What is the difference between cast iron and cast steel? from jiachuan's blog

Both cast iron and cast steel are Fe-C alloys. Due to the different contents of chemical elements such as carbon, silicon, manganese, phosphorus, and sulfur, they have different metallographic structures and exhibit many different mechanical properties and castability. It is generally believed that the carbon content of more than 2% is cast iron, and the carbon content of 0.1-0.5% is cast steel. Let's take a look at the differences between steel castings and iron castings according to their classification and applications.

cast iron

Grey cast iron. High carbon content (2.7% to 4.0%). Gray cast iron is the most widely used cast iron containing flake graphite (accounting for more than 80% of the total output of cast iron). Carbon is mainly flake graphite, gray, low melting point (1145 ~ 1250 ℃), small solidification shrinkage, compressive strength and hardness close to carbon steel, good shock absorption, used to manufacture machine bed, cylinder, box, etc. Structure.

Compacted graphite cast iron. It is obtained from grey cast iron treated with worms. The precipitated graphite is worm-like, between flakes and spheroids. Its chemical structure is similar to that of gray cast iron, its mechanical properties are similar to that of cast iron, and its castability is between gray cast iron and ductile iron.

Can be used to manufacture auto parts.

Ductile iron. The ductile iron obtained by spheroidization and inoculation to form gray cast iron water is called ductile iron. It has higher strength, better toughness and plasticity than ordinary gray cast iron.

Used in the manufacture of internal combustion engines, auto parts and agricultural machinery.

cast steel

Cast steel is an iron-carbon alloy with a carbon content below 2.11%. Cast steel has good comprehensive properties, weldability and workability, but compared with cast iron, its vibration absorption and casting properties are poor. Cast steel can be divided into cast carbon steel, cast low alloy steel and cast special steel according to chemical element composition.

Cast carbon steel. Cast steel with carbon as the main alloying element and small amounts of other elements. It can be divided into cast low carbon steel (with carbon content less than 0.2%), cast medium carbon steel (with carbon content of 0.2% to 0.5%), and cast high carbon steel (with carbon content greater than 0.5%). Its strength and hardness increase with increasing carbon content. Cast carbon steel has high strength, plasticity and toughness, and is low in cost. It is used in heavy machinery to produce parts with large loads, such as rolling mill stands, hydraulic press bases; manufacturing pillows, side frames, wheels and couplings on railway vehicles. Heavy-duty impact bearing parts such as shafts.

Cast low alloy steel. Cast steel containing manganese, chromium, copper and other alloying elements (total less than 5%). It has greater impact toughness and better mechanical properties can be obtained by heat treatment. Casting low alloy steel has better performance than carbon steel, which can reduce the quality of parts and increase the service life.

Cast special steel. Alloy cast steel refined for special needs. It usually contains a large amount of one or more alloying elements to obtain specific properties. For example, high manganese steel containing 11% to 14% manganese can withstand impact wear and is mostly used for wear-resistant parts of mining machinery and construction machinery; various stainless steels with chromium or chromium-nickel as the main alloying elements are used for valves in large-capacity power plants. Parts that are easy to corrode or work at high temperatures above 650°C, such as bodies, pumps, containers or turbine casings. chemical industry.

Generally speaking, cast iron has lower elongation, shrinkage and impact toughness than cast steel, and its compressive strength and shock resistance are also better than cast steel; cast iron is generally cheaper, while raw steel is more expensive because of material cost, energy and higher cost. The labor required to produce the final product. The main advantage of cast steel is design flexibility, which makes it ideal for parts with complex shapes and hollow cross-sections. They each have advantages and disadvantages, so the choice should be based on the application and its physical properties.