Difference between high carbon and carbon steel knives?

[josemartinlopez]

This is probably a stupid question, but why would someone buy a carbon steel knife over a high carbon knife or a good stainless steel?

My understanding is that the carbon knives are harder and can hold a better edge than stainless steel, but are reactive and you need to pay attention to them. There is not always a price difference. However, the high carbon knives are harder but much more reactive.

Thus, one sees why many people, especially non-professional cooks, would prefer to not deal with rust and just use stainless steel. There are some very good stainless steel knives (which do you think is the best workhorse stainless steel by the way?). However, if you are willing to take the extra care to properly wash and oil a reactive knife, then why do people not just buy high carbon knives? For example, there is not necessarily a price difference between a good white steel #2 knife and a carbon knife right? Is it simply because the high carbon knives are that much more reactive and you need to be much more careful with them?

Hope the question makes sense.

 

[tostadas]

I'm not sure what you mean by "high carbon". The better differentiation would be "stainless" vs "non-stainless". When people refer to "carbon" such as White #2, it generally means non-stainless.

 

[josemartinlopez]

I'm not sure what you mean by "high carbon".

Non-stainless steels below the grades of the top white/blue steel? I guess the question is, if price is not very different, why would you buy a lower "grade" of non stainless steel?

 

[Benuser]

Price, availability. In my understanding it's far from easy to get e.g. Shirogami outside of Japan. Very simple carbon steels as C60, C75, 1095, are unexpensive and plenty available, and can make fantastic blades.

 

[josemartinlopez]

So is it right to say that if you can get a knife from shirogami or aogami, etc., you would probably not have a need for a knife with the same specs in another non-stainless steel? In other words, there is generally no reason to buy a knife in another non-stainless steel other than shirogami or aogami, etc., unless the knife is not made in the highest grade steels or there is a particular reason?

 

[Benuser]

No, wouldn't say so. Excellent knives are available in other carbon steels as well.

 

[deskjockey]

The vast majority of people are served very well for everyday kitchen tasks with good stainless steels. Knife KNUTTS obsess over steels but, the reality is most of the time people are splitting hairs over subtle differences most normal users will never see or feel.

A bigger difference is edge geometry and knife construction.

Any good stainless steel knife made by a bladesmith who understands how to make a good knife will make you a great knife at a modest and moderate price point. With the cheaper production options, generally, the handle and final fit and polish suffers a little which might leave a few less rounded surfaces (think spine or heel) or handles with minor gaps or warps (really only noticeable if you look closely).

A ~$150 knife made from VG-10 for example is a solid choice for me. Do I want the Damascus look or some other cosmetic treatment? Do I want a Japanese or Western handle? How about a Saya? Then there are hammered or dimpled blades for good food release and other cosmetic blade treatments.

I do have a Gyuto LAZER with a carbon center but, I generally don't use it as much for normal everyday use because of maintenance and special handling concerns. As crazy as it sounds, sometimes using a knife that sharp is not the safest option for me. If I am distracted or the house is busy, it is simply too easy to get a wicked bad cut on my hand or some other body part, and properly drying and storing may not be conducive to good social interaction.

 

[Tim Rowland]

The Hitachi steels are nice and are highly praised/used by Japanese smiths because they are consistent and are locally available.
There are many many many other Carbon steels that perform equal to or better that are much more cost effective for smiths/knife makers outside of Japan.

examples of such would be:

52100, 80crv2, W1 tool steel, W2 tool steel, 26c3, CruforgeV, A2, and countless others available in Europe that I cant think of at the moment.

 

[Midsummer]

Heat treatment should be mentioned here. OP seems to be focussed on Aogami and Shirogami and is now aware that there are multiple other high carbon steels available. He should know that there are quite a few stainless steels available as well eg; Hap 40, ginsan, Vg 10, Vg max, Aus 8, Skd,...

Many will say that you should focus less on the steel and more on the maker. There are so many possible nuances to which a maker can contribute and one on the list is heat treatment. I have knives of white #2 that have vastly different feels on the stones, sharpen up differently, have different HRC's and have different edge retentions. All of these variable can be affected to varying degrees with the heat treatment of the knife. All of the steels can have physical characteristics to change due to heat treat.

 

[JayS20]

Not all people like patina or want to worry for rust. I don't use my Carbon knives at evening service rush. Personally also like stainless and semistainless steels, depends highly on the maker. Stainless are harder to sharpen but some also have quite a good edge retention.

 

[RolfK]

True! Maybe this can help in your thougts. I wouldn't be that focused on the type of steel. An important choice is if you want stainless or not. After that, the maker and his forging, heat treatment, profile, grind, sharpening are more important for the performance of the knife.

And like others said, the steel choice of the maker is often related to what's locally available. So yes, a Japanese maker will often rely on shirogami/aogami from Hitachi. But EU makers will source other steels from German, Swedish factories. And so on....
These steels also make excellent knives and a lot of custom makers use them.

