Cast iron is a term used to describe a variety of metal alloys. The alloying element in the manufacturing process of cast iron is iron. There are many factories around the world engaged in the production of this product. Because of its name, some people think that cast iron is essentially 100% iron. if not! In fact, carbon steel has a higher iron content than cast iron. To be considered cast iron, primary iron alloys must contain more than 2% carbon to be considered final cast iron alloys. Cast iron contains small amounts of other alloys, of which manganese and silicon are the two most popular. These additional alloying elements are used to further modify the properties of the cast iron and thus determine the specific cast iron alloy designation. There are different types of cast iron, including:
- Malleable iron: It has graphite nodules, which makes it more ductile than other cast irons while having excellent strength properties.
- Gray Cast Iron: Compared to other cast irons, it has a graphite shell which improves its machinability.
- White cast iron: This type of iron contains a high amount of iron carbide, which makes it very brittle, but it is very resistant to wear.
- Malleable Cast Iron: This cast iron is basically white cast iron that has undergone a special heat treatment to convert iron carbide into graphite nodules. This cast iron is ductile.
To make cast iron, iron ore is heated in a furnace to melt it. The molten metal is then poured and finally solidifies into an ingot. The cast iron ingot is remelted into the final shape. During this remelting process, cast iron can undergo various metallurgical changes through the introduction of alloying elements or heat treatment processes. 
Typically, this is where cast iron falls within the specifications of one of the four groups mentioned above. Cast iron has better fluidity than steel when melted. Cast iron also has a low melting point. These two properties make cast iron ideal for the casting process, which is part of the reason why cast iron is so popular. However, the use of cast iron has declined over the past few centuries as steel production and forming techniques have improved. The production of ductile iron in the world is growing very fast. Among the cast metals, it is second only to gray cast iron and has the largest production (approx. 10 million tons/year). Mohan claimed around 1920 the ability to produce ductile iron by adding magnesium to a cast iron melt (an alloy of magnesium, nickel, calcium and silicon). In the 1940s, researchers in the United States, Great Britain, and Germany invented the industrial method of producing this cast iron. They did. In the production method of this type of cast iron, the main difference is the way of adding magnesium to the cast iron melt, the process of adding magnesium in the tunnel can be after the invention of spheroidal graphite cast iron. For those familiar with this type of cast iron production, the basic concept of producing non-brittle cast iron using a chamber to react magnesium with a melt in a mold may not be new. Solving the damping problem with magnesium in the melt in the pot and realizing the extremely fine spherical graphite structure have always been the wheels. To achieve this requires invention and innovation through learning and experience. In 1968 Dunes of Great Britain completed the task and the results of the research and inventions carried out in 1974-7 were passed on to the foundry industry. 
The method is based on dissolving magnesium in the melt in a chamber called an interaction chamber, which is part of a channel system. Cast iron is widely used where high hardness and wear resistance are required. This is because steel can often be modified to have more desirable structural properties than cast iron in many projects. But before steel became popular, cast iron was somewhat popular for construction. Cast iron is also economical due to the basic requirements for alloying elements and cheap production methods. Therefore, the use of cast iron is widely used throughout the world today. Some of the most common uses of cast iron include: The above irons are selected:
- brake disc
- Gears and gear discs
- kitchen utensils
- decorative building parts
- Different types of shafts and rods
- Construction of mining equipment
The most important properties of cast iron The following is one of the most important properties of cast iron:
- pounding
- hard and fragile
- later rusted
- heat resistant
- very high resistance
- it has different types
- reasonable price
- heavyweight
What are the characteristics of cast iron?
- melts without becoming mushy
- High corrosion resistance
- High compressive strength
- heat resistance
- low impact resistance
- High vibration absorbing capacity
- crispy
- Its melt flow is good
- The melting temperature is lower than steel
- good throwing skills
- easy to manufacture
- Affordable
- heavyweight
What is gray cast iron? Gray cast iron is one of the most widely used cast irons in the industry. In the market, when you hear the word cast iron, it usually means gray cast iron. The color of this cast iron is gray due to the presence of a large amount of graphite, hence its name. This cast iron has a low cooling rate. Gray cast iron has a coarse and dark grained cross section. The properties of gray cast iron depend on the hardness of the grinding phase and the size, number and distribution of the graphite flakes. According to BS1452:1977, as the thickness of this cast iron increases, its strength decreases. What is ductile iron? Characteristics such as excellent wear resistance, low melting point, good machinability and flexibility make it an ideal specialty choice in industry. The graphite in this cast iron is spherical. 
