Blue Steel #1 - High Carbon Steel

Blue Steel is regarded by many as one of the pinnacles of edge retention and hardness in Japanese kitchen knives. You may see them being used in high end restaurants, and their cutting power is something we believe everyone should experience at least once in their lives if they can. This blog will go into detail as to how Blue Steel #1 might be a steel for your next knife worth considering!

Blue Steel #1 (Aogami 1) - Outstanding Edge Retention

Blue Steel (also called Aogami) is a material created by adding chromium and tungsten to White Steel, which enhances the steel's resistance to wear and tear damage. Among the Blue Steels available, Blue Steel #1 is most well known for its high carbon content and sharp cutting edge.


High potential, but not beginner friendly

It’s difficult to recommend Blue Steel #1 to first-time carbon steel knife buyers, especially if they plan on maintaining the knife themselves.

Due to its high hardness levels, a forged Blue Steel #1 kitchen knife is more resilient against wear and tear as stated earlier. However, this also includes reslience against sharpening the blade itself as sharpening involves shaving the blade down. Due to this abrasive resistance, the steel can potentially slip on whetstones during sharpening. In other words, Blue Steel #1 is a material more suited to users who already have experience and skill with using and maintaining carbon steel kitchen knives. While beginners can still use the blade, they will find maintaining it to be significantly more challenging.


Despite a limited userbase, its exceptional cutting power is attractive 

When slicing sashimi with a Blue Steel #1 knife, the blade will "pull cut" through effortlessly, with an almost frightening level of smoothness.

Due to Blue Steel knives being forged thoroughly, they retain amazing strength and flexibility even with an extremely thin blade. You almost can’t feel it cutting as it slices through!

If sharpened correctly, you won’t need to apply much hand strength when cutting either, allowing you to prepare dishes with minimal strain on the ingredients and your hands. A Blue Steel #1 knife can be considered a knife that will truly take you to the next level of culinary arts.


Steel Mapping Comparison

Steel material is crucial for indicating a knife's initial performance (amongst many other things related to craftsman ability and more). Below are some comparisons to give you some understanding showing what a particular step of the process does in terms of impacting sharpness, balance and maintainability.

Steel Material Heat Treatment/Forging Edge Sharpening Handle Attachment

Sharpness

Balance

Maintainability

Steel Material Heat Trt./Frg. Edge Sharp. Handle Attch.

Sharp.

Bal.

Maint.

There’s three key pointers in the above chart to focus on.

  • Steel Material has a large impact on sharpness and maintainability (ease of sharpening and resistance to rust).

  • Apart from sharpness, heat treatment and the sharpening process in knife creation also have a large impact on sharpness.

  • Measuring a knife’s strengths is more than just its sharpness. Balance and maintainability also need to be considered.

Based on the above steel mapping chart, Blue Steel #1 falls in this position on the graph below:

Japanese Knife Steel Chart - Blue Steel #1 (Aogami 1)

Amongst the steel knives manufactured in Japan, Blue Steel #1 falls on the higher side price-wise. It can be considered somewhat similar to White Steel #2 with a higher toughness and hardness rating. Also, it maintains its sharpness for a long time, again superior to White Steel #2.

However, this conversely makes these knives more difficult to sharpen. It’s a knife type for those who are okay with sparing no expense to whetstones and with effort to sharpening. In other words, if you don’t want to spend time sharpening and caring for your knife - this steel is perhaps not the one for you.

If you do come across a Blue Steel #1 knife that is easier to sharpen, it may have intentionally gone under a heat treatment in order to reduce its hardness.

A steel for those who enjoy sharpening and knife maintenance


Composition Comparison

Let’s compare Blue Steel #1 to other well known steel products via the table below.

Manufacturer Steel Name Carbon Silicon Cobalt Phosphorus Sulfur Manganese

Effect of Material

Hardness

Hardness (⅒ of Carbon)
Oxygen Removal

Decarburization Prevention
Toughness
Wear Resistance

Embrittlement

Embrittlement

Sulfur Removal
Toughness

Listed Value

Average

Maximum

Average

Maximum

Maximum

Average

Hitachi Metals

Yellow Steel #2

1.1

0.15

0.03

0.006

0.25

Hitachi Metals

White Steel #3

0.9

0.2

0.025

0.004

0.25

Takefu Special Steel

White Steel #2

1

Undisclosed

Undisclosed

Undisclosed

Undisclosed

Hitachi Metals

White Steel #2

1.1

0.15

0.025

0.004

0.25

Hitachi Metals

White Steel #1

1.3

0.15

0.025

0.004

0.25

Hitachi Metals

Blue Steel #2

1.1

0.15

0.025

0.004

0.25

Hitachi Metals

Blue Steel #1

1.3

0.15

0.025

0.004

0.25

Hitachi Metals

Blue Steel Super

1.45

0.15

0.025

0.004

0.25

JIS Standard

SK4

0.95

0.2

0.03

0.03

0.25

Hitachi Metals x Masahiro

ZCD-U

1.05

Undisclosed

Undisclosed

Undisclosed

Undisclosed

Manufacturer Steel Name Molybdenum Vanadium Nickel Tungsten Copper Chromium Hardness Rockwell Counter (HRC)

Effect of Material

Wear Resistance
Anti-Corrosion
Toughness

Wear Resistance
Decarburization Prevention

Toughness

Wear Resistance

Antibacterial Effects
Embrittlement

Anti-Corrosion

Changes in the quenching process

Listed Value

Average

Average

Average

Average

Maximum

Average

Hitachi Metals

Yellow Steel #2

56

Hitachi Metals

White Steel #3

55

Takefu Special Steel

White Steel #2

1

0.3

60

Hitachi Metals

White Steel #2

61

Hitachi Metals

White Steel #1

66

Hitachi Metals

Blue Steel #2

1.25

0.35

61

Hitachi Metals

Blue Steel #1

1.75

0.4

65

Hitachi Metals

Blue Steel Super

0.4

2.25

0.35

67

JIS Standard

SK4

0.25

0.3

55

Hitachi Metals x Masahiro

ZCD-U

Contains

Contains

59

Maker Steel Name Carbon Silicon Cobalt

Effect

Hard.

