Which steel to choose for your knives?

There are several types of steel, eachwith different qualities depending on the percentages used of the components. There are so-called " carbon " steels, mainly composed of Iron and Carbon (0.6 to 1%), andso-called " stainless " steels, combining Carbon (0.2 to 1%), Chromium (12 to 17%), Molybdenum (0 to 1%) and Vanadium (0 to 2%). Each of these components has its own specificity, guaranteeing high quality. Carbon, for example, ensures hardness, molybdenum and vanadium anti-corrosion, and chromium rust-proofing. The choice of steel is always a juggling act between corrosion resistance and mechanical strength.

So you need to pay close attention to the presence of these components when you buy your knives! Because the fewer the components, the lower the price and the lower the quality!

Carbon steel:

Steel is made of pure iron in the form of crystals, with carbon grains dispersed between them.

There are three types of carbon steel: mild steels, medium-carbon steels and high-carbon steels.

The carbon content of the steel influences the strength of the blade. In terms of performance, carbon steel is thinner and less hard than stainless steel. The sharpness of the blade is therefore greater than that of a stainless steel blade. What's more, sharpening is easier thanks to its fine structure.

The higher the carbon content of a steel, the harder it will become during heat treatment. However, the harder the blade, the more brittle it will be. Although it is sharper, care must be taken not to damage it. Also, a carbon steel blade is rather sensitive to corrosion and is not recommended for use in damp environments.

Stainless steel :

Iron oxidizes significantly in the presence of air and humidity. However, at the beginning of the twentieth century, metallurgists realized that by adding large quantities of chromium, steel could resist corrosion. Steel becomes stainless from a concentration of 16% Cr.

Mixing carbon steel with metals such as chromium, molybdenum and vanadium offers greater resistance to corrosion.

Stainless steel blades are certainly resistant to corrosion, but they are less sharp than a steel blade containing a lower concentration of chromium. The higher the chromium carbon content, the greater the formation of chromium carbide, which is detrimental to the formation of a fine, even edge.

Stainless steel also requires less maintenance than carbon steel.

A few details on working with steel:

Hammered steel knives have a very special design. As well as being aesthetically pleasing, they feature a series of dimples for perfect cutting: your food won't stick to your blade!

Damascus steel knives are particularly sharp. In fact, these knives boast unrivalled steel quality, thanks to a blend of hard and soft steel layers that give the blade a certain hardness and flexibility.

With these few indications, you can now determine the type of steel that will suit your knives. Namely, a stainless steel blade for resistance against corrosion and light maintenance, or a blade with a high carbon content for optimum cutting quality but greater sensitivity to corrosion. But how doyou choose between the different types of steel on the market? The KnifeLeader team has looked into the matter, and here are some useful answers...

The different types of steel :

European steel

This steel is made up of a series of numbers and letters with no head or tail. Here are its main characteristics:

X: corresponds to stainless steel, the basis of all steel compositions.

Cr: these letters correspond to chromium, which increases the stainless capacity of a blade (thus reinforcing the X).

Mo: for Molybdenum, which promotes strength and corrosion resistance.

V: for Vanadium, which also increases blade strength and slows wear. It is often combined with molybdenum.

Thus, the basic composition of a stainless steel is spelled as follows: X50CrMoV15. Here we find the letters explained above accompanied by 2 numbers:

50 corresponds to the carbon content, i.e. 0.5%.

15 stands for Chromium content, equivalent to 15%.

This steel is widely used in cutlery. You'll find it in German-made Wüsthof knives, for example. Its cutting properties and ease of sharpening are very good. It is ideal for both professional and private users who love good recipes.

This steel has a hardness generally ranging from 55 to 58 HRC on the Rockwell scale.

However, it is important to note that even if 2 knives from different brands have the same steel composition (e.g. X50CrMoV15), their quality may differ. Cutlery manufacturers use different sources of steel, and even if the composition is similar, the steel used may differ according to its origin. The steels themselves will be the same on paper, but they will influence the overall quality of the blade created.

Of course, the workmanship of the various brands will also be a factor in the final quality of a blade, for the same composition. It goes without saying that the expertise of some cutleries will not be the same as that of others.

Aogami steel

Aogami steel (or Blue Paper Steel) is a top-of-the-range Japanese steel. It owes its nickname of blue steel to the color of the paper in which it is packaged. It is one of the carbon steels used mainly by Japanese master blacksmiths.

Aogami steel is available in three ranges according to carbon content:

Aogami 1: contains 1.2% and 1.4% carbon. It also contains 1.5% tungsten and 0.4% chromium. The hardness of this steel is 63 HRC on the Rockwell scale.

Aogami 2: similar to Aogami 1, but with a lower carbon content. It reaches 1.2%. Blade hardness is therefore slightly lower, at 62 HRC.

Aogami Super: this has a higher carbon content than its two brothers, at 1.5%. Its tungsten content varies between 2 and 2.5%. Its hardness is very high, reaching 65 HRC on the Rockwell scale.

