What is SK-5 Steel?

SK-5 steel is modern steel with hardness of hrc65. It is used in making a variety of hand tools like knives. SK-5 steel is the Japanese equivalent of American 1080 steel.

An example use is:  WORKPRO Utility Knife Blades.

It is made by combining iron and carbon. Other elements, like manganese, nickel, chromium, sulfur, vanadium, silicon, phosphorus, and molybdenum, are added to enhance rigidity, ductility, and tensile strength.

SK-5 is not stainless steel. The low amounts of chromium (0.3%) in this steel grade make it non-stainless steel. For steel to be considered stainless, it should have at least 11% of chromium, which is not the case with SK-5 steel.

The quality and toughness of steel depend on the components that go into its makeup and forging process as well as how well it was tempered.

At its core, SK-5 steel is Japanese high carbon steel comprising approximately 0.9% manganese and 0.8% carbon. Its alloy gives it high hardness, increased strength, and excellent abrasion resistance.

On the Rockwell C scale (HRC), SK-5 ranks approximately 65, meaning it is very hard steel, ideal for making utility blades.


SK-5 Steel Composition

SK-5 is one of the best grades of steel, thanks to the elements used to make it. Here are the elements used in the SK-5 steel makeup and forging process.

0.8 to 0.9% of carbon: SK-5 steel has a significantly higher amount of carbon element. The high amount of carbon increases the hardness, elevating wear resistance. Notably, high carbon amounts decrease the strength of steel grade.

Up to 0.3% of chromium: Although the chromium amount is far way low to make SK-5 steel stainless, it boosts edge retention, hardness, and tensile strength.

0.25 silicon: The silicon content increases strength

0.3% of manganese: Manganese makes the steel harder. The amount is kept low because too much manganese can increase brittleness.

Up to 0.25% nickel: It increases hardness and boosts brittleness, ensuring no room for brittleness.

Up to 0.03% of sulfur: The sulfur content in SK-5 steel makes it easier to machine or work with.

Up to 0.03% of phosphorus: It boosts the steel strength.

Up to 0.25% copper: The copper in SK-5 prevents surface oxidation

These elements come together to form the robust SK-5 steel that can be used in making a variety of tools and weapons.

The properties of SK-5 steel immensely depending on its chemical properties. Here are properties that make it one of the most preferred materials for utility blades.


Hardness: SK-5 steel has a hardness of up to 65 HRC attributed to the high carbon content in its composition. This considerably high Rockwell hardness makes this steel grade exceptionally resistant to abrasion and wear. Thanks to its rigidity, it can be used to craft reliable blades for most outdoor adventures.

Edge retention: This Japanese steel offers impressive edges. The high amount of carbon makes it very hard with excellent edge retention.

Toughness: toughness tends to lessen when hardness increases. Although the high hardness of Sk-5 makes it less tough, it has a reasonable level of toughness.

Corrosion resistance:  SK-5 is not stainless steel. All the same, the tiny amount of chromium provides decent corrosion resistance. Proper care will ward off rust and corrosion in the future.

Sharpenability: SK-5 is a hard steel that can rate up to 65 HRC. The fine grain and carbon carbides make it quite hard, meaning sharpening your blade to achieve a super-sharp edge is a bit challenging.

SK-5 is tough steel providing an excellent balance between hardness and toughness. It is a perfect option for making tools and weapons where primary operations and precision usages immensely rely on edge superiority.

If you’re looking for a rigid, tough blade with superior edge-holding ability, you might consider tools made with SK-5 steel. Its composition allows the steel to achieve a nearly perfect balance of outstanding blade toughness and excellent edge holding ability.

Compare to other types:

65mn Carbon