What Is Alloy Steel?
Alloy Steel is a type of steel made from combining carbon steel with one or more elements known as alloys. Physical and chemical properties vary according to their composition.
Alloy Steel generally contains elements such as carbon, chromium, nickel, molybdenum, manganese, and vanadium, which combine with iron to improve the steel’s strength, corrosion resistance, wear resistance, durability, and machinability.
Alloy Steel can be produced in a variety of ways, but it is generally formed by mixing iron and the elements to be added at high temperatures and then cooling.
Post-treatment such as heat treatment and fabrication may also be required.
Uses of Alloy Steel
1. Aircraft
Alloy Steel, such as stainless steel and titanium alloys, are used because high strength and high corrosion resistance are required. Examples include jet engine parts and landing gear.
2. Automobiles
High tensile strength steels are especially used because of the high strength and hardness required. Examples include chassis and body panels.
3. Construction
Because strength and durability are required, steel materials with high earthquake resistance are used. Examples include high-rise buildings and bridges.
4. Energy
Alloy Steel with high heat and pressure resistance is used because it is required to be used in high temperature and high pressure environments. Examples include nuclear power plants and thermal power plants.
5. Medical Instruments
Alloy Steel such as stainless steel and titanium alloys are used. Examples include artificial joints and dental implants.
Implants are a type of medical device that are implanted inside the body and made from artificially created materials.
6. Tools
Alloy Steel such as high speed metal and molybdenum steel are used because of their wear and heat resistance. Examples include drills and cutting tools.
High-speed steel (HSS) is a type of high-performance steel made by adding alloying elements such as chromium, molybdenum, and vanadium to iron, and is widely used in cutting and machine tools since it can withstand high temperatures and cut and machine at high speeds.
Properties of Alloy Steel
The main properties of alloy steel are as follows:
1. Strength
Alloy Steel is stronger than pure iron and can withstand high loads and impacts. It is used in structures such as bridges, skyscrapers, and aircraft, as well as in automobile chassis and engine parts and tools.
2. Hardness
Alloy steel is tough and has high hardness. It is used for high-load parts such as tools, machine parts and gears.
3. Abrasion Resistance
High abrasion resistance prevents wear due to grinding and abrasion, and is used for high-load parts such as tools, machine parts, gears, and bearings.
4. Corrosion Resistance
Corrosion resistance is increased by added alloying elements. Alloy steels such as stainless steels are used in applications such as food processing equipment and medical instruments.
5. Heat Resistance
Alloy Steel has high heat resistance due to the alloying elements added. They are used for parts used in high-temperature environments and in nuclear power plants.
6. Corrosion Resistance
Alloy Steel has high corrosion resistance because the alloying elements added to the steel prevent the formation of oxides and corrosion products and protect the surface. Alloy steels are used in chemical plants, etc., taking advantage of their high corrosion resistance.
Types of Alloy Steel
There are many types of alloy steel. The following are typical examples:
1. Carbon Steel
Carbon Steel is an alloy steel in which carbon is the main alloying element and is composed only of iron and carbon. It is widely used because of its high strength and low-cost production.
2. Stainless Steel
Stainless steel is a steel to which chromium is added as a major alloying element. It has excellent corrosion resistance. It is suitable for applications such as food processing and medical equipment.
3. Tool Steel
Tool steel is a steel to which carbon, chromium, vanadium, and other alloying elements are added, featuring high hardness and high durability. It is widely used for cutting tools, dies, and machine tools.
4. Nickel Steel
Nickel steel is a steel to which nickel is added as the main alloying element, and is characterized by high strength and heat resistance. It is used in high-temperature environments such as aircraft and nuclear power plants.
5. Chromium Molybdenum Steel
Chromium molybdenum steel is a steel to which chromium and molybdenum are added as major alloying elements, and is characterized by high strength and durability. It is used for structural parts of automobiles, rolling stock, ships, etc., and for hydraulic equipment, etc.
6. Manganese Steel
Manganese steel is a steel to which manganese is added as the main alloying element, and is characterized by high wear resistance. It is used for railroad rails, construction steel, machine parts, etc.
7. Aluminum Steel
Aluminum steel is a steel in which aluminum is added as the main alloying element, is lightweight and has excellent corrosion resistance and workability. It is used for automotive parts, aircraft parts, construction materials, etc.
Other Information on Alloy Steel
1. Impact Resistance
Alloy Steel may become brittle due to its high hardness and strength. This is due to the fact that the blending of elements in alloy steel causes the crystal structure to become less uniform and localized crystal defects are more likely to occur. These defects can expand as stress is applied, eventually leading to fracture.
Alloy Steel is also harder and more brittle than ordinary steel, and can be easily damaged by impact.
2. Weather Resistance
Alloy Steel generally contains elements such as chromium, copper, phosphorus, silicon, and aluminum. These elements form an oxide film on the surface of the steel, preventing corrosion and deterioration. In particular, when chromium is added in large amounts, the oxide film is very tough and extremely resistant to corrosion.
Alloy Steel is therefore suitable for outdoor use. For example, it is used for automobile parts, building exteriors, bridges and other structures, ships, and wind power generation towers. It is also used for parts and equipment used in harsh environments such as areas with strong salt damage and tropical regions.
However, weather resistance varies depending on the environment in which it is used, so appropriate alloy steel should be selected.
Periodic maintenance and repairs are necessary because corrosion progresses when the oxide film on the surface is damaged.