Opinions of super blue blade steel please

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The Mastiff
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Postby The Mastiff » Thu Jan 09, 2014 5:56 am

Super Blue has 1.5% carbon and 2.5% tungsten (tungsten is very heavy so that is similar to 0.75% vanadium) and 0.5% vanadium,
Cliff, any way to break that down for me without getting to just mathematical formula? Are you stating 2.5% tungsten is more or less equivalent to .75% V ? In what way? They produce different carbides ( size and hardness) so what does this mean ?

Thanks,

Joe
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Postby kbuzbee » Thu Jan 09, 2014 6:00 am

The Mastiff wrote:Cliff, any way to break that down for me without getting to just mathematical formula? Are you stating 2.5% tungsten is more or less equivalent to .75% V ? In what way? They produce different carbides ( size and hardness) so what does this mean ?
Cliff tends to focus on carbide volume, so I'm guessing that? But I found that statement confusing too, Joe.

Ken
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Postby Cliff Stamp » Thu Jan 09, 2014 7:38 am

kbuzbee wrote:Cliff tends to focus on carbide volume, so I'm guessing that?
Tungsten and Vanadium both form MC carbides (M is the alloy, C is carbon) which means they form in a 1:1 ratio with carbon, one vanadium atom + one carbon = one carbide unit. A M3C carbide would have three alloy atoms for one carbon atom.

(the carbides form in huge aggregates much bigger than an atom, that is just the ratio of atoms in the aggregate)

However when you look at steel compositions they are by weight, not by atom. Since Tungsten is almost 4x the weight of Vanadium to find the effect of it you need to divide by 4 to get the amount.

There is a complication in hot-soak steels (HSS for example) because the tungsten carbide will start to dissolve in the austenite at 2150F (chromium carbide does much lower at 1650 F).

The reason that these steels often have very high tungsten is exactly because it dissolves as once it is in the austenite it will then come out in the tempering. When it comes out of the austenite in the tempering it again forms carbides and this provides a very strong secondary hardening and hot-hardness (resistance to softening). This is why when you look at a tempering curve you will see steels soften but then at around 950F they will have a sharp peak where they increase.

(molybdenum does a very similar thing as tungsten but it forms m2c and m6c carbide and the carbides are softer and it also tends to dissolve in other carbides such as the very large chromium ones).

(Note there is a very large difference in the carbides which form during the tempering and the ones which do not dissolve in the austenization. The ones which form in the tempering are very small < micron .)



Vanadium carbide is very difficult to dissolve in the austenite and has a very low solubility and thus is added mainly for wear resistance as it does not provide the same kind of secondary hardening response that Tungsten does. In very low amounts (< 0.5%) Vanadium is added as a pinner/boundary point to keep the austenite grain from growing (as again it doesn't dissolve).

In short,

-for hot soak steels, tungsten is for secondary hardening-hot hardness, wear, and also for grain pinning (as not all of the carbide will dissolve)

T1 for example is a HSS - Tungsten steel, 18% tungsten.

-for cool soak steels, tungsten is main for wear, and secondary for grain pinning

Because vanadium is harder / more available it has mainly replaced tungsten for this.

-vanadium is always for wear and grain pinning, and in very small amounts is mainly for grain pinning only

Niobium is making inroads to vanadium in small amounts due to it being similar to vanadium but even more of what you would want in the desired attributes.

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Postby Minibear453 » Thu Jan 09, 2014 10:24 am

So.. does that mean Tungsten provides finer carbides than Vanadium does? Making Superblue more "refined" in its grain than say.. Vanadium?
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Postby WorkingEdge » Thu Jan 09, 2014 12:58 pm

holy smokes. Cliff, I tried finding a basic metallergy test or reference but no idea where to start. Any recommendations? hoping to learn enough to make your posts understandable.

thx

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Postby jackknifeh » Thu Jan 09, 2014 1:58 pm

WorkingEdge wrote:holy smokes. Cliff, I tried finding a basic metallergy test or reference but no idea where to start. Any recommendations? hoping to learn enough to make your posts understandable.

thx
Master's degree, nothing less. :) I think it's good for him to include the info he does because some people get a lot out of it. I just read and get what I get. The rest I just forget about it. Asking him to explain what he just said results in more confusion. Here is my level of understanding steel and the knife edge. This works perfectly fine for me. Picture a rack of pool balls. The pool balls represent one atom or carbide and the empty space represents "other" stuff in steel. The 2 1/4" pool balls are 8Cr13MoV. The front of the front ball is the edge apex. It can't get any sharper than the size of the ball will allow. Smaller balls will result in a sharper edge. S30V balls are half the size. So the front ball being smaller is sharper. Do you want to see a burr? Take another ball and sit it beside the front ball. To remove the burr you want to abrade it down to the line where the other balls are. You don't want to straithen the burr. This would be represented by moving the burr (the extra ball) around to in front of the front ball. That little flap of steel is very weak and will snap off when you start using the knife leaving a crappy (industry term) edge.

