M398 Steel Testing – Edge Retention, Toughness, and More

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Larrin
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M398 Steel Testing – Edge Retention, Toughness, and More

Postby Larrin » Mon Oct 26, 2020 8:47 am

New article summarizing a whole range of experiments I performed on the new Bohler M398 steel. I tested edge retention, toughness, corrosion resistance, heat treatment, and hardness. And I included some discussion on how it compares to other steels in its general category including S110V, S90V, S125V, S60V, and ZDP-189. https://knifesteelnerds.com/2020/10/26/ ... -and-more/
http://www.KnifeSteelNerds.com - Steel Metallurgy topics related to knives

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby Holland » Mon Oct 26, 2020 10:47 am

Great article as always!
-Spencer

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Junction | Gayle Bradley 2 | Mantra 1 | Chaparral 1 | Dragonfly 2 | Leatherman Skeletool

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby JD Spydo » Mon Oct 26, 2020 3:36 pm

It doesn't surprise me that this M398 is good. Because I sure love my M390 Military model. It's been a dream of an EDC folder.

I'm going to have to make it a point to test drive a blade made with M398. I do hope that they make a C-36 Military model or a Para2 model with it.

I'm sold on Bohler-Uddeholm. I look forward to using more of their blade steels.

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby JD Spydo » Mon Oct 26, 2020 3:51 pm

Hey Larrin I got a question to ask you. I would have PMed you about this but this is something I think that the rest of the gang will also be interested in as well. It mentions that Niobium is one of the alloys in this M398 blade steel. I've heard of Niobium before and I've seen it on the periodic element chart but I never was exactly sure what it's purpose is as a steel alloying element.

After having this hobby and/or special interest of knives for close to 20 years I'm literally embarrassed to say that Niobium is one alloying element I really don't know much about. If you could enlighten us I would appreciate it and I'm sure my Spyder-Brethren will appreciate it too.

The knowledge you share with us has been great Brother and I always look forward to reading your threads. Oh one other thing if you could also mention other blade steels that contain Niobium I would love to know which ones they are. Thanks Again LARRIN :)

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Larrin
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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby Larrin » Mon Oct 26, 2020 3:59 pm

JD Spydo wrote:
Mon Oct 26, 2020 3:36 pm
It doesn't surprise me that this M398 is good. Because I sure love my M390 Military model. It's been a dream of an EDC folder.

I'm going to have to make it a point to test drive a blade made with M398. I do hope that they make a C-36 Military model or a Para2 model with it.

I'm sold on Bohler-Uddeholm. I look forward to using more of their blade steels.
I’m not a big fan of the M398 but maybe you will enjoy it more in a knife.
http://www.KnifeSteelNerds.com - Steel Metallurgy topics related to knives

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Larrin
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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby Larrin » Mon Oct 26, 2020 4:00 pm

JD Spydo wrote:
Mon Oct 26, 2020 3:51 pm
Hey Larrin I got a question to ask you. I would have PMed you about this but this is something I think that the rest of the gang will also be interested in as well. It mentions that Niobium is one of the alloys in this M398 blade steel. I've heard of Niobium before and I've seen it on the periodic element chart but I never was exactly sure what it's purpose is as a steel alloying element.

After having this hobby and/or special interest of knives for close to 20 years I'm literally embarrassed to say that Niobium is one alloying element I really don't know much about. If you could enlighten us I would appreciate it and I'm sure my Spyder-Brethren will appreciate it too.

The knowledge you share with us has been great Brother and I always look forward to reading your threads. Oh one other thing if you could also mention other blade steels that contain Niobium I would love to know which ones they are. Thanks Again LARRIN :)
M398 does not have any niobium in it. However, I do have an article about niobium additions to steel: https://knifesteelnerds.com/2019/02/18/ ... fe-steels/
http://www.KnifeSteelNerds.com - Steel Metallurgy topics related to knives

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby JD Spydo » Mon Oct 26, 2020 4:11 pm

Larrin wrote:
Mon Oct 26, 2020 4:00 pm
JD Spydo wrote:
Mon Oct 26, 2020 3:51 pm
Hey Larrin I got a question to ask you. I would have PMed you about this but this is something I think that the rest of the gang will also be interested in as well. It mentions that Niobium is one of the alloys in this M398 blade steel. I've heard of Niobium before and I've seen it on the periodic element chart but I never was exactly sure what it's purpose is as a steel alloying element.

After having this hobby and/or special interest of knives for close to 20 years I'm literally embarrassed to say that Niobium is one alloying element I really don't know much about. If you could enlighten us I would appreciate it and I'm sure my Spyder-Brethren will appreciate it too.

The knowledge you share with us has been great Brother and I always look forward to reading your threads. Oh one other thing if you could also mention other blade steels that contain Niobium I would love to know which ones they are. Thanks Again LARRIN :)
M398 does not have any niobium in it. However, I do have an article about niobium additions to steel: https://knifesteelnerds.com/2019/02/18/ ... fe-steels/
Well I apologize and I must have read that wrong :o . It's been a hard weekend with very little sleep but I did read that on one of those pages but maybe I got it in the wrong context.

I'm actually anxious now to get a blade alloyed with Niobium and test drive it first hand. It's most interesting to see the profound differences that some of these alloying elements can do for blade steels. For instance I've always had great luck with steels that have a significant vanadium content. It sure makes it tough to sharpen but it does some interesting things for blade steels. The blade steel 440V ( S60V) has a high vanadium content. It is a monster to sharpen but it's probably my favorite blade steel for fully serrated models.

