SK4 Carbon Steel vs Aogami #2

Detailed metallurgical comparison between JIS SK4 Tool Steel and Blue Paper Steel #2.

SK4

SK4 Carbon Steel

JIS SK4 Tool Steel

A standardized Japanese Industrial Standard (JIS) carbon tool steel. Slightly higher carbon than SK5 and lower than SK2, making it one of the most balanced general-purpose tool steels in the JIS classification. Widely used for saw blades, knives, and hand tools where consistent heat treatment and predictable performance matter more than ultimate edge retention.

carbon0.90–1.00%manganese0.10–0.50%silicon0.10–0.35%
Sharpness
7
Edge Retention
6
Ease of Sharpening
9
Rust Resistance
3
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AOGAMI-2

Aogami #2

Blue Paper Steel #2

Similar to Aogami #1 but with slightly lower carbon and tungsten content. Offers an excellent balance of edge retention and toughness, making it the most-used steel among Japanese master blacksmiths. The sweet spot of the Aogami family — demanding enough to be worthy, forgiving enough to be reliable.

carbon1.05–1.15%chromium0.20–0.50%tungsten1.00–1.50%
Sharpness
8
Edge Retention
8
Ease of Sharpening
7
Rust Resistance
4
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