Toughness of S35VN and ELMAX

[bluelighthawaii]

That would be sweet, but I think I'm going to go for just a 60-61 rc for all three.

The steels are

CPM154
S35VN
And Elmax.

I'll send them to Brad for heat treatment
All will get a 2000°f aus for 30min
Immediate cryo.
Double temper at 350-400 depending on as quenched hardness for each steel.
I'm thinking a neck knife and some testing coupons to send to a lab.
Testing will be done by end of summer as I get the cash flow to pay for it through working overtime at work.

Let's see what the toughest is since there is so much disagreement.

Hey DeadboxHero, I really appreciate you actually getting and testing the 3 steels. These are the 3 I have been wondering about. Finally feels like there will be a real comparison and not just theory or speculation. Very excited to see how things go!

 

[DeadboxHero]

Hey DeadboxHero, I really appreciate you actually getting and testing the 3 steels. These are the 3 I have been wondering about. Finally feels like there will be a real comparison and not just theory or speculation. Very excited to see how things go!

Thanks, it will be done by the end of summer since I've got other things taking up my income.
I'll start another thread and link it to this one.

 

[whp]

Thanks, it will be done by the end of summer since I've got other things taking up my income.
I'll start another thread and link it to this one.

I also look forward to seeing your results.

 

[bluelighthawaii]

Thanks, it will be done by the end of summer since I've got other things taking up my income.
I'll start another thread and link it to this one.

Hey DeadboxHero,
Were you able to create the 3 knives in ELMAX, S35VN, and CPM 154? And most of all, test them? I have been waiting all summer to find out the results! It is like waiting for the next season of GOT, the anticipation made it tough and I needed to distract myself with other things. Anyhow, hope things are going well.

 

[Mo2]

I have to remember DeadboxHero = big brown guy on YouTube. I have not seen any yt videos on his channel as of late. Probably busy with RL. I'm looking fwd to an update on this as well as his new bonded diamond stones

 

[maximus83]

A better question is why does it matter? Toughness should be relegated for fixed blades. Most folders all meet the minimum criteria of 250lb per square inch as thats on average the most a human hand can apply. Both will be just fine and not bend or warp under that type pressure.

If this is for a fixed blade and we are using it to baton with...go with 3v, it crushes both and I haven't had a single issue with it rusting or pitting on me.

Mostly agree with this. I'm still interested to hear the toughness discussion play out amongst different steels, to me that's inherently interesting regardless of the application (folder, fixed, bolt cutter, whatever). But it's also easy to see that with folders, if using them for the typical applications that most people do most of the time (not batoning and similarly stressful tasks), the steel toughness doesn't matter for daily use. S30v works. S35vn works. 154cm works. Elmax works. Others too. What you care about is mainly the edge retention, cutting performance, how easy it is to sharpen, and the stainless aspect of the equation.

 

[maximus83]

Interesting. So according to this chart, 440c is as "tough" as S30/S35 and 154cm? I believe it is actually, and maybe even slightly tougher.

My comment here is slightly wandering from the point of this thread, but seeing 440c right there with these premium steels in the toughness rating, is a reminder of how often we get into steel fads, but sometimes the actual differences are not large. Just like everybody else here, I usually want a new folder that I'm spending any significant $$ on to have a "premium" steel, according to whatever is currently understood as "premium." But the fact is, even these older steels like 440c, if they have a great heat treat, blade geometry, and hardness scale, can perform as well as the newer premium steels in a good design. This is why you still see a lot of companies like Buck making a lot of their designs with steels like 420, just using a really good heat treat. Honestly, take a well designed fixed blade like the Gerber Strongarm in 420HC, with a good heat treat: I'd pit that blade right up there with $300 fixed blades using premium steels, in every category except edge retention and of course, the ergonomics of the handle design.

Elmax is tougher than S35VN, although both are plenty tough.

Check out this link (graph at bottom):
http://www.bucorp.com/media/Toughness_testing_for_knife_steels.pdf

The chart shows toughness of various powder stainless steels at various hardnesses.