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby Wartstein » Mon Oct 26, 2020 4:26 pm

Thanks Larrin, very interesting read (and as always written in a way so that average (and non-native-speaker) joes like me still can understand the content).

Though not a steel that would interest me personally, given your comparisons to other options.
Top three going by pocket-time: Endura 4 in VG 10/Micarta-scales; Stretch 1 in VG 10; Endura 4 in HAP 40

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby Rp5 » Mon Oct 26, 2020 6:24 pm

Great write-up Larrin. Thanks.

Maybe the knife-makers of the world will find a heat treatment strategy to unlock a better toughness/edge retention balance, but from your initial results it doesn't seem like it will immediately supplant the more familiar steels. The corrosion resistance seemed pretty good compared to the sample. Fun to see something new.

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby Larrin » Mon Oct 26, 2020 7:31 pm

Rp5 wrote:
Mon Oct 26, 2020 6:24 pm
Great write-up Larrin. Thanks.

Maybe the knife-makers of the world will find a heat treatment strategy to unlock a better toughness/edge retention balance, but from your initial results it doesn't seem like it will immediately supplant the more familiar steels. The corrosion resistance seemed pretty good compared to the sample. Fun to see something new.
Heat treatment can only do so much to overcome the inherent effect of microstructure. If the steel is already 30% brittle carbides even making the other 70% tougher isn’t going to work miracles.
http://www.KnifeSteelNerds.com - Steel Metallurgy topics related to knives

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby TomAiello » Mon Oct 26, 2020 7:35 pm

We definitely need an M398 Mule. :)

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby Ankerson » Mon Oct 26, 2020 8:26 pm

Larrin wrote:
Mon Oct 26, 2020 8:47 am
New article summarizing a whole range of experiments I performed on the new Bohler M398 steel. I tested edge retention, toughness, corrosion resistance, heat treatment, and hardness. And I included some discussion on how it compares to other steels in its general category including S110V, S90V, S125V, S60V, and ZDP-189. https://knifesteelnerds.com/2020/10/26/ ... -and-more/

Well can't have everything. LOL

Pass.... ;)

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby RustyIron » Mon Oct 26, 2020 9:21 pm

Larrin wrote:
Mon Oct 26, 2020 7:31 pm

Heat treatment can only do so much to overcome the inherent effect of microstructure. If the steel is already 30% brittle carbides even making the other 70% tougher isn’t going to work miracles.
This question popped into my head this afternoon when I was reading your article... or maybe it was one of your other articles I wandered upon. Somewhere I got the impression that harder equals better edge retention, but at a loss of toughness.

So as an knife maker, do we shoot for maximum hardness for a particular flavor of steel, or do we back it off a little in the interest of making a more durable blade? Or is this question too simplistic to have an absolute answer?

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby Larrin » Tue Oct 27, 2020 5:46 am

RustyIron wrote:
Mon Oct 26, 2020 9:21 pm
Larrin wrote:
Mon Oct 26, 2020 7:31 pm

Heat treatment can only do so much to overcome the inherent effect of microstructure. If the steel is already 30% brittle carbides even making the other 70% tougher isn’t going to work miracles.
This question popped into my head this afternoon when I was reading your article... or maybe it was one of your other articles I wandered upon. Somewhere I got the impression that harder equals better edge retention, but at a loss of toughness.

So as an knife maker, do we shoot for maximum hardness for a particular flavor of steel, or do we back it off a little in the interest of making a more durable blade? Or is this question too simplistic to have an absolute answer?
I have an article about hardness here: https://knifesteelnerds.com/2018/11/12/ ... -hardness/

To have optimal cutting performance you need thin, acute edges. A thin edge doesn’t just need toughness to avoid chipping but also hardness to avoid rolling and deforming.
http://www.KnifeSteelNerds.com - Steel Metallurgy topics related to knives

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby FRNFanboy » Tue Oct 27, 2020 8:43 am

Seems like M398 is a result of the market’s tendency to prize edge retention above all else. Stellar edge retention, poor toughness and rust resistance. I’d like to see a side by side comparison with Maxamet.

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby TomAiello » Tue Oct 27, 2020 8:54 am

FRNFanboy wrote:
Tue Oct 27, 2020 8:43 am
Seems like M398 is a result of the market’s tendency to prize edge retention above all else. Stellar edge retention, poor toughness and rust resistance. I’d like to see a side by side comparison with Maxamet.
Was M398 developed as a cutlery steel?

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Larrin
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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby Larrin » Tue Oct 27, 2020 9:15 am

M398 was developed as a plastic mound steel. So it would be more correct to say it was developed for wear resistance above all else. Though that translates to edge wear as well.
http://www.KnifeSteelNerds.com - Steel Metallurgy topics related to knives

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby Tucson Tom » Tue Oct 27, 2020 9:17 am

TomAiello wrote:
Mon Oct 26, 2020 7:35 pm
We definitely need an M398 Mule. :)
I was feeling relieved to see that this was a steel I could simply not get interested in. Until this comment came along .... :rolleyes:

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby Cycletroll » Tue Oct 27, 2020 11:02 am

Great article Larrin!
I find s90v to be really the minimum toughness/edge retention balance I will buy in a stainless steel.
I appreciate that you put M398 in a context that correlates to end user balance and performance.

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Re: M398 Steel Testing – Edge Retention, Toughness, and More

Postby sal » Wed Oct 28, 2020 8:30 am

Thanx Larrin,

Very informative, as usual.

FYI, we have almost 5,000 lbs coming in different thicknesses.

sal


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