What is white cast iron? This cast iron is white in color and has less carbon in it. Therefore, it is less flexible. On the other hand, its compressive strength and wear resistance are excellent. White cast iron cools faster than other cast irons. Therefore, most of the carbon is deposited in the form of Fe3C. This phase, called cementite, increases hardness and reduces flexibility. White cast iron is not as malleable as other cast irons. because its freezing point is higher. White cast iron is often used to make small items. The white cast iron section has fine-grained and coarse-grained grain. What is malleable iron? The soft shape, malleability and good mechanical properties are the outstanding properties of this type of cast iron. This cast iron is produced by heat treating white cast iron. In this way, the iron carbide breaks down and the free carbon is deposited in the form of powder. The characteristic of this cast iron is that most of the carbon in it is in the form of irregular balls. What is pressed graphite cast iron? The graphite in this cast iron is in the form of thick flakes. This structure makes it a cast iron between gray cast iron and ductile iron. The graphite form of this cast iron is also known as flake, pseudo-flake, dense flake, pseudo-flake and worm-like. The production process for pressed graphite cast iron is similar to that of ductile iron, and strict metallurgical control is required. By e.g. addition of alloying elements, titanium should be added so that less spherical graphite is formed. What is alloy cast iron? Since malleable cast iron and compressed graphite cast iron are not high alloys, alloy cast iron is used. 
In malleable iron, the presence of alloying elements prevents the hammering process. The life of compressed graphite cast iron is not long. Alloy cast iron is produced when wear resistance, heat resistance, and high corrosion resistance are required. They are also used in applications that require unusual properties, such as low thermal expansion and non-magnetic properties. It is often difficult to identify and specify the properties required for alloy cast iron. For this reason, they are identified by their chemical composition. Cast iron manufacturing process around the world Producing cast iron happens in many ways and the cast iron manufacturing process is very different around the world, of course, the products of them are also very different as well. It is important to note that over 95% of cast iron is iron, resulting in an incredibly high electrical resistance for this alloy. Of course, you have to keep in mind that depending on the carbon content of this alloy, the industry sees many different types of cast iron, each with their own unique characteristics and properties that can perform special roles in different tasks. industry. Today this alloy is used in many industries and many chemists are looking to produce the best and most corrosion resistant of the alloys to increase the efficiency of this alloy.
- The difference between cast iron and steel
Many people confuse this alloy with steel, or see no difference between the two alloys. Although these two alloys have very significant differences from each other, the main difference is the amount of carbon used in them. Note that the amount of carbon used in this alloy is much higher than in steel, and it is also found in the list of cast alloys. Also, this alloy is more inflexible and drier than steel, which is one of the main differences between this alloy and steel. 
One of the most important ways to distinguish steel from this alloy is to use the spark test, where if the spark length is short and its color is red. There is no doubt that the metal in question is this alloy, and if the spark is long in length and white in color, it can be concluded that the metal is steel. Other inspection methods include chip testing and observation of the surface of two metals, which require great expertise. Application of cast iron In the previous chapters we have given you many explanations about cast iron and its types, we have shown that by varying the amount of carbon used in combination with iron, you can see many different types of this product without a doubt is that each type it is used in an industry. Among the most important uses of this alloy are bridge construction, street manhole covers, pipes, machinery, vessels, gas pipes, plastering, roof trusses and decorative windows, etc. Of course, you have to keep in mind that many researchers are now looking to discover other properties of cast iron in order to increase its use and replace this material with many other metals. Compressed graphite cast iron Compressed graphite cast iron is placed between the eutectic chambers, similar to the graphite in gray cast iron, but larger and rounded at the ends, so this cast iron is called "vermicular graphite cast iron". If you add less sodium or magnesium to cast iron, you will not produce ductile iron, but pressed cast iron. When using compressed graphite to make cast iron, the graphite is not flake, and the content of spherical graphite is less than 20%. The production process of compressed graphite cast iron is very similar to that of ductile iron, requiring precise metallurgical control and the addition of rare earth elements, but the production of compressed graphite cast iron requires the presence of another alloying element such as titanium. 
to reduce the formation of spherical graphite. Compressed graphite cast iron retains the castability of gray cast iron, has high tensile strength and has a certain ductility. The background structure of this cast iron can be adjusted by adding alloying elements or by heat treatment.
- High alloy cast iron
Cast iron alloys are used in environments where oxidation, corrosion and corrosion resistance must be maintained. In this type of cast iron, the graphite can be in flake or ball form.
- Ductile Iron or Ductile Iron
In the melting process, a cast iron in which the graphite turns into spherical graphite through a series of operations is called ductile iron. Graphite cast iron is brittle (ductile) cast iron, spheroidized, which is known to be the reason for its high electrical resistance. The color of ductile iron scrap is very similar to the color of steel. In this type of cast iron, we do not always reach the ideal, they just determine the percentage of it based on the amount of spheroidization. Ductile iron was introduced at the Foundry Society convention in Philadelphia, USA in 1948 and developed in the 1950s. Finally, in the 1960s, it was widely welcomed by manufacturing companies. This cast iron is composed of 3.7% carbon, 2.5% silicon, 0.3% manganese, 0.01% sulfur, 0.01% phosphorus and 0.04% magnesium, which distinguishes it from gray cast iron and the presence of magnesium. Magnesium and sodium are used to make ductile iron, which is economical from a magnesium point of view. In order to improve and better recover magnesium, some additives of other elements are combined with it to reduce magnesium consumption and adjust its nominal value.