Anyway, when you understand steel and the knife edge like I do you can understand why my head hurts trying to understand what Cliff writes. :) He explains steel with a Mont Blanc. I use a crayon that is flat on one side. :)

Jack

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Postby xceptnl » Thu Jan 09, 2014 2:02 pm

jackknifeh wrote:...He explains steel with a Mont Blanc. I use a crayon that is flat on one side. :)

Jack
LOL, :p
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sal wrote: .... even today, we design a knife from the edge out!
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Postby Cliff Stamp » Thu Jan 09, 2014 3:23 pm

Minibear453 wrote:So.. does that mean Tungsten provides finer carbides than Vanadium does?
In equal amounts Tungsten and Vanadium will form similar sized carbides.

However the size of the carbides produced is dependent not only on the nature of the material but the amount of it. Tungsten and Vanadium will naturally form smaller carbides than Chromium for example but if you put a large amount of Tungsten or Vanadium in a steel and a small amount of Chromium in another steel the Chromium carbides will be smaller.

The carbides in S110V for example are mainly Vanadium based but there is so much Vanadium in the steel that the carbides are larger than the Chromium ones in AEB-L (more than 10X the size).
WorkingEdge wrote:Any recommendations?
Verhoeven's books are available and made for knife makers, they are a decent place to start. I would recommend reading any actual academic text just to get use to the language because it will allow you to read the current literature and that is where the research is carried out. Any text book is out of date by the time it published.
jackknifeh wrote:....Smaller balls will result in a sharper edge. S30V balls are half the size.
8Cr13MoV has in general smaller carbides than S30V. This is because the amount of carbide in S30V is so high that the carbides aggregate (clump together). While the individual carbides in 8Cr13MoV are larger there are simply not enough of them to clump.

As an analogy, imagine putting 10 adults in a large room. The put 50 kids in another room. Even though the kids are much smaller they are likely to form into clumps as kids do and if you look at the clumps of kids vs the groups of adults, the clumps of kids can still be larger.

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Postby WorkingEdge » Thu Jan 09, 2014 3:26 pm

I like your analogy. ;)

I did understand that part from his previous posts. Just wanting to learn more about the different phases steel goes through during the heating / cooling / tempering process.


jackknifeh wrote:Master's degree, nothing less. :) I think it's good for him to include the info he does because some people get a lot out of it. I just read and get what I get. The rest I just forget about it. Asking him to explain what he just said results in more confusion. Here is my level of understanding steel and the knife edge. This works perfectly fine for me. Picture a rack of pool balls. The pool balls represent one atom or carbide and the empty space represents "other" stuff in steel. The 2 1/4" pool balls are 8Cr13MoV. The front of the front ball is the edge apex. It can't get any sharper than the size of the ball will allow. Smaller balls will result in a sharper edge. S30V balls are half the size. So the front ball being smaller is sharper. Do you want to see a burr? Take another ball and sit it beside the front ball. To remove the burr you want to abrade it down to the line where the other balls are. You don't want to straithen the burr. This would be represented by moving the burr (the extra ball) around to in front of the front ball. That little flap of steel is very weak and will snap off when you start using the knife leaving a crappy (industry term) edge.

Anyway, when you understand steel and the knife edge like I do you can understand why my head hurts trying to understand what Cliff writes. :) He explains steel with a Mont Blanc. I use a crayon that is flat on one side. :)

Jack

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Postby SolidState » Thu Jan 09, 2014 5:38 pm

Hey Cliff,

Do you use electron microscopy and EDX to get the metal to carbon ratios in those carbides? I've been looking for good projects involving the metallurgy of steel, and now that I have a good number of samples, it seems like this carbide problem may be fun to study on the old Zeiss. Do you have any suggestions?
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Postby SolidState » Thu Jan 09, 2014 5:38 pm