In that chart,
PM 14-2-4 CrMoV is S30V
PM 14-2-3 CrMoVN is S35VN
PM 14-4 CrMo is CPM 154
14-4 CrMo is 154 CM

 

[Twindog]

Interesting. So according to this chart, 440c is as "tough" as S30/S35 and 154cm?

You have to look at hardness, too, not just the toughness rating.

S30V and S35VN are both tougher than 440C at the same hardness. As a general rule, softer steel is tougher than harder steel because it's more likely to roll or dent than chip.

So 440C at 56 Rc is tougher than 154CM at 60 Rc, but 154 CM at 54 Rc is much tougher than 440C at 56 Rc.

One weakness of the chart is that it doesn't compare toughness for all these steels at the same hardness, but you can extrapolate to some extent.

 

[Lapedog]

You have to look at hardness, too, not just the toughness rating.

S30V and S35VN are both tougher than 440C at the same hardness. As a general rule, softer steel is tougher than harder steel because it's more likely to roll or dent than chip.

So 440C at 56 Rc is tougher than 154CM at 60 Rc, but 154 CM at 54 Rc is much tougher than 440C at 56 Rc.

One weakness of the chart is that it doesn't compare toughness for all these steels at the same hardness, but you can extrapolate to some extent.

At equal hardnesses though isn't 440c supposed to he quite tough due to its lower carbide inclusion?

I know powdered steels are supposed to partly remedy the problem of big carbide inclusions thus improving toughness.

So I guess I am asking is the fact that Elmax and s35vn are powdered steels provide enough benefit to overtake the advantage 440c has in toughness due to less inclusions.

 

[Twindog]

Powder steels will have less inclusions (imperfections) and smaller, more evenly distributed carbides then their ingot counterparts.

Generally, the greater the carbide load, the less tough the steel. The powder steel process allows much greater loads of carbides than their ingot counterpart while maintaining good toughness (resistance to chipping and breaking).

Power steel also allows for steels to be run a bit harder. Hardness is a good proxy for strength (resistance to rolling, denting and deforming).

440C is less tough than Elmax by a lot, and it's also less tough than S30V and S35VN. It will have larger carbides, more inclusions and more clumping of carbides.

 

[me2]

Toughness in steels is not uniform in all directions, in terms of length, width, and thickness directions. According to Crucible, the toughness of S30V and 440C are basically the same in the rolling direction. It's the transverse direction where the powder steels have an advantage. How this affects things in a knife depends on the orientation of the edge and blade relative to the direction of rolling of the original plate.

In the hardness range used for knives, it is not a good assumption that softer steels are tougher. There are temperature ranges during heat treating that lower both hardness and toughness. It is somewhat steel specific.

Higher carbide volume and higher dissolved carbon both lower toughness. Powder steels aren't tougher on average than their conventionally produced counterparts, but are more uniform. CPM type steels might have an average toughness of 30 + or - 5, while conventional steel might be 30 + or - 10.

 

[Twindog]

You make good points, but really the issue is complicated. Generally, softer steels will be tougher (resistance to breaking or cracking). In the chart you can see that -- softer 154CM will generally be tougher than harder 154CM.

The same with alloys with more carbide loads. Some steels (3V) will have higher carbide loads than simple steels and still be tougher. Although there are plenty of cases where the opposite is true.

The powder process will, according to the steel companies, improve the toughness of blades compared to ingot steels of the same alloy. When carbides are coarse and clumped and you have a greater chance of inclusions (contaminants in steel), as you do in ingot steels compared to powder steels of the same alloy, you're going to have blade more vulnerable to breaking or chipping (less tough).

 

[DeadboxHero]

I haven't forgotten Josey, just been busy with life.

I have the blanks cut and coupons made.

I'll send them to Brad at Peter's heat treatment when I get the money saved.

At the latest by the end of March. Maybe sooner but I have to save for my anniversary in February haha sorry bros, priorities man.
Real life comes first.

In the meantime What kind of testing are we talking about? I was going to just baton through 1/4 aluminum rod with the grinds at 0.020 behind the the edge,15dps and 61hrc for all. Then I'd just see which one takes the least damage.

