Ingot is commonly used name for the large sized castings produced in a foundry or during iron making. There are no specific standard dimensions for ingots. In steel plants, the molten metal from the blast furnace is poured into large, cylindrical laddles. So during steelmaking, ingots are usually shaped as shown below.Notice how the ingots are mounted on special ingot car. Large steel plants use internal rail lines for transporting ingots to different shops which roll these ingots into sheet or coils.

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Billet and Blooms are generally smaller in size. If the cross section of a casting is a square, it is called a billet. Billets have a cross section are of less than 36 sq. inches . Blooms have rectangular cross sections. The name Bloom comes from Bloomery. Another condition for a bloom is that the cross section must be greater than 36 sq. inches.

Ingots are very large casting products, greater in size and shape than blooms, billets and slabs. Ingot generally has rectangular/square cross section, but it is not necessary that it should be uniform through out its length. (Ingot may have variable cross section.)
 

Billet is also a casting product. In new era of industry, generally the billets are made with the help of machine called as CCM (continuous casting machine).Billet has a square cross section area , but cross section area of billet should be same throught its length. The cross section area if billet is always less than 36 in2. The Billets are used in the manufacturing process of Steel Rebars.

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