Why carbon steel?

[Grapevine]

I've been a knife enthusiast for awhile but am fairly new to the intricacies of blade steel. I understand the general tradeoffs between hardness, toughness, edge retention, ease of sharpening, etc. What I'm confused about is the indication I get from these forums of the general better performance of carbon steels vs. stainless.

If corrosion resistance wasn't an issue, what features of carbon steels like 1095, 01, and 52100 better than stainless steels with the same amount of carbon? Are the carbon steels harder, tougher, easier to sharpen, hold an edge longer, or what combination of these features?

And why is it that they are that way compared to the stainless with the same carbon content? Does the addition of Chromium do negative things to the performance (again corrosion resistance not being an issue)?

Or is there no performance difference between carbon steels and stainless with the same carbon content other than price, ie. you get more bang for your buck?

 

[Coonskinner]

I won't try to address all your individual questions, because there are others more knowledgeable in the technical department who are better qualified to do that. But I will tell you why I tend to prefer carbon steel blades over stainless.

Performance is a very relative term, and everyone has different criteria they go by. The major advantage stainless steels have over carbon steels is their corrosion resistance. However, this is not a big deal to me since I live on the high plains, and don't mind doing the minimal maintenance necessary to keep carbon steel blades rust free. In fact, I enjoy it, just like I enjoy cleaning my favorite guns. The maintenance of a fine tool is not a drudgery to me, but rather a pleasure.

No doubt some of my preference for carbon steels is due to the fact that I have fairly traditional tastes in knives. I like slipjoints, and traditional pattern hunters, Bowies, and Camp knives. To me, putting a stainless steel blade on one of these knives would be like putting a scope on a Winchester Model 94...out of place. On the basis of aesthetics, there is nothing more beautiful in steel to me than the patina a carbon steel blade develops over a period of time.

Regarding performance, some of my opinions are probably subjective. I like the feel of the edge I can put on a good carbon steel blade better than the kind of edge I get with most stainless steels. I like the way they cut. I like the way they feel on a stone, and how easily they sharpen up. And based on my limited experience, few if any steels can rival or exceed the performance of a steel like 52100 forged by a smith who knows what he is doing. Even the 52100 used by Marbles is an incredible performer.

But even simple carbon steels like 1095 and 1084 have done a good job for me and completely satisfied me.

There are stainless steel knives that work well. I own some of them. Things like heat-treat, edge geometry, blade shape, etc. are as important at least as the steel involved, so an easy, pat answer to your question is difficult if not impossible to arrive at.

The best thing for you to do is try some knives for yourself, see what you like, and enjoy the process.

 

[Keith Montgomery]

I think that for most people the difference in performance between stainless and carbon steel is not that much of a factor. For normal everyday use, both steels will do an excellent job. Low lloy carbon steel is tougher than stainless because Chromium does adversely affect the toughness of steel. I find that most low alloy carbon steels are tempered to a lower RC value and so are easier to sharpen. Edge retention should not be as good as with a harder steel, but I find that the low alloy blades that I have hold an edge just fine.

If corrosion and stain resistance is something that you would find useful in a blade then do not think that you have to accept an inferior steel to get these traits. This is not the case. Stainless steels make superb blades as do low alloy steels. Maybe what you should do is try knives of both types and find out for yourself which steel you prefer.

Also keep in mind that if stain and rust resistance is of great importance to you, then Stellite and Tallonite do a better job in this area than any stainless steel. Have fun checking them all out. I do.

 

[martin j]

Originally posted by Grapevine
Are the carbon steels harder, tougher, easier to sharpen, hold an edge longer, or what combination of these features?

...

Or is there no performance difference between carbon steels and stainless with the same carbon content other than price, ie. you get more bang for your buck?