AUS8 steel

AUS8 is a steel of Japanese origin, specially created to combine hardness, strength and efficiency (how cool is that?). It is stainless, which makes it particularly appreciated in cutlery and, of course, by culinary professionals. It contains 0.8% carbon, 14.5% chromium, 0.25% vanadium and, of course, molybdenum.

If we want to highlight its many qualities, we can mention its perfect balance between robustness, performance and longevity, its incredible rust-resistance, its increased resistance to knocks and its flexibility. What's more, you can easily achieve optimum sharpness with this type of steel!

AUS10 steel

Here's another steel in the AUS family: AUS10! Like its little brother AUS8, it is of Japanese origin and is stainless! Its hardness is higher (reaching 60 HRC) thanks to its higher carbon content: between 0.9% and 1.1%. It also contains chromium, manganese, molybdenum, nickel and vanadium (everything you need, in fact).

Thanks to its high carbon content, the cutting edge is long-lasting (you won't need to sharpen it very often). What's more, it's aesthetically pleasing, as AUS10 steel is often covered with a beautiful damask finish.

Cromova steel

This steel is used exclusively by Global for the design of its Japanese knives. It has the particularity of having a carbon content of 0.8% (slightly higher than standard steel), and contains a little chromium, molybdenum and vanadium. Its structure is quite fine, and knives made from it can be sharpened with ease.

Hardness is between 56 and 58 HRC.

SG2 / SGPS steel

SG2 steel is a very high-grade stainless steel used mainly in the manufacture of Damascus steel (multi-layered, as explained below). It is considered one of the best steels in the world by many blacksmiths. This one's a bit special: it's made from sintered steel powder. Sintering is a highly technical process which involves heating the powder to a very high temperature to weld the micro-particles together.

SG2 steel is sometimes called SPG2 or SGPS (but don't worry, it's the same steel). It contains carbon, chromium, molybdenum, vanadium and a little manganese. It's the perfect balance between edge retention, efficiency and strength! In fact, the hardness of SG2 steel blades reaches 63 HRC!

VG10 steel

This is a stainless steel, but with a high carbon content that makes it harder (around 1%, or 0.5% more than standard steel). As a result, the cutting edge will last longer, but will also be a little harder to sharpen when you need to take care of it - that's the disadvantage of VG10. To wash them, you'll need to do so by hand, and not leave them in the sink for too long, even if they are stainless.

Most of the time, this steel is surrounded by other layers of steel to protect it. This may be 1 layer, or several layers (32, 66...), leading to damascus steel. These various layers also protect it from possible breakage, as this very hard core will be surrounded by a "flexibility layer".

There is a small variant of this steel, called VGMAX, which has a small additional cobalt content.

Damascus steel

As mentioned above, this is a multi-layered steel much appreciated in the kitchen, particularly by the Japanese. In fact, it consists of a steel core (like VG10, for example) surrounded by several superimposed layers of hard and soft steels.

In addition to producing a highly original blade with unique veining, this process gives you greater "flexibility" and resistance to corosion.

Other steels

There are several other steels, of course, but you won't come across them very often. For example, SKD11 (which is a stainless steel powder) and many others... But let's not get bogged down in a complex explanation.

Things to remember :

The composition and various alloys of the steel will determine several key factors to be taken into account when purchasing a knife.

Hardness, which, as we've seen, depends to a large extent on carbon content. This will also influence the quality of the cutting edge. However, it's important to understand that a very hard knife will also be more fragile because it's less flexible (it's a bit illogical when you put it like that, but it makes sense, trust us!).

The degree of oxidizability, which depends on the chromium, and which will be a vital component if you're working with moist products such as fish.

Shock resistance, where you'll need to choose a steel that contains carbon but has been properly heat-treated to prevent it from shattering at the slightest blow.

Ease of sharpening, which will be higher if a knife is less hard, but also less long-lasting.

All these characteristics should be taken into account at the time of purchase!

Here's a small table summarizing all this information:

Main characteristics of different steels :

And so that you don't have to look all over the place for the characteristics of the steels, we've come up with a table that's just too cool for you. In it, you'll find scores out of 10 for the main characteristics of the different steels (and we've added the carbon content, because it's always good to remember it):

A quick reminder of the terms before getting started (just so we're all clear on this):

Carbon rate: a very useful indicator of a blade's average hardness. The higher the carbon content, the stiffer the steel, and therefore the longer its cutting edge and razor-sharp finish.

Razor edge: the higher the index, the easier it is to penetrate food without breaking the fibers.

Edge durability: the higher the index, the longer the edge.

Easy to sharpen: an alloy can be more or less easy to maintain, depending on its components. Here, we indicate how easy it is to maintain the blade's cutting edge. The higher the index, the better.

Shock resistance: Here, the softer the steel, the more resistant it is to shocks, as it absorbs them and deforms slightly. The harder the steel, the more teeth it will make.

Corrosion resistance: depending on its chromium content, a steel is considered oxidizable or stainless. Here, the higher the index, the more resistant the steel will be to corrosion, although traces may appear after prolonged immersion in water or in a dishwasher (that's why there's no such thing as a 10!).

Now you're ready to choose the steel best suited to your needs!