Hey Cliff,

Do you use electron microscopy and EDX to get the metal to carbon ratios in those carbides? I've been looking for good projects involving the metallurgy of steel, and now that I have a good number of samples, it seems like this carbide problem may be fun to study on the old Zeiss. Do you have any suggestions?
"Nothing is so fatal to the progress of the human mind as to suppose that our views of science are ultimate; that there are no mysteries in nature; that our triumphs are complete, and that there are no new worlds to conquer."
Sir Humphry Davy

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Postby Cliff Stamp » Thu Jan 09, 2014 7:04 pm

WorkingEdge wrote:
Just wanting to learn more about the different phases steel goes through during the heating / cooling / tempering process.
In the as-bought state the steel is ferrite + cementite + alloy carbide. This stage is used because it is very easy to grind and machine. Ferrite is the main body of the steel, cementite is a particular type of iron carbide which forms in steel because carbon does not dissolve very well in ferrite.

When the steel is heated it will transform into austenite. The critical aspect of this phase is that it will dissolve massive amounts of the alloying elements. In fact if you soak steel hot enough the austenite will dissolve all of the alloy, but in general you don't want that. Some of the alloy will be left undissolved as you want some of the carbides to stay for wear resistance and to prevent the growth of the austenite which forms in pieces (grains).

If the steel is cooled rapidly it will not form ferrite again but instead martensite. The critical part here is that the martensite can hold very high amounts of carbon in it and the more carbon in it the harder and stronger it gets. This is the critical property that is achieved by the entire process. The maximum martensite hardness comes at about 0.6% carbon, above that is mainly for carbide formation.

The reason that cold is used is because it is necessary to ensure all of the austenite changes to martensite. Austenite is very soft and weak so you generally don't want it left in the knife, especially in the edge. If you soak for a very long time (a day) then a particular type of carbide (eta) will form which can increase wear resistance.

When the knife is tempered it will form tempered martensite, and a number of things happen to the steel. The alloy starts to come out of the martensite, the martensite starts to soften, the carbides starts to coarsen and this is why the steel gets softer and weaker.

I am simplifying it quite a lot and generalizing, but that is the basic process. There are lots of interesting things which can happen if you do things wrong which is very common as often people have no idea what they are doing which is why you can see crazy things like 5160 being more brittle than D2.

Have you ever had a knife edge which is both soft and weak but also brittle and wondered how such a thing can happen at the same time?

This is often a sign of the steel being over soaked (too high a temperature) which means the austenite grain grew very large, too much alloy dissolved and too much austenite remained and was not turned to martensite (the more alloy dissolves the harder it is to change to martensite).

-with too much alloy dissolved the wear resistance suffers and the edge wears down quickly

-with too much austenite left the edge will be weak and soft in random places

-what is worse the austenite will change to martensite over time and is now untempered and very brittle, again in random spots

-the very large aus-grain also makes the steel very weak and brittle at the same time

If you use a knife like this you find :

-edge is hard to sharpen, very gummy
-rolls and dents easy
-chips easy at the same time
-wears down and grinds too easy

and you wonder why anyone would like HYPE-X as is doesn't seem overly impressive. This is one of the things you need to be careful of when trying to figure out steels from knives because you are not just seeing the steel but also how it was processed.

SolidState wrote:Do you have any suggestions?
You only need 1000X to get the carbide fraction, in fact beyond that and your field of vision would be too low to estimate the volumes (from the areas). The critical thing to realize of course is that the carbide fractions/volumes are dependent on the austenization temperatures/times. Sandvik is fairly nice in this regard as they show the as-quenched micro-graphs in various states and show what the steels look like both under and over soaked.

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Postby Fred Sanford » Thu Jan 09, 2014 7:14 pm

Just wanted to add that I am one of the old forum members and I truly value what Cliff has to say. He's very knowledgeable on this stuff.

It's easy to see that he enjoys it as well. If you don't watch some of his videos on YouTube you should if you are interested in all things steel and edge related. Good stuff.
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Postby Cliff Stamp » Thu Jan 09, 2014 8:52 pm

jackknifeh wrote:To make sure I understood your post, based on my answers to your questions, do you think I will like super blue?
Yes.

The reason I asked those questions is because steels are not inherently good or bad as a general performance qualifier. They have different properties and you simply have to pick the steels which have the properties that you want in a particular knife.

How would you react if you were going for a hike in fairly hot and dry conditions and I gave you a very well insulated knee high winter boot and kept telling you how well made/high quality it was. That seems kind of silly doesn't it? But people do this all the time recommending a steel without considering the application simply because a steel is "super".

