Japanese ZCD-U ‐ High Carbon Steel

~에 의해 Sakai Ichimonji 2023년 10월 13일

When carbon steel comes to mind, people often think of the ones that are more universally known and produced such as White Steel and Blue Steel. However, some knife manufacturers want to go that extra mile and create a steel that is uniquely theirs, and that fits their vision. Sometimes they will also go to other steel manufacturers to collaborate on this - and this is precisely what Masahiro has done with Hitachi Metals to create ZCD-U Steel. This blog goes into detail about precisely what that steel is, how it’s useful in your kitchen and also contains a little bit of history about how Japan handled kitchen knife creation in the past.

ZCD-U Steel - A steel that embodies the visions and techniques of Masahiro

ZCD-U Steel is an original steel material created by the knife manufacturer Masahiro, based in Seki City, Gifu Prefecture.

This steel, highly favored in butchers and yakiniku (Japanese barbecue) restaurants, is known for its durability whether it has a sturdy edge or even when sharpened thinly. The inclusion of trace amounts of vanadium and tungsten adds to its durability, providing a solid feel and a sense of ruggedness in its use.

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 + Forging	Making Edges	Handle Attach.
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, ZCD-U Steel falls in this position on the graph below

It’s true that there are steel materials even harder than ZCD-U, such as Blue Steel Super. However, excessively hard materials can be challenging to sharpen and may have a propensity to chip due to their brittleness, so they must be handled with extreme care.

ZCD-U Steel is produced by a knife manufacturer long cherished in the professional field. It has some toughness while still maintaining the inherent characteristics of carbon steel, in that it sharpens relatively easily compared to stainless steels.

You can almost feel how the materials were specifically chosen for the tasks this steel excels at.

A carbon steel which has some toughness that make it durable

Composition Comparison

Let’s look at the tables below and explore the composition of ZCD-U more deeply. You may notice something special about this steel in both material tabs.

MAJOR MATERIALS
SECONDARY MATERIALS

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

MAJOR P1
MAJOR P2
SECONDARY P1
SECONDARY P2

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

As ZCD-U Steel is made and developed independently by Masahiro (also a knife manufacturer) specifically, they do not show its material composition. However, the inclusion of vanadium and tungsten has been officially shown by the manufacturer. While we do know such materials are part of the steel's composition, we still don't know the precise amount of each material.

Buying a ZCD-U Steel Knife

A hand pulling out steel from a hot furnace.

As is the case with carbon steel knives, rust is a risk with ZCD-U Steel knives. When you’ve finished using it, make sure to properly wash it with detergent, and dry it very well before storing it.

Moreover and perhaps rather uniquely, ZCD-U Steel knives often have not had the final sharpening applied to them, and it is expected that the purchaser does it themselves.

This is because the processing of these knives has not changed in many decades.* Whether this is good or bad is hard to say, and it depends on the user as some users have specific sharpening preferences - such as professional chefs. Anyway, it’s a good time to remember that all Sakai Ichimonji Mitsuhide knives come with a free sharpening ticket with no expiration date, so you can use it to apply that final sharpening if you wish at purchase.

*Note: From the post-war period to the early Heisei era, it was generally understood that the final sharpening was something chefs would do according to their own personal preferences, so that the knife would work best for them. During this time, it was thought that because items were made based on this idea, reasonably priced and high-quality knives were in higher circulation.

Conclusion

Let’s quickly recap the two key points of ZCD-U Steel here:

ZCD-U is a Masahiro proprietary developed steel material that incorporates the characteristics of carbon steel while having toughness.
Knives made from ZCD-U are often sold without the final sharpening, leaving it to the user to complete this step. We can help with this.

Our range of ZCD-U Steel knives is a little smaller compared to our other steels (as always, we carry more in store), but we are proud of what we sell and the Shinco Honesuki is highly rated, even being used by popular influencers in the kitchen knife space.