The thoughts about the difference of (high) carbon and stainless knives can also be tricky. Also stainless steels can have quite some carbon in it. They can get stainless by the high amounts of chromium, not because they don't have carbon. Please see for example the stainless AEBL steel, this website can be helpfull for you to check steel compositions: zknives

Thus, one sees why many people, especially non-professional cooks, would prefer to not deal with rust and just use stainless steel.

Not always true. Most non-professional knife addicts around here have a lot of carbon knives. And a pro cook in a busy kitchen may like stainless knives, because it's easier to care. They don't want patina/rust in their pro kitchen, also because of legal food regulations. In my home kitchen only the wife is yelling at me - not the government.

 

[LostHighway]

This is probably a stupid question, but why would someone buy a carbon steel knife over a high carbon knife or a good stainless steel?

My understanding is that the carbon knives are harder and can hold a better edge than stainless steel, but are reactive and you need to pay attention to them. There is not always a price difference. However, the high carbon knives are harder but much more reactive.

Thus, one sees why many people, especially non-professional cooks, would prefer to not deal with rust and just use stainless steel. There are some very good stainless steel knives (which do you think is the best workhorse stainless steel by the way?). However, if you are willing to take the extra care to properly wash and oil a reactive knife, then why do people not just buy high carbon knives? For example, there is not necessarily a price difference between a good white steel #2 knife and a carbon knife right? Is it simply because the high carbon knives are that much more reactive and you need to be much more careful with them?

Hope the question makes sense.

This isn't a stupid question but IMO you are attempting to oversimplify the question of steel alloy selection. I strongly suggest you start reading Knife Steel Nerds which is a great source of information.
All steels that I'm aware of are (edit for clarification: effectively) carbon steels. It is the presence of carbon in the alloy that changes the metal from iron into steel (over simplification noted) but the amount of carbon present is typically small (<2% in most cases).
Alloy selection attempts to find the appropriate balance among cost (and availability), edge retention, corrosion resistance, and toughness (resistance to fracture and micro-fracture). However, the final performance of the knife is also influenced by heat treatment, grind, and profile.
There is no one perfect alloy. A user working on a fishing boat in the Eastern Mediterranean is likely to be far more concerned about corrosion resistance than a home cook in Las Vegas, Nevada. A cook in restaurant doing 200 covers a night might put a premium on edge retention. A sushi chef might select for ease of sharpening to a very fine edge.
As knife maker, @Tim Rowland, noted there are lots of other viable steels for kitchen knives beyond the Shirogami and Aogami alloys.

 

[josemartinlopez]

attempting to oversimplify the question of steel alloy selection

I'll read Knife Steel Nerds... you're right, I end up oversimplifying as Google wasn't providing more in-depth information and made this seem one dimensional.

 

[Blerghle]

It can be very confusing reading knife descriptions. A lot of stainless steel knives are marketed as "high carbon stainless", which is just trying to get across a level of quality. You can look down an aisle in Wal-Mart and see basically any knife described as "high carbon", which doesn't mean much.

In the idiom of the forums, there are basically 3 kinds of steel:

Carbon (fully reactive, on average the easiest to sharpen with the least edge retention)
Semi-stainless (Reactive enough that you wouldn't call it stainless, an in-between option)
Stainless (Very little reactivity, on average hardest to get a great edge, typically you're paying a bit more to get one with good edge retention and sharpenability)

For me, I prefer carbon steel for the most part now that I am just cooking at home. No kids, easy enough to care for them, prefer the ease of sharpening and I like the look of patina. When I was in restaurants, I often preferred stainless or at least stainless cladding because of the hectic environment and time pressure not allowing for prompt cleaning/drying.

 

[jacko9]

The quantity of knife making material is very large but at a base level;

1) Iron and Carbon = Steel

2) Steel and Chromium = Stainless Steel

After that adding quantities of elements will give you an almost infinite variety of useful knife material.

 

[Nemo]

The terminolgy is a bit confusing because it's commonly used impreciely (including by me).

Steel is by definition an alloy of iron and carbon (up to 2% C, anything above that is technically a cast iron). So really, all steel is carbon steel.

"High carbon steel" is simply any steel with a C content of over 0.5%. This includes some pretty soft steels (such as most decent quality Western stainless) but also most of the steels that we like in good kitchen knives (many of which ahave around 1% C).

"Carbon steel" is usually used to denote a non-stainless steel (Cr content below 1-2%).

"Stainless steel" has varying defiitions. Most have Cr content 14% or more but what's really important is the free Cr which is affected by the C content as well as by other alloying elememts. Really high carbon steels like ZDP 189 (3% C, 21% Cr, so technically it's a cast iron) are not stainless even though they have masses of Cr because most of the Cr is tied up in carbides and is not free in the iron matrix.

Semistainless is in between. Most often 4-6% Cr.

The hardness of a steel is determined by several things- carbon content, alloying elements and (most importantly) heat treatment. Hardness is important for being able to hold an acute edge angle without the edge rolling. It probably contibutes to edge retention but wear resitance (often imaparted by hard carbides formed by alloying elements) is probably more important (assuming that the knife is hard enough to prevent the edge from rolling).

