Alloy Steel | The Four Types of Steel (Part 2)

This article is the second in a four-part series on the different types of steel. Read Part 1.

Alloy steels are made by combining carbon steel with one or several alloying elements, such as manganese, silicon, nickel, titanium, copper, chromium and aluminum. These metals are added to produce specific properties that are not found in regular carbon steel. The elements are added in varying proportions (or combinations) making the material take on different aspects such as increased hardness, increased corrosion resistance, increased strength, improved formability (ductility); the weldability can also change.

The most important and desired changes in alloy steel are:

1. Increased hardenability.
2. Increased corrosion resistance.
3. Retention of hardness and strength.

Nearly all alloy steels require heat treatment in order to bring out their best properties. 

Alloying Elements & Their Effects

• Chromium – Adds hardness. Increased toughness and wear resistance.
• Cobalt – Used in making cutting tools; improved Hot Hardness (or Red Hardness).
• Manganese – Increases surface hardness. Improves resistance to strain, hammering & shocks.
• Molybdenum – Increases strength. Improves resistance to shock and heat.
• Nickel – Increases strength & toughness. Improves corrosion resistance.
• Tungsten – Adds hardness and improves grain structure. Provides improved heat resistance.
• Vanadium – Increases strength, toughness and shock resistance. Improved corrosion resistance.
•  Chromium-Vanadium – Greatly improved tensile strength. It is hard but easy to bend and cut.

The most commonly used grades of Alloy Bar:

• Grade 4140 – Chromium Molybdenum Steel
• Grade 4340 – Nickel-Chromium-Molybdenum Steel
• Grade 6150 – Chromium Vanadium Steel
• Grade 8620 – HSLA -Nickel-Chromium-Molybdenum Steel

This article is the second in a four-part series on the different types of steel. Read Part 3 to learn more about Stainless Steel grades and its attributes.