definition:
Carbon steel: mainly refers to the mechanical properties depend on the carbon content of steel, generally not adding a lot of alloying elements of steel, sometimes called ordinary carbon steel or carbon steel. Carbon steel, also known as carbon steel, contains an iron-carbon alloy with a carbon content wc of less than 2%. In addition to a small amount of silicon, manganese, sulfur and phosphorus, carbon steel can be divided into carbon steel, carbon structural steel, carbon tool steel and free-cutting structural steel according to the application. Carbon structural steel is divided into three parts. It is structural steel and martensitic steel. Chinese structural steel can be divided into low carbon steel (wc ≤ 0.25%), medium carbon steel (wc 0.25% - 0.6%) and high carbon steel (wc > 0.6%). According to the content of phosphorus and sulfur, carbon steel can be divided into ordinary carbon steel (higher phosphorus and sulfur), high-quality carbon steel (lower phosphorus and sulfur) and high-quality steel (lower phosphorus and sulfur). The carbon content of carbon steel is higher. High, the higher the carbon content. The higher the hardness, the higher the strength and the lower the plasticity.


Alloy steel: Based on carbon steel, one or more alloying elements are intentionally added to improve the performance and process properties of iron-based alloys, called alloy steel. Alloy steel refers to 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, cerium, zirconium, etc., some also contain some Non-alloyed elements. - Metal elements (such as boron, nitrogen, etc.) steel. According to the content of alloying elements in steel, it can also be divided into low alloy steel, medium alloy steel 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 amount of alloy elements ≤ 5%), B alloy steel (total amount of alloying elements > 5 to 10%), C high alloy steel (total amount of alloying elements > 10%).


Advantages of carbon steel:
Carbon steel has the characteristics of high strength, good ductility, good toughness and low cost, and is used to manufacture heavy machinery parts. The total amount of gold is generally less than 5%, it has a large impact toughness, and can obtain better mechanical properties by heat treatment. The cast low alloy steel has better performance than carbon steel, can reduce the quality of parts and improve the service life. .


Advantages of alloy steel:
In addition to iron, carbon steel, other silicon, sulfur, phosphorus and other impurities, 45 steel can be used as general structural steel, 65 steel can be used for general spring steel, tool steel; in addition to chromium, manganese, molybdenum, titanium, etc. In addition to the elements, 65 steel can be used for general spring steel and tool steel. Tantalum, niobium, boron, silicon and nickel alloy steels have achieved the properties required for high temperature, high elasticity, wear resistance, high strength and high toughness. Alloy steel is superior to carbon steel in hardness wear resistance, hardenability and corrosion resistance. Carbon steel is widely used in mechanical parts.


Carburizing speed comparison
All carbide forming elements (titanium, chromium, molybdenum, etc.) increase the carbon concentration on the surface of the permeation layer, while non-carbide forming elements (silicon, aluminum, nickel) reduce the carbon concentration on the surface of the diffusion layer. However, the effects of these alloying elements are not always the same. In the same grade of carbon steel or alloy steel, the content of alloying elements and carbon elements is not necessarily the same.