BY-Cast Products

Physical characteristics of cast iron

Cast iron click picture

DEKA Cast iron exists as a metal matrix containing a proportion of free (uncombined) carbon.

The matrix normally has a perlitic structure giving the material similar mechanical characteristics to steel containing +/- 0,9% carbon.

The free carbon is present in the form of very thin plates or lamellae. This free carbon is inert to most compounds which attack metals.

 

The structure and composition outlined above give cast iron the following properties:

  1. Cast iron has an elasticity comparable with spring steel.  E.g. Piston sealing rings in gasoline and diesel engines are normally made of cast iron.
  2. The elasticity is stable against time and is retained up to relatively high temperatures.
  3. Cast iron has excellent resistance to corrosion over a wide range of operating environments.  Initially the surface will slightly rust but the rusting is then practically arrested at the carbon lamellae.  The corrosion resistance of cast iron is much better than that of steel, including most stainless steels.  Stoves and fire grates if made of carbon steel would be burned out in a fraction of the lifetime of cast iron.  Uncoated cast iron pipelines for drinking water supply have an almost indefinite life.  There are many other examples of the durability of cast iron in the chemical and process industries.
  4. The resistance of cast iron to erosion is well-known.  In pneumatic handling and drying systems for abrasive powders cast iron liners are frequently fitted inside ducts to protect the steel duct from excessive wear.

In light of these properties it must be anticipated that an airpreheater with cast iron tubes will have a much longer service life than one with steel elements operating under identical conditions, even if the cast iron and steel elements were initially of equal thickness.