Aogami #1 San Mai Stainless Clad Knife Steel Billet

Premium Japanese carbon steel combining extreme sharpness, high hardness potential and excellent edge retention.

Aogami #1, also known as Blue Paper Steel #1 or Blue #1, is one of the highest-performance traditional Japanese carbon steels available to bladesmiths.

It builds on the ultra-pure foundation of White Paper Steel, with added alloying elements including tungsten and chromium to improve hardness potential, wear resistance and edge retention.

The result is a steel capable of exceptional cutting performance, with improved durability and edge holding compared with White steels, while still retaining the fine grain structure and refined sharpening response prized in premium Japanese kitchen knives.

This San Mai billet combines an Aogami #1 carbon steel core with stainless outer cladding, giving makers the best of both worlds: a high-performance carbon cutting edge supported by lower-maintenance stainless outer layers.

Aogami #1 is capable of very high hardness and excellent edge stability, but rewards disciplined heat treatment. Proper temperature control, quenching technique and tempering are essential to unlock the steel’s full potential.

Favoured by experienced bladesmiths producing premium kitchen knives, Aogami #1 delivers aggressive sharpness, excellent edge retention and the distinctive cutting feel associated with high-end Japanese blades.

Suggested heat treatment

The following heat treatment information is intended as a starting point only. Results will vary depending on equipment, temperature control, quench medium, section thickness and final blade geometry.

Austenitising:
Hold at 800–830°C

Hold time:
Approx. 10 minutes

Quench:
Oil or water*

Temper:
180–200°C for 2 hours x 2

Expected hardness:
Approx. 62–64 HRC

* Water quenching may achieve higher hardness, but carries a higher risk of cracking.

Blue #1 compared with White #1

Blue #1 generally offers better edge retention than White #1, but is not quite as easy to sharpen.

With a similar carbon content to White #1, approximately 1.25–1.35% carbon, Blue #1 also contains small amounts of chromium, manganese and silicon, as well as tungsten at approximately 1.50–2.00%. The tungsten content is a major contributor to the improved wear resistance and edge retention.

Some makers report that Blue #1 can hold a keen edge noticeably longer than White #1 at the same hardness and blade geometry. We have not yet tested this claim in-house, so this should be treated as general maker feedback rather than a guaranteed performance figure.

Expert-level steel

Aogami #1 is best suited to experienced makers familiar with high-carbon Japanese steels.

There is a higher risk of cracking, especially when chasing higher hardness in the 62–65 HRC range. Careful heat treatment, controlled grinding and appropriate blade geometry are important to get the best result from this specialty steel.

There is a lot to study with traditional Japanese steels, but a simple distinction is:

White #1 is known for extreme sharpness potential and ease of sharpening.
Blue #1 offers improved edge retention and wear resistance, but requires more effort to sharpen.

Heat treatment information for this steel is not as clear-cut as more common Western knife steels, so the above should be treated as a starting point for testing and refinement.