Alloy steel is a type of steel that improves its properties by intentionally adding certain alloying elements to the base carbon steel. These alloying elements can significantly enhance the steel's hardness, strength, wear resistance, toughness, corrosion resistance, and high-temperature resistance. Here are some common alloying elements found in alloy steel and their functions:

Common Alloying Elements and Their Functions

• Chromium (Cr)

  • Increases corrosion resistance, heat resistance, and hardness.
  • Forms an oxide layer with oxygen, protecting the internal structure of the steel.
  • Enhances hardness and strength, improving wear resistance and cutting performance.

• Molybdenum (Mo)

  • Enhances strength, hardness, toughness, and wear resistance.
  • Improves high-temperature and corrosion resistance.

• Titanium (Ti)

  • Provides solid solution strengthening and grain refinement, improving hardness, wear resistance, and high-temperature resistance.
  • Enhances cold working performance.

• Nickel (Ni)

  • Increases toughness, strength, and corrosion resistance.
  • Enhances elasticity and impact toughness.

• Manganese (Mn)

  • Improves toughness, strength, and wear resistance.
  • Acts as a deoxidizer and desulfurizer, enhancing the hardness and strength of ferrite and austenite.

• Silicon (Si)

  • Increases strength, hardness, fatigue strength, corrosion resistance, and oxidation resistance.
  • Promotes the formation of hard, corrosion-resistant nitrided layers in nitriding steel.

• Tungsten (W)

  • Enhances strength and wear resistance, improving hot hardness.

• Vanadium (V)

  • Simultaneously increases strength and toughness, enhancing wear resistance and temper stability.

• Aluminum (Al)

  • Improves oxidation resistance and suppresses aging phenomena in low-carbon steel.

• Copper (Cu)

  • Enhances atmospheric corrosion resistance, strength, and yield ratio.

• Rare Earth Elements

  • Improve plasticity and toughness, enhancing special properties (such as heat resistance, corrosion resistance, and oxidation resistance).

Other Common Alloying Elements and Their Functions

In addition to the elements mentioned above, other alloying elements also play important roles in specific applications:

• Cobalt (Co)

  • Used in special steels and alloys to increase high-temperature hardness.

• Boron (B)

  • Acts as an alloying element under certain specific conditions.

• Phosphorus (P), Sulfur (S), Nitrogen (N)

  • May also act as alloying elements under certain specific conditions.

Classification of Alloy Steel

Based on application, alloy steel can be categorized into three main types: alloy structural steel, alloy tool steel, and special performance steel. Based on the content of alloying elements, it can be divided into low alloy steel (total alloying element content less than 5%), medium alloy steel (total alloying element content between 5% and 10%), and high alloy steel (total alloying element content greater than 10%).

By carefully selecting and adding these alloying elements, alloy steel can meet the demands of various applications and exhibit excellent overall performance.