Specific Weight of Cast Iron, Its Properties, Types and Value Table

Cast iron is an alloy of iron with carbon and other additional elements. The carbon content in cast iron must not be lower than 2.14 percent. Cast iron is a good material for producing cast parts that work under low dynamic loads and moderate stresses.

Compared with steel, cast iron has a relatively low cost and good casting properties. It is also usually easier to machine than many steels, but it welds poorly and has lower ductility and impact toughness.

Table of Specific Weight of Cast Iron

Because cast iron is a complex material, calculating its specific weight independently in field conditions is practically impossible. Such measurements are carried out in special chemical laboratories. However, its average specific weight is known: for gray cast iron it ranges from 6.6 to 7.8 g/cm³, and for white cast iron from 7.0 to 7.8 g/cm³.

For easier calculations, the table below gives values for the weight of cast iron, the specific weight of cast iron and these values depending on the units of measurement.

Properties of Cast Iron

The carbon content gives the alloy increased hardness while reducing toughness and ductility. Carbon may be present in two main forms: graphite and cementite. Cast irons contain constant impurities such as manganese, silicon, phosphorus and sulfur, and sometimes alloying elements such as nickel, aluminum, chromium, vanadium and others.

The melting point of cast iron is usually about 1150-1200 °C, depending on composition. This is roughly 300-400 °C lower than the melting point of pure iron.

Types of Cast Iron

Depending on the amount of cementite and the form of graphite, four types of cast iron are distinguished:

• White cast iron. Carbon in this type is in a bound state. This cast iron has a light fracture because of the cementite in its structure. It is divided into eutectic cast iron with about 4.3 percent carbon and hypereutectic cast iron with 4.3 to 6.67 percent carbon. This type is used, among other purposes, to produce malleable cast iron by annealing.
• Gray cast iron. This type is an alloy with about 1.2 to 3.5 percent silicon; the rest is iron and carbon, along with impurities of sulfur, manganese and phosphorus. A significant part of the carbon in gray cast iron is present as flake graphite. The material has a distinct gray fracture color.
• Malleable cast iron. This type is obtained by additional annealing of white cast iron, which forms flake-like graphite. The metal matrix is pearlite and ferrite. The name comes from its increased toughness and ductility, as well as higher strength and impact resistance. This type is used to make complex-shaped parts such as brake shoes, elbows, tees and rear axle housings for vehicles.
• Ductile cast iron. This type contains spheroidal graphite formed during crystallization. This form of graphite weakens the metal matrix less and does not concentrate stress as strongly.