Carbon is the main alloying element of steel materials, so steel materials can also be called iron-carbon alloys. The main role of carbon in steel is:
Form a solid solution structure to improve the strength of steel, such as ferrite and austenite structures, all of which are dissolved in carbon;
2. The formation of carbide structure can improve the hardness and wear resistance of steel. For example, cementite, Fe3C, is the carbide structure.
Therefore, in steel, the higher the carbon content, the higher the strength and hardness of the steel, but the plasticity and toughness will also decrease. On the contrary, the lower the carbon content, the higher the plasticity and toughness of the steel, and its strength. , Hardness will decrease accordingly.
Therefore, the level of carbon content determines the use of steel: low carbon steel (carbon content <0.25%), generally used as profile and stamping materials; medium carbon steel (carbon content <0.6%), generally used as mechanical parts ; High carbon steel (carbon content> 0.7%), generally used as tools, knives and molds.
