Alloy Steel VS Carbon Steel

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Carbon steel: mainly refers to the mechanical properties depend on the carbon content of steel, and generally do not add a lot of alloying elements of steel, sometimes called plain carbon steel or carbon steel. Carbon steel, also known as carbon steel, carbon content WC less than 2% iron carbon alloy. Carbon steel in addition generally contains a small amount of silicon, manganese, sulfur, phosphorus can be divided according to the use of carbon steel carbon structural steel, carbon tool steel and free-cutting structural steel three carbon structural steel is divided into structural steel and machine structural steel, which can be divided into low carbon steel (WC ≤ 0.25%), medium carbon steel (WC 0.25% - 0.6% ) and high carbon steels (WC> 0.6%). According to phosphorus and sulfur content, carbon steels can be divided into ordinary carbon steels (phosphorus and sulfur are higher), high quality carbon steels (phosphorus and sulfur are lower) high-quality steel (phosphorus, sulfur lower) the higher the carbon content of carbon steel, the higher the hardness, the higher the strength, but lower plasticity.

Alloy steel: based on carbon steel, one or more alloying elements are deliberately added to improve the serviceability and process performance of the iron-based alloy is called alloy steel. Alloy steel refers to the steel containing silicon and manganese as alloying elements or deoxidizing elements, other alloying elements such as chromium, nickel, molybdenum, vanadium, titanium, copper, tungsten, aluminum, cobalt, niobium, zirconium and other elements, and some also contain some non-metal elements (such as boron, nitrogen, etc.) steel. According to the amount of alloying elements in steel, but also can be divided into low alloy steel, medium alloy and high alloy steel.

Chemical composition difference 
(1) Carbon steel: a. Low carbon steel (C≤0.25%); b. Medium carbon steel (C≤0.25 ~ 0.60%); c. High carbon steel (C≤0.60%).
(2) Alloy steel: a low alloy steel (total content of alloying elements ≤ 5%) b. Alloy steel (total content of alloying elements> 5 ~ 10%) c. High alloy steel (total content of alloying elements> 10%.

Carbon steel advantages:
Carbon steel has high strength, ductility and toughness, low cost, used in heavy machinery for the manufacture of heavy load parts. The total amount of gold is generally less than 5%, has greater impact toughness, and can be obtained by heat treatment better mechanical properties cast low alloy steel has better performance than carbon steel, can reduce the quality of parts and improve service life.

Alloy steel advantages:
In addition to iron in steel elements containing only carbon steel, carbon steel, other silicon, sulfur, phosphorus and other impurities, 45 steel can do general structural steel, steel 65 can do general spring steel, tool steel; In addition to other elements of chromium, manganese, molybdenum, titanium, tungsten, vanadium, niobium, boron, silicon and nickel alloy steel to achieve the desired properties such as high temperature, high elasticity, abrasion resistance, high strength, high toughness and so on. Alloy steel hardness wear resistance, hardenability, corrosion resistance than carbon steel excellent. In the mechanical parts of the wider use of carbon steel.

Carburizing speed comparison

All carbide-forming elements (titanium, chromium, molybdenum, etc.) increase the carbon concentration on the surface of the infiltration layer, and non-carbide forming elements (silicon, aluminum and nickel) reduce the carbon concentration on the surface of the diffusion layer. However, the influence of these alloying elements is not always the same, and the contents of alloying elements and carbon elements in the same grade of carbon steel or alloy steel are not necessarily the same.