Just address these matters, yes GENERALLY speaking carbon stells (or what are categorised as "carbon steel" since all steel has carbon) are, in use, much easier to sharpen because they are non-alloy or simple low alloy. Others can explain better but yes, more alloying elements, espcially the chromium makes for harder sharpening, it is trade off for higher corrosion resistance.
Also, higher chromium and other aloying elements I believe cause formation of different carbides which also provide different plus/minus, for example vanadium carbides are very hard for cutting but may also be more difficult for sharpening than carbide formation in simple non or loow alloy steel. Also, I suspect gains here may also compromise to varying degree, the toughness for higher wear resistance, and so forth.
"Super stells" like CPM can excel in edge holding /wear resistance and corosion resistance due to complex carbide formations. but their stainless versions are compromise on toughness as result.
But perhaps there are changes here too, because s30v has promising results so far as excellent "balanced steel," tough + edge holding.
Simple non-alloys because they are tougher often can take finer( more acute) angle edge, which results in better cutting ability potentially. Traditional stainless risks brittleness or weakness to rolling at equivalent angles I believe.
More thoughtful commentators can probably offer better insight, but i hope this is clear.
Regards,
Martin

 

[fishbulb]

A quick trip through the archives will give you plenty of information on the various technical aspects and compositions of various steels. This will tell you very little compared to using them. I have found that (for me) 1095 or 1084 carbon steel are ideal in terms of performance and sharpenability.


Oddly, I don't like modern super stainless much at all. I have found that anything more "extreme" than 440C tends to be over-hardened and still doesn't work as well as 1095.



Price is another big factor for me. Look around at some of the internet knife stores:

Good quality 1095 fixed blade - approx. $30
Similar BG-42/ATS-34 etc. fixed blade - approx. $90

Considering that the carbon steel blade will likely perform as well or better than the stainless, that is a huge premium to pay for increased rust resistance.

 

[Cliff Stamp]

There is a misconception that carbon steels are better in all ways than stainless steels if you forget about corrosion resistance, this isn't true. Both can be made very hard (~64-67 RC), if desired, and thus can offer very high strength. Both can have very high alloy contents with extreme amount of carbide formers and thus the wear resistance will be high.

The only real drawback to stainless steels, is that they are more brittle and less ductile than a non-stainless steel of similar other properties. However, the very high wear resistant non-stainless steels (D2, M2, CPM-10V), are not tough either. And the really tough steels like L6 have disadvantages in terms of hardness limitations and wear resistance as compared to stainless steels like S90V or BG-42.

-Cliff

 

[John Frankl]

"There is a misconception that carbon steels are better in all ways than stainless steels if you forget about corrosion resistance, this isn't true. Both can be made very hard (~64-67 RC), if desired, and thus can offer very high strength."

Simple carbon steels will have extemely low strength at such high hardnesses (if they reach them at all). Most would shatter like glass on first impact.

"The only real drawback to stainless steels, is that they are more brittle and less ductile than a non-stainless steel of similar other properties. However, the very high wear resistant non-stainless steels (D2, M2, CPM-10V), are not tough either. And the really tough steels like L6 have disadvantages in terms of hardness limitations and wear resistance as compared to stainless steels like S90V or BG-42.

-Cliff"

How hard do you want your blades? Who will sharpen them for you? L6 at .7 of a percent carbon gets plenty hard AND you can sharpen in in the field--same for 5160 with a point less carbon.

One more plus that we have failed to mention for simple carbon steels is the ability of the maker to differentially heat treat them. Whether your blade is of 1084 or BG-42, what need do you have of a 61RC spine or tang? Such high numbers away from the cutting edge and point add nothing and subtract much (think of any situation where the knife must be hammered on the spine or flexed along its length, etc.).

It is obvious that I am a proponent of (forged) simple carbon steels. However, I truly believe that the maker will always be more important than the materials (assuming he is not using junk). For example, Randall Martin posted above, and I would rather have one of his knives than a forged one from someone I didn't know/trust. And, obviously, give me an Ed Fowler or Jerry Fisk blade any day of the year over a run of the mill stainless blade.

Subjective personal preference more than objective fact or superiority counts for a lot in these matters.

John

 

[Cliff Stamp]

John Frankl :

Simple carbon steels will have extemely low strength at such high hardnesses (if they reach them at all). Most would shatter like glass on first impact

Yes, which demonstrates low impact toughness, not strength which is a very different property.

How hard do you want your blades? Who will sharpen them for you? L6 at .7 of a percent carbon gets plenty hard AND you can sharpen in in the field--same for 5160 with a point less carbon.

