SU514036A1 - Cast iron - Google Patents

Description

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The invention relates to metallurgy, in particular to the production of cast iron for centrifugal casting.

Cast irons are known, which include carbon, silicon and manganese with the addition of various elements. The composition of cast iron is largely determined by the requirements imposed on the methods of making castings. So, for centrifugal casting of pipes into water-cooled metal forms, a high rate of metal crystallization and the associated formation of excessive surface chill is characteristic. To prevent such bleaching, expensive cast irons with a high silicon content are used.

Known cast iron following chemical composition, weight. %:

Carbon2.5-3.9

Silicon2.0-2.8

Manganese 0.2-0.6

Calcium 2.0-4.0

Best Else

Cast iron has the following properties:

Tensile strength at break,

kg / mm 16

Flexural Strength

kg / mm 52

Hardness IV, kg / mm 225

Cast iron

when the calcium content is 0.1 n

% has a modulus of ring strength of 0.3 weight. pipes 45 kg / mm.

The disadvantage of the famous cast iron

is a low modulus of ring strength.

The proposed cast iron differs from the known one in that it additionally contains boron in the following ratio of components, weight. %:

Carbon2.8-3.8

Silicon1,6-2,6

Manganese 0.5-1.0

Calcium0.05-0.1

Bor0,01-0,05

IronErest

This makes it possible to increase the modulus of ring strength.

From cast iron of the specified composition, the pipes with a diameter of 150mm are cast by a centrifugal method. The module of ring strength of pipes is 48-51 kg / mm.

Claims (1)

The proposed cast iron contains the usual amount of silicon and manganese and the optimum, in terms of tube quality, amounts of boron and calcium. Boron combines with nitrogen dissolved in liquid iron, as a result of which boron nitrides arise in the melt, the lattice of which has crystallographic and orientational correspondence with the graphite grit; due to this, boron nitrides serve as isomorphic underlays for growing graphite and improve metal graphitization. At the same time, calcium binds oxygen and sulfur adsorbed on graphite nuclei, and thereby ensures the growth of graphite of a more compact form, which also improves the mechanical properties of the metal. Claims of the invention: Cast iron containing carbon, silicon, manganese, calcium and iron, characterized in order to increase the ring-ring modulus, it also contains the following ratio of components. : Carbon 2.8-3.8 Silicon 1.6-2.6 Manganese 0.5-1.0 Calcium 0.05-0.1 0.01-0.05 Iron Else