What are the common types of cast iron produced by sand casting

Cast iron is a general term for a series of alloys mainly composed of iron, carbon, and silicon. In these alloys, the carbon content exceeds the amount that can be retained by austenite solid solution at eutectic temperature, and the carbon content of industrial and household cast iron is usually 2.5% -4.0%. Cast iron is made by reasonable proportioning and melting of new iron, scrap iron, recycled iron, ferroalloys, and other metal furnace materials. Its main component is iron, and it also contains small amounts of carbon, silicon, manganese, phosphorus, and sulfur, and may contain other alloying elements as needed. Let's take a look at several common types of cast iron.

Gray cast iron:

 Cast iron with carbon content mainly in the form of flake graphite, with a gray fracture surface and a matrix of ferrite, pearlite, and pearlite+ferrite. Gray cast iron from iron manufacturers has certain strength, good shock absorption, wear resistance, excellent machinability and casting processability, simple production, low cost, and is widely used in industrial production and civilian life.

Nurturing cast iron: still belonging to the category of gray cast iron, it is a hypoeutectic gray cast iron obtained after the inoculation of molten iron. The carbon that nurtures cast iron mainly appears in the form of flake graphite, with pearlite and ferrite as the matrix. The tensile strength and bending strength of cast iron can reach 200-400Mpa and 450-600Mpa, but its elongation and impact toughness are still relatively low. Therefore, it is commonly used in important castings with low dynamic loads and high static strength requirements, such as machine tool beds and engine cylinder blocks.

Ductile iron: 

It is cast iron that uses spheroidizing agents instead of heat treatment to treat molten iron, making most or all of the graphite spherical, and sometimes a small amount flocculent. However, after a certain heat treatment by the cast iron manufacturer, the matrix morphology of ductile iron will change. The matrix forms of ductile iron include ferrite, pearlite, ferrite with pearlite, bainite, and austenite with bainite. Ductile iron from cast iron manufacturers is a new type of structural material developed in the late 1940s. In addition to good shock absorption, wear resistance, machinability, and casting technology, it also has much higher strength, plasticity, and toughness than ordinary gray cast iron. Its tensile strength can reach 1200-1450Mpa, elongation can reach 17%, and impact value can reach 60J/cm2. Therefore, it has been used in production with complex stress and strength.

Creep graphite cast iron:

 It is a cast iron made by a cast iron manufacturer that has undergone creep treatment on molten iron, with creep graphite as the majority of the graphite. The matrix form of vermicular cast iron is ferrite, pearlite, or a combination of ferrite and pearlite. Creep graphite cast iron is a new type of cast iron material developed in the 1960s, with a tensile strength of up to 500Mpa, higher than gray cast iron, and better casting performance than ductile iron, with good thermal conductivity. Therefore, it has been used in the production of diesel engine cylinder heads, motor housings, transmission boxes, brake drums, hydraulic valve bodies, metallurgical ingot molds, etc.

Non magnetic cast iron:

 It is a type of cast iron with low magnetic permeability. The matrix used by cast iron manufacturers is austenitic, commonly referred to as austenitic cast iron, which can be divided into flake graphite austenitic cast iron and spherical graphite austenitic cast iron. It is mainly used for oil switch covers, transformer tail boxes, motor clamps, magnet brackets, submarine parts, etc.

In addition, sand casting technology includes processes such as molding, melting, pouring, insulation and cooling, and sand recycling. The core process is sand molding, and the quality of the molding directly determines the quality of the product. Sand molding is divided into manual molding and automated equipment molding. In the 21st century, automated molding gradually eliminates manual molding. Automated molding can effectively improve production efficiency and enhance the quality of casting production. In the article "Four Development Processes of Automatic Casting Molding Machines", you can learn about the development of sand casting molding machines in casting factories. The automatic green sand casting molding machine adopts horizontal parting, fully automated production, easy to use, and saves labor.