About the Different Types of Steel

When it comes to kitchen knives, steel is generally categorized into two main types: stainless and carbon (non-stainless). Traditionally in Japan, steel was often color-coded to make identification easier, as most steel types look similar. This led to names such as White Steel (Shirogami), which is still considered the purest and most prestigious knife steel in Japan today. Other commonly used steel types include Yellow Steel and Blue Steel.
Generally speaking, steel with a chromium content of more than 13% is classified as stainless. However, with advancements in metallurgy, many modern steels fall somewhere between fully stainless and carbon. Below is an overview of some of the most commonly used steels in Japanese knives, along with a few that stand out.

High-Carbon Steels (Prone to Rusting)

White Steel (Shirogami)
Steelmaker: Hitachi Metals
White Steel is regarded as the purest and most refined knife steel in Japan. It comes in three classifications—White #1, White #2, and White #3—each with different carbon content levels. White #1 has the highest carbon content (1.25-1.35%), allowing for a harder, sharper edge but requiring more maintenance.

Blue Steel (Aogami)
Steelmaker: Hitachi Metals
Blue Steel is essentially White Steel with added chromium and tungsten. The chromium provides slightly better rust resistance (though it is still not stainless), while the tungsten increases toughness. Like White Steel, it is available in three grades: Blue #2, Blue #1, and Blue Super (with the highest carbon content at 1.4-1.5%).

Yellow Steel (Kigami)
Steelmaker: Hitachi Metals
Yellow Steel is essentially unrefined White Steel with more impurities, making it slightly softer and less capable of holding an ultra-fine edge. However, it is also more affordable, making it a popular choice for budget-conscious buyers. Carbon content ranges from 1.05-1.15%.

Stainless and Semi-Stainless Steels

Note: While no steel is 100% stainless, the following types are much more resistant to rust compared to carbon steels.

VG10
Steelmaker: Takefu Special Steel
VG10 is one of the most widely used stainless steels in Japanese knife-making and serves as a benchmark for comparison. Many manufacturers in Seki, Gifu Prefecture, rely on VG10 due to its excellent edge retention and ease of maintenance. It is also commonly used in folding knives. It contains approximately 1% carbon and offers a great balance of performance and durability.

Gin3 (Silver 3)
Steelmaker: Hitachi Metals
Similar in composition to VG10, Gin3 contains 0.95-1.10% carbon and 13-14% chromium, making it a true stainless steel. However, it is more commonly used by smaller, artisan knifemakers rather than in mass production.

AUS10
Steelmaker: Aichi Steel
AUS10 is widely used in both Japan and the USA. With a carbon content of 0.95-1.10% and chromium levels between 13-14.5%, it provides a great mix of hardness and corrosion resistance. It is often compared to VG10 and Gin3 as part of “the big three” standard stainless steels in Japanese knives.

AUS8
Steelmaker: Aichi Steel
A softer version of AUS10, AUS8 contains approximately 0.8% carbon and is frequently used in more mass-produced knives. It is a great option for users who prioritize durability over ultimate sharpness, as it resists chipping while still maintaining a reasonable edge.

ZDP189
Steelmaker: Hitachi Metals
A relatively new, high-performance steel, ZDP189 boasts an impressive 3% carbon content, far exceeding most other steels. Despite this, it remains stainless due to its 20% chromium content. While it offers exceptional edge retention, it is notoriously difficult to forge and sharpen, making it more common in machine-produced knives. Home users should invest in high-quality sharpening stones to maintain a knife made from ZDP189.

Conclusion Understanding the different types of steel used in Japanese knives can help you choose the best knife for your needs. Whether you prefer the ultimate sharpness of high-carbon White Steel or the convenience of stainless options like VG10, each steel type has its own strengths and characteristics. Choosing the right steel can make a significant difference in your knife’s performance, longevity, and ease of maintenance.