those that have the desire to learn.

It's a unique time to be a knife fanatic.

We never had a Metallurgist in the past producing knife specific information for the community.

When I started getting into it, it used to be a lot harder to process all the material science and metallurgy information in the past. Now it's never been easier but one still has to read it and think deeply about it and the context of it all.
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Larrin
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Re: Toughness data

#3

Post by Larrin »

http://www.KnifeSteelNerds.com - Steel Metallurgy topics related to knives
ZMW
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Re: Toughness data

#4

Post by ZMW »

The rabbit hole gets deeper and deeper. I know about 0.0001% of the info that some of the guys/gals know on these forums, yet I know more then 99.99% of the general public. Between my normal job, most of my brain matter is dedicated to that data/info. So I only have minimal time to learn more about my hobbies. baby steps... But, I greatly appreciate the info
ZMW
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Re: Toughness data

#5

Post by ZMW »

Larrin - do you believe the data the manufactures post? They say Cruwear has a 60ft-lb toughness and the chart that you have from your tests shows closer to 20-25ft-lb.

That seems like a big variance. Or, are large variances normal due to HT and RC changes in the steel tested?
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Evil D
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Re: Toughness data

#6

Post by Evil D »

So many variables..
All SE all the time since 2017
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Larrin
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Re: Toughness data

#7

Post by Larrin »

Different test types give different numbers. That’s why you can’t compare between manufacturers. So we made a new test to compare between them.
http://www.KnifeSteelNerds.com - Steel Metallurgy topics related to knives
ZMW
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Re: Toughness data

#8

Post by ZMW »

It seems odd cpm would list 10v’s toughness based on a 59 rc. Lower rc would mean a little higher toughness right? that seems misleading since its usually 63 rc +/-
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Larrin
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Re: Toughness data

#9

Post by Larrin »

Your idea of "usually" may be skewed, but you can see results for a wider range of hardness in the datasheet: http://www.crucible.com/PDFs/DataSheets ... 202010.pdf
http://www.KnifeSteelNerds.com - Steel Metallurgy topics related to knives
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Re: Toughness data

#10

Post by ZrowsN1s »

I'm sure I've said it before, but thanks for all your hard work Larrin. Love reading your articles here, knifesteelnerds.com and on Instagram. Always dropping serious knowledge.
-Matt a.k.a. Lo_Que, loadedquestions135 I ❤ The P'KAL :bug-red

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Larrin
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Re: Toughness data

#11

Post by Larrin »

ZrowsN1s wrote:
Tue Jun 04, 2019 5:43 pm
I'm sure I've said it before, but thanks for all your hard work Larrin. Love reading your articles here, knifesteelnerds.com and on Instagram. Always dropping serious knowledge.
Doing my best!
http://www.KnifeSteelNerds.com - Steel Metallurgy topics related to knives
FK
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Re: Toughness data

#12

Post by FK »

Larrin,

I am hoping all the work you are contributing will some day result in publishing a book for knife steel metallurgy ?

Regards,
FK
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Re: Toughness data

#13

Post by Larrin »

FK wrote:
Wed Jun 05, 2019 9:14 am
Larrin,

I am hoping all the work you are contributing will some day result in publishing a book for knife steel metallurgy ?

Regards,
FK
I hope so. After I have all the major topics covered I would like to re-arrange and re-write the content into a book. That allows a narrative flow and "building on" previous concepts which isn't as possible with the website. As well as having the major subjects in one place.
http://www.KnifeSteelNerds.com - Steel Metallurgy topics related to knives
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