For light use, no chopping or edge twisting, as hard as they can get. Around 64 RC is possible with some of the high alloy stainless, and 65+ with the high alloy nonstainless. I sharpen them myself, and yes, this includes when I am outside the house, though it is rare that this is necessary.

One more plus that we have failed to mention for simple carbon steels is the ability of the maker to differentially heat treat them.

This can be done on stainless as well.

Subjective personal preference more than objective fact or superiority counts for a lot in these matters.

Lets not get too artistic here, there are real, measurable differences in how steels perform, and these will influence the blades in significant ways. Yes the maker has to be competent, but it is not like the forged makers are the only ones who know who to heat treat steels.

-Cliff

 

[Matt Shade]

John
You just have to get used to Cliff, he's sort of our Dr. Frankenstein here on the forums doing all sorts of horrendous experiments with blades. Makers shudder at the thought of him getting one of their knives
When he talks about strength, he's using it by its scientific definition meaning how something resists deformation. Steel at RC64-67 resists deformation very well. Rockwell testing involves seeing how much force is necessary for a diamond to deform/dent the steel a given amount, the higher the number the more force required. That translates to higher strength by Cliff's definition.
If he talks about toughness, he means what most of us consider strength, ability to take abuse ie. impact, flex, etc.


With modern day techniques carbon vs. stainless is becoming less of an issue. There are differences in both, but the same differences can be found between two different alloys of stainless or two different alloys of carbon also. Carbon steel is better for forging, and in some cases can be made to perform well more easily than stainless. The majority of carbon steel blades now, are either custom made, or from higher end manufacturers which can also add to the idea that carbon is always better, when really its just being used in knives that are made better.

 

[Jeff Clark]

For practical, civilized use, at moderate hardness, say 58 RC, I never stress a blade enough to notice toughness differences between stainless and non-stainless(aka carbon) steels. What I notice is that it is much easier to put a razor edge on the carbon steel--particularly for a moderately priced knife. Simple carbon steels are virtually always easy to sharpen. You would have to be trying to screw something up to make them hard to get to a razor edge. The grain structure is softer and more uniform. When you hone and strop them they tend to just keep getting sharper. Cheap stainless can be a real pain. The chrome makes for extra work to remove material by honing. It is also common for the chrome to muck up the grain structure of the steel and make it coarse. When that happens the edge won't take a fine edge or if you get a fine edge it breaks down very quickly. Better stainless alloys with better heat treatment don't suffer from this problem, but they are at least a bit harder to sharpen.

For uncivilized use which involves significant chopping or prying (or even throwing) you go a bit lower in hardness and the simple carbon steels are dramatically tougher. For a sword I would rather have 5160, 1060, or L6 alloys. This is more the category of alloys you find for machetes, kukuris, or axes. If you want your heavy blade to survive accidentaly hitting a nail or pebble in the bark of a tree you are better off with a simpler carbon steel. They will also work better than a non-stainless tool steel for this kind of work.

If you want your blade to stay sharp for a long time under less battlefield conditions and you are willing to pay for quality I like BG42 for stainless and 52100 for non-stainless. Both are tough enough for my use and easy to sharpen. If I had to pick a middle ground I would use D2. I don't really like the feel of edges above 61 RC so these alloys work well for me.

 

[Ed Fowler]

I compliment all who have contributed to this thread. I read honest well thought out comments. To me all steels are interesting, I have one problem, I have fallen hopelessly in love with 52100. There are many reasons why. To me, she has a soul, she is absolutely honest, once you understand her, she is reliable, predictable and willing to reciprocate for all you give. When you think you know all about her she will throw you a curve ball that awakens your interest. If you want to read about her there are reams of technical data available. She knows no limits, the maker is only limited by his imagination and devotion.

Thanks for some good thoughts.
Take Care

 

[frank k]

Stength is the ability of a material to resist external forces. There are many types of strengths, such as tensile, compressive, shear, bending, torsional, impact, ect.

 

[FK]

Ed,
You are well known for your detailed knowledge of 52100.

How do you control the quality of your raw steel? Is it obtained only from one mill, such as Timken in Canton, OH?

Do you request mill certs from your steel supplier?

