Cast iron or cast iron, is a type of fusion whose most common type is known as gray cast iron, which is one of the most used ferrous materials and its name is due to the appearance of its surface when it breaks. This ferrous alloy generally contains more than 2% carbon and more than 1% silicon, in addition to manganese, phosphorus, and sulfur.
A distinctive feature of gray iron is that carbon is generally found as graphite, assuming irregular shapes described as "flakes." This graphite is what gives the gray tonality to the rupture areas of the pieces made with this material. The physical and, in particular, the mechanical properties vary within wide ranges, responding to factors such as chemical composition, cooling rate after casting, size and thickness of the pieces, casting practice, heat treatment and microstructural parameters, such as; the nature of the matrix, shape and size of the graphite flakes.
A particular case is that of spheroidal graphite, which began to be used in the 1950s; Later it has displaced other types of malleable and gray iron. Among the first uses of this material were in Western Europe in 1313, specifically in the manufacture of cannons, and presumably at the same time, they were also used in the construction of pipes. Research conducted in 1455 is recorded for the first cast iron pipe that was installed in Germany at Dillenberg Castle. The manufacturing process for cast iron pipes has undergone profound modifications, from the old casting method to the modern centrifugal process.
The typical composition to obtain a graphite microstructure is 2.5 to 4% carbon and 1 to 3% silicon. Silicon plays an important role in the differentiation of gray cast iron to white cast iron; This is because silicon is a stabilizer for graphite. This means that it helps to precipitate graphite from iron carbides. Another important factor that helps the formation of graphite is the speed of solidification of the plaster.: a slow speed will tend to produce more graphite and a ferritic matrix; while a moderate speed will tend to produce a higher pearlite matrix. In order to achieve a 100% ferritic matrix, the melt must undergo an annealing heat treatment. Rapid cooling will partially or totally suppress the formation of graphite and instead lead to the formation of cementite, which is known as white mold.
