Each of these types of pig iron is available with a range of carbon and silicon contents, and the iron- founder is able to select the particular analysis most e suitable for his needs. Normally, if a high carbon pig g iron is required, the silicon content tends to be at the s, lower end of the silicon range, and vice versa. In all es types the sulphur content is low, at 0.05 per cent maximum. The composition of a pig iron should normally be known with certainty, since a certificate ng of analysis is nearly always available with each in delivery eir iron generally constitutes between 10 and 30 gh- per cent of the cupola charge, exact amount ow- de per ling upon the type of iron to be produced. The rro- main benefits from using pig iron are: 1. To provide carbon in conjunction with other metallic materials so that, with the carbon pick-up obtained in the cupola, metal of the correct carbon content can be tapped To provide, as far as possible, the necessary 9:43 06/10/20
2. To provide, as far as possible, the necessary amount of silicon in the charge, avoiding the need for excessive use of ferrosilicon. 3. To reduce the charged sulphur content and prevent the sulphur content of the tapped metal from rising to a dangerous level. 4. To ensure that the required maximum phosphorus content of the charge is not exceeded, taking into account the phosphorus contents of the returned and bought cast iron scrap that may also be in the charge The only disadvantage of using pig iron is that it is expensive, and it should therefore be used as econo- mically as possible. Refined irons are the second source of high carbon materials. They are generally produced in cupolas or electric furnaces from charges containing 50 per cent or more of steel scrap, the remainder of the charge consisting of either pig iron or suitable cast iron scrap. The composition of these irons tends to be similar to that of low-phosphorus pig iron in that the sulphur content is less than 0.05 per cent and the phosphorus content is between 0.1 and 0.2 per cent They can differ slightly from blast-furnace low. phosphorus pig irons in that carbon contents as low as 2.05 per cent can be obtained, and they may be alloyed with other elements, such as chromium and
K1 Visualizador de fotos de Windows Imprimir Correo electrónico Grabar Abrir carbon materials. They are generally produced in cupolas or electric furnaces from charges containing 50 per cent or more of steel scrap, the remainder of the charge consisting of either pig iron or suitable cast iron scrap. The composition of these irons tends to be similar to that of low phosphorus pig iron in that the r sulphur content is less thaiT 0.05 per cent and the phosphorus content is between 0.1 and 0.2 per cent. They can differ slightly from blast-fumace low- phosphorus pig irons in that carbon contents as low as 2.6 per cent can be obtained, and they may be alloyed with other elements, such as chromium and nickel. Refined irons tend to be as expensive as blast n furnace pig irons and, thus, should be used as econo- mically as possible. However, by the use of refined irons, some foundries having only modest technical control are able to produce high duty irons. As with ig iron, a certificate of analysis is nearly always available from the supplier with each delivery Medium-carbon materials Cast iron scrap provides a wide range of medium
