Best Hamon for a Practical Sword

One of the traditional Katana's most beautiful and appreciated characteristics is its hamon. The line between the cutting edge and the body of the blade, it is formed by differential hardening.

This was a necessity in pre-modern Japan, because the quality of iron, and thus the quality of steel, was poor.

With modern industrial steel, differential hardening provides improved retention, but also reduces a blade's resistance to bending and its impact resistance. 

sx105v Tool Steel

For example, in sx105v tool steel, which makes highly functional differentially hardened katana blades.

  HRC Warp
Impact Resistance
through-hardened 58 60-70° 80-90j
differentially-hardened 60-61/
20-25° 15j


T10 High-Speed Tool Steel

In comparison, the popular Longquan T10 clay-tempered blade is:

  HRC Warp
Impact Resistance
through-hardened 58-59/
15-20° >15j

Without clay-tempering, T10 high-speed tool steel is not suitable for sword blades, as they break easily.

W-2 Tool Steel

Another steel which snaps easily without differential hardening is W-2 cable steel.  The process not only makes a tougher, harder blade; but also gorgeous hamon activity. It's hardness, and warp and impact resistance are harder than sx105v.

  HRC Warp
Impact Resistance
through-hardened 59-59/
30° 25j

Other Considerations:

The type of hamon also has an impact on the practicality of blade.  Generally speaking, straighter hamon make for more durable blades than more intricate hamon.

Suguha Hamon:

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