RU2585912C1 - Method of producing high-strength iron with globular graphite - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly to foundry production, and can be used in production of casts of high-strength iron with globular graphite. In method, when filling ladle, in metal melt is added a mixture of calcium carbonate, barium carbonate and ferrosilicon 75 %, and treatment with spheroidising modifier is performed after filling ladle by feeding tribe-device of flux cored wire with spheroidising modifier FSMg18, wherein amount of each component of said mixture and flux cored wire is 0.12-0.15 % of weight of treated metal melt.

EFFECT: invention improves physical and mechanical properties of casts of high-strength cast iron, while achieving higher efficiency and stability of modifying effect.

1 cl, 1 tbl, 1 ex

Description

The invention relates to metallurgy, in particular to foundry, and can be used in the manufacture of castings from ductile iron with spherical graphite.

A known method of producing high-strength cast iron with spherical graphite (RF Patent No. 2134302, Bulletin of 08/10/1999).

The essence of the method consists in processing a metal of chemical composition, wt.%: C - 3.85-4.05, Si - 1.7-1.9, S <0.015 with a dust-like fraction of the FSMg-5 modifier (modifier fraction <1.5 mm ) in the bucket in the amount of 1.6-1.8% of the weight of the metal. There is also known a method of producing high-strength nodular cast iron, adopted as a prototype, including the processing of molten iron by introducing the FSMg-5 ligature modifier and ferrosilicon (RU, C1, C2 / C, 1/08, 07/15/94).

The disadvantages of these methods include the use of a modifier fraction> 1 mm, which dramatically increases the loss during screening, and also increases the consumption of the modifier when processing metal. The use of the fraction <1 mm in the prototype modifier method for producing high-strength cast iron with spherical graphite did not give stable results and, in addition, to provide the necessary Mg content ost. In cast iron, it is necessary to increase its consumption, which makes the process of modification low-tech.

The task of the invention is to increase the physical and mechanical properties of castings.

The technical result is an increase in efficiency and ensuring the stability of the modifying effect.

The specified technical result is achieved by the fact that the method of producing high-strength nodular cast iron includes the release of their furnace into a ladle of molten iron, introducing calcium carbonate and barium carbonate into the melt and 75% ferrosilicon in an amount of 0.12-0.15% each, then after filling the ladle melt is treated with a flux-cored wire modifier FSMg-18 using a tribamer in the amount of 0.12-0.15%.

The proposed method for producing high-strength cast iron with spherical graphite can improve the physical and mechanical properties of cast iron for castings (see table).

An increase in the content of components of pre-spheroidizing treatment (calcium carbonate, carbonate and ferrosilicon 75%) over 0.15% and spheroidizing modifier (powder wire modifier FSMg 18) over 0.15% leads to the appearance of residual cement in the structure, residual non-metallic inclusions.

A decrease in the content of the mentioned complexes of less than 0.12%, respectively, leads to a deterioration in the shape of graphite and the appearance of not only spherical graphite, but also vermicular, which is unacceptable for high-strength cast iron.

The effectiveness of the spheroidizing modifying treatment of the melt to produce spherical graphite increases if it is prepared to receive a spheroidizing modifier. The main methods of metallurgical preparation of the melt are: refining, inoculating and graphitizing treatments that are carried out by introducing a complex into the melt: calcium carbonate, barium carbonate and ferrosilium 75%.

An example of the method

To study the features of the method, experimental work was carried out to obtain high-strength cast iron with spherical graphite in an induction crucible made of synthetic cast iron and modifying treatments on small-capacity ladles up to 200 kg.

With the beginning of filling the bucket, a mixture is introduced into it: calcium carbonate, barium carbonate and ferrosilicon 75%.

After filling, the bucket is installed on the stand, where the flux-cored wire is introduced using a one-armed tribamer equipped with an umbrella covering the bucket to prevent metal splash and reduce heat loss.

After completion of the wire input, the metal bucket is sent to fill the molds.

Claims (1)

A method of producing ductile iron with spheroidal graphite, comprising releasing a melt from a furnace into a ladle and treating the melt in a ladle with a spheroidizing modifier, characterized in that when filling the ladle, a mixture of calcium carbonate, barium carbonate and ferrosilicon 75% is introduced into the melt, and the spheroidizing modifier is processed after filling the bucket by feeding a flux-cored wire with a spheroidizing FSMg18 modifier, the amount of each component of the mixture and powder th wire is 0.12-0.15% of the weight of the processed metal melt.