SK4 Carbon Steel vs Aogami #1

Detailed metallurgical comparison between JIS SK4 Tool Steel and Blue Paper Steel #1.

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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High-carbon steel alloyed with chromium and tungsten for enhanced wear resistance and edge retention. Ideal for hard woods and heavy use. Forged by masters who prize its demanding nature, it rewards a skilled sharpener with extraordinary edges that outlast almost any other carbon steel.

carbon1.25–1.35%chromium0.30–0.50%tungsten1.50–2.00%

Sharpness

9

Edge Retention

9

Ease of Sharpening

6

Rust Resistance

4

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