Regards,
FK

 

[Ed Fowler]

FK: A metalurgist called me about three or four years ago. He works for a steel outfit. They were inventoring their storage yard, (425 acres) and found a pour of 52100 that had been made and sold to another outfit. The other outfit had budget problems as I remember and could not complete the project. Over 100 5 1/2 inch round bars, 18 feet long and due to some facet of the steel industry they could not sell to anyone else and therefor it and it was scrap.
It was highly specked out and he got permission to work with it. He had read about my work with 52100 and asked if I would be interested in working with his steel. It is all the same melt, and so far what we have worked is without fault.

The absolute consistency of the steel is what has allowed us to achieve the results that were reported in Blade Magazine. I would start with another steel with much apprehension as we have come to know this steel well over the course of time through countless experiments and astronomical amounts of time. We keep learning and have increased the performance qualities considerably since the test blade in the article.

We may have access to some 15 1/2 inch round bars from another pour and plan on some work with them in the future. Some preliminairy results indicate that it does not take much variation in the chemistry to make significant differences in the nature of the steel.

I feel truly blessed to have the steel we are using.

 

[calyth]

I'm not sure how Carbon steel is better than stainless... but I keep hearing good things about it. Sometiems about how it holds a better edge.
Anyone know what kinda maintenance is needed?

 

[Cliff Stamp]

frank k :

Stength is the ability of a material to resist external forces. There are many types of strengths, such as tensile, compressive, shear, bending, torsional, impact, ect.

To be clear there is a rather large difference when a material is loaded slowly and when it is loaded quickly. The reason being that it takes time for the steel to deform at the crystal level. If you attempt a load quicker than this, you can induce brittle failure as the crystal splits. This is why generally you will see strength referenced as the property of materials to resist deformation under a slow rate of load change , and toughness as the ability to resist deformation under a high rate of load change.

Matt :

With modern day techniques carbon vs. stainless is becoming less of an issue. There are differences in both, but the same differences can be found between two different alloys of stainless or two different alloys of carbon also.

Yes, this is a rather critical point. The generalization of carbon vs stainless doesn't hold as well now with the common use of very high alloy stainless and nonstainless blade steels. S90V at 63 RC vs 1095 at 60 RC is a very different comparison than S30V at 59-60 RC vs M2 at 64-66 RC. Of course, to be precise, carbon steels generally mean pure carbon like 1095, not alloy steels like 52100, or really high alloy like M2. This is what causes the mixup in comparing stainless to carbon steels, you should be looking at overall alloy content not just Cr %.

Jeff :

Cheap stainless can be a real pain.

Yes, you have the worst of both possible aspects. The steel is soft and crumbly and thus doesn't hold a thin edge well, yet it is chock full of alloys which make machining it difficult compared to something like 1095.

calyth :

Anyone know what kinda maintenance is needed?

Depends on the enviroment, however except in extreme cases (high humidity, salt water exposure), a little oil along the edge is enough and the flats will just patina.

In regards to edge retention, it is not a clear win on carbon steels. While 52100 at 60 RC will outlast 440C at 58 RC on most materials, it won't outlast S90V (stainless) at 63 RC.

-Cliff

 

[Buzzbait]

Okay. Let's have a showdown to finally settle this. Somebody make up a stainless knife to the same specs as a Busse. We'll pit them against each other, and see which one wins.

I'll place my bets on the Busse.

 

[Grapevine]

But no one knows what INFI is made up of anyway (except for Busse). So you can't claim it to be a "simple" carbon steel.

 

[Cliff Stamp]

The chemical composition of INFI was posted on Bladeforums a number of years ago. It is public, if not well known, knowledge :

V 0.36% Vanadium
Cr 8.25% Chrome
Fe 87.79% Iron
Co 0.95% Cobalt
Ni 0.74% Nickel
Mo 1.3% Molybdenum
C 0.5% carbon
N 0.11% Nitrogen

-Cliff

 

[Grapevine]

.5% carbon? How strange. Aren't you suppose to have lots of carbon in order for the steel to be strong and tough? Is te Vanadium, Cobalt, and Molybednum compensating for the small amount of Carbon? Has anyone done an analysis of why INFI's the way INFI is?