Process for Production of Compacted Graphite Iron

a graphite iron and compacted technology, applied in the field of cast iron production, can solve the problems of affecting the cooling rate of the base iron, the sulphur level of the base iron is often variable, and the structure is sensitive to the cooling rate variation

Inactive Publication Date: 2009-07-23
NOVACAST
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0016]The reduced magnesium level in the castings has also the advantage that casting defects such as dross and micro-shrinkage are minimized.

Problems solved by technology

One problem is that the sulphur level in the base iron often varies.
However, with the in-mould treatment this is practically not possible as the treatment chamber is the same in each mould.
Another problem is that treatment with magnesium makes the structure sensitive to variation in cooling rate.
However high levels of cerium can increase the risk for certain casting defects such as formation of primary carbides and shrinkages.

Method used

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  • Process for Production of Compacted Graphite Iron

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Embodiment Construction

[0006]It is an object of the present invention to solve these problems.

[0007]The invention concerns a process for production of compacted graphite iron using in-mould addition of a magnesium alloy in accordance with claim 1. Preferred embodiments are defined in the dependent claims.

[0008]The amount of cerium is adjusted in relation to the sulphur content in the base iron. The cerium level should be adjusted according to the formula:

%Cerium=(%Sulphur−0.006)* 2.9+A.

[0009]The value for A varies preferably between 0.01 and 0.03 depending on the configuration of the casting i.e. variation in section dimensions and casting modulus. As cerium has a very high boiling point (3470° C.) and a high density (6.14 g / cm3) it does not show any fading effect. By adding cerium to the base iron it can be properly dissolved and less magnesium alloy has to be added in the reaction chamber in the mould as cerium also has a structure forming effect.

[0010]The treatment alloy preferably contains 3-6% magne...

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Abstract

A process for production of compacted graphite iron using in-mould addition of a magnesium alloy is disclosed. The process is characterised by a step of pre-treating the base iron in a ladle or in a furnace with an alloy containing cerium and performing a structure forming treatment in a reaction chamber in the mould using an alloy containing magnesium and lanthanum.

Description

FIELD OF THE INVENTION[0001]The invention relates to a process for production of cast iron with a structure predominantly consisting of compacted graphite shapes. The process is based on a combination of pre-treatment of a base iron and a final treatment in the mould.BACKGROUND ART[0002]Compacted graphite iron is a cast iron alloy with a graphite structure between flake type graphite shapes and spherical shapes. The graphite shape is determined by the conditions in the liquid iron during the solidification. Treatment of a base iron, preferably with a carbon equivalent between 4.0 and 4.4 and with a sulphur content below 0.02%, with a ferrosilicon alloy containing 4-10% magnesium can be used to achieve the compacted graphite structure. The magnesium content must be kept within very narrow limits usually within + / − 0.003% and with a level of about 0.008 to 0.015% depending on conditions of the base iron and the cooling rate in the casting to be produced. As used herein percent refers ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B22D27/00
CPCB22D27/20C22C37/10C21C1/105C21C1/08C22C33/08C22C37/00
Inventor SILLEN, RUDOLF
Owner NOVACAST
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