Hard. (⅒ Carbon)
Oxygen Rem.

Decarb Pvnt.
Tough.
Wear Res.

Listed Value

Average

Max

Average

Hitachi Metals

Yellow Steel #2

1.1

0.15

Hitachi Metals

White Steel #3

0.9

0.2

Takefu Special Steel

White Steel #2

1

Not Stated

Hitachi Metals

White Steel #2

1.1

0.15

Hitachi Metals

White Steel #1

1.3

0.15

Hitachi Metals

Blue Steel #2

1.1

0.15

Hitachi Metals

Blue Steel #1

1.3

0.15

Hitachi Metals

Blue Steel Super

1.45

0.15

JIS Std.

SK4

0.95

0.2

Hitachi Metals x Masa-
hiro

ZCD-U

1.05

Not Stated

Maker Steel Name Phos. Sulfur Mang.

Effect

Embrittlement

Embrittlement

Sulfur Rmvl.
Tough.

Listed Value

Max

Max

Average

Hitachi Metals

Yellow Steel #2

0.03

0.006

0.25

Hitachi Metals

White Steel #3

0.025

0.004

0.25

Takefu Special Steel

White Steel #2

Not Stated

Not Stated

Not Stated

Hitachi Metals

White Steel #2

0.025

0.004

0.25

Hitachi Metals

White Steel #1

0.025

0.004

0.25

Hitachi Metals

Blue Steel #2

0.025

0.004

0.25

Hitachi Metals

Blue Steel #1

0.025

0.004

0.25

Hitachi Metals

Blue Steel Super

0.025

0.004

0.25

JIS Std.

SK4

0.03

0.03

0.25

Hitachi Metals x Masa-
hiro

ZCD-U

Not Stated

Not Stated

Not Stated

Maker Steel Name Molyb. Vanad. Nickel

Effect

Wear Res.
Anti-Corrosion
Tough.

Wear Res.
Decarb Pvnt.

Tough.

Listed Value

Average

Average

Average

Hitachi Metals

Yellow Steel #2

Hitachi Metals

White Steel #3

Takefu Special Steel

White Steel #2

1

Hitachi Metals

White Steel #2

Hitachi Metals

White Steel #1

Hitachi Metals

Blue Steel #2

Hitachi Metals

Blue Steel #1

Hitachi Metals

Blue Steel Super

0.4

JIS Std.

SK4

Hitachi Metals x Masa-
hiro

ZCD-U

Has

Maker Steel Name Tung. Copper Chrom.

Effect

Wear Res.

Antibac.
Embrittlement

Anti-Corrosion

Listed Value

Average

Max

Average

Hitachi Metals

Yellow Steel #2

Hitachi Metals

White Steel #3

Takefu Special Steel

White Steel #2

0.3

Hitachi Metals

White Steel #2

Hitachi Metals

White Steel #1

Hitachi Metals

Blue Steel #2

1.25

0.35

Hitachi Metals

Blue Steel #1

1.75

0.4

Hitachi Metals

Blue Steel Super

2.25

0.35

JIS Std.

SK4

0.3

Hitachi Metals x Masa-
hiro

ZCD-U

Has

Comparing to Hitachi Metal’s White Steel #2 which is the most popular knife steel for Japanese cuisine knives, we can see that Blue Steel #1 has a higher carbon content. It also has a higher tungsten and chromium content than Blue Steel #2.

These contribute to the excellent edge retention, flexibility and toughness Blue Steel #1 is known for. On the other hand, due to its very high wear resistance, while it can maintain its sharpness for a long time it also can be very challenging to sharpen. Choosing the right whetstone and demonstrating patience when you do sharpen it is required.


Buying a Blue Steel #1 kitchen knife

Making of Japanese Knife

Blue Steel #1 truly shines in settings like high-end sushi restaurants, where the art of creating precise flavors and mouthfeels through sharp and clean cuts is paramount to the dining experience.

On the flip side, due to its higher carbon content this steel is very susceptible to rusting. The high hardness levels also make knives using this material vulnerable to low temperatures and impact damage like drops. It’s a premium material, but also requires delicate handling and careful usage.

It's important to note that this steel isn’t suitable for everyone due to its difficulty with maintenance. You may need to reconsider the whetstones you have and possibly purchase new ones. However, through the steady process of sharpening and cutting with the blade, you will steadily develop the skills to utilize the advantage of its hardness and toughness.

A skilled chef moves the blade swiftly and delicately, without any muscle strain. They work efficiently without exerting unnecessary force, ensuring minimal stress on the ingredients and thus improving the mouthfeel. Achieving this level of skill is only possible when you make a good knife using Blue Steel #1 your own.

For those who aspire to become a top-tier chef, this steel is one of the best.


Conclusion

Let’s recap the three key points related to Blue Steel #1.

  • Blue Steel #1 is a high-end steel known for its high hardness and resistance to wear.

  • Patience is required for sharpening, and you may need to reconsider your choice of whetstones or buy new ones.

  • This steel is highly recommended for those aspiring to become top-tier chefs.

If you have further questions about Blue Steel #1, don't hesitate to ask us! We carry a very large selection of Blue Steel knives, and our experts can help you find what is best for you, and even if this steel is ideal for your needs.


Here's a sample of Blue Steel #1 knives!