Carbon (C)

• Increases edge retention and raises tensile strength.
• Increases hardness and improves resistance to wear and abrasion.

Chromium (CR)

• Increases hardness, tensile strength, and toughness.
• Provides resistance to wear and corrosion.

Cobalt (CO)

• Increases strength and hardness, and permits quenching in higher temperatures.
• Intensifies the individual effects of other elements in more complex steels.

Copper (CU)

• Increases corrosion resistance.

Manganese (MN)

• Increases hardenability, wear resistance, and tensile strength.
• Deoxidizes and degasifies to remove oxygen from molten metal.
• In larger quantities, increases hardness and brittleness.

Molybdenum (MO)

• Increases strength, hardness, hardenability, and toughness.
• Improves machinability and resistance to corrosion.

Nickel (NI)

• Adds strength and toughness
.

Nitrogen (N)

• Used in place of carbon for the steel matrix. The Nitrogen atom will function in a similar manner to the carbon atom but offers unusual advantages in corrosion resistance.

Phosphorus (P)

• Improves strength, machinability, and hardness.
• Creates brittleness in high concentrations.

Silicon (SI)

• Increases strength.
• Deoxidizes and degasifies to remove oxygen from molten metal.

Sulfur (S)

• Improves machinability when added in minute quantities.

Tungsten (W)

• Adds strength, toughness, and improves hardenability.

Vanadium (V)

• Increases strength, wear resistance, and increases toughness.

Steel Production And Properties The following provides a very brief overview of steel treatment and properties:

By definition, steel is a combination of iron and no more that 2% carbon. Steel is alloyed with various other elements that combine to produce special properties. Once a particular alloy¹ combination (or steel type) is selected, specific procedures are used to maximize the unique qualities required for that steel to perform. Generally speaking, the process for converting a steel alloy into a premium knife steel is theat reating².

Heat treatment is the most important stage in the evolution of an alloy into a performance knife steel. The first step in the heat treatment process is to reach a critical temperature.³ This temperature is held for a specific amount of time (depending on the steel being hardened) and causes the steel to become austenetized.⁴ Heat treatment is one of the many factors that determines the grain size⁵ of the steel (a fine grain structure is more desireable for knife blades because it improves edge retention and enhances blade finish).

Next, the steel is quenched⁶ to achieve its maximum level of hardness.⁷ At this point, the steel is too hard and brittle for practical use and thus tempering⁸ is of key importance in bringing the steel to its ideal hardness level (different knife steels perform best at different levels of hardness). Tempering also increases wear resistance and toughness⁹ properties. When tempering, it is important to understand the interaction between hardness and toughness. An increase in yield strength¹⁰ and tensile strength¹¹ and a decrease in impact strength¹² and ductility.¹³ An increase in toughness is usually accompanied by the opposite effect (i.e. an increase in toughness and ductility and a decrease in yield strength and tensile strength). Therefore, high-impact knifes such as swords and machetes would benefit from a softer blade (to avoid blade breakage), while low-impact knifes such as pocket knifes may benefit from a harder blade (to improve wear resistance). Once tempering is complete, the final hardness of the steel can be determined using a Rockwell Test.¹⁴

For more detailed information of the above processes and properties, we recommend the following references that were used to compile this information: Metallurgy Fundamentals by D.A. Brandt (published by Goodheart-Wilcox) and Heat Treaters Guide by P.M. Unterweiser (published by ASM).

1. Alloy
   • A material that is dissolved in another metal in a solid solution; a material that results when two or more elements combine in a solid solution.
2. Austenetized
   • The basic steel structure state in which an alloying is uniformly dissolved into iron.
3. Critical Temperature
   • The temperature at which steel changes its structure to austenite in preparation for hardening.
4. Ductility
   • The tendency of a material to stretch or plastically deform appreciably before fracturing.
5. Grain Size
   • The physical size of the austenite grains during austenizing. The actual size can vary due to thermal, time and forging considerations.
6. Hardness
   • The resistance of a steel to deformation or penetration analogous to strength.
7. Heat Treating
   • Heating and cooling metal to prescribed temperature and the limits for the purpose of changing the properties and behavior of the metal.
8. Impact Strength
   • The ability of a material to resist cracking due to a sudden force.
9. Quenched Rapidly cooled from the critical temperature using water, oil, air or other means.
10. Rockwell Test
    • A measurement of steel hardness based on the depth of penetration of a small diamond cone pressed into the steel under a constant load.
11. Tempering
    • Reheating to a lower temperature after quenching for the purpose of slightly softening the steel, precipitating carbides, stress relieving.
12. Tensile Strength
    • Indicated by the force at which a material breaks due to stretching.
13. Toughness
    • The ability of a material to resist shock or impact.
14. Yield Strength
    • The point at which a steel becomes permanently deformed; the point at which the linear relationship of stress to strain changes on a Stress/Strain curve.