Why carbon steel?

In INFI the Nitrogen is Nitriding the alloys, similar to how Carbon would carbide them in regular steels.

-Cliff
 
Originally posted by Ed Fowler
I have one problem, I have fallen hopelessly in love with 52100.
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Now wait just a minute, Ed. I thought Kevin McClung said he'd never seen anybody cut anything with a bearing? ;) :D

Grapevine,
Lots of good answers so far to the question you've posed. If there's one common thread in the responses thus far, I'd have to say it revolves around the issue of grain size and structure. In simplest terms, your low alloy, high carbon steels tend to have a smaller and more uniform grain structure than that found in your typical production stainless blade. The forging techniques used by some bladesmiths (most often with the high carbon steels) can further refine this grain structure. Many of the advantages you see associated with carbon steels (i.e. takes a fine edge, is easy to sharpen, withstands hard impacts, etc.) can be attributed, at least in part, to this grain structure.

Stainless steels, on the other hand, by definition, contain high percentages of chromium in their chemistry. Some of this chromium reacts with the carbon present to form chromium carbides, and, as I think most would agree, there are pluses and minuses associated with the presence of these carbides in a blade steel. For one thing, they are harder than the surrounding steel. Thus, in theory, they can contribute to better wear resistance, while, at the same time, also making the blade more difficult to sharpen.

But I think it's even more important to understand how these carbides can react during the actual steel manufacturing process. As the steel is poured and begins to cool, these carbides have a tendency to seek one another out and clump together, if you will. Obviously the uniformity of the stainless steel's grain structure can suffer as a result. A fair portion of the concerns you hear being raised with respect to stainless steel's propensity for being brittle or chipping out can be traced back to this phenomenon.

To be fair, the quality of the heat treatment plays a huge role in determing just how prevalent any of these potential shortcomings may become, but even at that, the relative simplicity of the heat treat regimen again appears to favor the low alloy carbon steels. This is more of a factor in production blades than it is in the custom knife community (where much greater care can be afforded to the heat treatment of each individual blade).

Finally, it's worth mentioning that companies such as Crucible have overcome many of these perceived grain structure related shortcomings in stainless and high alloy steel through their unique manufacturing processes.
 
Cliff - Impact strength is toughness, in terms of strength of materials. Tensile strength is only one of many strengths, impact strength or toughness is another. Strength testing is generally done with a slow and steadily increasing load (impact testing is of course an exception).
 
Grapevine - usualy, toughness (impact strength) is higher at lower hardness and carbon contents. The reverse is usauly true when it come to hardnenability and tensile strength. Note that cobalt and nickel tend to inrease toughness. As Cliff pointed out, Infi is nirtated, which means it has a tough core and a very hard outter case.
 
Originally posted by frank k
... Infi is nirtated, which means it has a tough core and a very hard outter case.
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INFI contains nitrogen in the alloy composition, where nitrogen is bound up with the elements in the alloy, forming nitrogen compounds in the alloys. I am unsure which of the other elements nitrogen is combining with (Vanadium, Chrome, Iron, Cobalt, Nickel, or Molybdenum).

Cliff alluded to this when he said:

In INFI the Nitrogen is Nitriding the alloys, similar to how Carbon would carbide them in regular steels.
Click to expand...


INFI is not nitrated or nitrided in the traditional sense of a surface deposition or surface reaction with nitrogen or nitrogen compounds, in a gaseous or liquid form, in an oven, etc. These sorts of surface deposition or surface reactive techniques are what create a hard outer surface and don't affect what would typically be left as a softer/tougher inner core (similar to the colorful "case hardening" treatment often seen on handguns and older rifles).

At least that is my impression. I suppose a metallurgist could offer something more definitive, or Jerry Busse probably could.
 
Find me a stainless that comes close to Ed Fowler's 52100, or Wally Hayes' 52100, or that performs like CPM 3V or that can be turned into a traditional blade like a Yoshihara or Howard Clark or even a Wootz, and I'll say there no longer is an advantage in terms of performance or aesthetics.
I liked what KWM posted, as usual, but get a look at those beautiful knives in his avatar. He didn't post no stainless :). Cliff is persuasive, at least to me :). But Ed Fowler's post is poetry. And so are his knives, and the best "carbon" blades.
Maybe that's the biggest reason. Maybe the performance differences aren't that signifcant, the hamon and nie etc are largely ornamental and microstructure and carbides and all that will be moot because in a month there will be a new stainless, or a new plastic, that will outperform everything else anyway. hell, I'll try it, and I may love it.
But until then, my S30V doesn't match the performance of my CPM3V, my talonite and stellite don't do what my O1 can do [and in some respects, visa versa] and as good as 440C, ATS 34, and 440V etc are, I think my carbon blades, especially my forged blades, - and the Busses, gotta admit- do perform better. I know they sing to me a little more . :D
 
A lot depends on your location and usage, I suppose.

I live in a very dry climate, and store most of my knives in leather sheaths *gasp*. Rust just isn't an issue here. Plus, as most of these posts are pointing out, yes, some heroic things are being done with stainless to equal good old carbon steel. Why mess with sucess (for me)? I stick with carbon steel, and maybe by the time my grandkids are ready to buy knives then the crop of stainless will be equal to carbon steel. Until then, I'll keep buying the tried and true.

Again, if I was a scuba diver in Florida, I might have a different opinion.
 
The absolute best knife I've had is the M16 bayonet. It usually takes me six or eight hours to put the first edge on one of these, but I don't have to sharpen it again for a year or two, depending on how hard I abuse it.

Several of us were out one day, dumping brush, and not in a hurry to go get another load. So we decided to throw knives for a while. I was the only one who had anything we could use, and it was the bayonet. It's not balanced for throwing, so they bounced it off a tree for about an hour, into the rocky ground of the Ozarks.

After all that, I picked the knife up, made one pass down my shin with it, and it neatly cleaned all the hair off, no stubble. It was still sharp enough that you could push (not slice) it through a sheet of paper and peel off little thin strips of paper.

I tracked down the manufacturer and called them once. I think it was Camillus, but don't remember for certain. They told me it was 1095 carbon steel, heated in lead to between 1500 and 1600 F, then quenched in oil for 45 to 60 seconds.

I can get it about as sharp as I want it, and it'll hold it, even in heavy use. It just doesn't have the size and mass I like in a brush knife.

I've accidentally struck rock with it while trimming brush, and left a much larger mark in the stone than the edge. I had to hunt to find the nick in the blade that the rock made.
 
Better steels have Less chromium. Since all steels have at least some carbon, or they wouldn't be steels, the commonly called carbon steels could be more accurately called Low Chromium steels. Or high Ferrous Oxide steels. It all depends on your exposure.

Unless of course they have a theoretically impossible carbon content like Crucibles amazing alchemical magic mixes. Then it starts to be a lot tougher to knock the new-fangled stain resistant stuff than it was only a few years ago.

I should mention that what I think is better steel is a highly subjective and multiply-dependent, and normally biased opinion. Everyone is entitled to their own opinion, and around here, there is usually no shortage of different opinions.

Less Chromium is More. And less...

YMMV
 
Why carbon steel? Get yourself an $8 Opinel and see how it does house chores compared to any of our pretty stainless steel knives. Cut up some boxes, insulation, Saran wrap (a real eye-opener for me, because it just stretches if the blade isn't razor-like). Sharpen between jobs. See what gives you the cleanest, easiest cuts.
 
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