Once you narrow it down to a type of steel which is useful for a general type of application, just like a type of boot you need, then you can start to discuss the differences but the first thing you need to know is do you want a running shoe or a snowshoe. If you don't make that initial distinction then you are likely to make poor choices.

Even the very best snowshoe is a pretty poor piece of footware for swimming so it doesn't matter how good a snowshoe you buy the worse flipper would be much better.

If you start thinking about steels this way, that they are not good or bad, low quality or super, but they are simply different classes for different applications you will quickly start to understand them on a much deeper level. It isn't that hard, it just requires that initial perspective and the rest will come with use/experience.

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Postby eric m. » Thu Jan 09, 2014 9:09 pm

You definitely love what you do Cliff! How much of your life has been devoted to your studies/experimentation of steel? :)

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Postby Cliff Stamp » Thu Jan 09, 2014 10:00 pm

I spend about an hour each day answering questions in emails, pm, and on YT and the forums.

The stock work I do, when you see large piles of the same material cut is done when I am watching whatever I am studying at the time. Right now I am watching a lot of moral philosophy debates and lectures, so I spend 1-2 hours at that most days.

That is also when I do any sharpening. If you watch my video's it is also why I have a fairly odd way of sharpening as I hold the benchstone in my off hand, I don't put it on a desk. This is simply because I do it while watching debates and lectures on YT.

It is mainly a perspective thing. We have had blackouts here recently so I took some time to see what difference it made if I sharpened knives in the dark. It didn't make any, but I didn't expect it would, but that was an interesting way to spend some time without power anyway.

In general for direct functional use, it depends a lot on the time of year. I always carry/use knives for cooking, general utility and such, but in the summer and fall I do a fair bit of work outside (wood working) and I normally do a lot of comparative work at the same time. I burn wood and clear a lot of brush and while I am doing it for functional purposes I can gather data at the same time if I just take a notebook and make some basic recordings.

I have been doing this in a semi-serious way since the mid-nineties. But it isn't always consistent. I spent two years in India for example working and did little knife work there, but I could still observe a lot with how the natives used knives and that was valuable as well. I also took a teaching position for a couple of years where I had little time for anything else as I was researching at the same time (atomic physics).

But knives/steel is just one of the things I am interested in. I also study history, philosophy, negotiation, human behavior and other things.

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Postby 3rdGenRigger » Fri Jan 10, 2014 12:42 am

Cliff Stamp wrote:I also took a teaching position for a couple of years where I had little time for anything else as I was researching at the same time (atomic physics).

But knives/steel is just one of the things I am interested in. I also study history, philosophy, negotiation, human behavior and other things.
That's awesome...have you ever researched liquid fluoride thorium reactors? I'm convinced that it's where mankinds future energy needs reside. Kirk Sorenson has some really good talks on YouTube.

Anyhow...somewhat back on topic...I'm super stoked for my SB Stretch to finally come so I can try SuperBlue. I almost bought a CruWear Military today, but I was able to resist because I want a Kiwi4 more (When that appears).
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Postby nozh2002 » Fri Jan 10, 2014 1:34 am

More I read Cliff , more I think he is just artist of confusing people. I read him from 2002 and for ten years in
same area I did a lot of testing, learn how to sharpen... And he keep same talks without any visible results.
No tests, noting - just talks and talks with same confusion.

If you new and just read this - you may think that wow this is scientist!

If you reed this for last 12 years - same again and again, you may think the way I do - pathetic!
Set to be ignored by everybody.

Effectevely I am banned, but this is done the way nobody noticed, which means
Spyderco knows pretty well, that this ban is wrong and tries to hide that.

Made in USSR

http://nozh2002.blogspot.com/2011/07/ed ... sting.html

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The Mastiff
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Postby The Mastiff » Fri Jan 10, 2014 3:11 am

Thanks for the explanation Cliff. The carbide explanation actually answered a question I had for a while. Too lazy/busy to research it in tech type books that make my eyes go crosseyed in my old age. :)

Joe
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Postby The Mastiff » Fri Jan 10, 2014 9:20 am

Next Question.

Have Titanium carbides ever been used in steel or is this impossible due to temps or other reasons. I have seen steels that claimed to have some titanium but it was in an ad ( called D9 steel) and there was no way to verify the truth of the claim.

Joe
"A Mastiff is to a dog what a Lion is to a housecat. He stands alone and all others sink before him. His courage does not exceed temper and generosity, and in attachment he equals the kindest of his race" Cynographia Britannic 1800


"Unless you're the lead dog the view is pretty much gonna stay the same!"


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