It is customary to say that steel is a general term for steel and iron, but the actual steel and iron are different. The two are mainly divided by the amount of carbon. For the increase of carbon content, it is necessary to use a recarburizer, and a petroleum coke recarburizer[calcined petroleum coke & graphitized petroleum coke] is commonly used.
The carbon content classification standard for steel.
China has used the carbon content of steel as the grading standard for many years. In the national standard for casting carbon steel, regarding the steel grade, chemical composition and mechanical properties, the “ZG” in the grade indicates cast steel, and then The figure indicates the nominal value of the weight fraction of carbon in the steel, expressed in parts per million. Cast carbon steel is classified into three grades according to the phosphorus and sulfur content of its impurity elements, and the grades of grades of phosphorus and sulfur are less than 0.04% (I grade) steel; and the quality of grade II grade steel is less than 0.05%. Less than 0.06% is ordinary (III grade) steel.
1. Low carbon steel: usually C% <0.25%, called low carbon steel, low strength, good plasticity and weldability.
2, medium carbon steel: C% is 0.25 ~ 0.60%, called medium carbon steel, has higher strength, but poor plasticity and weldability.
3, high carbon steel: C%> 0.60%, called high carbon steel. Poor plasticity and weldability, but high strength and hardness after heat treatment.
More than 2% carbon is cast iron, and cast iron is mainly gray cast iron and ductile iron. Recarburizers[CPC & GPC] are often used in the smelting of cast iron.
1. Gray cast iron C%: 2.7%-3.9%. Ordinary gray cast iron is mainly cast iron in which carbon is precipitated in the form of flake graphite. Gray cast iron is widely used. In the total output of various types of cast iron, gray cast iron accounts for more than 80%.
2. Ductile iron C%: 3.5% -3.9%, ductile iron is a high-strength cast iron material, its comprehensive performance is close to steel, it is based on its excellent performance, has been successfully used for casting some force complex, strength Parts with high toughness and wear resistance. Ductile iron has rapidly developed into a cast iron material that is second only to gray cast iron and is widely used. The so-called "iron-based steel" mainly refers to ductile iron.