I don't think I'm interested in doing a flex test in a vice since I don't think there would be a huge difference between them, they would just snap in half.

But Yes, share your thoughts since the disagreement that fuels this testing is between us.
All in good fun of course, we all benefit from discussion.

-shawn

 

[fielder]

I'm fascinated to see the results.

 

[maximus83]

I haven't forgotten Josey, just been busy with life.

I have the blanks cut and coupons made.

I'll send them to Brad at Peter's heat treatment when I get the money saved.

At the latest by the end of March. Maybe sooner but I have to save for my anniversary in February haha sorry bros, priorities man.
Real life comes first.

In the meantime What kind of testing are we talking about? I was going to just baton through 1/4 aluminum rod with the grinds at 0.020 behind the the edge,15dps and 61hrc for all. Then I'd just see which one takes the least damage.

I don't think I'm interested in doing a flex test in a vice since I don't think there would be a huge difference between them, they would just snap in half.

But Yes, share your thoughts since the disagreement that fuels this testing is between us.
All in good fun of course, we all benefit from discussion.

-shawn

How much do you need to run the tests? I'm interested in results enough that if you want to crowd fund, I'd kick in a few $$ to help, maybe others would too.

 

[DeadboxHero]

How much do you need to run the tests? I'm interested in results enough that if you want to crowd fund, I'd kick in a few $$ to help, maybe others would too.

That's not a bad idea, hell I'd probably kick in a few bucks if someone else was doing this since I'd like to see more in-depth content that's not available currently.

A little rant, The big issue with testing steels and heat treatments is it costs money, when a company or maker puts in all that research and development to find out how to get the best performance they don't just want to give out what works for free cause it costs alot of time and money to figure it out.

So it would be a benefit to all to have private funded open source testing that Everyone can use, it wouldn't be the end all be all but a great data point and resource for people as well as make the stuff us knife geeks get excited about more accessible and less "on the fringe" of the knife community only known by "steel weirdos" haha

I've been holding back on crowd funding because I want to do this test first how it turns out also other can see if it meets there expectations and if it's something they would be interested in for funding other steel testing since us knife freaks are all very curious and I think we would all like to see how these steels really stack up to each other at some level.
So I'll hold off on the crowd funding for now until we see if it's something WORTH funding.

Here is where I'm at now.

The top knife is a prototype in 8670 steel just to see what I want for these knives.

They will look the same.

I've chosen a flat grind and thin stock and edge geometry so that no weakness can hide behind geometry and the steel can be better evaluated.

Chuck at Alpha Knife Supply didn't have the same stock thickness in Elmax as the other two.
So before I ship to heat treatment I'll grind the S35VN and the CPM154 which is at 0.110" closer to the 0.104" on the Elmax.
But it's not a big deal since the finished product will probably be closer to 0.090" at the spine like on the prototype in 8670 and I have to remove some of the decarb on the Elmax too.

The cost for heat treatment will total to about $130 with shipping and processing.


What are the little squares on the right?

Those are testing coupons.

The coupons are what I'm really excited about since whatever the "caveman" testing shows we can then geek out on the metallography and other Testing from a metallurgist lab down the road. But I won't have the funds to process the testing by the lab, sorry, need a new car next year. However if we get something exciting that's interesting enough to pique our curiosity then we can crowd fund that and even ship out for x-ray diffraction to see everything in the steel.

But yes, for now let's hang in there for March to come, family first.

-shawn.

 

[Higgs Particle steel]

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[mete]

These threads are great ! But of course what ever I design as HT you'll find a way to screw it up !!
Steels [most ] have directional properties and the benefit of the powder process is mostly in the transverse direction ! But all that can be overcome if you cross roll as NSM knows how to do !I wonder if Matt G had seen that in his visit ?
My own experience with toughness tests has been to take them as approximates not absolutes as in the field there are too many variables !

 

[Alberta Ed]

Does it really make any significant difference in real life use?

 

[Higgs Particle steel]

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