Steel Types And Metallurgy 101

Carbon steel has a carbon content ranging from 0.05% to 2.1% by weight. Carbon steel is hard, meaning great edge retention. It also takes an extremely keen edge. Furthermore, carbon steel is very responsive to sharpening stones because it lacks chromium (Unless the knife becomes very dull). Then, because it is a hard material, it takes a lot of effort to reestablish the bevel. Carbon steel is not stainless, and it is very reactive to anything with an acidic pH. So, more care and effort should be taken to keep it from rusting. It is recommended to cultivate a healthy patina, as this will help act as a protectant against rust.

Semi-Stainless Steel is much like high-carbon steel but with a moderate amount of chromium added. It will tarnish more slowly than carbon steel. Since the blade is not stainless, it is still recommended to cultivate the patina to help protect the blade’s surface.

Stainless Steel is achieved by the addition of at least 10.5% Chromium by weight. This science is almost magical. Chromium molecules bond with Oxygen molecules from the air. This forms Chromium Oxide, a clear hard skin that adheres to the steel. Knives made from stainless steel don’t require as much care. Take note that any stainless steel can rust in adverse conditions.

Powdered High Speed Tool Steel, sometimes called Particle Steel, or referred to as Powdered Metallurgy, is a specialty steel manufacturing process. Although manufacturers have their own proprietary methods, essentially the process involves superheating steel to liquefy it. It is then ejected through a fine nozzle into liquid nitrogen. The quick cooling atomizes the steel resulting in a uniform powder. The powdered steel then goes through a process of putting immense pressure from all sides, known as isostatic pressure, Hot Isostatic Pressure (HIP). Finally, the powdered steel is brought up to forging temperatures and formed into billets of carbon or stainless steels that can then be forged. This manufacturing process provides benefits in most areas. Such as increased wear resistance, increased toughness (better for chipping), better grindability & enhanced finishes. Powdered metallurgy grants bladesmiths the ability to heat treat knives to a harder rating on the HRC Rockwell Scale. Another benefit of Powdered Steel is that the elements are more evenly distributed in the alloy.

• It has the highest carbon content, offering the longest edge retention, but it is most brittle.
• 63 HRC
• C 1.25-1.35% | Mn 0.20-0.30% | P 0.03% | S 0.004% | Si 0.10-0.20%

• It is very common and less prone to chipping. It’s a popular choice due to a very good edge retention and easy sharpenability.
• 61-62 HRC
• C 1-1.15% | Mn 0.20-0.30% | P 0.03% | S 0.004% | Si 0.10-0.20%

• Is the most chip resistant (tough), but has shorter edge retention.
• 60 HRC
• C 0.80-0.90% | Mn 0.20-0.30% | P 0.03% | S 0.004% | Si 0.10-0.20%

• Great edge retention with a smooth cutting feel.
• 61-64 HRC
• C 1.25-1.35% | Cr 0.20-.50% | Mn 0.20-0.30% | P 0.03% | S 0.004% | Si 0.10-0.20%

• Is very common for Japanese double-bevel knives.
• 61-62 HRC
• C 1.05-1.15% | Cr 0.20-.50% | Mn 0.20-0.30% | P 0.03% | S 0.004% | Si 0.10-0.20% | W 1.00-1.58%

• Not only does Blue Super have added Chromium and Tungsten, it also has Vanadium and Molybdenum which promote wear resistance, toughness, & corrosion resistance. Blue Steel has fantastic edge retention.
• 61-65 HRC
• C 1.40-1.50% | Cr 0.30-.50% | Mn 0.20-0.30% | Mo 0.30-0.52% | P 0.03% | S 0.004% | Si 0.10-0.20% | W 2.00-2.50% | V 0.30-0.50%

• Has a lower Carbon content & is usually considered a lower quality steel. Generally you will not find cutlery made from AUS-6.
• 57-58 HRC
• C 0.55-0.65% | Cr 13.14.5% | Mn 1.00% | V 0.10-0.25% | Ni 0.50% | Si 1.00%

• Has a slight increase of Carbon along with increased amounts of Vanadium, making great wear resistance & edge retention.
• 57-59 HRC
• C 0.70-0.75% | Cr 13.14.5% | Mn 0.50% | V 0.10-0.26% | Ni 0.50% | Mo 0.10-0.30% | Si 1.00%

• Has the highest amount of Carbon in the series, giving it higher wear resistance & edge retention than AUS-8
• 58-61 HRC
• C 0.95-1.05% | Cr 13.14.5% | Mn 0.50% | V .10-0.27% | Ni 0.50% | Mo .10-.31% | Si 1.00

VG-10, sometimes called V-Kin (Kin in Japanese is gold), was created by Takefu Special Steel Co. Ltd in Takefu, Fukui prefecture in Japan. Considered one of the highest levels of stainless steels. It has a high carbon content, making the steel a very hard Rockwell rating of 60-62. The special combination of its elements gave rise to the name VG-10. The G stands for ‘Gold’ in reference to the ‘Gold Standard’ that this stainless steel is considered to be. It is extremely popular among chefs and food enthusiasts because of its ability to hold an edge, withstand rust and has a high level of durability. Not to be confused with VG-1, which is a capable stainless steel in and of itself.

