Blade Steel

SK-4 - Blade Steel

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Steel Composition

carbon 0.90 %
chromium 0.30 %
manganese 0.85 %
silicon 0.35 %

The SK-4 knife steel is celebrated for its excellent toughness and ease of sharpening. Originated from Japan, it is sometimes referred to as carbon steel because of its high carbon content. Despite not being stainless steel, it performs well in a variety of conditions and is commonly used for tools and cutlery.

What are the Benefits of SK-4?

The SK-4 blade steel is known for its excellent toughness which reinforces its durability. Its impressive edge holding capabilities make it an ideal choice for EDC knives. Because of its simple composition, it is also very easy to sharpen.

This knife steel is perfect for practical tasks such as cutting rope, slicing food or opening packages due to its sharpness and durability.

Disadvantages of SK-4 for Knives

Despite having great toughness, SK-4 steel has its potential downsides. As a non-stainless steel, it is not highly rust resistant and should therefore be kept dry to prevent corrosion.

The need for frequent maintenance might prove to be a challenge for some users who require a more low-maintenance knife steel.

Steel Rating

Steels with good edge retention will stay sharp longer, reducing the need for frequent sharpening

Edge Retention

3/6 Points

Toughness is the steel's ability to absorb energy and deform without breaking


4/6 Points

Corrosion Resistance measures how well the steel can resist rust and oxidation

Corrosion Resistance

2/6 Points

Sharpenability refers to how easily a knife blade can be sharpened to its desired edge


5/6 Points

This is a relative measure based on typical market values. The actual price can vary widel


6/6 Points

A higher HRC number typically indicates a harder steel, which can hold a sharper edge


57 - 61 HRC
Please be aware that this rating should be understood as a comparative measure. It's simply a rough estimation in relation to other knife steels.

How Rust Resistant is SK-4?

SK-4 steel is not known for its rust resistance. However, with proper care and maintenance, it can withstand damages through rusting. Regular oiling and drying after use will extend its longevity greatly.

While not extremely resistant, its performance can be maximized through proper care.

How Strong is SK-4?

With an HRC rating of 57-61, SK-4 steel can be considered as a hard knife steel. Therefore, it can maintain a sharp edge over extended periods of use. Benefitting from its hardness, SK-4 exhibits high wear-resistance which prolongs its lifespan.

For what is SK-4 known for?

The SK-4 knife steel has a reputation for its durability and ease of maintenance. Favorable for use in everyday carry knives because of its strength and edge sharpness.

Intended for users who require a reliable, tough, and resilient blade, the strength of the SK-4 is hard to beat.

Similar blade steels


In conclusion, the SK-4 knife steel provides a satisfactory mix of toughness and edge retention while requiring a bit of maintenance to prevent rusting. For those who value strength and are willing to put in some upkeep effort, the SK-4 emerges as a viable choice.