Besi Grafit yang Dipadatkan - Panduan Lengkap

Compacted graphite iron, also known as vermicular graphite iron, is a metal material that has attracted much attention in the field of materials science. With its special graphite form and excellent performance, it plays an important role in many industrial fields.

What is compacted graphite iron?

Compacted graphite iron (cgi) is a kind of cast iron material with unique graphite form. Its graphite is neither flaky like ordinary gray cast iron, nor spherical like ductile cast iron, but shows a tight, curled form in between. This special graphite form gives cast iron a series of excellent properties.

In the cast iron material system, the compacted graphite iron grades can be divided according to the different graphite forms. Different grades of it have different properties. And their unique graphite morphology determines their performance in strength and toughness. For example, higher grades of compacted graphite iron is be suitable for industrial areas with higher performance requirements.

Basic principle of compacted graphite iron

Graphite form

Graphite form of compacted graphite iron

The graphite morphology of it presents a wormlike shape. It consists of many small graphite sheets connected to each other to form a tight structure. This structure enables the graphite to be evenly distributed in the cast iron matrix. Thus effectively improving the mechanical properties of cast iron.

Formation Mechanism

In the casting process, by adding specific alloying elements, such as magnesium, calcium, etc., to promote graphite crystallization to form wormlike. These elements inhibit the growth of graphite, allowing it to form a relatively stable structure. At the same time, in the casting process, the cooling rate and solidification conditions also play an important role in the formation of graphite form.

Alloy composition

Compacted graphite iron is mainly composed of iron, carbon, silicon, manganese and other elements. Carbon is the main element in the formation of graphite, and silicon affects the form and distribution of graphite. In addition, the addition of magnesium, calcium and other elements can further adjust the shape and properties of graphite.

Properties of compacted graphite iron

Sifat Mekanis

Strength and toughness

Compacted graphite iron has high strength and toughness. Its graphite structure can effectively disperse the stress, improve the tensile strength of graphite iron to 400-600MPA. So that the cast iron is not easy to crack when bearing the load. Compared with gray cast iron, the strength and toughness of compacted graphite iron have been significantly improved. This makes it able to adapt to a variety of complex engineering environments.

Fatigue resistance

Due to the special form of graphite, it has good fatigue resistance. Under the action of cyclic load, graphite can effectively prevent the expansion of cracks. Thus it can extends the service life of cast iron.

Sifat Fisik

Koefisien ekspansi termal

Compacted graphite iron has a relatively low coefficient of thermal expansion. This means that when the temperature changes, its size changes less and it can maintain good stability. This characteristic makes it have better performance in high temperature environment.

Thermal conductivity

Compacted graphite iron has good thermal conductivity. Its graphite structure can effectively transfer heat, so that the cast iron can evenly dissipate heat during the heating process. This feature is particularly important for heat exchange components such as engines.

Process performance

Compacted graphite iron casting process

Casting process is the key link of quality and performance of compacted graphite iron. In the pengecoran process, the precise control of casting temperature, speed and other parameters can effectively avoid the adverse changes in the shape and distribution of graphite. For example, a suitable pouring temperature can disperse the graphite evenly and prevent the graphite from floating or polarizing. Thereby increasing the graphite’s binding force with the iron matrix. In addition, a reasonable cooling method is also crucial. By controlling the cooling speed, you can adjust the crystallization process of graphite, optimize the size and shape of graphite. And ultimately improve the mechanical properties and processing properties of it.

Processability

It has good machinability. You can machine it for cutting, drilling and grinding operations to meet different engineering needs.

Applications of compacted graphite iron

Automotive industry

Compacted graphite iron engine block

You can use it to manufacture engine blocks. Because its good strength and thermal properties can meet the high load requirements of engines. During engine operation, compacted graphite iron can effectively dissipate heat and improve the efficiency and reliability of the engine.

Braking Systems

The braking system requires cast iron to have good wear resistance and fatigue resistance. The characteristics of it enable it to meet the requirements of braking systems, improving braking effectiveness and safety.

Aerospace

The aerospace industry requires very high performance of materials. You can widely use compacted graphite iron in aircraft engines, wings and other components because of its light weight, high strength and good thermal properties.

Other Areas

Construction

In the field of construction, you can use it in the manufacture of structural parts and pipes. Its good strength and corrosion resistance can ensure the long-term stability of the building.

Mechanical manufacturing

In the machinery manufacturing industry, you can use it to manufacture various mechanical parts, such as gears, shafts, etc. Its good mechanical properties and processing properties can meet different production needs.

Compacted graphite iron advantages and disadvantages

Keuntungan

Good mechanical properties: With high strength and toughness, can withstand large loads.

Excellent thermal performance: Low coefficient of thermal expansion, good thermal conductivity. It is able to maintain stability in high temperature environment.

Good casting performance: It is able to produce high quality castings.

Disadvantages

The production process is complex: The casting process requires strict control of parameters, and has high requirements for equipment and technology.

High cost: Due to its special production process and performance requirements, the cost is relatively high.

Comparison of compacted graphite iron with other materials

Compacted graphite iron vs cast iron

Ordinary gray cast iron graphite sheet thick and uneven distribution, easy to withstand external stress concentration, low strength. Iron graphite is worm-like and evenly distributed, which can disperse stress and significantly improve strength and toughness. At the micro level, the lembaran grafit is combined with the substrate at a special interface to enhance the interaction. It can withstand high loads in the fields of mechanical manufacturing and meet the needs of key parts.

Compacted graphite iron vs aluminum

Aluminum density is low, in the case of high weight requirements have advantages. However, the strength and thermal properties of compacted graphite iron are outstanding. The mechanical properties of aluminum are affected at high temperatures, and the structural stability is reduced and easy to deformation. While the compacted graphite iron has good thermal stability and can provide reliable support in the aerospace field.

Compacted graphite iron vs ductile iron

Ductile iron graphite is spherical, toughness, good ductility. However, the strength and thermal properties of compacted graphite iron are better. And the strength of ductile iron is easily reduced by grafitisasi at high temperatures. The compacting graphite iron graphite structure is stable. And the advantages are obvious in the occasions with high strength requirements such as large mechanical key components and high pressure vessels. This can better meet the needs of complex working conditions.

How is compacted graphite iron made?

The production process of compacted graphite iron is as follows:

First, raw materials such as iron, karbon, and silicon are put into the furnace in proportion to temperature and melt.

Then alloying elements such as magnesium and calcium are then added and stirred at high temperatures to make the graphite form a wormlike shape. This process requires precise control of temperature and element ratios. The molten liquid is then poured into the mold. And during the cooling process, the graphite is gradually fixed to a compacted form.

Finally, the production of compacted graphite iron castings is completed through the process of demudding and cleaning. The whole process has high technical requirements and needs to strictly control each link.

Kesimpulan

As a unique material, compacted graphite iron has excellent properties and wide application prospects. Although its production process is complex and costly, its application scope will continue to expand with the continuous progress of technology. In the field of engineering in the future, compacted graphite iron will continue to play an important role in promoting industrial development.