C .96-1.05% | Cr 14.5-15.5% | V 0.10-.30% | Co 1.3-1.8% | Mo 0.9-1.2% | Co 1.30-1.50% | Mn 0.50%

Sometimes called V-Gold, it is the predecessor to VG-10. Also produced by Takefu Special Steel Co. Ltd in Takefu, Fukui prefecture in Japan. This high carbon stainless steel has elements of chromium, and molybdenum, which during forging, produce hard double carbide bonds. This creates abrasion and corrosion resistance. After heat treating, VG-1 ranges from 58-61 on the Rockwell Scale. VG-1 does not have vanadium, making it less wear resistant but does have nickel, which makes it tougher. It holds its edge and is easy to sharpen.

C .96-1.05% | Cr 13-15% | V 0.25-.35% | Co 1.3-1.8% | Mo 0.2-.40% | Ni 0.25%

Sometimes referred to as Gin-3, Ginsan or Silver-3. Produced by the Hitachi factory in Yasugi City, Shimane Prefecture, Japan. With 13.00 ~ 14.5% Chromium, it was created to produce stainless knives that function like high-carbon steel. It has a high carbon content of 0.92 ~ 1.10%, producing a steel with excellent sharpenability. Usually it ranks at 59-62 on the Rockwell scale and has a cutting feel and ease of sharpening similar to Shirogami carbon steel.

C .95-1.10% | Cr 13-14.50% | Mn 0.60-1.00% | Mo 1.0-2.0% | P 0.03% | Si 0.35%

Sweden is known to have extremely high-quality iron ore deposits. These very pure deposits also contain small percentages of other metal ores, making it a natural alloy. The Swedish steel industry has a long history spanning from as far back as the middle ages. Swedish steel is popular with Japanese blade-smiths due to its predictable nature and fine carbide microstructure. After heat treatment, Swedish steel exhibits high toughness, corrosion resistance, great edge retention, 60-66 HRC, and extreme sharpness.

C 0.95% | Cr 13.5% | Mn 0.70% | P 0.03% | S 0.01% | Si 0.40%

Is a common stainless steel for German cutlery. Often referred to as X50CRMOV15, it is widely regarded for its stainless properties, toughness, and great mechanical attributes. Produced by ThyssenKrupp. It’s comparable to AUS Steel, but has more Chromium, 15%, increasing its stain resistance. Added Molybdenum increases hardenability. Vanadium promotes a fine grain structure. Manganese gives this alloy better tensile strength.

C 0.55% | Cr 15% | Mn 1.00% | Mo 0.80% | V 0.20% | Si 0.50%

Produced by Buderus AG, it is 1.4116 steel with the addition of Nitrogen. It offers a fine microstructure of its components. Meaning during the steel processing, the elements are more homogeneous. This allows for higher hardness levels for heat treatment, usually 62 on the Rockwell scale.

C 0.55% | Cr 15% | Mn 1.00% | Mo 0.80% | V 0.20% | Si 0.50% | N 0.21%

A metal made by combining any two or more metallic elements.

Annealing is a thermal treatment process. After a knife is heated during the forging process then shaped and cooled, the steel is evenly brought back to a glowing temperature. This is done before the knife is quenched. This process will evenly re-crystallize the grain structure. This improves toughness and strength.

A billet is a solid length of steel, either square or round. Sections of a billets is then forged into a knife.

The steel's ability to resist deterioration and reactions from anything with an acidic pH.

Durability is how well a blade holds up to forces of bending, twisting, and cutting very hard food products. Hard translates to brittle, so softer steels are more durable.

Determined by the hardness of the steel, edge retention is the steel's ability to hold its sharpness. Hard steels hold for longer, while softer steels lose their sharpness sooner.

Forge Welding is a process that joins separate pieces of steel similar or dissimilar by heating them to a high temperature in a forge, then using enough pressure & force which welds them together. This may be done through hand, hammering, using power, hammers, or presses.

In short, steel is made up of grains. Smaller grains are desired, which means better wear resistance and greater toughness and strength.

The ability to be hardened through heat-treating processes.

A measure of the steel to resist permanent damage. Hardness is measured with the HRC Rockwell Scale.

The HR Rockwell Scales are a measure of hardness for metallic and polymer materials. All in all there are several Rockwell Scales, noted by a letter of the alphabet. For example, HRA, HRB, HRC, etc., where the last letter is the respective Rockwell Scale. The higher the number rating, the harder the material. The hardness of a material does correlate with its strength, wear resistance, and other properties.

When deciding on steel types, bladesmith, and in turn cooks & chefs consider properties such as edge retention, sharpenability, ease of maintenance, & pricing. These are all considerations which are inherently linked to the hardness of steel.

An ingot is metal that is cast from molten state into smaller usable sizes for remelting or reworking.

The feasibility of the steel to be manufactured.

Mild steel has a very low carbon content and is not hardenable. This will generally be found in Sanmai & Warikomi, Japanese blade constructions. Soft steel is clad (forge-welded) on the outside of hard steel. This creates shock absorption, and structural integrity.

A method used to harden steel by rapidly cooling it in water, oil, or air.

Sharpness is how well a blade's ability will cut through food products. Finer grain structure, harder steels, and carbon steels make for a blade that can take an extremely keen edge.

Strength is indirect reference to a metal's resistance against deformation from stress.

Reheating quench-hardened steel, then cooling again.

The blade's ability to be able to resist chipping and absorb shock before fracturing.

How well the steel will resist abrasive wear when slicing, cutting, and enduring impact. This translates to the strength of the steel's matrix, holding a finely sharpened edge.