Carbides are a double edged sword. They probably contribute to hardness in many steels but they limit the acuteness to which an edge can be sharpened because below a certain edge angle, the carbides get "pulled out " during sharpening and the edge collapses. The higher the carbide content, the less acute an angle can be maintained.

So there are lots tradeoffs in steel selection. If you want ultimate sharpness (acute edge angle), you need a hard steel but one without too many carbides. Simple high carbon steels like Shirogami (I'd probably also include aogami but not AS in this group), 1095 and 52100 do well here. The downside is that for these steels, most of the carbides are fairly soft iron carbides, so abrasion resistance is limited.

If you want ultimate edge retention, you need lots of hard carbides. Cr carbides can contribute but are not as hard as W and V carbides. The problem is that you can't maintain a very acute edge with these steels. A microbevel may help here. These steels are (a bit) more difficult to sharpen but can be a real pain to fully deburr.

In the end, the knifemaker needs to select a steel (and heat treat it appropriately) that suits the purpose of the knife. Then the sharpener needs to sharpen within the constraints of that steel.

 

[josemartinlopez]

If you want ultimate sharpness (acute edge angle), you need a hard steel but one without too many carbides. Simple high carbon steels like Shirogami (I'd probably also include aogami but not AS in this group), 1095 and 52100 do well here. The downside is that for these steels, most of the carbides are fairly soft iron carbides, so abrasion resistance is limited.

Thanks, you put it very well! I'm not a pro so think I would go for sharpness over edge retention, and don't mind polishing in between.

 

[Tim Rowland]

In retrospect I should have given a bit more information regarding the carbon vs. stainless part of your question.
Some have already given some information but here is what I can add with my knowledge. (Hopefully someone like @Larrin) may jump in and give a better explination.

All steels that can be hardened to a high enough degree to be used as a cutting tool have a decent amount of the element carbon in them. Lets say that amount is (usually) over .5% and up to say 2% on ultra high end PM steels like M4.
Over 2% carbon is rarely seen in steels used for anything with an edge (and only high end PM steels this high) but can be found for steels used in other industrial applications.

With the addition of the element Chromium (typically) found above 13% would be considered and marketed as Stainless Steel.

The wording of "carbon steel" or "high carbon steel" are a bit misleading as all steels have carbon in them and there are steels that are stainless like M390 that have a high carbon content.

Using AEB-L (a well known semi-stainless) as an example vs. White, Blue, 26c3, and M390 as a super high end Stainless

I hope this helps explain it a little bit better with the element table.

 

[josemartinlopez]

I hope this helps explain it a little bit better with the element table.

Certainly does! What are the other non-stainless steels that are popular other than the super hard ones talked about a lot here, and what other properties do they emphasize instead of sharpness?

 

[esoo]

Why use different steels? Simple - everything is a trade-off

hardness vs toughness vs sharpenability vs edge retention vs stain-resistance vs ....

For example - hardness vs toughness - your White Steel knife (hard) vs your typical German knife (tough). Your White steel will chip, your German knife will deform. So i'd rather use a German steel to break bones than a White one.

Or let's take Blue vs White - Blue has better edge retention vs White has easier sharpenability (as far as I've been able to read). If you love that fresh off the stones wicked sharp edge feel, you'll choose a White Steel over Blue. But the trade-off is that you'll have to freshen the white blade up more often.

And it also comes down to the treatment of the steel. I've got a Tojiro shirogami santoku. Pretty sure I can find a 1095 blade that could out-perform it at every turn.

It all really comes down to personal preferences as to which criteria a user wants - initial sharpness, edge retention, ease of sharpening, stain-resistance, acuteness of the edge, and on and on.

 

[deskjockey]

Heat treat can significantly impact knife traits. I have a 1095 carbon steel knife that is relatively rust-resistant and holds an excellent edge. I also have an ATS-34 knife that rusts relatively easily and has a brittle edge. Heat treat and temper make a huge difference that can make a 'super steel' underperform a simple rudimentary steel.

The other thing to consider, a knife with large carbides will be a very 'toothy' knife to use. A 'toothy' edge for me is awesome for loose material like manilla rope where the carbides really bite into and grab individual fibers during the cut.

 

[tostadas]

Non-stainless steels below the grades of the top white/blue steel? I guess the question is, if price is not very different, why would you buy a lower "grade" of non stainless steel?

Even if you have two knives with the same base steel type, depending on heat treat, the steels could have very different properties. It's not as simple as saying ALL white steel knives are better in a certain category than ALL blue steel knives. As someone mentioned earlier, if you want to get into the nitty gritty, you can research about the science behind steel treatment process. As an engineer myself, I find it very interesting, and you can spend months and even years learning about all of this. Youtube has some videos to get you started that summarize it pretty well.

 

[Nemo]

Also keep in mind that the cost of steel is only a small potrion of the cost of a knife, even for the so-called "super steels". Labour, skill and consumables (abrasives) make up the majority of the cost in any decent knife.