Cast Iron: The Important Elements and Derived Versatility
What is metal cast iron? Cast iron is a generic term for a high carbon, high silicon and iron alloy. It is similar to steel in strength, wear resistance, response to heat treatment and machinability, which are affected by the amount of carbon in solution with iron. Strength and wear resistance increases with the amount of combined carbon and as a result, machinability generally decreases.
The high content of carbon and silicon in cast iron gives them excellent fluidity and malleability. Their melting points are significantly lower than those of steel. Molten steel is less fluid than molten iron and is less reactive. Formation of lower density graphite during solidification makes it possible to produce complex shapes.
In today's competitive market place, there is persistent pressure to reduce prices and improve productivity. For example, Waupaca foundry offers high quality iron casting solutions which design engineers need to make longer lasting components. The use of more resistant materials though often means, increased manufacturing cost. Cast iron can be an excellent alternative to steel, offering a balance of mechanical properties, such as, durability and workability.
One of the main gains provided by cast iron constituents, is their capability to incorporate many design structures that often must be used as ingredients in other manufacturing techniques. As a result, a cost saving effect in manufacturing processes such as machining, can be realized if the proper design and manufacturing processes are understood and followed during the component’s formation and primary development.
Several factors can influence the tool life when machining iron. These include conditions such as: the size and distribution of graphite, the composition of ferrite, the cooling rate from the eutectic through the eutectoid temperature, and the presence of inclusions either endogenous or exogenous.
Some definitions associated with cast iron:
Gray cast iron: It is a hyper saturated carbon solution in a middle iron. Grey iron or Grey Iron Castings are made of a cast iron group forming flake graphite during solidification, compared with the spheroidal graphite morphology of ductile cast irons. In terms of composition, gray cast irons generally contain 2.5 to 4% Carbon, 1 to 3% Silicon, and manganese additions. Other alloying elements include chromium, copper, and nickel.
Ductile iron: also known as nodular iron contains magnesium traits, which then reacts with oxygen and sulfur in the molten iron. As a result, carbon precipitates.
White iron: It is a result of "chilling" selected areas of a casting in mould, thus preventing (graphitic) carbon leak out.
Regarding industrial pollution, improvements have been achieved in the industry regarding the major polluting substances, and that gradually, the environmental impact has changed for calls diffuse sources of pollution.
Fact is, as the major energy consuming sectors and pollutants, energy saving issues have raised concerns. Energy conservation and Industrial Waste Reduction are strongly related to the survival and development of the industry. That being said, the best option is to implement the ‘3R principle’ which is and is to Reduce, Reuse and Recycle.